Charging a battery with ARB fridge connected?

[Mayne]

Can this be done? Or is it verboten. I believe I've read that solar charging settups are being used, but I thought I read that charging the battery with the fridge hooked to said battery was not the best idea. Is this just the case while charging off a generator, or actual 110v charger?

Any clarity on this would ge fantastic.

Thanks
Mayne

 

[toymaster]

Not forbidden at all. What ever power source you are using must be putting out more power than the fridge is using for the excess to be stored in the battery. With a generator or AC charger this is not a problem at all. A solar panel depending on the size may not put out enough power to do both duties but you will still see longer life from the battery as the solar panel is helping out by producing some of the needed power.

 

[dwh]

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(If anyone is subscribed to this thread and can PM me my original post (before the editor ate half of it), please send it to me so I can fix this. Otherwise...I'm too pissed off right now to even bother trying to recreate it.)

Can this be done? Or is it verboten. I believe I've read that solar charging settups are being used, but I thought I read that charging the battery with the fridge hooked to said battery was not the best idea. Is this just the case while charging off a generator, or actual 110v charger?

Any clarity on this would ge fantastic.

Thanks
Mayne

Charging a battery while also running loads from it is perfectly OK, provided, as toymaster already noted, that the charger can put out enough power to supply all the loads and have something left over to feed the battery.


There is an issue if you are running loads while charging a battery with a 3-stage charger.

The issue is that many (most really) 3-stage chargers determine when to end the absorb stage by monitoring the amp flow. When the flow drops below a certain point (usually 1a-3a or so), the charger ends the absorb stage and switches to float stage.

If you have a few amps of loads running, the amp flow never does drop below the threshold, and the charger gets "fooled" into staying in absorb mode. This results in the battery getting%

 

[DaveInDenver]

Absorption mode will be constant voltage at 2.45V per cell with a current limit, the battery should be self regulating charge current and it would only be a problem I think if the charger was fooled into leaving absorption and returning to bulk. Another problem would be if the charger is fooled into staying in bulk mode because the load depressed the terminal voltage, so it misses a trigger voltage (typically 2.35V/cell). That's where a time-out is important. The charger remains at constant max current thinking the battery is still discharged and overcharges or overheats. In either case, be it a current surge or voltage dip, decent logic in the charger is important.

I've been running an Iota 45 with IQ4 for a few years into a pair of AGMs at home and I have no indication it's being fooled with the fridge cycling or ham radio use. The easiest thing to do is use a float tender immediately when pulling into the garage. The battery should be charged and there's no potential for overcharging. Even if the charger does not have enough capacity to run the fridge, the duty cycle should be low enough that the battery overall stays charged or at least very slowly discharges. But if you want to use a multiple stage charger but aren't sure about it, it's safest to unload the battery during charging, though.

 

[Mayne]

That helps clarify things. I see that the fridge most likely wouldn't get effected, but if done wrong , I could fry the battery.

 

[DaveInDenver]

That helps clarify things. I see that the fridge most likely wouldn't get effected, but if done wrong , I could fry the battery.

'Fry' is probably over worried but a poor charger could reduce the life of the battery.

 

[Mayne]

So just more economical doing it correctly. The fridge other than draw has really no part in this equation.
As you can tell I'm a bit careful of my fridge investment.

 

[dwh]

So just more economical doing it correctly. The fridge other than draw has really no part in this equation.
As you can tell I'm a bit careful of my fridge investment.

As regards the fridge, the only issue from running it while charging, is over-voltage. To get a battery to full charge, you have to raise its voltage a good bit over normal.

Some devices can be damaged by over-voltage, but your fridge almost certainly has built-in protection against both over- and under-voltage.

No worries there.

 

[DaveInDenver]

As regards the fridge, the only issue from running it while charging, is over-voltage. To get a battery to full charge, you have to raise its voltage a good bit over normal.

Some devices can be damaged by over-voltage, but your fridge almost certainly has built-in protection against both over- and under-voltage.

No worries there.

I'd agree, the fridge should be tolerant of anything a charging system might try to do to a battery with the possible exception of an equalization (which should be done carefully anyway). Heck, fridges are designed to run while the truck is being cranked, which is worse than any charger for noise and spikes, so I'd expect they have protection.

 

[dzzz]

I agree it's no problem.
All of us with installed 12v fridges plug into shore power. Vast numbers of RVs are charged every day with electrical devices running. The situation may not be ideal, but all chargers and 12v appliances have to be designed with this real world use.

 

[Driver-Navigator]

FWIW at OX12 I ran four Goal0 panels to a charge controller that was then hooked up to my main battery, while running my Engel fridge the whole time. No issues.

 

[fredgoodsell]

FWIW at OX12 I ran four Goal0 panels to a charge controller that was then hooked up to my main battery, while running my Engel fridge the whole time. No issues.

Kind of veering off topic, but how many watts each are the panels you're using?

 

[Driver-Navigator]

Kind of veering off topic, but how many watts each are the panels you're using?

Three Escape 30 briefcase panels at 30W each and one fold-up Nomad 27 at 27W, for a total of 117W max. They all run into the charge controller which IIRC is rated to 150W.

I'd really like to have a charge controller that displayed exactly how much power was going in and out of the system, but I was able to keep an eye on things pretty well using the display/controller for my IBS dual-battery system.