Well I think my batteries are toast

[cardude01]

When my boat got whacked by Dorian last year, or whenever the hell that was because there is no time anymore, the batteries were discharged to about 30% before I could get to the boat. When I brought the boat back across to FL they appeared to charge up fully, but this is the first time I’ve really tested them on this trip from Stuart to Jacksonville.

Started off with a 98% charge (according to my Balmar SmartGauge) the first day, and after the first night anchoring they were at 89% the next morning and got to 98% by the end of the day. Next morning they were at 85% and reached full charge after cruising all day. This morning they were at 78%, and after running all day they never reached more than 83%.

These are Lifeline AGM GPL-31XT 12v, 125 ah. I have four of them. Bought them in May 2015. Are they toast?

 

[PMF1984]

Well they are not charging, as opposed to not holding a charge. Perhaps just one is dead, dragging the others down. Have a multimeter by any chance?

 

[cardude01]

Well they are not charging, as opposed to not holding a charge. Perhaps just one is dead, dragging the others down. Have a multimeter by any chance?

I do. What should I test?

 

[rslifkin]

I do. What should I test?

If possible, isolate each battery for a little bit, then check voltage. If one is significantly different, it's suspect.

Also, when it's showing less than full charge, how many amps are going into the batteries after it's been charging for a while?

 

[cardude01]

Ok, will try to check all that tomorrow. Thanks.

 

[Frosty]

I happen to have GPL 31XT's also. I like how they squeeze extra amp hours into the Group 31 case*.

If there is not something egregious like one bad one, you might consider equalizing them, which Lifeline advocates for a situation like yours and which they call "conditioning." One thing I love about Lifeline is their very complete Battery Technical Manual, which is a free download and which gives you a clear, cookbook approach for their care and feeding. It's got plenty of information but IMO is not a slog to read.

You can also call and speak to real live people in Cali in their tech dept. which I appreciate but have rarely needed due to the manual.

They actually have two levels of bringing batteries back. The milder one is the conditioning, and the more serious one is "deep discharge recovery."

Here is a link to the current manual: (I see it was just revised May 6, 2020.... guess I had better replace my copy.

https://lifelinebatteries.com/wp-co...F-Lifeline-Technical-Manual-Final-5-06-19.pdf

I went to their site just now to get the most current manual link and happened to notice this "How do I know if I have a bad battery" article. Haven't read it myself yet, but here is the link:

https://lifelinebatteries.com/2015/08/how-to-tell-if-you-have-a-bad-battery/

The answer to one of the points leads to a blog post with more on equalizing, here (I still recommend downloading the manual though):

https://lifelinebatteries.com/2015/10/can-i-equalize-agm-batteries/

Frosty

* I contacted them a few years ago because I was curious how they got the "extra" ~20ah into the XT (125ah vs. 105ah for the regular Group 31). What they explained is that each plate has two sides and they connect with the opposite side of the adjacent cell. In a normal battery the plates on each end don't have "mates" for their outboard side plates; but in the XT they cut two plates in half and put one on each end so they all have mates, hence the extra amp hours.

 

[markpierce]

Realized my house batteries were "toast" (which happened late last year after eight years) when they no longer accepted charging. Thankfully, the engine battery was still operative so was capable of reaching the boatyard under power.

 

[Jeff F]

Could be the charging system too. Or the smartguage. Don't be too quick to assume it's a battery problem.

 

[cardude01]

I’m at anchor. I ran the generator all night with the battery charger on and got the batteries to 93%. Wondering about my alternator now.
It’s a Balmar 100 amp.

 

[FF]

Use your DC volt meter to measure voltage at the battery.


Under alt. underway or with a 120V charger 13.8 to 14.4 depending on how long you have been charging.

 

[High Wire]

Don't condemn the bank until you get a trend. Sometimes the battery monitoring system needs a reset.

 

[cardude01]

Don't condemn the bank until you get a trend. Sometimes the battery monitoring system needs a reset.

True. The boat has been sitting for awhile. And I really have no idea how that Balmar smartgauge works. Some kind of mysterious algorithm. [emoji41]

 

[Frosty]

I've been running a Smart Gauge along with a shunt-based meter on my bank of GPL-31 XTs since early 2015. That did include one bout of "sitting" and not charging at all in hot weather for three months (no loads either). So far the Smart Gauge has been accurate except for the caveat that it does not report accurately when charging. It's in the ballpark then, but that's about it. Once charging has stopped it comes into its own.

I run pretty much exclusively from solar, so that means that once the sun goes down each day, it's accurate. I suppose it could be a bit trickier if you are constantly charging.

If you really want to be sure about your bank, then I don't know of anything other than a 20-hour load test. I did one last year since the bank was five years old then and it was a bit of a pain due to being "off grid." I used an inverter and a few different incandescent light bulbs to keep the load right where it was supposed to be. That worked right up to the end but not ALL the way because the inverter shuts down at about 10.5 volts. But it was close enough to see where my batteries stood, and I didn't have (or couldn't think of) an easily adjustable DC load of the right size.

If the bank sat at a partial state of charge for some time -- especially it it was hot out -- then they would fairly certainly benefit from a conditioning (as described in manual). I have managed to do that just with a good long solar day (and specific settings on the controller), but it would be easier on shore power.

 

[catalinajack]

My batteries are three years old. When they reach six years, out they go. I have no interest in keeping steadily declining batteries around to squeeze a year or two more years of use and worry, eventually, that they crap out at an inopportune time.

Realized my house batteries were "toast" (which happened late last year after eight years) when they no longer accepted charging. Thankfully, the engine battery was still operative so was capable of reaching the boatyard under power.

 

[Frosty]

... I have no interest in keeping steadily declining batteries around to squeeze a year or two more years of use and worry, eventually, that they crap out at an inopportune time.

I agree. In my case my period of storage was unexpected, and the bank was only about 1.5 years old (in 2016). They seemed to have lost some capacity when I got back, so I consulted with Lifeline's manual and their technical department which resulted in my "conditioning" them. That apparently recovered them (late 2016); and when I did a 20-hour load test mid-2019 they were still looking good. So in my case it wasn't keeping an old, wheezing bank going on its last legs, but rather giving a restorative boost to a relatively young bank that had gone through a few months of hard times.

But too, I am in the US and can get new Lifelines shipped to me in under a week. If I were heading offshore, or had poor access to new ones for some other reason, I wouldn't hesitate to err on the side of "replace."

 

[DDW]

This is the problem I have with the Smart Gage. It tells you very little. 83% of what exactly? Smart Gage would have you believe that is 83% of the bank's present capacity, which it has made a guess at. A statistic without the reference is useless.

What you need to know is, how many amp hours were used, and what is the voltage? When charging, how many amps are going in, at what voltage? On a real battery monitor, if I have used 50AH from my 300AH bank and it is now at 11.9V I know the batteries are toast. That information is not available from the "Smart Gage".

 

[OldDan1943]

A. check for case swelling. IF present, replace all the batteries in the bank.
B. the local battery supplier will gladly do a load test on your batteries.
C. if you need new batteries, they will sell the new batteries "installed" and kart your old batteries away.

Have them check the output of the charger.
The young, strong lads who replace your batteries will be relieved to see you dont have 8D batteries. Usually, they send two guys to change batteries. Give them a $20 tip for lunch and be thankful you didn't have to lift the batteries. LOL

 

[Frosty]

I have both the Smart Gauge and a "real," shunt-based monitor (Victron BMV). I like them both for different purposes. The SOC on mine seems accurate. I say that because my sole source of charging most of the time is solar (and it's easy to keep track of one source). I can see it go into absorb and taper down to about 1.75 amps going into the bank, and around then is when it registers 100% charged. That means 100% of whatever the capacity of the bank is (it does not need to know the capacity).

The shunt-based meter, I adjust once per year or so, based on a combination of reasonable deterioration rate, plus my gut feeling from watching the bank (to tell me how much to reduce the bank capacity in the meter settings). And the year I did the 20-hour load test I used that data as well.

That said, I rarely look at the SOC on the shunt-based meter. I DO use it for other things, such as separating amp hours coming in from amp hours actually going into the battery bank, keeping tabs on any parasitic loads, and etc. I like having both, and the cost and hassle of replacing batteries makes it worth it to me.

I have occasionally recommended only the Smart Gauge if the person asking was someone who was not interested in learning the ins and outs of using or installing a shunt-based gauge.

If buying now I'd be interested in the Balmar SG200 which combines both and works in lithium banks (Smart Gauge doesn't due to consistent voltage). Don't know where it stands on the new product teething timeline.