Battery boil-over & smell

[herbsells]

Last night in bed our CO2 alarm went off, although showed "000" on the digital display. We awoke and smelled a sickening sweet smell, no headache, no grogginess, smell was only back in the bedroom (right over the battery bank) and we had no furnace running, fridge on a/c, stove turned off.
Couldn't figure out where odor was coming from until this am. Noticed our TRACE ENGINEERING remote panel showed battery bank was bulk charging at 30-45 amps even though we had virtually nothing running, (no fans, laptop computer is charging, phones are charging, fridge on a/c as we are plugged in to shore power.

We've been plugged in to shore power since we arrived Sept 15th and generally it shows "floating" and only occasionally illuminating the 15 amp light on the RC-6 remote panel (see attached photo), but this am moved to BULK and 45 or 90 amps.

Looking in the basement battery compartment, I see a little whisp of "smoke" coming out of one of the four 12v flooded lead-acid batteries, along with some noise that indicates boil over.

I had to shut off shore power at the pedestal because I don't see any other way to keep the TRACE system from charging the batteries. The power switch on the front of the TRACE charger (in the basement) only shuts off the inverter side, not the charging side.

By the way, I opened and watered (DI water) all six batteries on Sept 29th although we'd owned the (used) coach since November of 2015 and had never checked them until late September.

Here's my questions for you;
Does a battery cook and boil over only when it is being charged/overcharged or also when it is being discharged under load?

Although we've not done any dry camping, since we want to do that, a couple nights ago I shut off power to the pedestal and we tried out the power system. We started at 6pm at 12.74v and only ran the fridge on propane (w/ 12 volt control), an occasional light or two, intermittent furnace for about 3 hours, and LCD TV for about 4 hours. We went to bed at 12.34v, so during sleeping hours we only had fridge, patio light (LED) and DISH TV receiver on. Furnace did not run all night. When I got up at 6am, battery bank was down to 11v. Was this a tell-tale sign that that we had a problem? Or is this kind of lackluster performance to be expected from a bank of four 12v deep cycle batteries?

I'm concerned about the battery boil-over in that I don't know if it was just time for that particularly batter to die? Or do I have a problem with the TRACE charger/inverter?

I've heard that when replacing a bad battery in the bank, you should replace all (4) - Is that only if you can't find the same brand & model?

Considering a sealed battery because of no maintenance, but a little confused about the Optima series. Seems these are actually sealed lead acid vs the AGM. Any thoughts on those?

Sorry about all the questions, but if I can at least get one or two of these answered it will really help me to understand what's going on here.

[ByeTheWay]

Here are some links to help you

RV Electrical
RV Solar Electric Store

RV Solar electric publishes a small book, full of good information about batteries and solar. The top link if free.

[powercat_ras]

Be careful - lead-acid batteries that are outgassing ( "boiling" ) are producing flammable hydrogen gas a spark or open flame may ignite it if it becomes concentrated. Why lead-acid batteries MUST be installed outside of the living area and outside of enclosed un-vented basement compartments of the RV.

Based on the photo you posted, your converter/charger seems to have failed and is not behaving the way your status panel shows. You need to resolve this before replacing your batteries. I suspect that your batteries will have to be replaced, but a battery dealer can test them and make the "official" determination.

> Does a battery cook and boil over only when it is being charged/overcharged or also when it is being discharged under load?

When being overcharged. If battery fluid got below the top of the plates in any of the batteries then permanent damage was done.

> When I got up at 6am, battery bank was down to 11v. Was this a tell-tale sign that that we had a problem? Or is this kind of lackluster performance to be expected from a bank of four 12v deep cycle batteries?

No.

> I'm concerned about the battery boil-over in that I don't know if it was just time for that particularly batter to die?

No.

> Or do I have a problem with the TRACE charger/inverter?

Yes.

> I've heard that when replacing a bad battery in the bank, you should replace all (4) - Is that only if you can't find the same brand & model?

Yes, replace all even if you can find same brand and model.

> Considering a sealed battery because of no maintenance, but a little confused about the Optima series. Seems these are actually sealed lead acid vs the AGM. Any thoughts on those?

Optima Yellow Top are Deep Cycle AGM. Red Top are also AGM but are not deep cycle, don't use. All 4 need to be same: Flooded Lead-acid or AGM.

[twinboat]

Get that battery out of the bank and try your test again.

If things look normal, you found your problem.

Battery chargers are actually not that smart. They only look at and adjust volts. The battery is what determins how many amps it will accept at the chargers set voltage. Yours is delivering a good float voltage so the battery or batteries are bad.

You don't mention how old the batteries are but if one failed, the rest are close behind.

Get some Trojan wet or AGM batteries or Lifeline AGM, if your pockets are deep. If the budget is tight, get 4 Costco, or Sam's, GC2 batteries. A little different wiring but not a tough job.

Many here will explain.

Don't buy into the Optima hype. If you compare them to most compairable size batteries, you will discover that they are lower in capacity and weight. You don't get energy from the spaces between the cells.

[ga traveler]

What you are experiencing is what the battery folks call a thermal runaway. A battery is composed of dozens of plates. You start with a positive plate put a insulator between it and the next plate which is negative, another insulator and then another positive plate another insulator and then another negative plate and on and on. For starting batteries you uses many plates. For deep discharge you use thicker plates and less plates. The starting battery needs to put out a large amount of energy for a short period. (Starting the engine) The deep discharge battery puts out a long slow discharge. running water pumps, lights, etc. The plates are more prone to heating because of the prolonged use. The start battery is only used for 5 seconds or so. No time for it to really heat up. If one of the plates gets hot and twists or if the plates shed and cause a buildup between the plates, the battery shorts out internally and you have a thermal runaway. It is better to change all the batteries if they are not fairly new. (less than a year)

[herbsells]

ByTheWay, PowerCat, TwinBoat,and GA Traveler,

Thanks all for your input. The more I read, and the more I took your input, and the more I thought about it, I figured the easiest and quickest way to trouble shoot was to remove the smoking battery from the chain. I moved the cables so that only 3 batteries are hooked in parallel.

The batteries are Harris Professional Plus C31S-HDPFX, class 31 with 195 amp-hour reserve capacity. I figured taking one out of the loop still leaves me with nearly 600 amp-hour capacity.

When I first powered the system back up (about 1.5 hours ago) it was working in bulk mode, and the bank was pulling about 90 amps, after an hour it moved to absorption mode, brought the bank voltage to 14.3 and now only drawing about 15 amps. I'm confident that before long it'll be back to float mode pulling little to no current (alternately).

Thanks again to all four of you for your input and helping me troubleshoot and address this problem AND saving me hundreds of dollars as well!

[twinboat]

Glad to help.

By the way, you seem to be confusing reserve capacity with amp hours ( AH ). They are not the same thing.

There is a formular to convert one to the other, but I don't have it on hand.

Your gp 31 batteries are probably 95 to 100 AH at the most. So you are dealing with 300 AH, of which 1/2 of that is usable, to keep from depleting the batteries to below 50% capacity.

Google RC to AH conversion for the conversion.

Keep an eye on the remaining batteries. I had a 3, 4D battery bank, in a new to me boat, a few years back. All three cooked and were removed, one at a time within 2 months.

Update, Each battery is aprox. 82 AH for a total of 246 AH. You can get near that much capacity, 225 AH, out of 2, 6 volt GC 2 batteries wired in series. 4 would fit with room to spare.

[herbsells]

Originally Posted by twinboat

Glad to help.

By the way, you seem to be confusing reserve capacity with amp hours ( AH ). They are not the same thing.

There is a formular to convert one to the other, but I don't have it on hand.

Your gp 31 batteries are probably 95 to 100 AH at the most. So you are dealing with 300 AH, of which 1/2 of that is usable, to keep from depleting the batteries to below 50% capacity.

Google RC to AH conversion for the conversion.

Keep an eye on the remaining batteries. I had a 3, 4D battery bank, in a new to me boat, a few years back. All three cooked and were removed, one at a time within 2 months.

Update, Each battery is aprox. 82 AH for a total of 246 AH. You can get near that much capacity, 225 AH, out of 2, 6 volt GC 2 batteries wired in series. 4 would fit with room to spare.

So with 4 GC batteries, I would wire each set of two in series (to get 12 volts) and then wire each pair in parallel to double the AH to get a total AH of 550?

[twinboat]

Originally Posted by herbsells

So with 4 GC batteries, I would wire each set of two in series (to get 12 volts) and then wire each pair in parallel to double the AH to get a total AH of 550?

Yes, 450 AH.

2, 6 volt in series doubles the voltage.
2, pairs in parallel doubles the Amp Hours.