Battery overcharging

[UP WANDERER]

Hey Everyone
We have a 2017 Vengeance Toy Hauler that came with one battery, I added two more for a total of three for Boondocking but now The batteries seem to be overcharging. Are the Converters specific to how many batteries they support?

 

[FL-JOE]

I'm no expert when it comes to inverters, chargers, or much else electrical. I do know from my boating days and now my RVing experience that generally speaking when you have more than one battery on the same charging system they should all be the same age. I believe the theory is that if you add a couple new batteries to an older battery they will not charge at the same rate. Maybe your charger is overcharging the newer batteries because it can't get the older one up to speed?

 

[Buly]

How do you know they are overcharging? What is your charge voltage? Overcharged batteries will get very hot to the touch.

 

[UP WANDERER]

Thanks for the replies Guys, yeah one of the batteries was very warm almost hot.
Yup next chance I get I will check voltage on them.

 

[Kevin D Pem]

Fl-Joe is on target. surface resistance on an older battery will make it charge slower. Mix and match does not work. For flooded batteries (those you can add water to) a battery manufacture date older than 6mos different is not recommended.

This is what happens:
the older battery takes longer to charge up because of the resistance.
The new battery charges quickly.
The collective voltage( the voltage seen by the charger) reflects the uncharged state of the older battery. This keeps the charger charging when the new battery is fully charged. fully charged batteries heat up when additional charge is added.

The result is the new battery is distroyed while the older battery gets charged to capacity. If the battery is new take it out of the circuit until you replace the older battery. Don't take more than 6 months to replace the old battery or that new one will be the old battery, and distroy any new battery you put in to replace the old.
The rule of 6 mos applies to batteries on the shelf, not used in a system, so the next battery should be judged by the manufacturer date, not purchase date.