Hi Guys, I have recently changed over to a Jayco Expanda van, I had a 120w solar panel fitted with a 90ah battery, my problem is when I was on holiday recently I found when I switched the fridge to battery, the fridge was not keeping cool, upon investigation I found that I did n't have any supply from my car. My question is should the fridge still maintain its cooling from the caravan battery? The time it was running without power was approx. 5hours. The fridge is a Dometic and draws about 15A on 12v supply.
spida said
01:07 PM Apr 2, 2016
My understanding is that the 12v system is only a back up and that a fridge is better run on gas or 240v. I have managed to flatten the car battery (engine not running!) with the fridge on 12v - in 20 minutes!
Seer said
02:30 PM Apr 2, 2016
Hi Spida, thanx for the quick response but you cannot use gas or 240 whilst you are travelling
Radar said
03:30 PM Apr 2, 2016
We have our supply from the car battery running though a Andrson plug direct to the frig, this will disconnect when battery volts drops to 12.8
Our primary source of power is gas, using 12 volt on the move.
Our frig is a 3 way, 159litre with the best rating and has been very good this summer maintaining our food frozen while on the move, got game brought some ice cream keep it for 4 days.
Very happy with set up.
iana said
03:59 PM Apr 2, 2016
Sounds like you are asking two questions. You had a 90AH battery fitted to the van that can be charged by solar, and from the vehicle, but the fridge wasn't feeding from it. That may be correct, the three way fridge draws a lot of power, so it may not be wired into your 12v system.
However you should have a 12v supply from the vehicle, that connects to the van (pins 9 +10 on a 12 pin plug, now how do I know that :) ), but it may have a relay in the circuit that only allows power through, if the ignition is on. This is to supposably stop you flattening the vehicle battery.
Izabarack said
05:15 PM Apr 2, 2016
Seer wrote:
... and draws about 15A on 12v supply.
A 90 AH battery will not supply that draw for long. A 120 Watt panel would not keep up with that draw either. Drawing 15 Amps all the way from the alternator would need pretty heavy wiring to be effective. I would be looking at the car to van supply first and wiring size second.
Iza
PeterD said
11:37 PM Apr 2, 2016
Jayco vans do not have the DC element power for the fridge connected to the battery. The reason has been alluded to above, the fridge will flatten your house battery too quickly.
The Setec power supply fitted to your van has a diode in it to prevent the battery feeding back to the trailer plug. The power to the van through the trailer plug feeds to both the fridge and the battery through the Setec.
in transit said
09:57 AM Apr 3, 2016
got game brought some ice cream keep it for 4 days.
We can't keep ice cream for 4 days at home
Hylife said
12:21 PM Apr 3, 2016
15 amps is like having both your high and low beam headlights on at THE SAME TIME. Your 90Ah van battery will be two low to let your fridge work effectively in under an hour.
Trailer plug wiring is way too small to charge deep cycle batteries or run a fridge. Even with 6AWS wire 14 volts at the tug battery will be down to 12.8 after 6 meters or so and this is too low for charging &/or running the fridge.
You need a heavy duty wire run from the car battery to a 50Amp Anderson plug on the back of the car which plugs into an identical 50Amp Anderson plug on the van with heavy duty wire which runs to a DC-DC charger right next to the van battery. The DC-DC charger will "up" the voltage to compensate for the long run resistance of the wires, and most modern DC-DC chargers also have an inbuilt battery isolator so you wont flatten the car battery when the engine is off.
Radar said
05:45 PM Apr 3, 2016
in transit wrote:
got game brought some ice cream keep it for 4 days.
We can't keep ice cream for 4 days at home
It don't normally last long with me but the last couple of months I have lost the need for ice cream but was amazed how well it kept in our frig on gas over night and on 12volt while travelling.
Great comment Radar.Too many people are being sucked into the DCDC charger system.Common sense wiring and your fridge connected to the start battery where the alternator can read the draw(resistance) will run your fridge effectively and even your Waeco in the back of the truck too.
Seer said
07:09 PM Apr 3, 2016
I think I'll eat the peaches and cream before we start out that way it will be safely stored away. Thanks for the tip
Hylife said
02:35 PM Apr 5, 2016
patrol03 wrote:
Great comment Radar.Too many people are being sucked into the DCDC charger system.Common sense wiring and your fridge connected to the start battery where the alternator can read the draw(resistance) will run your fridge effectively and even your Waeco in the back of the truck too.
Mmmm, icecream.
Sorry patrol03, that only works when you are driving (engine running) for the small portable fridge in the tow vehicle. That just doesn't work for most van fridges.
Even huge 4 gauge wire from the tow vehicle battery to the mid point (over axel) of a small caravan will probably be at least 8 to 10 meters. The wires go each way so you have a 15 to 20 meters run and that will drop the 14volts at the tow battery to around 12.8V or less (under load) at the caravan battery. That just isn't high enough to charge a battery and whilst the terminal voltage will be maintained at 12.8V the battery capacity will drop to sweet FA within an hour or so of driving and then everything in your fridge gets warmer and warmer.
That's why we use DC-DC chargers, there's no being "sucked in" about it.
All those lovely new vans being built these days are coming with large compressor fridges. They don't run on gas, just 12 and 230 only, and the distance from your car engine creates the voltage drop problem. You need sufficient battery storage to run them and sufficient voltage (and current) to charge those batteries whilst driving. You get that from lots of solar on the roof or DC-DC chargers.
iana said
03:03 PM Apr 5, 2016
Sorry my WAECO RPD-215 is only 12-24v, they chucked in a 240v -12v transformer as well. But the fridge is 12-24v only. And yes its there in the fridge instruction book about the wire size, just wish the van manufacturers could read. The wiring on mine is way under size, according to the graph.
03_Troopy said
03:22 PM Apr 5, 2016
Hylife wrote:
patrol03 wrote:
Great comment Radar.Too many people are being sucked into the DCDC charger system.Common sense wiring and your fridge connected to the start battery where the alternator can read the draw(resistance) will run your fridge effectively and even your Waeco in the back of the truck too.
Mmmm, icecream.
Sorry patrol03, that only works when you are driving (engine running) for the small portable fridge in the tow vehicle. That just doesn't work for most van fridges.
Even huge 4 gauge wire from the tow vehicle battery to the mid point (over axel) of a small caravan will probably be at least 8 to 10 meters. The wires go each way so you have a 15 to 20 meters run and that will drop the 14volts at the tow battery to around 12.8V or less (under load) at the caravan battery. That just isn't high enough to charge a battery and whilst the terminal voltage will be maintained at 12.8V the battery capacity will drop to sweet FA within an hour or so of driving and then everything in your fridge gets warmer and warmer.
That's why we use DC-DC chargers, there's no being "sucked in" about it.
All those lovely new vans being built these days are coming with large compressor fridges. They don't run on gas, just 12 and 230 only, and the distance from your car engine creates the voltage drop problem. You need sufficient battery storage to run them and sufficient voltage (and current) to charge those batteries whilst driving. You get that from lots of solar on the roof or DC-DC chargers.
At 40A (a common capacity for DC-DC chargers) using 6AWG (B&S) cable, and 10M to your load, you'll get 1.07V voltage drop. So that will give you 12.93V at your battery, which is plenty while bulk charge is being done. When the current drops back at closer to charge rate to say 10A, you only get 266mV drop so you'll have in excess of 13.7V at your battery. So 4AWG would work even better.
Hylife said
11:26 PM Apr 6, 2016
03_Troopy wrote:
At 40A (a common capacity for DC-DC chargers) using 6AWG (B&S) cable, and 10M to your load, you'll get 1.07V voltage drop. So that will give you 12.93V at your battery, which is plenty while bulk charge is being done. When the current drops back at closer to charge rate to say 10A, you only get 266mV drop so you'll have in excess of 13.7V at your battery. So 4AWG would work even better.
Most DC-DC chargers until fairly recently were 20amp units, and even today the price premium for a 40A unit is more than four times that of a 20A unit even for the cheap brands.
Remember the whole circuit includes a return path which is another 10 meters.
Redo your calculations on 20meters wire length.
So many of vanners even with 4 or 6 gauge wires have had no success with decent van battery charging until putting in a DC-DC charger, me included. I gotta say that everyone I've spoken to that has tried to use the tug to charge the van has said the same thing. In the back of the tug, OK, but in the van they can't get the batteries over about 70%.
Each to their own I guess but it seems DC-DC just works, even on 8 gauge.
Oh and even GELL cells which require the lowest charge voltage still need 14.4 to charge fully, not 13.7, and AGM 14.8 and Calcium 15.3
-- Edited by Hylife on Wednesday 6th of April 2016 11:30:12 PM
TheHeaths said
06:57 AM Apr 7, 2016
Seer,
as alluded to by others. The fridge will not be connected to the battery in the van, and so will not work on 12 volt unless connected to the car.
Ours works fine when we are connected to the car and running, and maintains temperature in both the fridge and freezer section of the unit. I have a switch fitted that turns off the 12 volt from the car to the fridge when we are stopped so the battery doesn't flatten.
There should be a wire in the 7/12 pin socket on the car, or perhaps a separate Anderson plug on the car that provides the 12 volt power when you are driving.
You may need to get this checked out to find out if it is actually working.
KevinC said
08:20 AM Apr 7, 2016
Not wishing to offend anyone, I'm bit sceptical about all the extras folk fit to make their vans better. We use the Jayco as manufactured, except we've fitted a Fridge Switch to avoid the embarrassment of a flat vehicle battery when we stop driving. So we travel on 12v, camp on gas or stay in a park on 240v. This is how the system was intended to work, and this is what it does. No extra wiring or chargers. The wires in the tow and the van do the job perfectly. Fridge is always cold.
Maybe we're just lucky, or maybe Jayco made a mistake and got ours right. I certainly won't be rushing out to get a charger to make it "better."
03_Troopy said
08:29 AM Apr 7, 2016
Hylife wrote:
03_Troopy wrote:
At 40A (a common capacity for DC-DC chargers) using 6AWG (B&S) cable, and 10M to your load, you'll get 1.07V voltage drop. So that will give you 12.93V at your battery, which is plenty while bulk charge is being done. When the current drops back at closer to charge rate to say 10A, you only get 266mV drop so you'll have in excess of 13.7V at your battery. So 4AWG would work even better.
Most DC-DC chargers until fairly recently were 20amp units, and even today the price premium for a 40A unit is more than four times that of a 20A unit even for the cheap brands.
Remember the whole circuit includes a return path which is another 10 meters.
Redo your calculations on 20meters wire length.
So many of vanners even with 4 or 6 gauge wires have had no success with decent van battery charging until putting in a DC-DC charger, me included. I gotta say that everyone I've spoken to that has tried to use the tug to charge the van has said the same thing. In the back of the tug, OK, but in the van they can't get the batteries over about 70%.
Each to their own I guess but it seems DC-DC just works, even on 8 gauge.
Oh and even GELL cells which require the lowest charge voltage still need 14.4 to charge fully, not 13.7, and AGM 14.8 and Calcium 15.3
-- Edited by Hylife on Wednesday 6th of April 2016 11:30:12 PM
The 40A was used as a comparison for a DC-DC charger, on a best case scenario against just using the cable.
My calculations are based on the complete circuit length, ie supply and return length for a 10M cable run or 20M total.
My end voltage is based on a supply voltage of 14V, so if you alternator puts out more than that, say 14.2V, then add an extra 0.2 VDC to the end voltage at 10A charge rate.
Once you get to float charge you may only be drawing 5A and this will give you a voltage drop of less than 150mV over the full 20M of cable.
going up to 4AWG at 20M total, you get the following voltage drops.
40A - 670mV = 4.8% of 14V supply
10A - 168mV = 1.2% of 14V supply
5A - <85mV = 0.6% of 14V supply
I suggest the reason "So many of vanners even with 4 or 6 gauge wires have had no success", is due to:
1) Poor connections in their cabling,
2) they have variable voltage alternators,
3) They are only driving 3 or 4 hours and expecting the batteries to be fully charged from below 70% SOC. This won't be achieved with a DC-DC charger either,
4) They don't understand cable sizing, and are going by "Auto Cable" sizing ie 6mm Auto instead of 6AWG. 6mm Auto = 4.5sqmm 6AWG = 13.5sqmm
Many vehicles with variable voltage alternators can have the voltage increased by roughly 0.5V, by adding a diode into the alternator's battery voltage sense circuit, to introduce a voltage drop in that line.
If you use decent sized cable (6AWG min) in combination with a 40A DC-DC charger, you have the best of both worlds. If you don't want the expense of a 40A DC-DC charger, use 4AWG cable min, if your run is excessive (10M or further). Or you can get away with 6AWG for smaller vans where your run is under 10M
oldtrack123 said
11:13 AM Apr 13, 2016
Hylife wrote:
patrol03 wrote:
Great comment Radar.Too many people are being sucked into the DCDC charger system.Common sense wiring and your fridge connected to the start battery where the alternator can read the draw(resistance) will run your fridge effectively and even your Waeco in the back of the truck too.
Mmmm, icecream.
Sorry patrol03, that only works when you are driving (engine running) for the small portable fridge in the tow vehicle. That just doesn't work for most van fridges.
Even huge 4 gauge wire from the tow vehicle battery to the mid point (over axel) of a small caravan will probably be at least 8 to 10 meters. The wires go each way so you have a 15 to 20 meters run and that will drop the 14volts at the tow battery to around 12.8V or less (under load) at the caravan battery. That just isn't high enough to charge a battery and whilst the terminal voltage will be maintained at 12.8V the battery capacity will drop to sweet FA within an hour or so of driving and then everything in your fridge gets warmer and warmer.
That's why we use DC-DC chargers, there's no being "sucked in" about it.
All those lovely new vans being built these days are coming with large compressor fridges. They don't run on gas, just 12 and 230 only, and the distance from your car engine creates the voltage drop problem. You need sufficient battery storage to run them and sufficient voltage (and current) to charge those batteries whilst driving. You get that from lots of solar on the roof or DC-DC chargers.
Hi
IF the fridge was CORRECTLY wired to the Fridge MAKERS instructions it would have no effect on the van battery charging
& as long as the FRIDGE gets at least 12V at it's input while "ON" it will perform as intended& the Battery will be non the worse
Dc /Dc chargers are not the best FIRST step, just an inefficient EXPENSIVE way of overcoming voltage drop.
And forget about trying to run a 3way of solar panels ,they have gas for off 240V situations
But the unsuspecting public fall for the sale speil
If the Vehicle has a low voltage alternator , A DC DC charger may well be required to FULLY charge the van battery
.BUT that is ALL it should be doing ,charging the van battery
Running the fridge of it as well, simply puts extra load on the charger ,limiting its AVAILABLE power to charge the van battery even leading it to not see the true SOC of the van battery ,& thus defeating the very reason that it was designed for
-- Edited by oldtrack123 on Wednesday 13th of April 2016 11:21:57 AM
Radar said
06:01 PM Apr 13, 2016
oldtrack123 wrote:
Hylife wrote:
patrol03 wrote:
Great comment Radar.Too many people are being sucked into the DCDC charger system.Common sense wiring and your fridge connected to the start battery where the alternator can read the draw(resistance) will run your fridge effectively and even your Waeco in the back of the truck too.
Mmmm, icecream.
Sorry patrol03, that only works when you are driving (engine running) for the small portable fridge in the tow vehicle. That just doesn't work for most van fridges.
Even huge 4 gauge wire from the tow vehicle battery to the mid point (over axel) of a small caravan will probably be at least 8 to 10 meters. The wires go each way so you have a 15 to 20 meters run and that will drop the 14volts at the tow battery to around 12.8V or less (under load) at the caravan battery. That just isn't high enough to charge a battery and whilst the terminal voltage will be maintained at 12.8V the battery capacity will drop to sweet FA within an hour or so of driving and then everything in your fridge gets warmer and warmer.
That's why we use DC-DC chargers, there's no being "sucked in" about it.
All those lovely new vans being built these days are coming with large compressor fridges. They don't run on gas, just 12 and 230 only, and the distance from your car engine creates the voltage drop problem. You need sufficient battery storage to run them and sufficient voltage (and current) to charge those batteries whilst driving. You get that from lots of solar on the roof or DC-DC chargers.
Hi
IF the fridge was CORRECTLY wired to the Fridge MAKERS instructions it would have no effect on the van battery charging
& as long as the FRIDGE gets at least 12V at it's input while "ON" it will perform as intended& the Battery will be non the worse
Dc /Dc chargers are not the best FIRST step, just an inefficient EXPENSIVE way of overcoming voltage drop.
And forget about trying to run a 3way of solar panels ,they have gas for off 240V situations
But the unsuspecting public fall for the sale speil
If the Vehicle has a low voltage alternator , A DC DC charger may well be required to FULLY charge the van battery
.BUT that is ALL it should be doing ,charging the van battery
Running the fridge of it as well, simply puts extra load on the charger ,limiting its AVAILABLE power to charge the van battery even leading it to not see the true SOC of the van battery ,& thus defeating the very reason that it was designed for
-- Edited by oldtrack123 on Wednesday 13th of April 2016 11:21:57 AM
Hi All. All I can say is I have done something right with out extra expenses. 1. I charge a 2nd battery in the ute and run a 12volt low draw portable frig. 2. My anderson plug cable goes to the 3way frig for when travelling. 3. 3way on gas when stationary. 4. Solar charges the caravan house battery.
I like the kiss principal.
Seer said
07:10 AM Apr 23, 2016
Thanks a lot guys for your constructive comments, I have had an auto electrician wire my trailer plug with supply straight from the battery with an inline fuse, I will just have to watch out when I'm stopped. Maybe I will need to wire from the ignition.
Delta18 said
07:47 AM Apr 23, 2016
Seer wrote:
Thanks a lot guys for your constructive comments, I have had an auto electrician wire my trailer plug with supply straight from the battery with an inline fuse, I will just have to watch out when I'm stopped. Maybe I will need to wire from the ignition.
You can fit a "Fridge Switch" (google it) which is a Motion Sensor. If it cannot detect motion it will cut power to the fridge after a short time. This is to prevent it cycling on/off in heavy, stop/start traffic.
swamp said
08:43 PM May 14, 2016
hi
Run the 3-6awg cable from the car battery to a T connection in the van..
One way to the input of the Dc2dc charger .
One way to the fridge . [ optional ....Install a fridge switch ]
........When u have a dc2dc charger wired from the output to the battery . Never ever use this cable as a power supply for the 3 way fridge............
It will disturb the charger from working properly . The charger will think it has a flat battery when it does not, current draw from the fridge will be happening say 12-15 amps .The problem it will keep pumping in power and most likely over charge the batt .
How its suppose to happen
There will be a trigger point in amps say current draw less than 5 before it will swap from absorbtion mode 14.6 volts and drop down to float mode 13.6 volts. With out this process the charger will stay at the higher voltage 14.6 volts and potentially overcharge .
Hi Guys, I have recently changed over to a Jayco Expanda van, I had a 120w solar panel fitted with a 90ah battery, my problem is when I was on holiday recently I found when I switched the fridge to battery, the fridge was not keeping cool, upon investigation I found that I did n't have any supply from my car. My question is should the fridge still maintain its cooling from the caravan battery? The time it was running without power was approx. 5hours. The fridge is a Dometic and draws about 15A on 12v supply.
Hi Spida, thanx for the quick response but you cannot use gas or 240 whilst you are travelling
We have our supply from the car battery running though a Andrson plug direct to the frig, this will disconnect when battery volts drops to 12.8
Our primary source of power is gas, using 12 volt on the move.
Our frig is a 3 way, 159litre with the best rating and has been very good this summer maintaining our food frozen while on the move, got game brought some ice cream keep it for 4 days.
Very happy with set up.
However you should have a 12v supply from the vehicle, that connects to the van (pins 9 +10 on a 12 pin plug, now how do I know that :) ), but it may have a relay in the circuit that only allows power through, if the ignition is on. This is to supposably stop you flattening the vehicle battery.
A 90 AH battery will not supply that draw for long. A 120 Watt panel would not keep up with that draw either. Drawing 15 Amps all the way from the alternator would need pretty heavy wiring to be effective. I would be looking at the car to van supply first and wiring size second.
Iza
Jayco vans do not have the DC element power for the fridge connected to the battery. The reason has been alluded to above, the fridge will flatten your house battery too quickly.
The Setec power supply fitted to your van has a diode in it to prevent the battery feeding back to the trailer plug. The power to the van through the trailer plug feeds to both the fridge and the battery through the Setec.
got game brought some ice cream keep it for 4 days.
We can't keep ice cream for 4 days at home
15 amps is like having both your high and low beam headlights on at THE SAME TIME. Your 90Ah van battery will be two low to let your fridge work effectively in under an hour.
Trailer plug wiring is way too small to charge deep cycle batteries or run a fridge. Even with 6AWS wire 14 volts at the tug battery will be down to 12.8 after 6 meters or so and this is too low for charging &/or running the fridge.
You need a heavy duty wire run from the car battery to a 50Amp Anderson plug on the back of the car which plugs into an identical 50Amp Anderson plug on the van with heavy duty wire which runs to a DC-DC charger right next to the van battery. The DC-DC charger will "up" the voltage to compensate for the long run resistance of the wires, and most modern DC-DC chargers also have an inbuilt battery isolator so you wont flatten the car battery when the engine is off.
It don't normally last long with me but the last couple of months I have lost the need for ice cream but was amazed how well it kept in our frig on gas over night and on 12volt while travelling.
I think I'll eat the peaches and cream before we start out that way it will be safely stored away. Thanks for the tip
Mmmm, icecream.
Sorry patrol03, that only works when you are driving (engine running) for the small portable fridge in the tow vehicle. That just doesn't work for most van fridges.
Even huge 4 gauge wire from the tow vehicle battery to the mid point (over axel) of a small caravan will probably be at least 8 to 10 meters. The wires go each way so you have a 15 to 20 meters run and that will drop the 14volts at the tow battery to around 12.8V or less (under load) at the caravan battery. That just isn't high enough to charge a battery and whilst the terminal voltage will be maintained at 12.8V the battery capacity will drop to sweet FA within an hour or so of driving and then everything in your fridge gets warmer and warmer.
That's why we use DC-DC chargers, there's no being "sucked in" about it.
All those lovely new vans being built these days are coming with large compressor fridges. They don't run on gas, just 12 and 230 only, and the distance from your car engine creates the voltage drop problem. You need sufficient battery storage to run them and sufficient voltage (and current) to charge those batteries whilst driving. You get that from lots of solar on the roof or DC-DC chargers.
At 40A (a common capacity for DC-DC chargers) using 6AWG (B&S) cable, and 10M to your load, you'll get 1.07V voltage drop. So that will give you 12.93V at your battery, which is plenty while bulk charge is being done. When the current drops back at closer to charge rate to say 10A, you only get 266mV drop so you'll have in excess of 13.7V at your battery. So 4AWG would work even better.
Most DC-DC chargers until fairly recently were 20amp units, and even today the price premium for a 40A unit is more than four times that of a 20A unit even for the cheap brands.
Remember the whole circuit includes a return path which is another 10 meters.
Redo your calculations on 20meters wire length.
So many of vanners even with 4 or 6 gauge wires have had no success with decent van battery charging until putting in a DC-DC charger, me included.
I gotta say that everyone I've spoken to that has tried to use the tug to charge the van has said the same thing. In the back of the tug, OK, but in the van they can't get the batteries over about 70%.
Each to their own I guess but it seems DC-DC just works, even on 8 gauge.
Oh and even GELL cells which require the lowest charge voltage still need 14.4 to charge fully, not 13.7, and AGM 14.8 and Calcium 15.3
-- Edited by Hylife on Wednesday 6th of April 2016 11:30:12 PM
as alluded to by others. The fridge will not be connected to the battery in the van, and so will not work on 12 volt unless connected to the car.
Ours works fine when we are connected to the car and running, and maintains temperature in both the fridge and freezer section of the unit. I have a switch fitted that turns off the 12 volt from the car to the fridge when we are stopped so the battery doesn't flatten.
There should be a wire in the 7/12 pin socket on the car, or perhaps a separate Anderson plug on the car that provides the 12 volt power when you are driving.
You may need to get this checked out to find out if it is actually working.
Maybe we're just lucky, or maybe Jayco made a mistake and got ours right. I certainly won't be rushing out to get a charger to make it "better."
The 40A was used as a comparison for a DC-DC charger, on a best case scenario against just using the cable.
My calculations are based on the complete circuit length, ie supply and return length for a 10M cable run or 20M total.
My end voltage is based on a supply voltage of 14V, so if you alternator puts out more than that, say 14.2V, then add an extra 0.2 VDC to the end voltage at 10A charge rate.
Once you get to float charge you may only be drawing 5A and this will give you a voltage drop of less than 150mV over the full 20M of cable.
going up to 4AWG at 20M total, you get the following voltage drops.
40A - 670mV = 4.8% of 14V supply
10A - 168mV = 1.2% of 14V supply
5A - <85mV = 0.6% of 14V supply
I suggest the reason "So many of vanners even with 4 or 6 gauge wires have had no success", is due to:
1) Poor connections in their cabling,
2) they have variable voltage alternators,
3) They are only driving 3 or 4 hours and expecting the batteries to be fully charged from below 70% SOC. This won't be achieved with a DC-DC charger either,
4) They don't understand cable sizing, and are going by "Auto Cable" sizing ie 6mm Auto instead of 6AWG. 6mm Auto = 4.5sqmm 6AWG = 13.5sqmm
Many vehicles with variable voltage alternators can have the voltage increased by roughly 0.5V, by adding a diode into the alternator's battery voltage sense circuit, to introduce a voltage drop in that line.
If you use decent sized cable (6AWG min) in combination with a 40A DC-DC charger, you have the best of both worlds. If you don't want the expense of a 40A DC-DC charger, use 4AWG cable min, if your run is excessive (10M or further). Or you can get away with 6AWG for smaller vans where your run is under 10M
Hi
IF the fridge was CORRECTLY wired to the Fridge MAKERS instructions it would have no effect on the van battery charging
& as long as the FRIDGE gets at least 12V at it's input while "ON" it will perform as intended& the Battery will be non the worse
Dc /Dc chargers are not the best FIRST step, just an inefficient EXPENSIVE way of overcoming voltage drop.
And forget about trying to run a 3way of solar panels ,they have gas for off 240V situations
But the unsuspecting public fall for the sale speil
If the Vehicle has a low voltage alternator , A DC DC charger may well be required to FULLY charge the van battery
.BUT that is ALL it should be doing ,charging the van battery
Running the fridge of it as well, simply puts extra load on the charger ,limiting its AVAILABLE power to charge the van battery even leading it to not see the true SOC of the van battery ,& thus defeating the very reason that it was designed for
-- Edited by oldtrack123 on Wednesday 13th of April 2016 11:21:57 AM
Hi All. All I can say is I have done something right with out extra expenses. 1. I charge a 2nd battery in the ute and run a 12volt low draw portable frig. 2. My anderson plug cable goes to the 3way frig for when travelling. 3. 3way on gas when stationary. 4. Solar charges the caravan house battery.
I like the kiss principal.
You can fit a "Fridge Switch" (google it) which is a Motion Sensor. If it cannot detect motion it will cut power to the fridge after a short time. This is to prevent it cycling on/off in heavy, stop/start traffic.
hi
Run the 3-6awg cable from the car battery to a T connection in the van..
One way to the input of the Dc2dc charger .
One way to the fridge . [ optional ....Install a fridge switch ]
........When u have a dc2dc charger wired from the output to the battery . Never ever use this cable as a power supply for the 3 way fridge............
It will disturb the charger from working properly . The charger will think it has a flat battery when it does not, current draw from the fridge will be happening say 12-15 amps .The problem it will keep pumping in power and most likely over charge the batt .
How its suppose to happen
There will be a trigger point in amps say current draw less than 5 before it will swap from absorbtion mode 14.6 volts and drop down to float mode 13.6 volts. With out this process the charger will stay at the higher voltage 14.6 volts and potentially overcharge .
swamp