Dual Batteries, 1 Dry!

Steelhorzz · 10-31-2016, 08:30 AM

We're crossing the country and we're two weeks into our trip.

My DW smelled a "rotten egg" odor. I'm thinking either hot water heater, or batteries.
I checked the batteries first. Easy to get to under the stairs. (We have a GT 360).

One battery was fine, filled to the right level. The other was almost bone dry.

Of course during the trip I always check my control panel AND and it showed everything ok. (Four lights).
Well not so much.... ��

Both batteries were purchased at the same time about 8 months ago. Hooked up in series correctly. I checked them just before we left. Everything appeared fine then.

WHY would one "cook dry"?��
Any ideas ???
Thanks everyone in advance. ��

SidecarFlip · 10-31-2016, 08:42 AM

Internal issues. Batteries, like everything else made by man, are sometimes defective. Replace it and get warranty on the defective one.

Steelhorzz · 10-31-2016, 08:52 AM

Thanks SidecarFlip. That was my opinion too. I need to find a store that doesn't want to keep it overnight to charge it and test it.

(It would put us off schedule).

It would be nice if they just took my word for it....

SidecarFlip · 10-31-2016, 08:57 AM

I'd replace it. Most likely it's junk. If it boiled itself that low, the percentage of sulfuric acid went up to the point where the straight acid destroyed the inside anyway and no amount of adding water or charging will ever bring it back.

Basically, it's a boat anchor now.

bubbles · 10-31-2016, 09:57 AM

Quote:

Originally Posted by Steelhorzz

We're crossing the country and we're two weeks into our trip.

My DW smelled a "rotten egg" odor. I'm thinking either hot water heater, or batteries.
I checked the batteries first. Easy to get to under the stairs. (We have a GT 360).

One battery was fine, filled to the right level. The other was almost bone dry.

Of course during the trip I always check my control panel AND and it showed everything ok. (Four lights).
Well not so much.... ��

Both batteries were purchased at the same time about 8 months ago. Hooked up in series correctly. I checked them just before we left. Everything appeared fine then.

WHY would one "cook dry"?��
Any ideas ???
Thanks everyone in advance. ��

If you had 4 lights you must have been checking them when either connected to shore power or engine was running (false indication). Checking under those circumstances would indicate charging voltage is applied. I believe 3 lights will illuminate when checked otherwise and that may not indicate true condition. If voltage is very low (both batteries) then less than 3 will illuminate. By the way, I think you have 2, 12volt batteries and they are connected in parallel, not series.

ScottBrownstein · 10-31-2016, 10:07 AM

If you do have 2 12 volt units, this shows one of the drawback of parallel batteries. One of your batteries boiled off, which means that most of the current in the charge circuit was directed the the failed battery since it had a lower internal resistance. If they had been connected in series, you would have seen low voltage when not charging and immediately directed to the situation.

camaraderie · 10-31-2016, 02:20 PM

You've gotten good advice above. One thing I caught is you're relying on the idiot lights to inform you about your batteries. Bad choice.
Best choice IF YOU BOONDOCK would be a real battery monitor like the Victron or Trimetric.
Otherwise get a decent multimeter (one with clamp on AC/DC current testing is best) and learn how to use it at the battery terminals to check for charger function and battery condition. Assuming they are wet cells...a $10 hydrometer for checking each cell condition once every couple of months is another alternative that can head off trouble.
The idiot lights can only tell you whether your batteries are dead....or that your charger is working. They are unreliable for anything else.

rmoore0852 · 10-31-2016, 02:22 PM

12 V batteries have to be connected in parallel. Connecting 2 12 v batteries in series gives you 24 volts, which will immediately blow fuses or destroy the power converter.

RV's using 6 volt golf cart batteries connect in series to give them 12 V.

Steelhorzz · 10-31-2016, 03:57 PM

My mistake on term. Batteries are hooked up in parallel. (Neg to Neg, Pos to Pos. ) I have just gotten lazy using the control panel. Should have realized it when the LP said 3 lights and the gauge on the tank was under 1/4.
I've got a multi meter on the coach and use it when in storage. I check the batteries and charge them when necessary to offset the parasitic drain. Checking the fluid level first.
I'm gonna affix either a cable mounted or terminal mounted volt meter to each when I get home, so All I do is look under the steps to get a "read" on their condition at any time. I was just scratching my head as how one went "south". In only 2 weeks on the road. But I guess it happens. We were outing the MH/RV museum in Elkhart today. I mentioned to my DW. It's amazing how technology has advanced so far even in RVs.. But I'm not sure realiability has kept pace.....

rmoore0852 · 10-31-2016, 04:02 PM

I would consider replacing the other battery also. If they were bought at the same time then MAYBE the retailer will replace the other one also. If one battery shorted out internally, causing enough heat to boil off the water, then the current needed to get that hot came from somewhere. In this case it came out of the other battery. I know in diesel pickups that use 2 batteries, you always replace as a pair. If you only replace one battery after a failure, usually the other one fails relatively quickly.

larrybessette · 10-31-2016, 06:12 PM

I did the same thing as you several years ago and had a battery failure similar to what you described. I talked to a friend who is into marine recreation and he said to never connect two batteries in parallel without the proper switching and or regulating equipment between them. If you have a bad battery it will quickly destroy the other one.

I only run one battery now.

I'd replace them both.

SidecarFlip · 10-31-2016, 06:26 PM

All interesting except...Every diesel pickup I've owned has had 2 12 volt batteries wired in parallel...and I've never had an issue... In fact, it you trace the lines you'll find that they are both wired directly together with nothing between.... except battery cables.

Jonol · 10-31-2016, 07:10 PM

The TT converter is good to charge one battery at the time and you will never
have problem .

larrybessette · 10-31-2016, 07:53 PM

Yup you are right. Your truck has two batteries in parallel. The principal remains the same. Electricity is like water. It always tries to equalize. If one battery has low voltage or is shorted the good battery will continuously attempt to equalize the voltage until it is ruined.

Within that framework there are differences/ variables.
If your truck has a weak battery you replace it.
Your truck probably doesn't sit for long periods.
Your truck isn't on a charger continuously.
If my RV has a bad battery it may not be noticed for weeks/months since the RV is always on a charger and may not be used for weeks or months at a time.
If I have a bad battery and don't know it and go boondocking I may find myself in a jamb with no easy fix.

Same answer. If you have two batteries in parallel and one goes bad it can damage/ruin the
other one.

kirkwilliams2049 · 10-31-2016, 08:17 PM

Quote:

Originally Posted by Steelhorzz

We're crossing the country and we're two weeks into our trip.

My DW smelled a "rotten egg" odor. I'm thinking either hot water heater, or batteries.
I checked the batteries first. Easy to get to under the stairs. (We have a GT 360).

One battery was fine, filled to the right level. The other was almost bone dry.

Of course during the trip I always check my control panel AND and it showed everything ok. (Four lights).
Well not so much.... ��

Both batteries were purchased at the same time about 8 months ago. Hooked up in series correctly. I checked them just before we left. Everything appeared fine then.

WHY would one "cook dry"?��
Any ideas ???
Thanks everyone in advance. ��

Best advice: buy RV Electrical Systems by Bill and Jan Moeller. Everything you need to about your RV electrical. No I am not the author.

Tom48 · 10-31-2016, 11:37 PM

Within that framework there are differences/ variables.
If your truck has a weak battery you replace it.
Your truck probably doesn't sit for long periods.
Your truck isn't on a charger continuously.
If my RV has a bad battery it may not be noticed for weeks/months since the RV is always on a charger and may not be used for weeks or months at a time.
If I have a bad battery and don't know it and go boondocking I may find myself in a jamb with no easy fix.

Same answer. If you have two batteries in parallel and one goes bad it can damage/ruin the
other one.[/QUOTE]

You are correct that there are differences between RV and truck. Biggest one is that one battery can kill the other one but that's it in the RV. In our F250 we didn't catch the bad battery right away, probably because we do use it daily. One bad battery took the pair finally down to about 11 v and Ford warrantied both the good and the bad because they recognized that the other would be damaged by the bad one. The batteries were in warranty. The truck not.

Sad thing in the Ford diesel is that next the electronic module for the fuel injection failed, best bet as to cause----running on the low side of allowable voltage for too long before we caught the bad battery. Very expensive fix. RULE NOW IS WATCH BOTH BATTERIES AND REPLACE THE PAIR AT THE FIRST SIGN THAT ONE IS FAILING.

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