House Battery Drinking Lots of Water

[richard5933]

Check the voltage output on the charger when it enters float mode. Probably also should confirm that the charger is actually entering float mode and not staying at a higher level.

Contrary to what many people think, it's not the low current flow (amps) that makes the float charge suitable for long-term use. It's the voltage, and if it stays too high for too long, it will boil your batteries.

Could high voltage cause only one battery to loose that much water? Perhaps, depending on how they are connected. It is possible to have quite a voltage drop from one end of a battery bank to the other if things are connected using too-small cables or incorrectly.

All that said, it is more likely that you've got a bad cell(s) in that battery.

[Tha_Rooster]

Originally Posted by Gormleys

I have six 12v Type 31 Deep Cycle house batteries in parallel and usually top them off manually (due to clearance issues) every 2-3 months. During the past three months of the winter, the MH has been plugged in to shower power and on a good trickle charger. When I went out this week, five of six took the normal 2-3 ounce of distilled water per cell while the last battery took almost a gallon total. All of the batteries are at least five years old. Why would one battery take so much water? There is no visible sign of any leakage or damage. Won't that dilute the acid and ruin the battery? If so, should I just replace it, leave it out and live with five or spend lots of money and replace them all?



Thoughts from all of you sparkies out there?

I would say if you put a gallon of water in 1 battery it’s been boiling a lot and pretty sure it’s bad.

[arcaguy]

How are you hooking the charger up to the battery? If you are hooking up both charger cables to the same battery that is likely the cause of the battery going bad. The charger should be hooked up to the positive post of one battery and the negative post of the battery furthest from the first battery. That way the electrons must flow all the way through the battery bank thereby charging all of the battery pretty much equally. If both charging cables are hooked up to the same battery that battery will tend to get most of the charge as electricity takes the path of least resistance. Goo luck.

[twinboat]

Originally Posted by arcaguy

How are you hooking the charger up to the battery? If you are hooking up both charger cables to the same battery that is likely the cause of the battery going bad. The charger should be hooked up to the positive post of one battery and the negative post of the battery furthest from the first battery. That way the electrons must flow all the way through the battery bank thereby charging all of the battery pretty much equally. If both charging cables are hooked up to the same battery that battery will tend to get most of the charge as electricity takes the path of least resistance. Goo luck.

That would only be true if the cables between the batteries were grossly undersized.

6 feet of 2 gauge jumpers between 5 batteries will have a voltage drop of less then 1%, at 60 amps of current.

As batteries charge, the amperage they accept drops off. Once the first battery reaches full, each one in progression will also.

[L-M-L]

Check and see if the batteries that took lots of water are getting hotter than the others when you have them charging. If you have to replace some of the batteries, I would recommend replacing all of them. When the batteries are hooked up together, your best battery will be no better than the worse battery that is in the group. The worse batteries will pull down the good batteries.

[richard5933]

Originally Posted by twinboat

That would only be true if the cables between the batteries were grossly undersized.

6 feet of 2 gauge jumpers between 5 batteries will have a voltage drop of less then 1%, at 60 amps of current.

As batteries charge, the amperage they accept drops off. Once the first battery reaches full, each one in progression will also.

Of course it's also possible that corrosion is adding to the voltage drop to the other batteries, depending on the condition of things. Hard to know for sure without more information and perhaps a few photos.

[twinboat]

Originally Posted by richard5933

Of course it's also possible that corrosion is adding to the voltage drop to the other batteries, depending on the condition of things. Hard to know for sure without more information and perhaps a few photos.

If there was voltage drop, the charging battery still will not overcharge with a proper operating charger.

The rest will only be undercharged.

[richard5933]

Originally Posted by twinboat

If there was voltage drop, the charging battery still will not overcharge with a proper operating charger.

The rest will only be undercharged.

Kind of where I was going. If the charger isn't going to a proper float voltage it would overcharge, and my thought was that with poor wiring it could affect only one battery. Outside chance, I know, but something to consider if all the other more logical answer fail.

[Gormleys]

I am pretty sure that it was a bad cell in the one battery that caused it to boil out. The other batteries all seem to hold charges but they are all over six years old. I pulled them out and replaced them with four Trojan T-105 6v batteries with a self watering system. Though a bit more than I budgeted, I think that is the safest approach.

Thanks for all of the constructive discussion and comments!

[Piros1]

I think that was a good decision that you won’t regret. Trojan batteries are highly rated. Good luck and safe travels!

[mr.tommy]

Originally Posted by Gormleys

Yes, "shower power" is indeed the auto-correct version of "shore power." The charger involved is the coach's 3-stage built-in charger. It has settings depending upon how many batteries are installed - 200AH, 400AH and 800AH. It is supposed to be set to the closest value below the total amp hours of the installed batteries. These original six batteries are all 105 Amp Hour and the charger was set to 400AH.

I did take the battery in question out and ran it on a separate charger tester overnight. It will not hold a charge and only got to 17%. It is definitely bad.

So now I am faced with replace now or wait for the next battery to fail. But of course like everything else, battery availability is affected by Covid. "Good" AGMs are hard to locate. I am considering four 6v Trojan T-105s at 225AH each as replacements (if I can find them). They are a bit taller, but if I can install the Flow-rite autofill, they should be easier to maintain, weigh less than the original six and have more amp hours.

Thoughts?

I think that's a good plan. Our Trojan 105's are going on 5 years old, with an auto fill system and they're still going strong. Very good bats. However we upgraded to a 4 stage smart charger from Progressive Dynamics PD9200 Series. This thing is sweet compared to what our OEM charger was.

[Mile Marker 42]

Why not just run a 5 battery system for now and call it a day. How much dry camping do you do? High probability even 5 is too many for your boondocking needs??