Compressor Fridge.

Bass · Senior Member

Compressor Fridge.

Whenarewethere · Guru

My understanding is a 3 way fridge is drawing about 12 amp continuously. Batteries won't last long at that rate.

A compressor fridge uses about 12 to 20 AH per 24 hours. My fridge is around 9.5 to 12 AH per 24 hours.

Install thicker wire now then it is already done when you install the compressor fridge. The compressor fridge will draw about half its rated power. My 28L Waeco fridge actually runs at around 3.5 to 3.8 amps, its rated at 6.5 amps draw.

I have also replace wiring within the fridge & this reduces voltage loss by about another 0.17 volts. It's not much but a bit here & there all helps to keep the voltage up.

Look at the specs on the new fridge, it probably is around 8 amps but will actually draw around 4.5 to 5.0 amps, & it will only be on 15 minutes per hour at the most.

The best & easiest thing you can do for you fridge apart from heavy wiring is add insulation. I've used 2 thickness of the grey foam 10mm sleeping from Macpac. The grey was the best match for my Waeco!

Where I can I have used 6awg cable for the fridge & it only has a short run. I just tried to reduce voltage loss anywhere I could.

https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/

iana · Guru

Bass your fridge is 12v, not 240/12v. We have a 12v 217lt Dometic, and we had a similar problem. There is a power converter supplied for the fridge. It plugs into 240 and converts it to 12v, when it senses a lack of 240 the relays switch it over to the 12v circuit. It kept blowing the 15A fuse. Why have this, you van will have a 240-12v converter anyway. I just wired the fridge straight to the 12v supply from the van unit, and put the Dometic one in the bin, first problem solved.
Second problem we had GEL batteries supplied new with the van, I suspect because the batteries went flat during the build and commissioning process, i.e. 12v fridge or something, the batteries were probably rapidly charged, hence they were ruined, no capacity. Changed the batteries to AGM.
Third changed the solar system so the solar panels were in series, through an MTTP controller, and now get fully charged batteries on cloudy days, the other solar controller could never get the last part of the charge, i.e. the finishing voltage was just not there, when that happens the system goes on a downward spiral when the solar input is poor.

OK so first job find that 240-12v converter and by pass it, wire the fridge direct to the vans 12v system (10-15a fuse, check manual). If you wire the fridge direct to the batteries, you may not get a true reading of you battery condition.

Ask more questions if you need. Ours is now running as smooth as!

-- Edited by iana on Monday 7th of October 2019 07:22:07 PM

DeBe · Guru

(My understanding is a 3 way fridge is drawing about 12 amp continuously. Batteries won't last long at that rate.) He already has a 12V compressor fridge fitted.

Bass · Senior Member

Iana, your saying my compressor fridge (waceo 190lt ) is really 12v only and is stepped down by a regulator of sorts ?. I take it I will find this black box at top of fridge at back ? My controller BMpro 35 has fridge out put on it this controller i think could be at the bottom of all my problems and were thinking of wiring fridge direct to batteries thank you I will try your ideas when i get a chance. ( in middle of moving and new house is 5hrs away.

iana · Guru

Bass, spot on, I have attached a manual of the said box. Ours was on the floor under the fridge.

Bass · Senior Member

Thanks mate will look for it. Final option will be hard wire it to batteries via inline fuse etc.

Bagmaker · Senior Member

but even in perfect conditions you will run down half your capacity overnight.
Rule of thumb, 100A/h battery for a fridge per day.
I know they take way less blah blah blah
But its about right for us.

Peter_n_Margaret · Guru

I suspect that your problem is with the battery charging or the batteries, not the fridge.
480W of solar plus 240Ah of battery capacity should be enough to run 3 fridges comfortably.
I run 2 Danfos compressor units (one fridge and one freezer, both well insulated) and between 6pm and 9am (15 hours when there is no solar charging) they can use between 25Ah and 50Ah combined, depending on the temperatures.
Cheers,
Peter

T1 Terry · Guru

I think you will find the problem relates to poor wiring and everything else is a symptom of this initial error in design and has resulted in stuffed batteries. The first part is the solar wiring. 480w of solar will require 6B&S cable from the roof to the solar regulator and the same from the regulator to the batteries and even this will still see a 6.8% voltage drop. If the regulator was closer to the batteries, as in within 0.5mtr, that voltage drop would improve to under 5%, still not great for solar but I'm guessing a lot better than you have now. The average van out of the factory has 6mm auto cable run from the roof to the controller and on to the battery, 6mm auto cable is 4.3mm sq, 6B&S cable is any where from 13.5mm sq to 16mm sq, such is the stretch of the truth in manufacturing these days. The get even close to that conductor area and lower voltage drop the system would need 3 parallel runs of positive and negative cables the size the manufacturers use from the roof to the regulator and on to the battery.

The next thing to look at is how the batteries are linked together, if everything runs off one battery and the second battery just has a single wire linked to each terminal to the other battery, you are effectively running of one battery till it dies, then it kills the other battery. There is another thread here somewhere that goes into how batteries should be connected in parallel if you must parallel them at all. All house battery and big telecommunication power batteries are low voltage cells connected in series to build one big capacity battery and that is the way a battery pack should be built, even 2 x 6v batteries in series would be better than 2 x 12v batteries in parallel.
Next, the wiring from the house battery to the fridge, is that 6 B&S cable ALL the way, not with 6mm auto cable for the bit that goes to the battery so they could add an inline fuse?

A 12v compressor fridge anywhere close to 200ltr needs 80Ah @ min 12v per 24hrs, if the ventilation around the fridge is poor and the van inside temp is uncomfortably high, push that up to the 100Ah as mentioned before. The 480w properly wired can supply around 140Ah per day in good solar conditions in summer. That means is all the conditions are not close to ideal when it comes to wiring and fridge ventilation, you all trying to supply 100Ah per day from solar that is choked by undersize cabling so simply can not push the 30 amps or so through the cable and still maintain a high enough voltage to fully charge the batteries.
An MPPT controller was mentioned earlier and connecting the panels in series. This will work if all the panels are the same Vmp and OCV (marked on the label on the back of the panel) , it won't if they are different because the higher output panels will be dragged down to the lowest panel output. Simply adding an MPPT controller to the wiring the way it is will be a step backwards because the wiring isn't allowing the current to reach the controller.
If you do go with an MPPT controller, use a quality one that has separate voltage sensing wires that connect directly to the battery, but the same goes for a PWM controller, if you want to get the most out of the solar the controller must know what the genuine battery voltage is, not what the voltage is as it leaves the controller because this will always be higher than the battery voltage.

Just as a side thought, does your fridge have a condenser mounted either close to the compressor with a fan or just about covers the rear of the fridge? If it doesn't, it uses the walls of the fridge to dissipate the heat so need good air circulation from the bottom of each side and a path out at the top. If added insulation has been stuffed up the sides of the fridge it is working against the ability of the fridge to cool, not assisting it. So best double check that as well. Make sure there is a path up and away from the top of the fridge, not into a void that the hot air can not escape from because that stops the air from circulating past the condenser no matter where it is mounted.

T1 Terry

Whenarewethere · Guru

I have replaced the original 80mm fan in the fridge with a Noctua 120mm fan.

Now have replaced the Noctua 120mm fan with another Noctua fan which not only has a higher volume it has better pressure.

Now I can feel the air being pushed through the fridge to a greater degree even with a dust filter. It also barely used any more power to the first one I installed & less than the original fan as Noctua fans are really efficient. Well worth spending the money to save energy.

Anderson plug on the fridge & a filter, it's surprising the amount of dust that would otherwise cover the condenser. I still blow out the fridge with airgun after every trip & it is quite amazing the amount of dust in the fridge covering the condenser & everything else.

Bass · Senior Member

Sorry whenwearethere we are talking about a caravan fridge not a portable waeco. T1 Terry sorry but most of that went over my head but some where in there i suspect it may help will have to look at how batteries are hooked together ( **** of a spot for a 60+ with osteo ). Peter and margret i suspect you are right re: the controller (BMpro) have had problems with it. I will look for Iana's black box for now.

iana · Guru

Bass, I suspect you have a Jayco, and a newer model than ours, there is the possibility that those employed by, may have used a couple of brain neurons, and left that device out. If that is the case, then you would have a good cable run back to your BMpro, this then will eliminate one area of a problem.
To locate the black box remember it will be plugged into a 240 power socket via a black lead.
For your information we are atm running totally solar and will be for the next two weeks. We have the same battery AH's as you, but are running a bigger compressor Waco fridge, and have less solar than you.

Whenarewethere · Guru

I know, accountants have had too much say which fan & wiring is used, knobbling the performance of fridges.

Better quality fan/s & heavier wire will make all fridges more efficient.

iana · Guru

Just reading your original post again, re the 10.5v and the fridge not going, these fridges have a low voltage cut-out set to shut the fridge down at 10.5v.

Peter_n_Margaret · Guru

At 6pm your solar should have the batteries fully charged. The fridge could not have possibly used more power than the solar was producing if it was working properly, even on an overcast day.
Cheers,
Peter

Bass · Senior Member

don't have a Jayco have a Sentinal the wiring has been crap eg, the desiel heater had 12v wires from under the bed to the BMpro at rear of van and back to control about 10meters kept tripping out on under voltage wired direct to batteries ( as it should of been ) heavier cables now works like a charm. 240 v bed side power points to plug in you have to have your finger on the earth to feel socket cause you cannot see it. power point, usb socket and 12v socket under the table in top of shelf ok for youngsters but not oldies, etc etc. I even have a certificate ( signed ) by the plumber to say that the gas to our COMPRESSOR fridge is safe etc. I now suspect that the whole problem is the battery management system setec BMpro 35. even with fridge cold from start 240v turned off, 480watts of solar and 2 x125 a/hr batteries the system will be on its last legs by 6pm. If it wasn't for the fact that the chassis is fantastic and we took it right through the gulf and to the top last year without a single screw coming out etc i would of ditched it for a jacyo. I guess it is a matter of watch this space. Thank you all.

Bicyclecamper · Guru

Competent auto electrician, who knows solar as well as van power systems, is what you need. I know someone like that, but they are in the New England NSW

-- Edited by Bicyclecamper on Wednesday 9th of October 2019 05:16:21 PM

iana · Guru

Baz, have you had a look for that module yet? and what sort of batteries do you have, AGM or gel ?
I am beginning to suspect the problem may lie with the programing of your controller, but we need to eliminate the other things first.

Bass · Senior Member

sorry mate haven't checked out any thing yet, our house just went on the market and our new house is 41/2 hrs away not the smartest thing i have ever done and still working so been a bit hetic. I have agm Batteries and i are begining to suspect controller, pull 240v all shuts down, pull 240v all works fine ( changes over ) pull 240v all shuts down and cannot get solar or aux to work, plug 240v in all ok, plug 240v in and reading 12,8v all working, plug 240v in and reading 13.7v any wonder i'm old before my time. Took Trek controller off the other day to look behind it and G.F. Me what a mess ( BIG TIME ) lacking 5 spare years i screwed trek back for another day.

iana · Guru

Take it easy, I can hear you puffing from here. Its good you have AGM batteries. Tick off one box at a time, the best way to fault find.

Sarge9 · Senior Member

Bass, you might not need the encouragement, but all of us compressor fridge owners would ( I think) recommend you keep the compressor rather than go backwards to a 3 way.

Good luck with sorting your wiring out.

Sarge.

Bass · Senior Member

thanks mate but caravan put on backburner for a bit thought i'd beaten it, remission for 3 years but monday my surgeon bypassed my oncologist and sent me packin to peter mac in melbourne ( nice chap ) at least the rust in different area. all starts friday..... WOOPPEEE !!!!!!

Bass · Senior Member

Bit of an update, going through old posts tiding up a bit. WELL the cancer has returned and **** its angry my oncologist said maybe 24 months, BUGGAR. moved to murch and the oncologist at GV hospital said we can do something and put me on chemo designed by the KGB, far out was on chemo for 8 months in 2016 and that was a walk in the park compared to this. any way back to van, got the panels removed they were very cheap ones and wired with crap wire, enerdrive system installed and a zantec controller. the usless bmpro system bypassed. 2 x 200 A/HR batteries ( each has its own postcode lol ) All this done cause 3 way would not fit. golden valley solar said I will run out of water before I run out of power and so far he has been right although I am trying to prove him wrong. finished chemo, isolated and managed to get away for month fridge still runs nearly 24/7 but I no longer care.

Aus-Kiwi · Guru

All the best . Enjoy while
You can, Bass . Helping a friend in similar health !!

Magnarc · Guru

Hi Warren, there are times when problems with van fridges pale into insignificance when there are other more pressing things in ones life. Get into the great outdoors and give it a bloody big shake mate.

All the very best to and yours,

Phil.

Bass · Senior Member

Thanks guys it is what it is no point whineing I'll beat it again. If this covid thingy will back off we'll go to the Barrossa to see the grandkids (time waster numbers 3 and 7. then to hervey bay to see number 8. )
Cheers warren
Foot note going to lake Lascelles in a week or two cause we can.

Bass · Senior Member

Update still not have had a chance to use the van except for a few weekends. WELL the bloke who did all the wiring and upgrading at solar city caravans is full of &%#*@. firstly a 3 way fridge will fit. second I run out of power well before i empty 2 cans of Jim Beam. Example last night after the power shut down a few times during the day I discovered the water pump was faulty no problem replaced it ( I carry a spare.) batteries fully charged (13.2 volts ) at about 8pm, 1 light going for a while and the fridge, when I woke at 5.30am NOTHING system shut down Both batteries 260AHR each read 10.5 volts. were bush camping so said golly gee packed up and came home. Now the process begins, disconnect every circut for 24hrs leaving the van on solar and see if system shuts down. starting with the fridge. ( did the same last weekend away thank god for generators,
600 watts solar
xantrex controller.
2... 260 ahr batteries 520 ahr in total.

oldbloke · Guru

No expert here, but don't be in a hurry to exchange to a 3 way. 12v compressors are way better. Wish I had one.

iana · Guru

Is it possible that the power is going back through the solar panels at night, there should be a diode in the system to stop that. We have a compressor fridge and only 240ahs of battery, it lasts OK through the night.