battery questions and issues

[CODan]

new RV owner here - 2000 Tioga 24', had it thoroughly checked on and repaired when we got it, then it sat for 2 years unusued. Now I'm trying to get systems going.

Batteries were brand new 2 years ago.

When I parked it I pulled the 2 6V batteries (which were wired in series) and put one of the batteries on a trickle charger I use for my car and motorcycles. Unfortunately I charged ONE of the 6V batteries at 12 volts for about 12 hours before I discovered my mistake, then switched it to 12V.

Did I ruin this battery?

I correctly charged the other battery at 6V.

The batteries check out at 6V each when tested individually, or 12+ volts when wired in series.I took a photo for reference before I disconnected them so I know I got them right.

I've put the batteries back in, wired in series , but have problems when checking things out on 12V.

Everything works perfectly on 120 volts - heater, water pump, lights. But only the lights (LEDs) work when on 12 volts.

The water pump runs on battery (very quietly) but doesn't pump any water. I can't hear any water being moved at all. If I plug into 120 it works perfectly.


And it seems like the voltage goes down VERY quickly.

Any thoughts?

Thank you. I'm not generally dumb (just RVs) so maybe I'll be able to help one day.

[CODan]

No, were not uncharged. I charged them over the 2 years they sat in my garage, just used the wrong voltage the first day and now I have trouble with my 12V systems.

[Ron3rd]

Just my opinion but if the 2 batteries sat un-charged for 2 years they're probably dead for good

[CODan]

I edited my post - batteries were brand new 2 years ago.

They actually read 6+ volts. My volt meter doesn't allow me to read as exact as 6.4 volts, but that looks about right. Maybe I need a new volt meter.

When I removed the batteries I put them on the floor of my garage. I didn't wire them back together.

I put one of them on a 6V 6A charger but accidentally put the other on 12V, 2A for about 10 hours. Then it put it on 6V 6A. I swapped the batteries off the 6A charger for the rest of the winter, never more than a few hours each.

It never occurred to me to check hydrometer. All my batteries (car and mc) have been sealed for years. But I can look at these to see if they are different. Did not check water level or voltage.

I'm recharging them now via house power (they are in the RV) and then I will disconnect them and check them individually.

I'm an idiot about electricity.

Thank you all.

[Lwiddis]

After two years of neglect, these two will not perform well. Chalk it up to a learning experience and buy two new batteries.

[wopachop]

CODan wrote:

When I parked it I pulled the 2 6V batteries (which were wired in series) and put one of the batteries on a trickle charger I use for my car and motorcycles. Unfortunately I charged ONE of the 6V batteries at 12 volts for about 12 hours before I discovered my mistake, then switched it to 12V.

Did I ruin this battery?

I correctly charged the other battery at 6V.

So youre saying you put one of the 6v batteries on a battery tender? The 0.75a or the 5a?

What you did is actually a little trick that is good for the batteries. Ive used a 12v battery tender on 6v batteries to act as a poor mans equalization charge. Posted a thread on it here.

1. Did you check water level before charging?
2. Did you check voltage before charging? (what was it?)
3. What charger did you use to charge the single 6v battery?

Im guessing you might have wired them back in series, and then attached the battery tender to both batteries. That gets a little tricky because the individual cells are not balanced.

If they were my 6v batteries i would use your battery tender again. Charge them individually like you accidentally did before. But this time you have to be smart and careful. Charge them outside because they release a gas. You also need to be home so you can monitor voltage. If you have a 5a 12v battery tender that will work pretty good to bring life back to damaged 6v batteries.

[BFL13]

What is the hydrometer reading for each cell (three cells each)?

[2oldman]

The water in the batteries is almost surely low. Did you check it?

Healthy 6v should read 6.4v or so, and going down quickly under load is a sure sign they're toast. I think they're gone.