Recent Problems - Rapid Battery Draw Down and More

[Bob K4TAX]

If it works the way it came from the factory, then I'd connect it the same way with the new batteries.

The rule is "if it works, don't try to fix it".

To be absolutely precice, the drawing is the better way. However, either way won't may a hairs worth of difference.

Bob

[dward51]

That's a lot of water (a gallon across 2 batteries). You have definitely damaged them to some level and they may not ever properly charge or hold a load. At this point, try it and see how it goes.

I presume your inverter is also the charge controller for the solar? Or do you have a separate solar controller that pairs with the inverter? And is the inverter also your shore power converter charger? I've seen it both ways and I'm not familiar with your exact model and the specs don't make it clear. You might want to check the output of those as well.

Something else I did not see you talk about is how deeply do you discharge them when dry camping? Wet cell batteries are not supposed to be discharged below 50% capacity. So a 100amp battery should only be taken down to 50amps before fully recharging. It's easy to go lower when dry camping. To go below that will also damage them and decrease their life.

If you do find they are no longer going to work, you might want to think about changing to a golf cart type battery bank wired for 12v. You get heavier duty plates, better resistance to over discharge, and more amp capacity with golf cart batteries and they should work just fine with your existing charger and solar panel. Other option is Lithium, but price is much more of an issue and you will likely have to change out your converter/charger and solar charger (and inverter if you have one) unless they can be set for lithium batteries. That's just more expense over the cost of the lithium batteries if you go that route, but that will give you the absolute most dry camping time on a comparable amp capacity bank.

[Bob K4TAX]

Lead acid batteries including AGM's should never be discharged below 11.9 volts! This shortens battery life. Discharging below 11.5 volts is sure to cause permanent damage which is irreversible.

Loss of water is typically caused by overcharging for a long period of time thus boiling out the electrolyte. You'll need to check the converter to see that it does not overcharge the new batteries. If not, before long you will have new batteries which are defective.

A battery that charges but doesn't hold a charge or quickly shows a low discharge voltage is a defective battery.

Typically battery life is about 5 years as long as they are maintained properly. Abuse them and they quickly become heavy door stops.

Bob

[jsk125]

Well ..

One battery was toast. The other may be salvageable. I went to a nearby Interstate store.

I asked how the water could be baked off like that - now granted I didn't check them well - but in 27 years of camping this has never happened.

He had no answer other than 1) overcharging or 2 ) who knows.

The controller is supposed to not enable overcharging, correct? Driving the car might, but I typically have the fridge on, so it should be replacing lost amps at most.

I've bought two true deep cycle 12v, not the hybrid multi use batteries that came from the factory. The interstate guy is hanging on to the battery that does now show dead, and is charging, and will let me know. I'll use that as an emergency battery - and in the winter take out the two newer ones and let that old battery sit in there.

Also, I've setup a monthly reminder to check the fluid levels.

My primary concern is still "how" that happened, beyond my negligence. I've had batteries 2-3 years and barely had to put water in them ever.

Thanks for all the ideas and comments.

[dward51]

Since your TT is a 2002 model, this seems to be the new variable in the equation since you did not have this problem in the past 27 years. This would lead me to suspect the charging setup, mainly the solar.

Do you have a dedicated solar charge controller or are the panels basically just wired into the 12v system in the trailer directly? If you don't have a dedicated controller, I would add one as a 190watt panel can easily put out more than 10amp even being less than 100% efficient, especially on sunny days. If you have a solar controller, check the manual for any setup options and make sure yours is configured for the battery setup you have.

Next suspect would be the converter or inverter/converter if a combo unit. Look at the manual and see what jumper or other setup option there are and then check how yours are set. It may be set for a different battery chemistry type which could also cause over charging.

To me, these would be the obvious locations to start looking for a cause. If you don't find the root cause, you may end up having issues with the new batteries as well. At least eliminate these as possible contributing factors.

[jsk125]

I may have mistyped somewhere. It is a 2022 Rockwood Minilite 2511s .. 190w panel. There is a Go Power 30amp controller, and a built in converter already.

Jim

[GravelRider]

Where do you live?

Did you check the battery's fluid level when it was new? I wonder if it was never properly topped up when it was installed.

[tomkatb]

As your batteries come up in charge the smart charger backs off the voltage. My battery monitor records voltages and you can watch the smart converter go down in voltage.

If you do not, then the batteries get boiled. Sometimes they explode.

Old car chargers were not smart. You could easily ruin a battery.

Before time began they used to sell mini battery chargers with no controller. They could discharge batteries as well as overcharge.

[MNtraveler]

Originally Posted by jsk125

Well ..

One battery was toast. The other may be salvageable. I went to a nearby Interstate store.

I asked how the water could be baked off like that - now granted I didn't check them well - but in 27 years of camping this has never happened.

He had no answer other than 1) overcharging or 2 ) who knows.

The controller is supposed to not enable overcharging, correct? Driving the car might, but I typically have the fridge on, so it should be replacing lost amps at most.

As others have said and you now know, it's from overcharging. Our batteries are 7 years old and still working fine. The only occasionally need small amounts of water added. Often I check them after a multi-week trip and no cell in either battery needs water.

Now you can watch your new batteries more closely to see what is going on. This information from Progressive Dynamics (maker of great converters) should be helpful in showing how a good converter/charger "should" work to avoid overcharging and boiling your batteries:

https://www.progressivedyn.com/rv/charge-wizard/

Probably your RV has something like this but in all likelihood the solar charge controller either doesn't have this kind of logic or else it's busted. Of course, it's also possible your RV converter isn't working correctly. You will have to isolate them to know which is working and which isn't (or if it's something else). Remove the solar charge and watch what they RV converter does. Then use the solar charger and turn off the RV converter (at the circuit breaker box, or else there will be a separate breaker on the converter) and see how the solar charger works. Once you monitor each system separately, you will be very happy to know how everything works, but possibly mad at one or the other system.

Good luck.

[RavensRoost]

Originally Posted by tomkatb

Operator error.

Happens.

The modern rv is getting very complicated.

Sometimes solar controllers don’t. You now know the result. Not a solar fan. I live in the Midwest. Ohio.

Wet cell batteries fully charged will be fine without charging for 4-6 months.

Research batteries before buying. Measure.

GC 2 batteries are the best bang for the buck. However you have to check levels. Second best choice is lithium because of cost. Agm/maintenance free are expensive. Also do not last as long and are not as abuse proof.

I suspect in your case they would be toast. Already in the trash.

I have a 2511S with the same 12vdc fridge/solar panel package. The dealer wanted to set it up with 2 12 volt car batteries in parallel but I insisted on two 6 volt GC batteries in series and I have had no issues with the system. However, the only boondocking I've done with it was in the driveway when Dominion Energy had an extended outage

[Civilguy]

Originally Posted by RavensRoost

The dealer wanted to set it up with 2 12 volt car batteries in parallel but I insisted on two 6 volt GC batteries in series

This!