Help me not kill another battery bank

[crayiii]

Originally Posted by Thx4allthefish

Most AGMs will get damaged or shorten the life of the battery when discharged past 50%. Sounds like that's likely what happened. Though I think firefly is one of the ones that doesn't mind discharging past that.

We live aboard full time and never let these batteries drop below 12.5v. Our alarm is set for 12.5. That is to say until very recently when they crapped out. Then they dropped very low.

[sailorboy1]

Originally Posted by crayiii

All three Mastervolts failed. Firefly going in.

Good choice if your problem was caused by psoc issues. Mine have been doing well.

[Tillikum]

30 year batteries that stand all kinds of "abuse"?

https://www.youtube.com/watch?v=7ri_3c1Vklk

[skipgundlach]

My apologies: I'm away from my computer and so I just need to insert a "following"...

[donradcliffe]

Good choice. It sounds to me that you have a good charging and monitoring system, but got a bad battery manufacturer.

Originally Posted by crayiii

All three Mastervolts failed. Firefly going in.

[Tillikum]

Originally Posted by skipgundlach

My apologies: I'm away from my computer and so I just need to insert a "following"...

[skipgundlach]

So, now that I'm back at my computer, I have somewhat the same situation, though with almost (within days) 12 months on Trojan L16H-ACs.

Measurements are a TriMetric TM-2030-A as an amp counter, set for 93% (factory is 94; I started at 90 and found it did not match, at all, the other; now it usually arrives at 100% at about the same time as...), and a Balmar Smartgauge. The voltage levels support the depth of discharge indicated by the Balmar.

Very little time between 100% and 50% (BM), and ditto the apparent AH used (TM) - far fewer than would add up to the depth of discharge shown (e.g. this and an earlier AM: 102 and 103 AH used from 100%:TM, both cases 64% of an 870AH bank:BM).

Yet, when I've attempted charging with an AC-powered charger (Xantrex 2000XC), it goes into absorption nearly immediately, and usually into float long before I'd think it should based on the SOC. I've set the parameters to be the same as the Trojans.

I also have 720W through a Victron 100 | 50 MPPT controller; the default profile on that charger is the same as the Trojan batteries, so I've left it at that; it displays the same syndrome (VERY quick to go to float).


It's a very long story of potential interest as a separate topic so I apologize for horning in. But the symptoms are similar, other than that mine have been suspect from the beginning, and worsening to now where I wonder if they are dead (SGR after full charge and equalization, averaged, with +/- not exceeding .010, 1.225-1.230)...

I had a complete bank failure over some time in the prior set of Trojans, so I've been anal about recording stats - every time I pass the meters, which averages at about 10 recordings - and ALWAYS very early AM + a couple hours later, and an hour or so before, and as we go to bed - each day.

No decisions, just commentary that this seems to be going around...

[sailorboy1]

Personally I doubt any battery charger that the only control you have is to select from a predetermined battery type and can not program a tail current at absorption ever gets a battery fully 100% charged (mine can not). My guess is this the issue with most boats batteries over time.

Other than Skips batteries, based on history his boat has a battery demon.

[skipgundlach]

Originally Posted by sailorboy1

Other than Skips batteries, based on history his boat has a battery demon.

I'm not at all sure you're not right...

[john manning]

I have experienced a very similar problem with batteries. After a long period of trying to isolate the problem, when looking at a completely different problem, I found the cooling fan on my fridge compressor was faulty. The bearing had become very tight, the fan was trying to run continuously but hardly moving and the fridge compressor was on most of the time. There are probably other devices on your yacht that could cause the same effect.

[Chawes]

Batteries are a black art mystery. However I have learned this after having similar experiences. 1. Buy a tester that prints out status of battery. You put in manufacture parameters and test. Do not accept a battery that is not 100 per cent. One bad one out of six makes the team bad. Make sure you charge them fully at least once a month . Under charged batteries die a quick death. Hope this helps. Best of luck to you.

[walt41]

Avoid the speculation and buy a battery tester at NAPA for $50. It will tell you if the batteries are good by showing voltage under a known load.

[sailorboy1]

Originally Posted by walt41

Avoid the speculation and buy a battery tester at NAPA for $50. It will tell you if the batteries are good by showing voltage under a known load.

Wouldn't tell you anything of real ise for house batteries

[sailjumanji]

Originally Posted by sailorboy1

Wouldn't tell you anything of real ise for house batteries

I agree. We had to run traditional capacity test to quantify how bad the batteries were. Two different battery testers (auto battery shop and West marine) said the batteries were good. We them capacity tested at fixed 20 hr rate, and both batteries had lost 90% of their capacity.

[Pelican_38]

A question for the collective smart folks - is shallow discharge a possibility in killing this bank? You don't say what your amp hour usage is overnight, but you mention you recharge 100% during the day. Assuming solar stops charging at night and wind charges continuously, is it possible that you are only using a small percentage of the bank many nights and fully charging it back the next day leading to early failure based on shallow discharge cycle?

Is that a thing?