Battery addition
- Thread starter maulbeagle
- Start date
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Yes it will. The fuse is there to protect against cable damage, and it's highly unlikely that you'll get anything in there to do damage.
I can see two issues with the drawn circuit, maybe I am just reading things wrong? The ignition-sourced relay seems to power the fridge from the rear aux batteries only when the ignition is on, and the front aux battery is permanently connected to the rear ones. I think you meant for that relay to sit under the Setec, and the power for the Setec to be drawn from the aux to feed the rear aux batteries.
Here's how I'd do it. All of the earths (negatives) are connected just like yours - that's a good base. Positive power comes down from the aux battery but is only switched on by the relay when the ignition is on, and feeds power to the Setec charger which then supplies power to the currently selected battery which is permanently connected to the fridge.
I've numbered the connections on the relay.
The output of the relay feeds an inverter (the Setec is a mains-powered charger). This stops the inverter (and therefore the charger) from operating while the engine is off.
Am I making things muddier?
I can see two issues with the drawn circuit, maybe I am just reading things wrong? The ignition-sourced relay seems to power the fridge from the rear aux batteries only when the ignition is on, and the front aux battery is permanently connected to the rear ones. I think you meant for that relay to sit under the Setec, and the power for the Setec to be drawn from the aux to feed the rear aux batteries.
Here's how I'd do it. All of the earths (negatives) are connected just like yours - that's a good base. Positive power comes down from the aux battery but is only switched on by the relay when the ignition is on, and feeds power to the Setec charger which then supplies power to the currently selected battery which is permanently connected to the fridge.
I've numbered the connections on the relay.
The output of the relay feeds an inverter (the Setec is a mains-powered charger). This stops the inverter (and therefore the charger) from operating while the engine is off.
Am I making things muddier?
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maulbeagle
Member
The reason the fridge is only run on 12V when the car is running is so it can't drain the house battery.
I get the fridge cold on 240V before I leave home, then use the house battery (which is being charged by the car aux batt, which in turn is charged by the car main battery through a Redarc isolator) to run the fridge on 12V while driving.
Also, the house battery is only ever connected to the car aux batt while towing.
Wouldn't the setup in your diagram allow the fridge to drain the house battery ? It seems to have nothing between it and the battery to isolate it.
The SETEC (I thought) only charges the battery when on 240V, so I just use this when we get to a powered site, or at home to keep the battery topped up.
I'd like to avoid an inverter if possible.
I think my setup avoids anything draining batteries while the engine is off, but am happy to be corrected ?
Thanks again for all your advice.
I get the fridge cold on 240V before I leave home, then use the house battery (which is being charged by the car aux batt, which in turn is charged by the car main battery through a Redarc isolator) to run the fridge on 12V while driving.
Also, the house battery is only ever connected to the car aux batt while towing.
Wouldn't the setup in your diagram allow the fridge to drain the house battery ? It seems to have nothing between it and the battery to isolate it.
The SETEC (I thought) only charges the battery when on 240V, so I just use this when we get to a powered site, or at home to keep the battery topped up.
I'd like to avoid an inverter if possible.
I think my setup avoids anything draining batteries while the engine is off, but am happy to be corrected ?
Thanks again for all your advice.
Last edited:
Does your 3-way fridge use 12V if it's turned to gas? It should disconnect itself through the switch that chooses the energy source (and if it's an AES fridge, it will do it by itself).
I think the point of a house/auxiliary battery is to be drained, although 3-way fridges do draw lots of power. In our new van, we run the fridge from battery but drive an inverter to use 240V for the fridge - because the 12V input is unregulated, and the 240V input uses a thermostat. If you want to avoid the inverter and only have the Setec driven when connected to mains, your original diagram is pretty good.
I did consider it from a "let's just charge the batteries" perspective, that is a mistake. Yours looks just fine, in that case!
I think the point of a house/auxiliary battery is to be drained, although 3-way fridges do draw lots of power. In our new van, we run the fridge from battery but drive an inverter to use 240V for the fridge - because the 12V input is unregulated, and the 240V input uses a thermostat. If you want to avoid the inverter and only have the Setec driven when connected to mains, your original diagram is pretty good.
I did consider it from a "let's just charge the batteries" perspective, that is a mistake. Yours looks just fine, in that case!
maulbeagle
Member
my fridge only uses 12V when selected.
The thing is, I'd have it set to 12V while towing, then if I stop the car, I need to know it won't drain the battery, without having to crawl into the trailer (poptop Jayco Flamingo) and shift the selector.
So for a basic "add a second battery with selector switch" point of view, it looks OK ? The ORIGINAL diagram is how it is now, with just 100AH of AGM Battery. The PROPOSED is how I think I'd go about adding a second, 200AH AGM battery.
Thanks !
The thing is, I'd have it set to 12V while towing, then if I stop the car, I need to know it won't drain the battery, without having to crawl into the trailer (poptop Jayco Flamingo) and shift the selector.
So for a basic "add a second battery with selector switch" point of view, it looks OK ? The ORIGINAL diagram is how it is now, with just 100AH of AGM Battery. The PROPOSED is how I think I'd go about adding a second, 200AH AGM battery.
Thanks !
Sure does!
I don't think I'd be too worried about it draining the battery. First, your aux battery is still connected to the 100/200 pair at all times (so you might consider disconnecting before letting the Setec at it) and in real terms if you stop at a servo and fill the tank (10 mins) pay for it (2 mins) take a leak (4 mins) buy a coffee (8 mins at a McCafe, 30 seconds in the servo but make sure you have medical insurance) you're talking about a half hour stop. A fridge like ours (380W on 12V) is using a little over 30A, and in half an hour that's 15A total draw.
Even stopping for an hour won't cause a great deal of harm to the battery and with the alternator providing around 20-30A at mid-range throttle (after all other electrical expenses) you'll be fully charged again within the hour.
Drawing that from the aux battery which is separated from the starter by an isolator or VSR would be the best way to manage that too, keeps the starter 100% protected.
I don't think I'd be too worried about it draining the battery. First, your aux battery is still connected to the 100/200 pair at all times (so you might consider disconnecting before letting the Setec at it) and in real terms if you stop at a servo and fill the tank (10 mins) pay for it (2 mins) take a leak (4 mins) buy a coffee (8 mins at a McCafe, 30 seconds in the servo but make sure you have medical insurance) you're talking about a half hour stop. A fridge like ours (380W on 12V) is using a little over 30A, and in half an hour that's 15A total draw.
Even stopping for an hour won't cause a great deal of harm to the battery and with the alternator providing around 20-30A at mid-range throttle (after all other electrical expenses) you'll be fully charged again within the hour.
Drawing that from the aux battery which is separated from the starter by an isolator or VSR would be the best way to manage that too, keeps the starter 100% protected.
macka17
Member
Hi.
There are also multi outlet chargers.
with (mine has 4) wiring for whatever.
Total output (mine) is 20a. They go up to 50a.
Wire up say three battery's i x 70a and 2 x 80a.(example) requiring differing levels of charge.
The charger WILL charge each, as req'd. UP TO its COMBINED max or 20\30\40 etc amp.
Giving the higher no req'd to the one needing it most.
Mine is a marine. and cost an arm and a leg (ex last yacht). But worth it. Sitting in garage now with it's companion Trace solar\alt\wind, Pot regulator and 2 x dumps.
If anybody interested.
There are also multi outlet chargers.
with (mine has 4) wiring for whatever.
Total output (mine) is 20a. They go up to 50a.
Wire up say three battery's i x 70a and 2 x 80a.(example) requiring differing levels of charge.
The charger WILL charge each, as req'd. UP TO its COMBINED max or 20\30\40 etc amp.
Giving the higher no req'd to the one needing it most.
Mine is a marine. and cost an arm and a leg (ex last yacht). But worth it. Sitting in garage now with it's companion Trace solar\alt\wind, Pot regulator and 2 x dumps.
If anybody interested.
wa navigator
Member
My first question would be, do you need more than 100 ah ?, if so fit the 200, if not, sell the 200 and buy something else that you want or save the bucks ready for when the 100 dies.
