Charging 2-6 volt batteries

[camaraderie]

Originally Posted by goin2drt

First Happy Fathers Day.

Second I took the batteries in to the shop. They charged them and then put them on their machine. They said they were at 5.43 volts and the machine said to charge them, meaning they were not ok. The shop did not test the cells with a hydrometer. Fully charged shouldn't the batteries read over 6 volts.

I want to be extra safe as the last thing I want is to get stranded with not so good batteries.

Do you all say they need to be replaced?

Sorry...they are toast and BOTH need to be replaced...this is the equivalent of a 12V battery reading 10.86 after a FULL charge. 6.3V is a full charge on a 6V....2.1V per cell on wet cells.

Next time around in storage...suggest you remove negative battery cable after fully charging. This will hold you from self discharge for a minimum of 3 months...at which point they'll need to be charged again. Since you do apparently let the batts sit for extended times...it is also important for life cycles to make sure your battery charger has an equalization cycle as well as the "normal" three stage charging.

[camaraderie]

Originally Posted by richard rv

Good evening g2d..
I have worked with batteries most of my adult life and have seen a lot of changes in there design. A good battery will have a cell reading or 2.00volt per cell for a reading of 6.00 volt. A low battery will have a reading of 1.75 per cell (1.75×3cells=5.25). Your batteries are still good. I assume these are the house batteries lf so they are deep cycle batteries.this means that they were made to be discharged.this being said it means that it will take longer to charge up. The built in charger on your coach will charge them when you are plugged into a power supply or running the gen set. If your coach is like mine, look where your monitor for battery, water, waste tank is located and you should see a switch at the battery screen . it should say "use save".by pressing save you can shut down anything that is 12 volt and not repeat this again. Hope this helps

Did you notice that he said that his batteries said 5.43 AFTER being fully charged?? That is not a LOW battery...that is a toast battery. You can't go camping with those batteries.

[SKnight]

A 6V battery should read 6.3V fully charged (2.1V per cell) so 5.43V is pretty weak, probably in the 30% capacity range.

So I'd say they need to be replaced, just to be sure I'd have the gravity tested, but just off this here it looks like they're done.

[goin2drt]

Never mind. I was typing while Richard was. Sounds like I am good.

[SKnight]

Originally Posted by goin2drt

So if a full charge is 1 volt less am I asking for trouble to use these batteries?

Very possibly, your converter will keep trying to charge them and could hurt it, given enough time it could boil the water out making things worse.

You've got them out, they're looking marginal. I'd put fresh ones in.

If it's cost prohibitive you can drop one 12V regular deep cycle in there for now. You wouldn't have the capacity as before but it would get you by.

[camaraderie]

Originally Posted by goin2drt

So if a full charge is 1 volt less am I asking for trouble to use these batteries?

YES...I guarantee it. A totally dead 0% charge is 5.25V ... and you have 5.43 after a full charge. There is only .9V difference between a dead and a full new battery in 6V.
Don't take my word for it. Find your batteies Voltage on this chart and tell me how good they are.

[SKnight]

Originally Posted by goin2drt

Never mind. I was typing while Richard was. Sounds like I am good.

He doesn't seem to know that wet cell batteries create 2.1V per cell instead of 2.0V. I'm not sure I'd believe they're fine.

Measure the spec gravity of each cell, that will tell you the story.

[richard rv]

Excuse me I missed the part of FULLY CHARGED.how long was that ? 1hr 2 hr 3hr?

[goin2drt]

Ok. Well I will replace them. Like I said I don't want to take a chance.

Thanks for all the help on this as I do not understand batteries that well. These were Exide. I did a search here and it seems folks like Trojan or Interstate. I will start shopping for the best price around.

Thanks again.

[richard rv]

G2d if you are going to replace them walmart sells rv batteries. Got 2 in April down in pencola fla. Less than $200.00 my batteries were 10 yrs old.