Battery voltage discharge level.

[Jeremy-KHYC]

Originally Posted by a64pilot

No, that’s the whole boat draw, refrigeration, plotter, wind instruments, depth finder, lights, radio, AIS everything. I find 10 amps to be not high at all for a boat under sail and autopilot.

And I would agree under those conditions. I mistakenly read the OP to be saying that the autopilot alone used up 35-40 AH in a few hours. If you're running all those systems, that's not a strange draw to my mind.

[a64pilot]

Originally Posted by Jeremy-KHYC

And I would agree under those conditions. I mistakenly read the OP to be saying that the autopilot alone used up 35-40 AH in a few hours. If you're running all those systems, that's not a strange draw to my mind.

I did assume he only knows his total load as most of us do.

[Jeremy-KHYC]

Originally Posted by a64pilot

I did assume he only knows his total load as most of us do.

You mean, most people wouldn't flip breakers and watch isolated draw on the system as a first step in diagnosing a heavy drain? That's the first thing I would do, try to isolate whatever is taking so much juice.

[skipgundlach]

I've just received but not yet installed the replacement for my TriMetric 2020 (current # 2030) which is an amp counter along with other fancy stuff.

Out of frustration with very short life cycles, on the last set of batteries (4 L16H-AC/435AH Trojans), I also installed one of Mainesail's (well, he sells them and he's such a help to the cruising community I spent the few extra bux to get them from him) Balmar SmartGuages.

I'm still scratching my head about the readings I get from it, as, when the reefer isn't running, our ghost load (things connected directly to the buss with inline fuse rather than breaker) is under 2A, but the voltages don't have much parallel to what I see as SOC.

Before it finally went south, the TM2020 was reasonably (based on my known loads) accurate in CAH per day, but the percentages usually didn't match, at all, what I was seeing on the BSGauge.

And, I'm - again - about to blow well over a boat buck to replace the bank (my upgrade story available here on CF), the original 4 having failed, sequentially, from on-installation (New from vendor), through, eventually, almost 2 years for the next two, and at a few months ex-warranty, the last, a dead cell. Now the remaining two (which I've been limping along on under reduced loads, having taken out the last bad cell series-connected pair), which are both under a year old, are displaying failure-to-hold a charge, with, after much equalization, a 93% BSG reading, but ~1.240 SGReadings per cell with a 13.5V (under the ghost loads) reading (and curiously, only 6.5V per battery).

It's almost enough to make me want to take out the huge bank we have and put a genset in (where we took out the one that came with the boat), and convert to 120VAC.

Sheesh. OP I feel your pain.

[a64pilot]

It’s very likely that the Smart Gauge was reading the percentage of the banks actual capacity, not its original or labeled capacity, you said it was in need of replacing.
Actually I’ve found that to be the best use of my Smart Gauge, Lifeline says to equalize when you notice decreased capacity, but how do you notice decreased capacity?
With the Smart Gauge I notice it when I see my SOC in the morning being lower than normal when the AH used is the same, so then I equalize.

[john61ct]

Yes that is a key differentiator compared to SoC via Ah-counting, the SmartGauge does not need you to update Ah capacity as that declines.

No longer unique, as Balmar has been engineering their own version in-house in the very new SG200. This **also** incorporates coulomb-counting into its SoC guesstimates, but apparently does not display that data.

They've only tested/calibrated against a limited range of lead batteries, it seems to have mixed accuracy results there, but Maine Sail reckons it's pretty spot-on with his LFP bank.

Still, no matter what you use to guesstimate SoC, that 100% point for stop-charge adjustment is best measured directly in amps accepted, that is canon, against which the other means get calibrated.

[skipgundlach]

Originally Posted by a64pilot

It’s very likely that the Smart Gauge was reading the percentage of the banks actual capacity, not its original or labeled capacity, you said it was in need of replacing.
Actually I’ve found that to be the best use of my Smart Gauge, Lifeline says to equalize when you notice decreased capacity, but how do you notice decreased capacity?
With the Smart Gauge I notice it when I see my SOC in the morning being lower than normal when the AH used is the same, so then I equalize.

Heh.

I'm not sure of the replacement cite; the Trimetric 2020 had clearly failed. I got the Smart Gauge because I wanted not to have to fiddle with the TM's capacity ratings; that was before the TM had exhibited its failure.

And, it is the nature of the batteries (the indicated and/or expected amphour use vs the rated SOC) which led me to believe that they, too, are toast, which was supported by my SGRs in the face of an indicated charge (SOC) a good 15 points higher than the SGR readings.

I think they're taking only a surface charge, and are very quick to decline in voltage...

[john61ct]

Just like voltage, SGR is not a stable indicator of SoH.

Only load testing / capacity benchmarking, ideally compared to the actual peak Ah (**not** trusting mfg rating) is accurate.

An internal battery resistance benchmark is also very useful, but there are so many variables, needs strictly controlled conditions, and only using the same calibrated tools over time.

[a64pilot]

Well with a Smart Gauge and an AH counting battery monitor you can get a pretty educated guesstimate on capacity, just try to draw them down at a 20 AH limit to some SOC, the lower the more accurate, but I stop at 50%. That should take 10 hours of course, then double the AH withdrawn and you get your capacity.
Now I don’t pretend this it be as accurate as taking them apart and to a lab that can hold exact amp draw over 20 hours, but it ought to give you an idea.
I’d try equalizing them and deep cycling once or twice before I tossed them myself.

[skipgundlach]

Originally Posted by a64pilot

Well with a Smart Gauge and an AH counting battery monitor you can get a pretty educated guesstimate on capacity, just try to draw them down at a 20 AH limit to some SOC, the lower the more accurate, but I stop at 50%. That should take 10 hours of course, then double the AH withdrawn and you get your capacity.
Now I don’t pretend this it be as accurate as taking them apart and to a lab that can hold exact amp draw over 20 hours, but it ought to give you an idea.
I’d try equalizing them and deep cycling once or twice before I tossed them myself.

Does an indicated SOC in the 30s qualify for deep discharge (overnight from essentially full)?

They've been equalizing for a couple of weeks now, on solar, once fully charged...

[conachair]

Originally Posted by a64pilot

Well with a Smart Gauge and an AH counting battery monitor you can get a pretty educated guesstimate on capacity, just try to draw them down at a 20 AH limit to some SOC, the lower the more accurate, but I stop at 50%. That should take 10 hours of course, then double the AH withdrawn and you get your capacity.
Now I don’t pretend this it be as accurate as taking them apart and to a lab that can hold exact amp draw over 20 hours, but it ought to give you an idea.
I’d try equalizing them and deep cycling once or twice before I tossed them myself.

Do coulomb counters factor in temperature?
Just had a thought, in the heat of the summer my smartgauge after a nights discharged showed the 2 x T105's as being quite a bit fuller than the BEP meter, the other night in the cooler air they seemed to tally up much better. Maybe something to do with the batteries basically having more capacity in the heat?

[sailorboy1]

Originally Posted by skipgundlach

Does an indicated SOC in the 30s qualify for deep discharge (overnight from essentially full)?

They've been equalizing for a couple of weeks now, on solar, once fully charged...

Don’t quite how you do it, but you are a mighty battery hunter/killer.

[a64pilot]

Originally Posted by skipgundlach

Does an indicated SOC in the 30s qualify for deep discharge (overnight from essentially full)?



They've been equalizing for a couple of weeks now, on solar, once fully charged...

You have been equalizing them for weeks?

[a64pilot]

Originally Posted by conachair

Do coulomb counters factor in temperature?

Just had a thought, in the heat of the summer my smartgauge after a nights discharged showed the 2 x T105's as being quite a bit fuller than the BEP meter, the other night in the cooler air they seemed to tally up much better. Maybe something to do with the batteries basically having more capacity in the heat?

An amp hour counter doesn’t factor in heat, but I’d guess a Smart Gauge may. It “knows” SOC”
In truth I have no idea how it works, so I won’t speculate, I have theories as does everyone.

[conachair]

Originally Posted by a64pilot

An amp hour counter doesn’t factor in heat, but I’d guess a Smart Gauge may. It “knows” SOC”
In truth I have no idea how it works, so I won’t speculate, I have theories as does everyone.

So unless you're batts are at 30C (looks like from trojans datasheet) , then a amp counter percentage capacity reading will be wrong...