Battery Charger

I have deep cycle (4 ea) 6 volt golf cart battery wired together for 12 volts on my house side and (2 ea) 12 volt batterys wired together for 12 volts on the start side.

My shore powered battery charger is wired to charge both banks. It is a smart three stage battery charger.

Does it matter that the battery charger is chargeing two different kind of batterys?

I leave it connected all winter while the boat is laid up (in the water) and have to add significant water to each of the batterys each spring.

It seems like it is over charging but it shouldn't be if it is a smart charger.

Looking for more information, thanks.

The fact that your house batteries are six volt batteries wired in series and your starting batteries are twelve volt batteries wired in parallel doesn't make them "two different kind of batterys". "Kinds" of batteries refers to the chemistry or construction i.e flooded cell, AGM, or gel batteries.

If all the batteries are flooded cell batteries or all are AGM batteries, you are fine. Actually if the six volt batteries are flooded cell and the twelve volt batteries are AGM, you're probably OK as the charging requrements are very similar.

Remember that once you leave the dock, your boat's alternator is charging all the batteries, regardless of the chemistry or construction.

BTW: Two six volt batteries wired in series are electrically the same as a single twelve volt battery. A six volt battery contains three two volt cells wired in series. A twelve volt battery contains six two volt cells wired in series. Connect a cable from the positive terminal of one six volt batery to the negative terminal of another six volt battery and you have six two volt cells wired in series - a twelve volt battery.

As for having to add significant water to the batteries, you need to define "significant", but you shouldn't let them get low enough that you have to add a lot of water. Check and add water at shorter intervals. You may be overfilling the batteries.

If you have one weak or partially shorted battery, this could cause the charger to try to compensate and overcharge the others. Have them all load tested.

Ditto what Rwidman said. In addition if you think you're using too much water, check the actual float voltage with a digital volt meter at the battery. Somebody on this forum will tell you what the float voltage should be, I can't remember. Make sure the charger is set for Lead / Acid not Gel.

You can google for links that will tell you the % of charge relative to the voltage reading to two decimals. I have it printed out and use it for reference since I have an older charger and don't leave my charger on all the time.

Our flooded 12v batteries are maintained by 90watts of solar (we are on a swing mooring),via multistage regulators. One stage is "equalization" which can be set on (happens monthly) or off (never happens). We use equalization,the regulator instructions say you need to check levels when you do;I do and it is definitely necessary to top up. I`m thinking that would apply to any smart regulator with an equalization phase, whatever the power source. BruceK

Charger

I bet that problem is that one battery is bad and the charger is over chargering to compensate for it.

I think it would be worth my time to replace them all. They are only three years old but I did have a problem with my glow plug controller that caused a short and heavy load on batteries before I found it. (Actually caused an over heat problem with the controller to the point where it caught fire!)

Thanks for all the input.