Boondocked: How long should battery power last??

[jackconn]

In week 7 of our 3-month trek with Rockwood Mini Lite 2104S, purchased in March. New to the RV world and just spent first night of 3 nights boondocking (sort-of) in campground with hookup sites filled. We were very stingy using power since setting up mid-day yesterday. Used nothing but a few lights, the water pump a little, cell phone charger and what little power the gas fridge takes. Battery at 8V this morning and refrig in error mode. Hooked up to the Jeep to re-charge (ran Jeep part of the time) and monitoring voltage now. The single Interstate SRM-24 battery has dropped about about 2V in an hour.

This doesn't seem right - shouldn't the battery charge last more than about 16 hours assuming we're careful to not use more power than necessary? And I'm a bit surprised that the Dometic dual-mode refrig takes any power at all in gas mode, and won't run at 8V. (Goes into error mode at about 8.5V.)

Trying to get a site with hookups at this park for this stop, but this will certainly limit our camping options until I make whatever mods needed for at least a few days of boondocking. Guessing it's a bad (new) battery but maybe I'm expecting too much. Any other ideas out there?

[A32Deuce]

You may have trashed the bat. 50% is 12 volts.

[Mountndream]

its highly possible that the battery had already been damaged. If you didn't use a battery disconnect, the battery was probably close to dead before you started unless you put it on a charger.

the other issue you will have is that charging from the Jeep is going to take a LONG time to recharge.

DW and I had a 2015 2109s and we put 2 6v batteries for boondocking trips. Even then, we had a 2000w inverter generator to charge after 3 days or so

[jackconn]

Thanks for quick replies! What would trash the battery? Connecting and disconnecting from the Jeep?

What is the advantage of using 2x 6V batteries rather than 2x 12V batteries? Was thinking of adding a 2nd battery anyway after we get home, just to extend the boondock capacity.

[jeff64]

From my experience, the only way to evaluate batteries is with a capacity tester(toaster type) and hydrometer that accurately measures specific gravity. Since it's a new battery...
You might want to consider a 2000W inverter generator in conjunction with a 15/3A conventional battery charger. Like Mountaindream mentioned, trying to recharge battery using vehicle charging system is a LONG time deal and not real efficient method

[mkosu04]

this is a 12 V battery system, not 24V.
https://www.apexbattery.com/intersta...2SfxoCyz3w_wcB

You probably have some parasitic losses that you don't know about.
Perhaps try putting in a disconnect to shut down any other electronics except the fridge (and the CO and smoke detectors if hardwired) when you are dry camping?

Otherwise you will need to check the rated power usage on the fridge and calculate how long it will last for your 75 Amp Hour battery.

Also check whether your fridge is a 2-way or a 3-way?
Does your fridge have a fan in it?

These things could increase power usage.

[325BH]

Originally Posted by jackconn

In week 7 of our 3-month trek with Rockwood Mini Lite 2104S, purchased in March. New to the RV world and just spent first night of 3 nights boondocking (sort-of) in campground with hookup sites filled. We were very stingy using power since setting up mid-day yesterday. Used nothing but a few lights, the water pump a little, cell phone charger and what little power the gas fridge takes. Battery at 8V this morning and refrig in error mode. Hooked up to the Jeep to re-charge (ran Jeep part of the time) and monitoring voltage now. The single Interstate SRM-24 battery has dropped about about 2V in an hour.



This doesn't seem right - shouldn't the battery charge last more than about 16 hours assuming we're careful to not use more power than necessary? And I'm a bit surprised that the Dometic dual-mode refrig takes any power at all in gas mode, and won't run at 8V. (Goes into error mode at about 8.5V.)



Trying to get a site with hookups at this park for this stop, but this will certainly limit our camping options until I make whatever mods needed for at least a few days of boondocking. Guessing it's a bad (new) battery but maybe I'm expecting too much. Any other ideas out there?

There are probably many parasitic loads that you are not aware of... and add up.

Other issues:
You may not have started with a 100% charged battery
Just because an item consumes a small amount of power on propane mode, doesn't mean it can run on too low of voltage
If you ran down to 8 volts, that battery is probably dead permanently. 12 volts is 50% discharged and is all you should drain it to
Your usage of items drained more than you think

To boondock, you really have to know the math.

[johnm1]

When we had the "normal" dealer installed group 24 battery it lasted about what you got out of it. Maybe a day, maybe 2 but nothing more than than. We had to recharge 2x a day every day with the generator. Like mkosu04 stated, you only have 75AH (amp hrs) to work with before the battery get's down to 50% capacity. Lower than that and you start to damage the battery (ie: shorten it's life or it may not recharge well).

- Are your lights LED or incandescent? If incandescent, they suck power like crazy.
- The water pump is a huge power pig as well. Best to use the campgrounds bath house.
- The fridge needs power for the gas valve and electronics.
- The water heater takes power when turned on as well - same reasons as fridge.
- There are "phantom" loads that you can't control such as the carbon monoxide detector and all of our light switches are lighted so they draw power even if the lights aren't on.
- Even if the radio isn't on, the clock display is.

[Mountndream]

Originally Posted by jackconn

Thanks for quick replies! What would trash the battery? Connecting and disconnecting from the Jeep?

What is the advantage of using 2x 6V batteries rather than 2x 12V batteries? Was thinking of adding a 2nd battery anyway after we get home, just to extend the boondock capacity.

the battery was probably dead from before you hooked up. the parasitic draws drained it down and killed its capacity

I use 2 6v because I get a few more amp hours when i boondock in the NP's. Some people like using to 2 12v. its a personal preference based on my usage

your Jeep most likely has enough current to maintain the charge of your batteries, but not charge them

at 8v. You are going to need to replace that battery

[bikendan]

If you're serious about dry camping or boondocking, you need to have a better setup.
As was said, modern RVS have numerous parasitic power drains, because of all the modern conveniences.

A single cheap marine battery, like most dealers install, will only last one night. Less if you run the furnace.

So, minimum is a two battery setup, 6v golf cart batteries being the best.
Then an inverter generator or solar system to recharge the battery.

As was said, most tow vehicles only provide a trickle charge.
You may not even have any charge coming through the 7 pin connector.
Have you tested it to see if it does?

The battery is probably toast.

[kcmusa]

and dont forget the heater in the fridge!

[bikendan]

Originally Posted by kcmusa

and dont forget the heater in the fridge!

Yep, think it's an issue with my new TT.

[rockfordroo]

Originally Posted by kcmusa

and dont forget the heater in the fridge!

X2. The climate control heater (door heater) is a 6 watt heater and pulls 0.5 amps.

See pg 2.

[McCormickJim]

In addition to my Georgetown 31L5, I have a Lance 1575, with a single, 12v battery. When summertime boondocking with the Lance, I carry a 110W Zamp solar charger. I use all 12V appliances as needed and never run out of battery. I'm conservative and turn off things not in use, but other than that conservatism, everything just keeps running and the battery stays at 12v or greater. There obviously is no AC available, but I can use the heater when needed, but I set it at a VERY low temperature and use nice sleeping bags instead of battery power and propane.

For summer boondocking, when the AC is needed, I carry a Honda 2000W, gas powered generator.

If your refrigerator is a 3-way, be sure to keep it on propane, even when going down the road. If you have it on 12v while rolling, it will draw more from the battery than your jeep can keep up with. You'll get to your campsite with a drained battery. The only time your refrigerator should be turned to 12v is never.

[Schvarak]

Originally Posted by jackconn

Thanks for quick replies! What would trash the battery? Connecting and disconnecting from the Jeep?

What is the advantage of using 2x 6V batteries rather than 2x 12V batteries? Was thinking of adding a 2nd battery anyway after we get home, just to extend the boondock capacity.

Having read all of the thread, one question that hasn't been asked yet is very important! You say you're into week seven of your trip. We're all your previous stops always connected to shore power? If not, that answers that important question. 6-7 week's of camping without continuous shore power will burn up the voltage quickly. When towing between stops, like others have said will only be a trickle charge that won't charge the battery much at all. Since its a new rv, you should have a one year warranty on the new battery try to get it replaced under warranty. Also as has been said, parasitic discharges will quickly eat up the voltage in 7 weeks. Make sure you get a cheap disconnect switch to eliminate the parasitic discharges.
See below for one that costs around $5.
That'll work wonderfully with a dual battery system. I'm very experienced with it (Had to replace 2 batteries in my MH) that had been trashed by parasitic discharge over a month of storage. Good luck with your situation!

[EricE]

One thing nobody has mentioned yet is that you cannot add battery capacity by just adding another battery to your system. If you want a two battery system, you purchase two of the same batteries together at the same time from the same dealer. If you want a four battery system…purchase them all together.
Since you battery is likely damaged, you can get two at the same time. The reason for this is the battery must have the EXACT same capacity and charge characteristics. They will be wired together (not isolated). If they were different the charge would flow back and forth between them and they would wear out in short order.

[Schvarak]

Originally Posted by EricE

One thing nobody has mentioned yet is that you cannot add battery capacity by just adding another battery to your system. If you want a two battery system, you purchase two of the same batteries together at the same time from the same dealer. If you want a four battery system…purchase them all together.
Since you battery is likely damaged, you can get two at the same time. The reason for this is the battery must have the EXACT same capacity and charge characteristics. They will be wired together (not isolated). If they were different the charge would flow back and forth between them and they would wear out in short order.

Exactly, i forgot to mention that in my previous post! I had different batteries that i replaced both with after mine went bad😁

[camaraderie]

A group 24 battery has about 7o amp hours of power. You can use 35 of these safely. (50% rule). Right now my laptop is using 2 amps so I can use it for about 17.5 hours before my battery needs to be recharged with a real 3 stage charger and it will take 4-6 hours of generator to do this since at maximum...the battery will only accept about 18 charging amps and taper off rapidly after that till it reaches 100% charge. To put back in 35 amps via solar you would need roughly 140 watts of panels...double that for a two battery setup cause it is pretty evident that 35 ain't enough!
You can see that one battery is totally insufficient for boondocking but it is fine if you are plugged in somewhere. If you want to boondock...you need to expand your battery bank to meet your typical needs and expand your charging method (generator or solar) to feed your upgraded bank.
As others have said ...your group 24 is likely toast now. If you plan on doing boondocking be sure you get TRUE deep cycle batts...not dual purpose deep cycle.

[Herk7769]

Originally Posted by rockfordroo

X2. The climate control heater (door heater) is a 6 watt heater and pulls 0.5 amps.

See pg 2.

Bingo. This is my first "goto" for a short lived battery. The newer refrigerators have no way to disconnect the "Climate Control" when on battery power like the older ones did.

You will need to remove the Climate Control power wire (behind the fridge light) when you boondock with a fridge without a switch.

[Hardhead]

Another thing you might want to consider is placing an ammeter (current) meter in series with the positive terminal of the battery(ies) and monitor exactly how much current your unit is drawing. Turn everything off first, the try turning things on one at a time. Based on how much current is being drawn from the battery, you should be able to figure out approximately how long the battery will last (give or take). It'll also give you an idea which items are the power pigs if you don't already know.
Another thing you may want to consider (as mentioned earlier), is to invest in a portable generator with a battery charger output. It'll save you a lot of headaches especially when the weather starts getting colder. Good luck. :-)