6V Batteries Water Levels Different

[rvb]

I have 2 Trojan T105 6v batteries in series which are charged by both a 400w solar system and an intelligent 120v battery charger. Both have been fully charged with the trailer heated over the mild winter in Texas and are inside in a vented marine box. After 4 months I checked and topped up the batteries. The battery connected to the TT positive cables water level was almost full, but, the battery on the negative cable was wet on top and down 1/2 way to the plates. Both batteries are the same age (2 years).

Is it normal for batteries in series to charge differently? Should I rotate them periodically for equal life?

Otherwise they have and are performing great.

[HowieE]

Disconnect them and check the voltage on each and the check each cell with a hygrometer.

If you see differences you may be up for new batteries

[Boxite]

They don't care if they're in series or not unless one of them is damaged in some physical way. If they're sitting protected in storage...shouldn't pose a problem.

The negative cell being a bit lower than the other end is not unusual or meaningful. Being wet on top probably means they've been charging more than necessary, and bubbling a bit. If the TT is in long-term storage, a more sophisticated charger might help.
Are you saying they are presently in storage...and BOTH a solar AND a charger are connected? I'd drop the solar during storage if it's not a sophisticated maintainer-type.

[rvb]

I usually check the water and equalize the batteries every 45 days. This time it has been 4 months because I have recuperating from shoulder surgery which may be why a difference is noticeable. I was just wondering if that was normal. I will check the specific gravity in each cell of both batteries when fully charged.

By storage I mean in my driveway hooked up to shore power, ac & furnace, refrig., water pump on and some occasional use including sleeping. With the shoulder pain, I find I can sleep better in the trailer than the house. We are in it daily, just not as much use as if we were out camping.

My 120v charger is a Progressive Dynamics 70 series Intelligent charger with charge wizard which lets me monitor and change charge level. Solar is a Bogard 2030-solar charger controlled by a Trimetic 2030-RV meter. I monitor usage, solar input and thru-put and the thru-put when the batteries are charged is 0.

The batteries are 2 years old and I have never had any problems with charging or AH in use. When boondockng with the furnace running and a cpap on an inverter I am down to 82% in the morning (40 degrees at night in October) and fully charged by 1:00 pm.

[masseyfarm]

From my experience, it is always the battery on the positive cable that requires a bit more top off of water?
http://www.airforums.com/forums/f313...ml#post1410268

I experience this on every battery inspection, and I rotate batteries each time. (approx. every 8 - 10 months.)

Dave

Originally Posted by rvb

I have 2 Trojan T105 6v batteries in series which are charged by both a 400w solar system and an intelligent 120v battery charger. Both have been fully charged with the trailer heated over the mild winter in Texas and are inside in a vented marine box. After 4 months I checked and topped up the batteries. The battery connected to the TT positive cables water level was almost full, but, the battery on the negative cable was wet on top and down 1/2 way to the plates. Both batteries are the same age (2 years).

Is it normal for batteries in series to charge differently? Should I rotate them periodically for equal life?

Otherwise they have and are performing great.

[alano]

For batteries in series, I don't think there's a reasonable explanation why one battery should be depleted more or less of electrolyte in the absence of a fault condition or unequal temperature exposure. There's nothing unique about either battery that could possibly affect the electrolyte level.

Now, if you introduce a fault condition, perhaps an internal fault in one of the batteries, or let say there's ionic contamination on the outside of one of the batteries such that a parasitic current drain occurs between the positive and negative terminals, then an imbalance could result and affect the long-term health of the batteries under charge.

For batteries in parallel, it's important that the charge and discharge currents passing through both batteries be identical. This means that all the positive connections should be connected to the positive terminal on one of the batteries and all of the negative connections should be connected to the negative terminal on the other battery. In the absence of a fault condition, this might explain different electrolyte levels.

[AWCHIEF]

My Trojans do the same. Voltage levels are within spec so I just top them off with distilled water until the next time I decide to check them.

[Boxite]

RVB... just as a suggestion, I'd ask you to consider what might occur in your absence, while you have the water pump ON...or water supplied from a pressure-source... should a water line break or a sink-faucet fail......if your grey tank valve is closed..... (or if your toilet water-supply-valve failed with the foot-pedal/flush-knife-valve also closed...etc.)

Chances are your first observation will be water pouring out from the trailer floor onto the ground....

(To all: When leaving the campsite in an RV park ... I recommend turning the "Y"-fitting valve [if you use one] or the water-supply-valve OFF ... while you're away from your coach. There's no need to have constant water-pressure applied to an unattended RV.)

[MelGoddard]

Originally Posted by Boxite

RVB... just as a suggestion, I'd ask you to consider what might occur in your absence, while you have the water pump ON...or water supplied from a pressure-source... should a water line break or a sink-faucet fail......if your grey tank valve is closed..... (or if your toilet water-supply-valve failed with the foot-pedal/flush-knife-valve also closed...etc.)

Chances are your first observation will be water pouring out from the trailer floor onto the ground....

(To all: When leaving the campsite in an RV park ... I recommend turning the "Y"-fitting valve [if you use one] or the water-supply-valve OFF ... while you're away from your coach. There's no need to have constant water-pressure applied to an unattended RV.)

I do it as a matter of protocol!
It only takes once to ruin your day.

[MelGoddard]

Originally Posted by MelGoddard

I do it as a matter of protocol!
It only takes once to ruin your day.

I DID have a large water leak from a hose to an accumulator that I had just purchased; because 'Idiot child' at the dealership did not tighten a hose clamp properlyl Soaked the whole bottom insulation.
Fortunately, my DW and I were just outside on our chairs, when it started.

It caused the Service Dept. a whole afternoon of warranty labour to replace the soaked insulation. (I tightened the clamp myself.)
And myself a day away from my home a hundred kilometres away.