Battery losses & charging from a vehicle

[climb_on]

We are heading out on a month long trip on Wednesday and I got to thinking about a potential issue we might face during one particular leg of the trip.

After camping for a few days as we travel from MN to CO, we will be parking the camper in an "overflow lot" for 6-7 days while we stay in our condo in Breckenridge CO. The batteries will be fully charged when we park it and it the camper will be unused. We will then be heading out back out and doing some dry camping for 3-4 days before getting to a campground with shore power.

My questions are:

1. If I turn off the batteries when parked in the "overflow lot" how much loss will the batteries have when we get back on the road? I realize this can't be quantified exactly...but will it be significant?

2. Will I be able to recover all my losses (if any) while traveling to our dry camping location in a 4 hour trip?

3. Generally how effective is the charging system from a vehicle to replenish the RV Batteries?

I have (2) 6v Costco Golf Cart Batteries - 220AH

[mena661]

climb.on wrote:
I built it as part of a graduate project and just didn't have time to install it before this trip.

Use it as a portable until you do. Strap it to a small ladder, aim it at the sun. If you have time, buy a Morningstar MPPT 15A controller and some #10 wire off of ebay.

blw2 wrote:
I've read that self discharge is up to approx 5% per month, I believe that was the number.....

For 6V batteries it can be that much if they are new or nearly new. 12V discharge much slower.

[blw2]

I've read that self discharge is up to approx 5% per month, I believe that was the number.....

[Harvey51]

We never plug in while camping and rely solely on engine charging. If you disconnect, no problem. With the fridge running, you will run the batteries down too far sitting for a week, damaging them.

[RvBill3]

Regarding recharging while traveling: Not sure about your Toyota, but my Chevy Avalanche says that running with tow/haul mode ON will slightly elevate the idle speed, assuring that the charge line to the trailer will charge batteries more quickly.

[Canadian_Rainbi]

climb.on wrote:

Did you mean 4 hours @ 60 amps? I have just 220 total AH as the (2) batteries are wired in series.

I thought if I disconnected the batteries, will the fridge would still work on propane? Is that not correct?

No, that is not correct. The fridge needs 12 volts to run the circuit board that controls the cooling.

Too bad that you don't have time to install that solar panel. It would do the trick. I run 420 Watts of panels for 480 AH of battery.

[climb_on]

Passin Thru wrote:
2 Yes and depends. Now for the real answers/ Depends on the amperage draw. Leave the Fridge on propane and it still needs battery to run but with fresh batteries will run for a year. $ hrs at 60amps will charge a battery.Charging systems vary. A 120 AMP system is twice an fast as a 60 AMP so it's hard to say. 440 AH batteries are big so go for it.

Did you mean 4 hours @ 60 amps? I have just 220 total AH as the (2) batteries are wired in series.

I thought if I disconnected the batteries, will the fridge would still work on propane? Is that not correct?

[MrWizard]

Moved from technology corner

[climb_on]

smkettner wrote:
If the battery is truly off then it will lose no charge in one week.
I recommend removing the negative battery cable if you are not absolutely certain the switch cuts all connections.
The vehicle charging is generally fairly slow especially above 90%.

And I need to give a plug for 100+ watts of solar would make this a non-issue. Might make the boondocking part go smoother too.

Thanks. Your comment about solar is well received...I have a 250w watt panel sitting in my garage waiting to be installed. I built it as part of a graduate project and just didn't have time to install it before this trip.

[time2roll]

If the battery is truly off then it will lose no charge in one week.
I recommend removing the negative battery cable if you are not absolutely certain the switch cuts all connections.
The vehicle charging is generally fairly slow especially above 90%.

And I need to give a plug for 100+ watts of solar would make this a non-issue. Might make the boondocking part go smoother too.

[Passin_Thru]

2 Yes and depends. Now for the real answers/ Depends on the amperage draw. Leave the Fridge on propane and it still needs battery to run but with fresh batteries will run for a year. $ hrs at 60amps will charge a battery. Charging systems vary. A 120 AMP system is twice an fast as a 60 AMP so it's hard to say. 440 AH batteries are big so go for it.