The direction may have wandered from using a different controller and expecting that to solve the problem to looking at the cause of the problem in the first place. Always better to fix the cause than attempt to cover it up. Insufficient solar harvest to cover the loads is a symptom, excess draw from the fridge appears to be the major cause of the problem. This means either the symptom is treated by increasing the total solar harvest area available, or the cause is treated so the harvest available now will be sufficient.
Its got to be remembered that those with a three way fridge don't have this problem, they are running the fridge on gas, and even if the batteries are completely flat, they can use a torch at night, and the fridge is still running. We however are totally dependant on 12v.
More solar is probably the easiest over all, but that still doesn't sort the fridge in hot conditions not coping problem. That one is a lot more difficult. The fridge problem is based on a fridge design that could not do the required job much above 32*C. The engineers that designed it consider that to be an extreme temperature and that is common belief among engineers outside Australia. You might be able to improve the sub standard insulation if the fridge has an external condenser grille/radiator, but if it is inside the walls of the fridge like modern refrigerators that will stop the thing from being able to reject the heat it is attempting to pull out of the cabinet. The major problem is the whole design is under sized, the evaporator can not absorb enough heat from inside the cabinet, the condenser can not eject enough of the heat and the compressor is not up to the job.
I think the above statement hits the nail on the head. Even though it is rated tropical, it appears it cannot handle extreme temperatures.
The first thing is to ensure the fridge has the best operating conditions available, like a pathway for the heat to exit above the fridge. Ideally this would be through the roof, but if this is not possible then the outside vent must be above the top of the fridge and it must have fan assistance to pull the hot air outside and away from the fridge cabinet. The next thing is to ensure there is a path for cold air to enter all around the base of the fridge so it can carry the heat away and outside. This path needs to include the walls of the fridge because you need to keep them cool no matter what insulation is used. Much easier to not have the heat there trying to enter the fridge than adding layers to slow its enter.
It is installed as per the manual, it is vented via the roof. But it looks like the compressor assy came out of a portable chest type freezer, so the fan and condenser are facing north south, not vertically as in another post (shoddy workmanship).
The long term fix is to use a fridge/freezer that was designed for Australia's harsh climate and extensively tested to make sure it is up to the task. The Australian standards offer this proof of performance and will only award those models that can pass the test. There are no low voltage fridges with these Australian standards certification that I know of, but I'd be happy to be corrected if I have that wrong. All 240vac household fridges with a star rating have had to pass this test first. Ask anyone who has installed an inverter technology household fridge and see what they think of it, the cost surprisingly low compared to a low voltage unit and the energy use is better than the low voltage units.
T1 Terry
As for the fridge, one idea I have been thinking about, but not really serious about at the moment, is that with extreme temperatures we would probably be holed up in a caravan park. Now we were in a park when Adelaide had a heat wave and our thermometer under the awning was at 48 degrees. The air con would be going, it is possible with a bit of re-work to build a bypass of the compressor cooling air from inside the van. The top vent is there, it has two vents at the top, and just opening a cupboard door and mounting a van in the floor, this would circulate air cooled by the air con behind the fridge.
However two overcast days and our power is way down. Will see how the batteries have charged by the end of the day.
Whenarewethere said
01:26 PM Mar 9, 2019
To be clear, the fridge has a seperate condenser with a fan, rather than the walls of the fridge dissipating heat. If so it would be better to add insulation to the fridge.
Replacing the condenser fan with a higher pressure fan or adding a second fan to push more air through the condenser.
Add a baffle around the condenser so no air is simply recirculating behind the fridge. I had this design fault in my esky so I added a baffle. The air is pushed & or pulled through the condenser at higher pressure & can only go outside. Killing 2 birds with one stone.
iana said
10:15 AM Mar 10, 2019
Today, overcast as was yesterday, and the day before. 12 - 12.4V coming in from the panels at 2.4A. How can this charge a battery, if I had a MPPT controller the voltage would be 36v wired in series. House batteries well down, will see how they are by the end of the day.
Extraordinary Rendition said
02:40 PM Mar 10, 2019
Electronics isn't that difficult to understand. Wading through the waffle and missinformation will consume far more time than informing yourself of the Theory that engineers (such as the one you will become once you have trained yourself) will use to design a system that will provide satisfaction.
DeBe said
06:17 PM Mar 10, 2019
Here in SA the last 2 days have had very overcast days, My 160W solar panel struggled to put out 2A at 12.6V at the battery. If theres not enough sun then you are not going to get mutch out of a solar system. They don't perform the imposible.
Jaahn said
07:44 PM Mar 10, 2019
iana wrote:
Today, overcast as was yesterday, and the day before. 12 - 12.4V coming in from the panels at 2.4A. How can this charge a battery, if I had a MPPT controller the voltage would be 36v wired in series. House batteries well down, will see how they are by the end of the day.
Iana
I do not believe that a MPPT controller will get much more out of your panels under the same conditions. You are currently getting 29Watts out of your three panels. If you can get more by them in series I would be surprised. But say you get 50% more because the voltage is higher for charging, that is only 3.6A. No magic answer.
As DeBE says his 160W panel is only putting out 28W. If there is not enough sun then there is not enough power and juggling it will only tinker around the edges. I use my MH engine alternator as my emergency topup if needed.
Good luck. Jaahn
Whenarewethere said
09:08 PM Mar 10, 2019
2.4amps is not much, but it depends how overcast it is. You are not going to get miracles with MPPT.
Have you tested the amps individually on the 3 panels.
T1 Terry said
02:16 PM Mar 12, 2019
iana wrote:
Today, overcast as was yesterday, and the day before. 12 - 12.4V coming in from the panels at 2.4A. How can this charge a battery, if I had a MPPT controller the voltage would be 36v wired in series. House batteries well down, will see how they are by the end of the day.
The 12.4v would be very close to the battery voltage because the panels are connected to the battery via the PWM controller. The 2.4 amps says they are charging your battery. The fact 3 x 12v = 36v isn't anything to do with the ability to charge the battery, current flow is the bit that charges the battery and this is the amps part of the measurement. If each panel is putting out the same amount that would mean you were getting 0.8 amps from each panel. It must have been very heavily overcast to cause that, but are you sure you had absolutely no shadow over any part of any one of the panels? Even the shadow from an overhead power line or from a radio aerial will reduce the output from any panel it touches to virtually zero. Shade on a bit of one panel and the other 2 panels may have actually put out 1.2 amps each.
T1 Terry
swamp said
12:56 PM Mar 22, 2019
hi
Iana
The difference between series and parallel is voltage drop efficiency. The series system is least effected .
BUT
A small physical sized parallel system can get good efficiency if large cables are used . The increased cable size xtra cost is minimal.
A parallel system will tolerate shade far better .
My experience is with 400w MPPT . The system gets a boost of 13--15% in amperage when system operating normally. When the batteries are greater than 30% flat amperage boost goes up to 25-30%. All this tested in Nth Qld sun in hot weather eg 30deg cel .
If chasing Mppt a Projecta IDC45 would have worked . I prefer Mppt because roofing area on van is limited/fixed so to get more amps mppt is the only way . 450watt 24.5 amp system mppt at 20%= xtra 4.8 amps ,, 30%= xtra 7.2 amps
Additional amps = approx. and extra 120watt panel
There always is a portable 150-200 watt set
iana said
01:36 PM Mar 22, 2019
At the moment, going on advice given, I am staying with the PWT controller and looking at setting up a portable 200w panel. This I will use to charge the van and or the ute. aux. At the moment we are for about 9 days totally on solar, and have been running for about 6 weeks on solar with 240 available if required.
Just so happens we are holed up on kangaroo island, sunshine variable. I am wondering if part of the problem we have is voltage drop to the fridge, and of course the wiring is not easilly accessible to take a measurement. If the fridge motor, even though it runs on lower voltage is not driving the compressor as it should, then this would account for the erratic run times we are having.
denmonkey said
03:12 PM Mar 22, 2019
Why not take the panels and controller out of the equation for a test.
Hook up a constant 12v source and see what happens then.
power it from near the battery and another test right at the fridge.
This will at least help you narrow it down a little.
cheers Brett
T1 Terry said
11:48 AM Apr 3, 2019
iana wrote:
At the moment, going on advice given, I am staying with the PWT controller and looking at setting up a portable 200w panel. This I will use to charge the van and or the ute. aux. At the moment we are for about 9 days totally on solar, and have been running for about 6 weeks on solar with 240 available if required.
Just so happens we are holed up on kangaroo island, sunshine variable. I am wondering if part of the problem we have is voltage drop to the fridge, and of course the wiring is not easilly accessible to take a measurement. If the fridge motor, even though it runs on lower voltage is not driving the compressor as it should, then this would account for the erratic run times we are having.
An alternate method of improving the wiring to the fridge is to use a heavier cable from the battery to behind the fridge and add a suitable relay. You can then use the original wiring to drive a relay so all the control part operates the same but the relay can switch full battery power direct to the fridge via the heavier cable.
T1 Terry
iana said
06:42 PM Apr 3, 2019
OK exiting Kangaroo island tomorrow, been existing for the last week on 100% solar, no TV and sitting in the dark as our voltage gets below 12v. Where we were staying, the owner just happened to be the solar installer for that area of the island. he had a look at the system and said all the wiring for the panels is good re wire size etc, but said that I had to change to a Mppt controller. I had way to many things on the roof causing shadows, plus this time of the year when the sun is getting low, more shadows from trees. So all is arranged to get a new controller, wiring is all straight forward.
Measured the voltage drop to the fridge, and it was for the length of wire bugger all, not worth worrying over. Terry our fridge is only 12volt, so it is wired direct to the Setec controller. No relays required. However I may end up putting a relay in the water pump circuit, the cable length to and from the Drifter panel when the pump is running makes some of the lights flicker, by using that circuit to energise a control relay, and taking the pump feed direct from the battery will fix that, but that is on my future to-do list, not for now.
I pick up the Mppt GSL 60 watt regulator when I am in Adelaide, will post the results when I have installed.
T1 Terry said
11:48 AM Apr 4, 2019
It will be interesting to hear what you think of the GSL MPPT controller, but please use ##$$$@@** type symbols to replace the words you really want to say :lol: I have a collection of these things in the scrap bits bin but granted, they were early versions, so hopefully they have upped their game.
T1 Terry
Ron-D said
09:56 AM Apr 5, 2019
Terry You seem to be on a campaign to convince people that mppt controllers are no good ,everything I have seen on other forums and read seem to indicate thats absolutely ridiculous,there a few of us that travel together that have changed to Victron mppt controllers and the difference in charging the batteries is amazing, I cant argue with you because Iam no electrical guru but seeing is believing and you bagging mppt can only be impressing ,as peter has stated your true believers,you fit lithium batteries thats something I hnow nothing about ,but I wonder about your knowledge as far as lead acid batteries in caravans go,with our experience comparing the two, mppt has made a massive power gain,and to switch back would Be stupidity at the highest level...
-- Edited by Ron-D on Friday 5th of April 2019 10:09:04 AM
T1 Terry said
11:31 AM Apr 5, 2019
Ron-D wrote:
Terry You seem to be on a campaign to convince people that mppt controllers are no good ,everything I have seen on other forums and read seem to indicate thats absolutely ridiculous,there a few of us that travel together that have changed to Victron mppt controllers and the difference in charging the batteries is amazing, I cant argue with you because Iam no electrical guru but seeing is believing and you bagging mppt can only be impressing ,as peter has stated your true believers,you fit lithium batteries thats something I hnow nothing about ,but I wonder about your knowledge as far as lead acid batteries in caravans go,with our experience comparing the two, mppt has made a massive power gain,and to switch back would Be stupidity at the highest level...
-- Edited by Ron-D on Friday 5th of April 2019 10:09:04 AM
Must be quite a few stupid yet happy campers out there then Ron. If you can link all the panels in series and remain below the maximum voltage of the controller and you have long cable runs, go for it, MPPT will work better than a PWM controller in this configuration.
If you are using solar panels with a much higher Vmp than required by the battery for end of charge voltage in hot conditions, then MPPT will work better than a PWM controller.
If you have sensibly balance between solar Vmp to required max battery voltage and have used the correct size wiring, connecting the panels in parallel will work better with a PWM controller than with an MPPT controller. Rewiring the solar into a series string yet the cabling is heavy enough for a parallel connection will result is less output than a quality PWM controller can extract from the solar array.
If you swap out a PWM controller for an MPPT controller but still connect a well match Vmp to required battery voltage array of panels in parallel, yet get a better result, either the PWM controller was crap or there is series problems with your wiring.
Logic applies, forget any goobldy goop sales nonsense. An MPPT controller requires more of the harvested solar power to function than a quality PWM controller. If you have the system already set up to run at its optimum on a PWM controller then logically the energy lost as heat through an MPPT controller is energy you do not have for battery charging.
T1 Terry
iana said
12:09 PM Apr 5, 2019
Oh dear, here we go again!.
I can say that in our van we do have long cable lengths between panels installed by Jayco, and expanded foamed in place within the roof. So the cable lengths would be 2 x 3m lengths, which I understand is really 2 x 6m lengths, and 1 x at least 8m (16m length).
Heat is a concern, as the regulator has a built in fan, the comartment which can take the regulator is sealed, so I need to have air supply in and out.
It is very difficult to work out what to do as there are so many conflicting opinions. But on that note I am not saying anybody is wrong in what they are saying.
I have noticed that in our case the power problems begin when the batteries don't get a full charge each day, and the charger is only playing catch-up, i.e. the batteries don't get the 14 volt charge to finish off. From there its a down hill ride.
But I have concluded that if one really wants a low energy, solar powered van, you need to start from the wheels up. So many things need to be changed to make the grade. I am also talking about water use as well here.
Ron-D said
08:59 AM Apr 6, 2019
Terry our systems are just 160 watt portable panels and a single conventional battery ,as sure as night follows day the different between mppt and pwm is amazing ,you Have lithium batteries which are lighter and much easier to charge maybe even a lower spec regulator can produce good results,maybe the way you rig things is more suitable to pwm ,but with a conventional battery and a portable panel that lots of campers use,our mppt puts considerably more into the battery,seeing is believing we have tried both types of reg,I am being absolutely truthfull here I dont have anything to sell it does not matter to me what people use,our basic systems does everything we need very well,and beyond a shadow of a doubt pwn was very ordinary with its charge rate compared to mppt,with the fridge on gas a 120 amp battery thats all We have ever needed to freecamp,money is not the issue with us why waste it on things you dont need...
-- Edited by Ron-D on Saturday 6th of April 2019 09:13:08 AM
T1 Terry said
12:53 PM Apr 6, 2019
Ron-D wrote:
Terry our systems are just 160 watt portable panels and a single conventional battery ,as sure as night follows day the different between mppt and pwm is amazing ,you Have lithium batteries which are lighter and much easier to charge maybe even a lower spec regulator can produce good results,maybe the way you rig things is more suitable to pwm ,but with a conventional battery and a portable panel that lots of campers use,our mppt puts considerably more into the battery,seeing is believing we have tried both types of reg,I am being absolutely truthfull here I dont have anything to sell it does not matter to me what people use,our basic systems does everything we need very well,and beyond a shadow of a doubt pwn was very ordinary with its charge rate compared to mppt,with the fridge on gas a 120 amp battery thats all We have ever needed to freecamp,money is not the issue with us why waste it on things you dont need...
-- Edited by Ron-D on Saturday 6th of April 2019 09:13:08 AM
But are you the average RV traveller? In your case the long cable run from the position the portable panels are sited back to the house battery would suit high voltage/low current from the panels to the MPPT controller mounted close to the battery. The controller can then convert the high voltage/low current to low voltage high current and the set would be superior to a PWM if the long cable run was not heavy cable.
An example using your set up, distance from panels back to the van is 10mtrs, the absolute max output from the panels is 14 amps and the Vmp is 16v ) a hot 12v nom. panel with a name plate 18v Vmp)
This is the result using 6 B&S cable for the 10 mtr run. Voltage drop is 0.36v and the voltage @14 amps input to the PWM controller would be 15.64v, plenty to bring a 12v lead acid battery up to fully charged in an acceptable time frame.
This is the result using 6mm auto cable, 1.16v drop and now only 14.8v @ 14 amps. No room for any further losses and the voltage differential is so low the battery charging would be low/slow.
Now let's look at joining two x 80w 12v panels in series, the voltage is doubled and the amps halved, 0.58voltage drop and 31.42v @ 7 amps available at the controller
If a PWM controller was used with this same set up and 6mm auto cable run, there would only be 7 amps max available to charge the battery.
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy, 220w - 10% = 198w divided by 14.8v = 13.37 amps.
Yes, you get more battery charging current available out of the smaller diameter cable run (6mm auto cable) but less than the same set up using 6 B&S cable and a PWM controller that does not convert any of the electrical energy to heat. This is not actually correct, there are some losses through the transistor in the PWM controller, but very little, maybe 0.25% of the total throughput, a rounding error rather than a noticeable loss.
Did that help explain what I'm trying to convey?
T1 Terry
markf said
02:03 PM Apr 6, 2019
T1 Terry wrote:
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy,
T1 Terry
I call BS on the 10% loss figure.
A bit of rudimentary research will reveal that there are very, very few MPPT regulators on the market with claimed efficiencies less that 95% with most being 97 or 98%. Victron for example claim peak efficiency of 98% for their SmartSolar MPPT 100/20.
Over the last three weeks I've done a bit of experimenting with PWM and MPPT controllers and have proven, for my case, that a quality, name brand, MPPT controller easily trumps a quality PWM controller from the same manufacturer.
-- Edited by markf on Saturday 6th of April 2019 02:04:03 PM
Whenarewethere said
02:18 PM Apr 6, 2019
Ron-D wrote:
160 watt portable panels and a single conventional battery.....
.....with the fridge on gas a 120 amp battery thats all We have ever needed.....
I have made my fridge so efficient that 120 watts of solar with MPPT is sucking the life out of the sun!
I also use my setup to charge cameras & mobiles, & fan for hot nights & charge a 4 Olight torches when needed.
Have also made the mobile charge quicker adding some heatsinks.
A bit more battery capacity would be nice but up till today have never been short of resources, even pumping up tyres at a 100amps when too lazy to lift the bonnet!
I had less than zero experience on solar a year ago, life is too short to waste pointless effort, put in MPPT & get it right the first time, have a beer & procrastinate!
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy,
T1 Terry
I call BS on the 10% loss figure.
A bit of rudimentary research will reveal that there are very, very few MPPT regulators on the market with claimed efficiencies less that 95% with most being 97 or 98%. Victron for example claim peak efficiency of 98% for their SmartSolar MPPT 100/20.
Over the last three weeks I've done a bit of experimenting with PWM and MPPT controllers and have proven, for my case, that a quality, name brand, MPPT controller easily trumps a quality PWM controller from the same manufacturer.
-- Edited by markf on Saturday 6th of April 2019 02:04:03 PM
All in how the manufacturer writes the spin, have a look at this chart from a well known MPPT manufacturer and you will see how the 98% claim can be made, then what the reality is
Now add in the difference between the perfect voltage compared to the voltage chosen by the controller, the output loss while the controller determines the actual battery voltage and what it decides is the optimum panel voltage that suits the controller .... I think you will find 10% is being generous.
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy,
T1 Terry
I call BS on the 10% loss figure.
A bit of rudimentary research will reveal that there are very, very few MPPT regulators on the market with claimed efficiencies less that 95% with most being 97 or 98%. Victron for example claim peak efficiency of 98% for their SmartSolar MPPT 100/20.
Over the last three weeks I've done a bit of experimenting with PWM and MPPT controllers and have proven, for my case, that a quality, name brand, MPPT controller easily trumps a quality PWM controller from the same manufacturer.
-- Edited by markf on Saturday 6th of April 2019 02:04:03 PM
All in how the manufacturer writes the spin, have a look at this chart from a well known MPPT manufacturer and you will see how the 98% claim can be made, then what the reality is
Now add in the difference between the perfect voltage compared to the voltage chosen by the controller, the output loss while the controller determines the actual battery voltage and what it decides is the optimum panel voltage that suits the controller .... I think you will find 10% is being generous.
T1 Terry
Perhaps you should restudy those curves
Especially the ones for13V & 16.5V peak power point.& a battery at 12'8V
Both over 95%
oldtrack123 said
02:57 PM Apr 16, 2019
markf wrote:
T1 Terry wrote:
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy,
T1 Terry
I call BS on the 10% loss figure.
A bit of rudimentary research will reveal that there are very, very few MPPT regulators on the market with claimed efficiencies less that 95% with most being 97 or 98%. Victron for example claim peak efficiency of 98% for their SmartSolar MPPT 100/20.
Over the last three weeks I've done a bit of experimenting with PWM and MPPT controllers and have proven, for my case, that a quality, name brand, MPPT controller easily trumps a quality PWM controller from the same manufacturer.
-- Edited by markf on Saturday 6th of April 2019 02:04:03 PM
Now you have started something
Wait for the barrage of B%**&(- t
But bear in mind T1 is basing all his comments on his" experiments" with LI batteries. & panels with a bit lower PPP
The results would not be quite the same with LA batteries being used over a wider range of SOC voltages [somewhat a different state of affairs]& which T has some problem understanding
With that for consideration by all knowledgeable members, I will withdraw from further input.
-- Edited by oldtrack123 on Tuesday 16th of April 2019 03:01:24 PM
T1 Terry said
03:14 PM Apr 16, 2019
Peter, please post the specs for a panel with a Vmp of 13v, wouldn't a panel with a Vmp of 13v charging a battery at 12.8v have a 100% efficiency? Also, note the current generated by the MPPT controller where those efficiencies occur, the efficiency drops after the 50% capacity point is passed, also note the poor efficiency at 100w or less, that period where the MPPT choir sing the praises about how well they perform in poor light conditions. Try being honest here Peter, the figures you think look good would look even better with a PWM controller doing the job, the Vmp to battery voltage is as close to perfect for direct charging as you can get. Now, isn't the claim that MPPT controllers are at their best when the panels are connected in a series string creating a very high input voltage compared to battery voltage? So the graph should be viewed at the 98Vmp level shouldn't it, or do you suddenly want to change your story now?
The other interesting thing is your claim about the MPPT controller being at its best when the battery voltage is down around the 10.5v mark, wouldn't that be the voltage Morningstar would use rather than 12.8v? What value is an efficient controller once the battery has reached 12.8v?
The chart doesn't paint a very good over all picture when the claim for max efficiency using a battery and solar voltage that would far better suit a PWM controller, does it Peter. Surely if these things were as good as you claim they would use the voltages you claim they work best at ..... maybe another case where the theory doesn't mirror the reality
T1 Terry
-- Edited by T1 Terry on Tuesday 16th of April 2019 03:15:27 PM
oldtrack123 said
10:32 AM Apr 17, 2019
T1 Terry wrote:
Peter, please post the specs for a panel with a Vmp of 13v, wouldn't a panel with a Vmp of 13v charging a battery at 12.8v have a 100% efficiency? Also, note the current generated by the MPPT controller where those efficiencies occur, the efficiency drops after the 50% capacity point is passed, also note the poor efficiency at 100w or less, that period where the MPPT choir sing the praises about how well they perform in poor light conditions. Try being honest here Peter, the figures you think look good would look even better with a PWM controller doing the job, the Vmp to battery voltage is as close to perfect for direct charging as you can get. Now, isn't the claim that MPPT controllers are at their best when the panels are connected in a series string creating a very high input voltage compared to battery voltage? So the graph should be viewed at the 98Vmp level shouldn't it, or do you suddenly want to change your story now?
The other interesting thing is your claim about the MPPT controller being at its best when the battery voltage is down around the 10.5v mark, wouldn't that be the voltage Morningstar would use rather than 12.8v? What value is an efficient controller once the battery has reached 12.8v?
The chart doesn't paint a very good over all picture when the claim for max efficiency using a battery and solar voltage that would far better suit a PWM controller, does it Peter. Surely if these things were as good as you claim they would use the voltages you claim they work best at ..... maybe another case where the theory doesn't mirror the reality
T1 Terry
-- Edited by T1 Terry on Tuesday 16th of April 2019 03:15:27 PMat hate for theory, that you do not understand shows again.
I will make just two comment
[1] How much of your "experimenting" was a true comparison between the different types of regulators on both la batteries & lithium [With the Las in various SOC]
I would suggest very little??
[2]Why so selective, by picking a panel working @ 13V PPP. Simply because it suits your argument?
I think I made that very point a long time ago, not sure on which forum.
Your use of panels with a PPP just above the battery voltage & batteries[ Li ] with a small voltage range over their SOC.
Quite different to using with LAs with a quite large SOC range[ possibly from 11.8V to 14.5V]
I would remind all members, keep the above in mind when reading any of T's posts
With that, I will withdraw from posting, before this ends up in another loooong useless thread
So Back to [1] above what is your answer to that??
T1 Terry said
01:43 PM Apr 17, 2019
As the only reply to you Peter, 2 yrs testing on 28 x 105ah Vision 12v seal lead acid batteries, ex BlueScope No.6 Blast Furnace back up power battery bank. Sadly, the engineers there made the same assumptions as you about how good lead acid batteries were and how to charge them. The battery back up failed 20 mins in when it was supposed to supply for 2 hrs. the result was a major failure in the tapping on the furnace and huge financial losses.
I was trying to build a battery bank that could power the Big Bus air con over night. Not a hope and I made my first observations about linking multiple 12v batteries in parallel. Even though the voltages were the same, the SOC was not resulting in 24 stuffed batteries and 4 still useable that I later resold.
I will admit, I was some what naïve back then and listened to all the "experts" said on the now defunct CMCA forum. You may remember the battles between myself who had the hands on experience and 24 stuffed batteries, against the theory masters who said that wasn't what happened :roll:
This was the starting point for my investigations into lithium batteries. I had at least learnt from the previous disaster not to believe anything you read unless you have confirmed it by your own repeatable hands on testing. That cost me an initial $10,000 and additional sums as I bought various equipment to test including even more MPPT controllers.
You see Peter, I didn't just read about something and form an opinion from there, I actually spent my own money and tested people's theories to see if they held up against the cold harsh reality test. I do understand why many armchair experts simply stick to forming opinions from what they have read, it's a cheaper alternative to actually testing to see if you are correct .....
I wish you were going to Stone The Crows, we have a number of practical demonstrations planned for the two talks we are presenting and it would be wonderful to have you on stage to explain just what the equipment was showing :lol:
T1 Terry
iana said
09:29 AM Apr 18, 2019
OK you guys, I have a PMT regulator in one hand, and a 60 amp MPPT regulator in the other, we need to capture as much sun power as possible, and need to be able to get out batteries up to full charge. Do I fit the PMT with the panels in parallel, or the MPPT with the panels in series. Simple question, I have both solar controllers.
markf said
09:39 AM Apr 18, 2019
iana wrote:
OK you guys, I have a PMT regulator in one hand, and a 60 amp MPPT regulator in the other, we need to capture as much sun power as possible, and need to be able to get out batteries up to full charge. Do I fit the PMT with the panels in parallel, or the MPPT with the panels in series. Simple question, I have both solar controllers.
For my money if they are your only two options I'd go MPPT with panels in series.
If it was me (which it isn't) I'd go with MPPT with panels in parallel.
Peter_n_Margaret said
09:39 AM Apr 18, 2019
iana wrote:
OK you guys, I have a PMT regulator in one hand, and a 60 amp MPPT regulator in the other, we need to capture as much sun power as possible, and need to be able to get out batteries up to full charge. Do I fit the PMT with the panels in parallel, or the MPPT with the panels in series. Simple question, I have both solar controllers.
Depends if they are good ones or crap and it also depends on the panel voltage.
A good MPPT controller will out perform a good PWM controller, especially if the panel voltage is above about 18V.
As for the fridge, one idea I have been thinking about, but not really serious about at the moment, is that with extreme temperatures we would probably be holed up in a caravan park. Now we were in a park when Adelaide had a heat wave and our thermometer under the awning was at 48 degrees. The air con would be going, it is possible with a bit of re-work to build a bypass of the compressor cooling air from inside the van. The top vent is there, it has two vents at the top, and just opening a cupboard door and mounting a van in the floor, this would circulate air cooled by the air con behind the fridge.
However two overcast days and our power is way down. Will see how the batteries have charged by the end of the day.
To be clear, the fridge has a seperate condenser with a fan, rather than the walls of the fridge dissipating heat. If so it would be better to add insulation to the fridge.
Replacing the condenser fan with a higher pressure fan or adding a second fan to push more air through the condenser.
Add a baffle around the condenser so no air is simply recirculating behind the fridge. I had this design fault in my esky so I added a baffle. The air is pushed & or pulled through the condenser at higher pressure & can only go outside. Killing 2 birds with one stone.
Iana
I do not believe that a MPPT controller will get much more out of your panels under the same conditions. You are currently getting 29Watts out of your three panels. If you can get more by them in series I would be surprised. But say you get 50% more because the voltage is higher for charging, that is only 3.6A. No magic answer.
As DeBE says his 160W panel is only putting out 28W. If there is not enough sun then there is not enough power and juggling it will only tinker around the edges. I use my MH engine alternator as my emergency topup if needed.
Good luck. Jaahn
2.4amps is not much, but it depends how overcast it is. You are not going to get miracles with MPPT.
Have you tested the amps individually on the 3 panels.
The 12.4v would be very close to the battery voltage because the panels are connected to the battery via the PWM controller. The 2.4 amps says they are charging your battery. The fact 3 x 12v = 36v isn't anything to do with the ability to charge the battery, current flow is the bit that charges the battery and this is the amps part of the measurement. If each panel is putting out the same amount that would mean you were getting 0.8 amps from each panel. It must have been very heavily overcast to cause that, but are you sure you had absolutely no shadow over any part of any one of the panels? Even the shadow from an overhead power line or from a radio aerial will reduce the output from any panel it touches to virtually zero. Shade on a bit of one panel and the other 2 panels may have actually put out 1.2 amps each.
T1 Terry
Iana
The difference between series and parallel is voltage drop efficiency. The series system is least effected .
BUT
A small physical sized parallel system can get good efficiency if large cables are used . The increased cable size xtra cost is minimal.
A parallel system will tolerate shade far better .
My experience is with 400w MPPT . The system gets a boost of 13--15% in amperage when system operating normally. When the batteries are greater than 30% flat amperage boost goes up to 25-30%. All this tested in Nth Qld sun in hot weather eg 30deg cel .
If chasing Mppt a Projecta IDC45 would have worked . I prefer Mppt because roofing area on van is limited/fixed so to get more amps mppt is the only way . 450watt 24.5 amp system mppt at 20%= xtra 4.8 amps ,, 30%= xtra 7.2 amps
Additional amps = approx. and extra 120watt panel
There always is a portable 150-200 watt set
Just so happens we are holed up on kangaroo island, sunshine variable. I am wondering if part of the problem we have is voltage drop to the fridge, and of course the wiring is not easilly accessible to take a measurement. If the fridge motor, even though it runs on lower voltage is not driving the compressor as it should, then this would account for the erratic run times we are having.
Hook up a constant 12v source and see what happens then.
power it from near the battery and another test right at the fridge.
This will at least help you narrow it down a little.
cheers Brett
An alternate method of improving the wiring to the fridge is to use a heavier cable from the battery to behind the fridge and add a suitable relay. You can then use the original wiring to drive a relay so all the control part operates the same but the relay can switch full battery power direct to the fridge via the heavier cable.
T1 Terry
Measured the voltage drop to the fridge, and it was for the length of wire bugger all, not worth worrying over. Terry our fridge is only 12volt, so it is wired direct to the Setec controller. No relays required. However I may end up putting a relay in the water pump circuit, the cable length to and from the Drifter panel when the pump is running makes some of the lights flicker, by using that circuit to energise a control relay, and taking the pump feed direct from the battery will fix that, but that is on my future to-do list, not for now.
I pick up the Mppt GSL 60 watt regulator when I am in Adelaide, will post the results when I have installed.
T1 Terry
Terry You seem to be on a campaign to convince people that mppt controllers are no good ,everything I have seen on other forums and read seem to indicate thats absolutely ridiculous,there a few of us that travel together that have changed to Victron mppt controllers and the difference in charging the batteries is amazing, I cant argue with you because Iam no electrical guru but seeing is believing and you bagging mppt can only be impressing ,as peter has stated your true believers,you fit lithium batteries thats something I hnow nothing about ,but I wonder about your knowledge as far as lead acid batteries in caravans go,with our experience comparing the two, mppt has made a massive power gain,and to switch back would Be stupidity at the highest level...
-- Edited by Ron-D on Friday 5th of April 2019 10:09:04 AM
Must be quite a few stupid yet happy campers out there then Ron. If you can link all the panels in series and remain below the maximum voltage of the controller and you have long cable runs, go for it, MPPT will work better than a PWM controller in this configuration.
If you are using solar panels with a much higher Vmp than required by the battery for end of charge voltage in hot conditions, then MPPT will work better than a PWM controller.
If you have sensibly balance between solar Vmp to required max battery voltage and have used the correct size wiring, connecting the panels in parallel will work better with a PWM controller than with an MPPT controller. Rewiring the solar into a series string yet the cabling is heavy enough for a parallel connection will result is less output than a quality PWM controller can extract from the solar array.
If you swap out a PWM controller for an MPPT controller but still connect a well match Vmp to required battery voltage array of panels in parallel, yet get a better result, either the PWM controller was crap or there is series problems with your wiring.
Logic applies, forget any goobldy goop sales nonsense. An MPPT controller requires more of the harvested solar power to function than a quality PWM controller. If you have the system already set up to run at its optimum on a PWM controller then logically the energy lost as heat through an MPPT controller is energy you do not have for battery charging.
T1 Terry
I can say that in our van we do have long cable lengths between panels installed by Jayco, and expanded foamed in place within the roof. So the cable lengths would be 2 x 3m lengths, which I understand is really 2 x 6m lengths, and 1 x at least 8m (16m length).
Heat is a concern, as the regulator has a built in fan, the comartment which can take the regulator is sealed, so I need to have air supply in and out.
It is very difficult to work out what to do as there are so many conflicting opinions. But on that note I am not saying anybody is wrong in what they are saying.
I have noticed that in our case the power problems begin when the batteries don't get a full charge each day, and the charger is only playing catch-up, i.e. the batteries don't get the 14 volt charge to finish off. From there its a down hill ride.
But I have concluded that if one really wants a low energy, solar powered van, you need to start from the wheels up. So many things need to be changed to make the grade. I am also talking about water use as well here.
Terry our systems are just 160 watt portable panels and a single conventional battery ,as sure as night follows day the different between mppt and pwm is amazing ,you Have lithium batteries which are lighter and much easier to charge maybe even a lower spec regulator can produce good results,maybe the way you rig things is more suitable to pwm ,but with a conventional battery and a portable panel that lots of campers use,our mppt puts considerably more into the battery,seeing is believing we have tried both types of reg,I am being absolutely truthfull here I dont have anything to sell it does not matter to me what people use,our basic systems does everything we need very well,and beyond a shadow of a doubt pwn was very ordinary with its charge rate compared to mppt,with the fridge on gas a 120 amp battery thats all We have ever needed to freecamp,money is not the issue with us why waste it on things you dont need...
-- Edited by Ron-D on Saturday 6th of April 2019 09:13:08 AM
But are you the average RV traveller? In your case the long cable run from the position the portable panels are sited back to the house battery would suit high voltage/low current from the panels to the MPPT controller mounted close to the battery. The controller can then convert the high voltage/low current to low voltage high current and the set would be superior to a PWM if the long cable run was not heavy cable.
An example using your set up, distance from panels back to the van is 10mtrs, the absolute max output from the panels is 14 amps and the Vmp is 16v ) a hot 12v nom. panel with a name plate 18v Vmp)
This is the result using 6 B&S cable for the 10 mtr run. Voltage drop is 0.36v and the voltage @14 amps input to the PWM controller would be 15.64v, plenty to bring a 12v lead acid battery up to fully charged in an acceptable time frame.
https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=1.296&voltage=16&phase=dc&noofconductor=1&distance=10&distanceunit=meters&eres=14&x=60&y=18
This is the result using 6mm auto cable, 1.16v drop and now only 14.8v @ 14 amps. No room for any further losses and the voltage differential is so low the battery charging would be low/slow.
https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=4.132&voltage=16&phase=dc&noofconductor=1&distance=10&distanceunit=meters&eres=14&x=70&y=15
Now let's look at joining two x 80w 12v panels in series, the voltage is doubled and the amps halved, 0.58voltage drop and 31.42v @ 7 amps available at the controller
https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=4.132&voltage=32&phase=dc&noofconductor=1&distance=10&distanceunit=meters&eres=7&x=84&y=19
If a PWM controller was used with this same set up and 6mm auto cable run, there would only be 7 amps max available to charge the battery.
Using an MPPT controller the 31.42 v @ 7 amps = 220w. Convert this to 14.8v and allow for a 10% loss through the MPPT controller where electrical energy was converted to heat energy, 220w - 10% = 198w divided by 14.8v = 13.37 amps.
Yes, you get more battery charging current available out of the smaller diameter cable run (6mm auto cable) but less than the same set up using 6 B&S cable and a PWM controller that does not convert any of the electrical energy to heat. This is not actually correct, there are some losses through the transistor in the PWM controller, but very little, maybe 0.25% of the total throughput, a rounding error rather than a noticeable loss.
Did that help explain what I'm trying to convey?
T1 Terry
I call BS on the 10% loss figure.
A bit of rudimentary research will reveal that there are very, very few MPPT regulators on the market with claimed efficiencies less that 95% with most being 97 or 98%. Victron for example claim peak efficiency of 98% for their SmartSolar MPPT 100/20.
Over the last three weeks I've done a bit of experimenting with PWM and MPPT controllers and have proven, for my case, that a quality, name brand, MPPT controller easily trumps a quality PWM controller from the same manufacturer.
-- Edited by markf on Saturday 6th of April 2019 02:04:03 PM
I have made my fridge so efficient that 120 watts of solar with MPPT is sucking the life out of the sun!
I also use my setup to charge cameras & mobiles, & fan for hot nights & charge a 4 Olight torches when needed.
Have also made the mobile charge quicker adding some heatsinks.
A bit more battery capacity would be nice but up till today have never been short of resources, even pumping up tyres at a 100amps when too lazy to lift the bonnet!
I had less than zero experience on solar a year ago, life is too short to waste pointless effort, put in MPPT & get it right the first time, have a beer & procrastinate!
All in how the manufacturer writes the spin, have a look at this chart from a well known MPPT manufacturer and you will see how the 98% claim can be made, then what the reality is
Now add in the difference between the perfect voltage compared to the voltage chosen by the controller, the output loss while the controller determines the actual battery voltage and what it decides is the optimum panel voltage that suits the controller .... I think you will find 10% is being generous.
T1 Terry
Perhaps you should restudy those curves
Especially the ones for13V & 16.5V peak power point.& a battery at 12'8V
Both over 95%
Now you have started something
Wait for the barrage of B%**&(- t
But bear in mind T1 is basing all his comments on his" experiments" with LI batteries. & panels with a bit lower PPP
The results would not be quite the same with LA batteries being used over a wider range of SOC voltages [somewhat a different state of affairs]& which T has some problem understanding
With that for consideration by all knowledgeable members, I will withdraw from further input.
-- Edited by oldtrack123 on Tuesday 16th of April 2019 03:01:24 PM
Peter, please post the specs for a panel with a Vmp of 13v, wouldn't a panel with a Vmp of 13v charging a battery at 12.8v have a 100% efficiency? Also, note the current generated by the MPPT controller where those efficiencies occur, the efficiency drops after the 50% capacity point is passed, also note the poor efficiency at 100w or less, that period where the MPPT choir sing the praises about how well they perform in poor light conditions.
Try being honest here Peter, the figures you think look good would look even better with a PWM controller doing the job, the Vmp to battery voltage is as close to perfect for direct charging as you can get.
Now, isn't the claim that MPPT controllers are at their best when the panels are connected in a series string creating a very high input voltage compared to battery voltage? So the graph should be viewed at the 98Vmp level shouldn't it, or do you suddenly want to change your story now?
The other interesting thing is your claim about the MPPT controller being at its best when the battery voltage is down around the 10.5v mark, wouldn't that be the voltage Morningstar would use rather than 12.8v? What value is an efficient controller once the battery has reached 12.8v?
The chart doesn't paint a very good over all picture when the claim for max efficiency using a battery and solar voltage that would far better suit a PWM controller, does it Peter. Surely if these things were as good as you claim they would use the voltages you claim they work best at ..... maybe another case where the theory doesn't mirror the reality
T1 Terry
-- Edited by T1 Terry on Tuesday 16th of April 2019 03:15:27 PM
I will make just two comment
[1] How much of your "experimenting" was a true comparison between the different types of regulators on both la batteries & lithium [With the Las in various SOC]
I would suggest very little??
[2]Why so selective, by picking a panel working @ 13V PPP. Simply because it suits your argument?
I think I made that very point a long time ago, not sure on which forum.
Your use of panels with a PPP just above the battery voltage & batteries[ Li ] with a small voltage range over their SOC.
Quite different to using with LAs with a quite large SOC range[ possibly from 11.8V to 14.5V]
I would remind all members, keep the above in mind when reading any of T's posts
With that, I will withdraw from posting, before this ends up in another loooong useless thread
So Back to [1] above what is your answer to that??
I was trying to build a battery bank that could power the Big Bus air con over night. Not a hope and I made my first observations about linking multiple 12v batteries in parallel. Even though the voltages were the same, the SOC was not resulting in 24 stuffed batteries and 4 still useable that I later resold.
I will admit, I was some what naïve back then and listened to all the "experts" said on the now defunct CMCA forum. You may remember the battles between myself who had the hands on experience and 24 stuffed batteries, against the theory masters who said that wasn't what happened :roll:
This was the starting point for my investigations into lithium batteries. I had at least learnt from the previous disaster not to believe anything you read unless you have confirmed it by your own repeatable hands on testing. That cost me an initial $10,000 and additional sums as I bought various equipment to test including even more MPPT controllers.
You see Peter, I didn't just read about something and form an opinion from there, I actually spent my own money and tested people's theories to see if they held up against the cold harsh reality test. I do understand why many armchair experts simply stick to forming opinions from what they have read, it's a cheaper alternative to actually testing to see if you are correct .....
I wish you were going to Stone The Crows, we have a number of practical demonstrations planned for the two talks we are presenting and it would be wonderful to have you on stage to explain just what the equipment was showing :lol:
T1 Terry
For my money if they are your only two options I'd go MPPT with panels in series.
If it was me (which it isn't) I'd go with MPPT with panels in parallel.
Depends if they are good ones or crap and it also depends on the panel voltage.
A good MPPT controller will out perform a good PWM controller, especially if the panel voltage is above about 18V.
Cheers,
Peter