Both batteries have slight bulge, low water

[sivartb000]

My 5th has two batteries in series. It has been sitting with batteries connected, but with a battery disconnect, for about 6-8 months without being charged. Both have a bulge at the positive and the short sides, no cracks, no signs of leakage on one/maybe minimal signs of leakage on the other. One battery had water just to the top of the plates, the other had water just above the top on one side and below the top of the plates on the other (probably just not perfect level ground). One read 3v the other 6v.

I’m hoping I can get atleast one more trip out of them, or maybe more?

What are my next steps? I believe the batteries are 3 or 4 years old.

Sorry for the sideways pictures, not sure why it’s doing that.

[8.3Oilbuner]

Hi sivartb000; In my opinion the bulge is not something out of the normal. The 3V and 6V readings are an indicator, to me, the batteries are toast! You can try recharging them but I think the voltage is too low for some chargers to even work on a battery that low. I would say its battery buying time!

[Capacitor]

These are 6 volt batteries, correct? Add distilled water and charge them. Check voltage after rest and again a week later.

[GuyG]

In my experience with batteries once thought to be dead/toast, the slower you can recharge them the better. I've used a 10 amp charger for years and it might take a week to get a "dead" battery back but it works. After about 24 hours, I often unplug the charger overnight then plug it back in in the morning. Slow is key.

[wopachop]

Do you have a regular 12v battery tender? Or any type of charger?
You can put something like a 5amp 12V battery tender on your 6v battery. Loosen the caps and charge it outside because of the fumes.
Monitor the voltage. You want the 6v battery to reach 8.1volts. Dont let it go over that. The amount of amps the charger works at will determine how long that takes.
On my 6v healthy batteries, it takes over an hour to give an idea.
If the charger doesnt want to start you can jumpstart the 3v battery real quick to trick the charger and get it to start pumping amps.

[twinboat]

You do need to charge each battery separately with a 6 volt charger.

They will not balance out if you use a 12 volt charger across both.

A low output 6 volt charger for 24 hours each may get you a few more trips, but probably not dry camping.
If you have slides, they may not operate properly either.

Sent from my SM-A025V using iRV2 - RV Forum mobile app

[wopachop]

If you have a charger with 6v mode that is the safer option.
But if all you have is a 12v charger that can still work. You just need to monitor battery voltage very carefully and stop the charge if the batteries go over 8.1v.
For something like a common12v 5amp charger you can let it sit on a 6v battery for hours and it will stay at 7volts. Ive done it to my batteries a few times as a way to perform an equalization charge.
To be clear you would charge the batteries separately. I would start with the battery at 6v. Get that charged up. Then work on the battery at 3v. Chance you might need to use jumper cables with the charged 6v battery to briefly raise the voltage of the 3v battery in order to start the charge.
Not ideal. But can work. Get by for another trip hopefully. If you have a 12v charger with adjustable amps, then use that to your advantage. If the battery voltage rises to 8.1v too quickly, then reduce the amps. Try to rig it so youre close to 8v for a couple hours. The battery will bubble but that is normal. Dont breathe the fumes. Have some baking soda water ready if you have some. Clean splatter up with that liquid.

ALso if not too late, dont fill the water up to max level yet. It will rise slightly as you charge. You just need the water to cover the plates. Fully charge. THen top off the water level.

[sivartb000]

Thanks everyone. I have a 6v/6amp charger, and picked up some distilled water and will give that a shot.

[wopachop]

If your charger has an equalization mode for flooded 6v that would be a good setting to choose.
Its hard to charge bad batteries because their voltage spikes high prematurely. The charger shuts down early because it thinks the battery is charged based off the voltage.
Simple trick around that is to unplug the charger and then plug it back in. If you could easily put a small load on the battery between each charge that would be ideal.
For example my motorcycle battery is toast. I hook up the charger and let it complete a cycle. Then just turn on the headlight real quick. That drops the voltage and the charger starts back up again. Repeat that process over and over and eventually you end up putting some amp hours back into the battery. Leaving the charger hooked up for 7 days straight doesnt work as well because most chargers go into a float voltage.

[YC1]

Bulging batteries and 3 volts on one.

Time to replace them. No one really buys batteries, we just rent them.

Those batteries, expecially the 3 volt one likley will not recover much. You are just asking for issues while trying to enjoy your trip.

Be extremely careful charging and if you do need to add water, there is a high likelyhood of explosive gasses gathering about. Be sure things are vented and always wear safety gasses.

You can get the voltage up, and even find good specific gravity on a battery, and due to physical issues inside they can do some really crazy things.

When something physical such as a bulge appears, just imagine how tought that battery housing is and what it takes to make it bulge. Things are not going well inside for sure. Don't spoil your trip by trying to squeak some more time. Batteries are the heart of your RV.

[Mudfrog]

Originally Posted by sivartb000

Thanks everyone. I have a 6v/6amp charger, and picked up some distilled water and will give that a shot.

Sounds like a plan! You're only out the water if it doesn't work.

[96 Wideglide]

Originally Posted by Mudfrog

Sounds like a plan! You're only out the water if it doesn't work.

Huh !

If you have flooded lead acid golf cart batteries, you ALWAYS need to have distilled water at hand!

[tmw188]

Replace them, they have basically aged out as a wet cell battery, and the fact that they have not been maintained is even worse. It’s a easy fix to solve and won’t be wasted money as some things are.

[Persistent]

Originally Posted by sivartb000

My 5th has two batteries in series. It has been sitting with batteries connected, but with a battery disconnect, for about 6-8 months without being charged. Both have a bulge at the positive and the short sides, no cracks, no signs of leakage on one/maybe minimal signs of leakage on the other. One battery had water just to the top of the plates, the other had water just above the top on one side and below the top of the plates on the other (probably just not perfect level ground). One read 3v the other 6v.

I’m hoping I can get atleast one more trip out of them, or maybe more?

What are my next steps? I believe the batteries are 3 or 4 years old.

Sorry for the sideways pictures, not sure why it’s doing that.

Lots of good advice posted above on recovery.
Water above plates.
Slow charge separately for a very long time.

I recommend you replace both batteries. At least replace the one at 3 volts with another old 6 volt battery if you have one. That combination may work a little for a while.

Bulging and low water indicate they were overcharged. That is a too high a voltage for what they could absorb. Charging consumes water. Overcharging consumes lots of water. Overcharging produces heat which can soften the case and allow it to bulge.

Batteries may have been sulfated last time you charged them. Sulfated batteries are easier to overcharge. "Boiling" and heating occur more easily.

Freezing could cause a bulge, but probably not in your area.

Storing flooded cell lead acid batteries that are in good condition can last 6 months. Batteries in poor condition will probably not last that long. Fully recharge for 14 to 18 hours before voltage drops to 12.4 (6.2 volts).

In Wisconsin we have to worry about freezing batteries when they are discharged.

The three volt battery is probably heavily sulfated. It would require special procedures and equipment and take maybe a month or more to recover 80% of specified capacity.

The 6.0 volt battery should be recoverable. However, pairing it with a new battery will only provide a poor performance over time.

See attached file for how to store lead acid batteries.