Batteries good?

[navybanker]

Camper back from repairs from dealer and two batteries hooked up parallel. Group 27 deep cycle and three year old Interstates. Level up shows 11.9 volts so use my multimeter and it shows 12.0 on batteries. Call dealer and they check it in storage next to dealership and says the batteries are fine. I checked voltage on wires on top of battery box with power from both batteries. They say different from automobile batteries?? I hear something new everyday but this has me puzzled. No power supply in storage. I haven't tried anything to see if things work. Want to make sure camper is ready to go when go on next trip. Storage lot is one hour away. Educate me!!

[rohrmann]

Sounds like you need to get some power to the rig and get the batteries recharged. Once the voltage is back to normal, I'd disconnect the negative cable from the battery bank so you don't drain them before your next outing. If you can't get a power source, you might just pull them out and charge them at home. Before pulling them, take photos of all the cable positions so you can see the + and - marks on the batteries. That way you get them back in without blowing the reverse polarity fuses.

[Daryles]

Maybe put a flexible 12v solar battery charger on the roof. Run the cables down to the battery.
Take it down before you hit the road.

https://www.amazon.com/VICEMOB-Maint...jaz10cnVl&th=1


If your rig is pre wired for solar, use that wiring. Instal a solar panel and MPPT (charge controller).

[navybanker]

Thanks for the comments. The "dealership" service department told me they would recharge the batteries if they were discharged once the repairs were finished before they moved camper from their "back" lot to the storage lot. I repeatedly asked them to use the battery disconnect I installed on top of the battery box. The back lot is the graveyard of batteries! They move campers from the storage lot to their back lot for sometimes weeks before the repairs are made. Sorry for the rant as my purpose is to solve battery issue. This is my third fifth wheel so have many pics of every nook and corner of the camper. Pics are very helpful. I learned the hard way about polarity fuses on my first camper. I have considered the small solar units but they may grow legs or be damaged by wind if not secured. Always disconnected ground or used the new disconnect switch when leaving the camper in storage.
Several "auto" mechanics have told me that batteries with volts below 12.1 volts are dead. That maybe false.

"Thinking" about just selling the fifth wheel since there is no decent dealership near by. But, not a good time for that! Age is an issue also. It has been an outstanding 15 years going coast to coast and north and south. You guys are amazing and have helped me with many dumb questions thru the years.

[Foldbak]

Charge and test using this.
https://www.harborfreight.com/100a-6...iABEgJjkvD_BwE

[Lee-CI]

Originally Posted by Foldbak

Charge and test using this.
https://www.harborfreight.com/100a-6...iABEgJjkvD_BwE

Not as cheap as taking the batteries to AutoZone or O'Riely's for load testing, but well worth the price not having the hassle of taking the batteries out and toting them to town and back for testing. Leave it to Foldbak to find another golden nugget at Harbor Freight.

[navybanker]

On the charger and read 62% and 12.18 volts (batteries in "parallel") when charger turned on . May have to eat crow! I have acquired a taste for it. It hit me tonight that these are marine/rv/deep cycle batteries especially after had to set charger to deep cycle. Not auto batteries?? Supposedly, have a very good charger that will tell you every problem with batteries. No messages of symbols thus far. Now reading 78%.

[bcrvman]

Originally Posted by navybanker

On the charger and read 62% and 12.18 volts (batteries in "parallel") when charger turned on . May have to eat crow! I have acquired a taste for it. It hit me tonight that these are marine/rv/deep cycle batteries especially after had to set charger to deep cycle. Not auto batteries?? Supposedly, have a very good charger that will tell you every problem with batteries. No messages of symbols thus far. Now reading 78%.

The easy way to tell if you have rel deep cycle batteries is to look at the labelling and see if the initials CCA or MCCA or the words Cranking Amps or Marine Cranking Amps or similar appear. If any of those are seen, ir is NOT a true deep cycle battery. If you need them because you boondock, the most common is Trojan T-105. Inexpensive but 6V so you need 2. They will have twice the power of the average RV 12V not because there are 2x6V, but because they are 225AH batteries (usable of course is 1/2 of that).
As to voltages and %charged, see the following link. I will assume you now know that the batteries (Lead Acid) have to be kept above 50% or they perish in days/weeks. By now you probably know that at 11.9 or 12 the batteries are useless, you want 12.6. Of course if you have a cheap meter that is +-20% accurate then it will be useless since the difference between good at 12.6V and empty(50%) at 12.06 is about 4%. This jeans a battery meter with 1% accuracy minimum is needed. I have 6 Lithium batteries and NEVER use a VOM, I only measure with a shunt.
HOWEVER If you never plan on boondocking, then get any old FLA and ALWAYS keep the RV plugged in, but at some pint the slides won't work without a fresh battery. Plugging in can not provide enough power, only very healthy batteries can.
https://www.rvtechlibrary.com/battery/bat_volts.php

[N1282X]

It always amazes me these people that take their trailers in for service and let them be held hostage for weeks or months at a time. My trailer is far too valuable to me to let somebody else have it on their lot. Perhaps some of us just like the dealer to store their trailer for them myself I prefer to have mine in my RV garage under cover

[navybanker]

The camper is stored next door to dealership and has a gate to go in or out. Storage lot is owned by previous owner of dealership. I have asked them to not take the camper to their back lot until ready to work on. Repeatedly told them to disconnect the battery cut off switch installed if taken in even for a few days. Didn't happen! We could have taken to Camping World but??? The dealership is now owned by a three state operation and mostly new people. We do not boondock. Batteries are now reading 12.9 after 24 hour charging. The lack of good service and age has us deciding to sell if a reasonable price can be found. Not about to spend more money on better batteries since we used these type on three fifth wheels and the only problem has been the dealerships! Thank you

[phillyg]

You said,, "Several 'auto' mechanics have told me that batteries with volts below 12.1 volts are dead. That maybe false." I've heard similar, yet I've had two sets of batteries in fifthwheels get drained down to nearly nothing, and I've charged and used them for a long time. The current set is two years from the last drain down and still strong. I'm now using a small solar panel while in storage.

WRT a dealership, "'Thinking' about just selling the fifth wheel since there is no decent dealership near by." After an RV is past the warranty period, I try never to use any dealership for repairs. I'd rather DIY it or call in mobile service if I can't do something.

[Foldbak]

Originally Posted by phillyg

You said,, "Several 'auto' mechanics have told me that batteries with volts below 12.1 volts are dead. That maybe false." I've heard similar, yet I've had two sets of batteries in fifthwheels get drained down to nearly nothing, and I've charged and used them for a long time. The current set is two years from the last drain down and still strong. I'm now using a small solar panel while in storage.

WRT a dealership, "'Thinking' about just selling the fifth wheel since there is no decent dealership near by." After an RV is past the warranty period, I try never to use any dealership for repairs. I'd rather DIY it or call in mobile service if I can't do something.

Google is our friend
A typical 12-volt auto battery will have around 12.6 volts when fully charged. It only needs to drop down to around 10.5 volts to be considered fully discharged. If it drops down below that, the battery will become damaged due to excessive sulfation.
As a general rule.

[Rod Spohn]

On my old C class before I bought my 5er and I put a small solar panel in the window to keep the batteries changed while in storage. It worked very well for us. Anyway no worries about theft. Just my 2 cents.

[tjblocker]

Short chemistry discussion...
When a lead acid battery is being discharged, sulfates come out of the battery acid solution to coat the battery's plates. This sulfate coating is soft and if the battery is charged shortly after discharge then the sulfates return to solution leaving the plates resulting in good clean plates. This back and forth thing happens with every discharge and charge cycle. The battery discharges while sulfates form on the plates, and then during charging the sulfates leave the plates. But not completely, which is why lead acid batteries have a limited life. With each cycle some sulfates become permanent.

If the sulfates that form on the plates are allowed to remain for very long the sulfates harden and become permanent. This permanent coating interferes with the generation of electricity. This is the number one cause for lead acid battery failure. Lead acid batteries must never ever be stored in a discharged state. This is best maintained with a 4 stage charger. Modern RVs have one, and old RVs do not. And equalization should be preformed periodically (once per month) to force more of this sulfate coating to leave the plates and return to solution. In storage, the battery needs to be held to a minimum of ~12 volts (~50%). Lower voltages encourage sulfate formation. Also, to get max life from one the resting voltage should not fall below 12 volts, and better yet not below 12.6 (unless in use).

On an aside, if you took a brand new lead acid battery and discharged it, and if you stored that battery for a long period of time in this discharged state you can utterly destroy the battery even though it's been through virtually no charge/discharge cycles. Batteries should be kept as close to 12.6-12.7 volts as possible.
Storing batteries in a disconnected state is good advice. Attaining a full charge as soon as possible after discharge is also a good idea. using true deep cycle is excellent advice, but these have to be installed in pairs.

And if you boondock then avoid marine batteries. Using something like Trojan 105 6volt is a much better idea. These batteries resist sulfation better.

Last advice, for best life don't ever let the voltage fall below 12 volts. And know that a battery under load will read artificial low voltage and one being charged will read high. Resting battery voltages are what matters.
HTH
Tom

PS I avoid all this BS by using a LIFEPO4 bank.