I think I'm looking at new batteries.

[joshuajim]

I have a pair of interstate Costco 6v that are about 3 years old. We don't boondocks anymore and the trailer is at the ranch and hooked up constantly. PD9855 (?) does the charging.

I did a SOC and all 6 cells are 1.275 or slightly higher. I checked the voltage on the positive (connection) battery and it is about a half a volt higher than the negative (connection) battery.

When I put the Meanwell on the positive battery bubbles like crazy and the negative battery barely bubbles.

I reversed the battery and the negative battery still does not bubble much. I cleaned all the connections and the interconnect cable reads 0 ohms.

I'm pretty sure it means new batteries.

[joshuajim]

OP here. Checked the batteries after setting overnight without any drain. 6.42 & 6.43 (12.85) with Fluke meter. Checked SOC with refractometer and all cells were slightly over 1.3. Guess there is nothing to worry about.

1.3 seems high and this is the first time I used a new refractometer. I calibrated it with distilled water at the same temp as the battery.

Gonna throw them back in and see how it goes.

[DFord]

Have you tried "equalizing" them?

Testing and Equalizing My RVs 4 Golf Cart Battery Bank

Battery University - BU-404: What is Equalizing Charge?

HOW TO: Maintain & Equalize RV Batteries

[time2roll]

9855 sounds like WFCO not the far better PD.

Let them sit disconnected and see if voltage holds up 12.65+ for a few days.

I would continue to use them until they develop other issues.

[BFL13]

The bubbling could mean something (or not).

The one that bubbles more is the one with the higher voltage? Doesn't fit with the way a battery will bubble more when it is older near end of life. Besides their SGs are ok. If sulphated, SG would be more like 1.260 as its max.

To try new ways around in case of some uneven charging for whatever reason, I would also swap the series connector to the other posts and now use the old series ones for pos and neg, just to vary things.

[joshuajim]

BFL13 wrote:
I always had different voltages with 6s in series. If the total was 12.6v, that might be 6.2 plus 6.4.

You get more like 6.0 plus 6.6?

I would give the pair a deep cycle to say 50% SOC and then a recharge and see what the SGs are after that. Maybe now a difference will appear, or maybe the voltages will even up some. Hard to tell now with all the SGs looking good if anything is wrong.

They might just need a bit of exercise. Battery specs recommend doing that every so often if they are on a float for a long time.

I'll give the deep discharge a try. I am concerned with the significant difference in bubbling between the 2 when on desulfation. They have been on "float" for a couple of months. Not much camping in the Mojave in summer.

[MEXICOWANDERER]

BFL x 2

[wanderingaimles]

Are you still using the trailer, other than where it's parked now? IF not, or if never without hookups available, you may want to simplify to a single 12 VOLT rv/marine battery just to simplify.

[BFL13]

I always had different voltages with 6s in series. If the total was 12.6v, that might be 6.2 plus 6.4.

You get more like 6.0 plus 6.6?

I would give the pair a deep cycle to say 50% SOC and then a recharge and see what the SGs are after that. Maybe now a difference will appear, or maybe the voltages will even up some. Hard to tell now with all the SGs looking good if anything is wrong.

They might just need a bit of exercise. Battery specs recommend doing that every so often if they are on a float for a long time.

[Lwiddis]

Hooked up constantly bothers me. I keep my batteries on a light duty solar system with a controller. Three years isn’t exceptional.