Running off starting battery

[Firebuild]

Can anyone tell me how much is safe (in terms of battery juice) to run off the starting battery overnight?

I ask because I just read something from fridge maker ARB suggesting that a fridge can easily run for 24 hours and still leave you enough to start the vehicle, and I'm wondering if that's true.

 

[XERTYX]

I would doubt that statement very seriously. Personally I wouldnt risk running more than a cell phone charger overnight if that off of the starting battery.

Starting batteries arent designed to be heavily discharged like a marine deep cycle battery is. It might work for a while but eventually it would lead to an early death of your battery leaving you stranded and with warm spoiled food to eat until you can get help.

Many 12v compressor fridges dont use very many amp hours per day and could easily be ran off of an auxiliary battery which could be charged by solar and the vehicles alternator.

The trouble with alternator charging either to an auxiliary battery or to the starting battery at a deep depth of discharge is that it would take several hours to replace the juice.

 

[highdesertranger]

it depends. it's not the most ideal way to do it but some people have been successful doing it. the most important thing is, how are you going to recharge it? for long life the battery should be recharge to 100% everyday. using the alternator to do this job is also not ideal for long battery life.

ARB is being very irresponsible if they are leading you to believe that this is a viable option.

highdesertranger

 

[Firebuild]

It was actually  quote from ARB on someone else's website. I'm going to hope it was a misunderstanding. I'm not really planning on doing it myself, but I was curious if there was anything to it.

 

[XERTYX]

I'd imagine that if this was their official statement it was meant for weekend warriors camping for 24 hours then driving back 7 hours to the safety of the concrete jungle. Or perhaps for over the road truck drivers or someone who would have many many hours of wheel time in their future after a short stay.

 

[Firebuild]

Right, I guess it you were moving continuously it could be a decent plan.

 

[highdesertranger]

to be fair ARB sells a lot to your weekend warrior expedition vehicle types. they go out for 2, 3, or 4 days and do lot of driving. so for these types of users it would work fairly well.

note, I am not taking anything away from ARB, they have good stuff.

highdesertranger

 

[whatsananna]

So, along those lines, I have a 125 ah AGM house battery attached via battery isolator to start battery. I drive 40 minutes each way to work and my van is my daily driver.

How far down can I let the house battery safely go on the voltmeter - 12.0? 11.8?

And would my 40 minute commute recharge it done twice daily?

(Part time van dweller currently - husband prefers the 5th wheel.)


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[highdesertranger]

"And would my 40 minute commute recharge it done twice daily?"

maybe if lightly discharged.

"How far down can I let the house battery safely go on the voltmeter - 12.0? 11.8?"

I wouldn't go below 12.4-12.5. 12.2 is 50% you should never go below 12.2. and if you do go that low it's going to take 6-8 hours of driving at highway speeds to recharge. never take it to 11.8 or 12.0, doing this more than a few times will drastically shorten battery life.

disclaimer, battery voltage is a poor indicator of state of charge.

highdesertranger

 

[whatsananna]

Thank you!!

I also have a solar suitcase but can’t have that out in the parking lot at work.


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