Coach Batteries in Motor Home

[SCGolfer]

Yesterday, lost shore power in campground (everyone).. My coach lights went out almost immediately.
checked coach batteries. both batteries out of water. Filled with water. Within two hours of shore power bbeing restored, I turned off shore power to see if batteries had been recharged and lights worked, voltage was 13.1 and wall mount display said batteries were top condition.
This morning heard what sounded like boiling condition in one of the batteries. Opened caps on top of batterey and could see water/acid moving and could smell the "rotten egg" smell. Went to Auto Zone, bought hydrometer, battery acid levels fine. Took some of the acid out of one cell that I think I had overfilled and put some water in another cell that I couldn't see any water in. left the cell caps loose, reconnected shore power and batteries seem to be working fine, no boiling and voltage check is good even when I turn the shore power off at breaker switch outside. Three hours later; batteries in great condition according to gauges.
Question: Did I somehow fix the issues since everything seems to be working okay and there's no more boiling OR is there something going on that I should check and/or replace?
Thanks in advance for anyone's help.

[pianotuna]

Hi,

What were the hydrometer readings?

[zman-az]

sailor_lou wrote:
However, first you need to repair/replace you battery charger (converter) or inverter (if you have a combined converter/inverter unit). The unit is overcharging the batteries and this needs to be corrected before going any further.

This is not always true. When a cell in a battery goes bad the charger keeps charging because it does not know the battery is bad and then you get boil over.

In this case it sounds like the batteries may be bad and that is what happened. Also if the batteries were dry and you fill them up to the full level you will also get boiling. When discharged battery acid turns to water and the level drops, charge the battery up and the level rises. So if you top off a dead battery odds are you will get spillage. Its best to fill a dead battery just above the plates, charge and if they fully charge fill to the normal level with more distilled water.

It is possible that the OP batteries can still be saved even though the went dry. The newer the batteries the better chance you have of saving them. If they are 5 years old you may need new ones. BTW, did the levels on all the cells of your batteries remain at the same level. Even though its says good the levels should be consistent with all 6 cells in the battery. If one is way lower than the rest you have a battery going bad.

If the OP batteries are bad I would replace them first and then hook backup to RV and watch them. Put a voltmeter on them after fully charged and make sure the voltage is not to high. If the start to boil you will then need to replace the charging unit on your RV.

[J-Rooster]

I did the same thing 2 years ago was told that I needed new batteries. I went down to Les Schwab Tire to get 2 new batteries and the service Tech told me to wait that he wanted to do hydrometer test. The batteries tested in the high 490's he told me too go that I didn't need new batteries and this is my third year on the coach batteries. I had two dry cells prior to going to Les Schwab.

[mena661]

Two hours won't do squat when you're batteries are essentially at 0 volts. It will take a few DAYS to get them back up IF they weren't messed up by going dry. And it sounds like they did get messed up.

[sailor_lou]

Typically when batteries are boiled dry or even below the level of the plates, they should be replaced. However, first you need to repair/replace you battery charger (converter) or inverter (if you have a combined converter/inverter unit). The unit is overcharging the batteries and this needs to be corrected before going any further. Good luck.

Lou
05 Travel Supreme Envoy

[Jagtech]

The wall mount voltmeter is just that - a voltmeter. It won't really accurately indicate the capacity of your batteries, just the voltage with the charger running, at the present time. The hydrometer test is much more telling.
I'm betting you will be replacing those batteries soon, for best results.

[DianneOK]

Moderator note.....I am moving this to the Motorhome forum for a better response.

[2oldman]

Naughty boy letting those batteries dry up.

Not good that a cell you supposed filled up was low the next day. I would replace them immediately. Going dry is not good.