Bad battery or bad controller?

[kstock11]

2 year old group 29 Interstate battery with 95 watt solar panel EtI installed Go Power system. One cell reads low with hydrometer. Readings in trailer read "dead" this morning at 8Am. By 9:00 14+ volts and 100% charged with just solar. Battery always kept charged with solar. Thoughts?

[thoer]

Did the low reading cell change significantly after the charge?

[padlin]

Current readings from hydrometer, and solar controller? Do you have a voltmeter with you?

Might try disconnecting the battery for an hour or more, then checking the gravity.

[kstock11]

OK, disconnected for 1 hour & retested with hydrometer. Same readings - 5 cells in green & one cell in the red. I do have a voltmeter (although have never used it) as I am home right now. (Just got back from an 8 day trip - 6 of which were off grid.

[escape artist]

Originally Posted by kstock11

OK, disconnected for 1 hour & retested with hydrometer. Same readings - 5 cells in green & one cell in the red. I do have a voltmeter (although have never used it) as I am home right now. (Just got back from an 8 day trip - 6 of which were off grid.

Hi: kstock... Sounds like "Dead cell disease" to me!!! Alf
escape artist N.S. of Lake Erie

[Ron in BC]

Could be a dead cell, it happens. I had one a couple of years ago in a battery only a few months old. They tested it, confirmed it was a one cell problem and replaced it.

Ron

[padlin]

Bummer, probably too late, but here's the link to Interstates warranty, check the chart.

http://www.interstatebatteries.com/s..._USenglish.pdf

[kstock11]

Yeah, I saw that - 1 year. Now the next decision is what to replace with. I'm considering another identical replacement, or else Trojan. I notice that Trojan AGM has a 48 month free replacement warranty. More for the battery, but..... Trojan is a Group 31, my current battery is a group 29. Same size though.

[cpaharley2008]

I replaced my Group 29 with dual 6 era bought at Sam's Club, under $200 and the box is big enough.

[fudge_brownie]

The dual six volt will give you a bigger bucket to draw from. Particularly important if you are off grid. The dual Interstate will give 234 Ah versus my guess of 110 Ah you currently have. I spent a week in North Carolina last fall during the hurricane and I do not believe we saw the sun for five days. The Interstate GCX series and the Trojan T105's are the industry standards. Not sure about the batteries from the big box guys.

[kstock11]

Jim, Which ones did you get? I show the Interstate SRM-29 as 210 reserve capacity. Do the 6 volts give you much more than than? Or am I reading the numbers wrong?

[padlin]

I think the SRM-29 is either 95 or 126 Ah, Interstate twin 6's are 232 Ah.

[Brian B-P]

Originally Posted by kstock11

I'm considering another identical replacement, or else Trojan. I notice that Trojan AGM has a 48 month free replacement warranty. More for the battery, but..... Trojan is a Group 31, my current battery is a group 29. Same size though.

Those "group" numbers identify which size and configuration the battery is as defined by BCI, so Group 29 and Group 31 are not the same physical package. Strangely, I had difficulty finding a BCI group chart showing both Group 29 and Group 31, but I found one at BCI Battery Group Size Chart

29NF: 330 x 140 x 227 mm (13" x 5 1/2" x 8 15/16")
31: 330 x 173 x 240 mm (13" x 6 13/18" x 9 7/16")

They are the same length, but the 31 is wider and taller. Some manufacturers are pretty loose with these specs, so actual dimensions vary.

I assume that Escape offers the Group 29 (SRM-29) because that's the largest 12V battery of this type offered by Interstate (their normal battery supplier). If it fits in the box, I would rather put in a Group 31 for more capacity, and it is a more common size in deep-cycle batteries anyway.

[Brian B-P]

Originally Posted by kstock11

I show the Interstate SRM-29 as 210 reserve capacity. Do the 6 volts give you much more than than? Or am I reading the numbers wrong?

The "reserve capacity" of a battery is how long (usually in minutes) it can deliver a a specific amount of current before dropping to a threshold voltage. In this case, the Interstate SRM-29 has a reserve capacity of 210 minutes at 25 amps.

Reserve Capacity is a spec normally applied to automotive batteries, rather than to deep-cycle batteries, but it is valid for both. The more typical spec for deep-cycle is the 20-hour capacity C20), which is the current (in amps) multiplied by the time (in hours) when discharged over 20 hours.

210 minutes (or 3.5 hours) at 25 amps is 87.5 amp-hours, but at the slower rate of discharge over 20 hours it would do better.

The 25-amp reserve capacity of a pair of the GC2-sized 6-volt batteries offered by Escape is 474 minute (or 8 hours); this is 198 amp-hours.

Originally Posted by padlin

I think the SRM-29 is either 95 or 126 Ah, Interstate twin 6's are 232 Ah.

95 amp-hours (C20) for the SRM-29 sounds reasonable, and I agree the spec is 232 amp-hours (C20) for a pair of Interstate GC2-XHD-UTL. So, the SRM-29 could deliver 4.8 amps for 20 hours, while the pair of GC2-XHD could deliver 11.6 amps for 20 hours.

The pair of GC2 batteries weigh 128.2 pounds, more than twice the weight of the single Group 29 at 59.7 pounds. It's not surprising that the big pair have more than twice the capacity.

[cpaharley2008]

But remember mine were in the rear where there was negative effect on tongue weight, your will be up front in your box where it will increase your tongue weight.

[kstock11]

Now I'm thankful that I didn't get the storage box in the front! My 2 hoses, 2 electric wires and all hook up materials are in the back, thus countering the future added weight to the tongue. For some reason, ETI installed a group 27 battery box so I'm now shopping for a dual 6 volt box to put them in.

[Brian B-P]

Originally Posted by kstock11

2 year old group 29 Interstate battery...

Originally Posted by kstock11

For some reason, ETI installed a group 27 battery box so I'm now shopping for a dual 6 volt box to put them in.

I'm confused... if the original battery was a Group 29 (Interstate SRM-29), was it jammed into a box intended for a Group 27 (such as a SRM-27)? They're pretty close in size...

width x length x height
SRM-27: 6.75" x 12.75" x 9.50"
SRM-29: 6.75" x 13.00" x 10.00"

It appears from earlier discussions that when Escape builds a 19' with dual batteries and no storage box, the batteries are mounted in separate boxes; it would make sense to use a single box sized for the 12V battery when the dual 6V option is not purchased.

If tongue weight is a concern and you're more than doubling the battery weight, you could look at relocating to inside under a (front) dinette seat.

[Brian B-P]

Originally Posted by kstock11

... I'm now shopping for a dual 6 volt box to put them in.

Keep in mind that you can get boxes sized to place the rectangular batteries end-to-end or side-by-side, so you can choose the one which works best for mounting, wiring, and packaging with the other stuff on the trailer's tongue... and you can use two separate boxes.

[AKCamper]

Originally Posted by kstock11

OK, disconnected for 1 hour & retested with hydrometer. Same readings - 5 cells in green & one cell in the red. I do have a voltmeter (although have never used it) as I am home right now.

Kevin,
The one thing I noticed about this thread was something I was trying to point out on another thread. With a simple hydrometer (a little too simple for me I like one that at least gives you numbers to go by) you determined without taking your trailer to an RV shop that you had a bad cell. The beauty of a flooded battery. With a sealed battery you need more test equipment and diagnosis becomes more difficult. A hydrometer shows specific gravity variations as well as state of charge.
A weak or dead cell is easy to determine even by a novice and if a battery is still under warranty (I have seen it a lot) no battery salesman can't argue with the facts. Just my humble opinion.

Also just like to mention, we really enjoyed seeing your trailer in South Carolina last winter.
Cody

[kstock11]

Thanks for everyone's advice on this thread. I was able to take care of the one item I wasn't sure of when spec'ing out our 19. Group 29 or 2 six volts? Effective today, I now have two six volt batteries installed. Looking forward to many days of boondocking.