Battery conundrum

[GUMPY]

Let me explain, firstly I am 250 miles away from the boat. The sealed LA batteries are 4 years old but have not had that much use over the last 3 years. Batteries are normally on float charge in winter and 500w of solar in summer. Charge voltage set at 14.4v and float at 13.4v  Everything on the boat is switched off, master switch and solar charging is still on.  I have a setup that sends me a text message if the batteries are below 72% and resets once the SOC  is above 90%.

So what's been happening:

When I left the boat 5 weeks ago the batteries were AFAIK  fully charged.

Every morning at about 0530 for the last few days I have been getting a message saying battery below 72%, by lunchtime it has reset so should be above 90% or at least Smartgauge which triggers the text thinks it's above 90%. All other alarms on the SG are disabled as I got caught once before like that.

I am trying to think of a reason why the SOC would appear to drop 20% overnight when nothing is on.

I have one idea and the thought of it is pushing me to do a 500mile round trip on Monday to disconnect the solar😱

Does anyone have any thoughts as to the cause?

 

Edited September 17, 2022 by Loddon

[Tony Brooks]

The start of a shorting cell in a battery?

[mrsmelly]

Duff battery?

Make a hell of a mess when they go bang, like a hand grenade one I had to deal with!!

[cuthound]

8 minutes ago, Tony Brooks said:

The start of a shorting cell in a battery?

 

I agree, this is typical of a shorting cell.

[rusty69]

Bilge pump 

[Tracy D'arth]

Bilge pump, Solar blocking diode duff, radio, inverter quiescent, gas alarm, touch control lights?

[GUMPY]

15 minutes ago, Tracy D'arth said:

Bilge pump, Solar blocking diode duff, radio, inverter quiescent, gas alarm, touch control lights?

None of those they are all off,  unless it's the solar blocking diode. Didn't realise that it could drain batteries with MPPT controller in between.

22 minutes ago, rusty69 said:

Bilge pump 

No it's manual

36 minutes ago, Tony Brooks said:

The start of a shorting cell in a battery?

 

27 minutes ago, cuthound said:

 

I agree, this is typical of a shorting cell.

 

35 minutes ago, mrsmelly said:

Duff battery?

Make a hell of a mess when they go bang, like a hand grenade one I had to deal with!!

 

This is what I was thinking hence my trip on Monday. 😟🤔☹️

Hopefully Monday won't be to late😱

[peterboat]

41 minutes ago, Loddon said:

None of those they are all off,  unless it's the solar blocking diode. Didn't realise that it could drain batteries with MPPT controller in between.

No it's manual

 

 

 

This is what I was thinking hence my trip on Monday. 😟🤔☹️

Hopefully Monday won't be to late😱

I had a blocking diode go down it took my batteries down to 10 volts in hours so don't think its that

[GUMPY]

Just got back from a 540mile round trip to the boat.

Disconnected all the batteries, solar panels  and shut the whole boat down.

By the time I left after about an hour two domestics an the start battery were at 13.43v the other domestic had dropped to 13.24v.

My suspicion when I return in a few weeks is that the battery that is at 13.24v will be much lower voltage  than the rest

I checked the start as well since when on charge Its connected to the rest via a VSR.

I'm just glad it was the solar and not the 60amp batrery charger that was on when I spotted this.

Lets see in 3 weeks.

 

[GUMPY]

Now comes the decision (probably, I have yet to go back to the boat) about replacing the batteries. The present ones are three Leoch SFL-130DT which have lasted 4 years cost to replace like for like is £330.

I am looking at some LAGM-130 (pdf attached) cost of £447.  If the new SFL last as long as the old ones then the AGM will have to last 5.5years to break even on time/cost.

However we are looking at 200 v 600 cycles which means they could last 3 times as long.

Anyone got any good/bad experiences of AGM batteries.

There is a possibility that I might have given up boating in 4 years so won't care if they die which is the reason I am not considering anything more exotic🥱

LAGM-130.pdf

Edited October 2, 2022 by Loddon

[peterboat]

51 minutes ago, Loddon said:

Now comes the decision (probably, I have yet to go back to the boat) about replacing the batteries. The present ones are three Leoch SFL-130DT which have lasted 4 years cost to replace like for like is £330.

I am looking at some LAGM-130 (pdf attached) cost of £447.  If the new SFL last as long as the old ones then the AGM will have to last 5.5years to break even on time/cost.

However we are looking at 200 v 600 cycles which means they could last 3 times as long.

Anyone got any good/bad experiences of AGM batteries.

There is a possibility that I might have given up boating in 4 years so won't care if they die which is the reason I am not considering anything more exotic🥱

LAGM-130.pdf 1.94 MB · 2 downloads

My mate Martin who is a liv aboard bought similar he shopped around and bought them cheaper than Leoch were selling them, he is impressed with them. He has solar like yourself. 

[nb Innisfree]

1 hour ago, Loddon said:

Now comes the decision (probably, I have yet to go back to the boat) about replacing the batteries. The present ones are three Leoch SFL-130DT which have lasted 4 years cost to replace like for like is £330.

I am looking at some LAGM-130 (pdf attached) cost of £447.  If the new SFL last as long as the old ones then the AGM will have to last 5.5years to break even on time/cost.

However we are looking at 200 v 600 cycles which means they could last 3 times as long.

Anyone got any good/bad experiences of AGM batteries.

There is a possibility that I might have given up boating in 4 years so won't care if they die which is the reason I am not considering anything more exotic🥱

LAGM-130.pdf 1.94 MB · 3 downloads

I replaced FLA (lasted 2.5 years) with AGM, despite nearly wrecking them with too low a charging voltage (misidentified type of AGM) but subsequently recovering them they were still going strong after 7 yrs when we sold the boat. 

Edited October 2, 2022 by nb Innisfree

[GUMPY]

19 minutes ago, peterboat said:

My mate Martin who is a liv aboard bought similar he shopped around and bought them cheaper than Leoch were selling them, he is impressed with them. He has solar like yourself. 

AGM or the SFL

[peterboat]

11 minutes ago, Loddon said:

AGM or the SFL

AGM, it was a choice between valence secondhand or brand new Leoch AGM at his age it was the right choice, this year solar has done the job very well 

[cuthound]

1 hour ago, Loddon said:

Now comes the decision (probably, I have yet to go back to the boat) about replacing the batteries. The present ones are three Leoch SFL-130DT which have lasted 4 years cost to replace like for like is £330.

I am looking at some LAGM-130 (pdf attached) cost of £447.  If the new SFL last as long as the old ones then the AGM will have to last 5.5years to break even on time/cost.

However we are looking at 200 v 600 cycles which means they could last 3 times as long.

Anyone got any good/bad experiences of AGM batteries.

There is a possibility that I might have given up boating in 4 years so won't care if they die which is the reason I am not considering anything more exotic🥱

LAGM-130.pdf 1.94 MB · 4 downloads

 

When my boat was new 15 years ago, it was specified with 4 x 6 volt 225Ah Lifeline AGM  batteries.

 

They are still on the boat and have now dropped to about 50% of their original capacity but still enough for my leisure use.

 

I would replace like for like if it wasn't for the price.

 

These are the current equivalent batteries.

 

https://www.tayna.co.uk/marine-batteries/lifeline/gpl-4c/

[GUMPY]

Im very tempted by the AGM, I think the next owner of the boat will thank me for it🤔

Charge voltages at 25C seem to be 14.6v and 13.5v, means my VSR won't do much as start alternator is fixed at 14.4v.

All the rest of my charge sources are variable Including the alternator.

 

I will see what's actually happened to the original batts on the 12th when I go up to the boat. I can collect new ones from Market Harborough so no need to get them delivered.

[GUMPY]

Here I am again having got to the boat and poked around at the batteries.

I have on "loan" from Amazon 🤭 a battery tester, yeah, yeah, yeah, I know.

 

Some interesting results.

All batteries are showing a voltage of between 12.81v and 12.84v both on my meter and the tester.

 

Tester results:

All register as 98% SOC

The batteries have a MCA of 900.

 

Battery 1

CCA of 649

SOH of 52%

IR of 4Mohm

 

Battery 2 test 1

CCA of 117

SOH of 2%

IR of 22.4Mohm

 

Battery 2 test 2

CCA of 261

SOH of 8%

IR of 9.9Mohm

 

Battery 3

CCA of 612

SOH of 46%

IR of 4.24Mohm

 

My thoughts are that the first test on battery 2 there was a bad connection and that with two tests it seems that battery 2 is the one that is causing problems allthogh quite how I have yet to determine.

 

I can't see how the device works as it's to small to put any form of meaningful load on the battery, so I assume it works on resistance, capacitance and voltage.

 

Is there anything I have missed?

 

Now decision time, do I muddle through until next year with two batteries or do I get three new AGM this week knowing that the price will be higher next April when I need them.

 

[peterboat]

1 hour ago, Loddon said:

Here I am again having got to the boat and poked around at the batteries.

I have on "loan" from Amazon 🤭 a battery tester, yeah, yeah, yeah, I know.

 

Some interesting results.

All batteries are showing a voltage of between 12.81v and 12.84v both on my meter and the tester.

 

Tester results:

All register as 98% SOC

The batteries have a MCA of 900.

 

Battery 1

CCA of 649

SOH of 52%

IR of 4Mohm

 

Battery 2 test 1

CCA of 117

SOH of 2%

IR of 22.4Mohm

 

Battery 2 test 2

CCA of 261

SOH of 8%

IR of 9.9Mohm

 

Battery 3

CCA of 612

SOH of 46%

IR of 4.24Mohm

 

My thoughts are that the first test on battery 2 there was a bad connection and that with two tests it seems that battery 2 is the one that is causing problems allthogh quite how I have yet to determine.

 

I can't see how the device works as it's to small to put any form of meaningful load on the battery, so I assume it works on resistance, capacitance and voltage.

 

Is there anything I have missed?

 

Now decision time, do I muddle through until next year with two batteries or do I get three new AGM this week knowing that the price will be higher next April when I need them.

 

Are you going to use the boat? Would one new battery drag the other two up? Only you can know what's best, but if it's not going to used until April I would muddle through on two 

[MtB]

What does SOH mean?

 

State of health perhaps? A meaningless term Shirley. 

 

 

[GUMPY]

8 minutes ago, MtB said:

What does SOH mean?

 

State of health perhaps? A meaningless term Shirley. 

 

 

Yes,  State of Health

Don't know how it's defined but if two are are higher than the other then I guess that one is not well.

Tempted to muddle through but the AGM are a good price and Batt 1 can replace the starter which after 10 years has a SOH of 23% despite showing 12.94v after standing for a couple of weeks.

[MtB]

4 hours ago, Loddon said:

Don't know how it's defined but if two are are higher than the other then I guess that one is not well.

 

You and everyone else!

 

I've never seen the meaning of "state of health" defined by anyone using that term, ever. So like you, we are all guessing as far as I know. 

 

Does anyone here seen a definition of what is being measured? If it is measuring something specific, why do they not just say what is being measured? 

 

I'm off for a Goggle about it, I might be back! 

 

 

Edit to add: 

Ok there are lots of web pages saying (in summary) there is no consensus on what it means but there is a Wikipedia page that sums it up:

 

"As SoH does not correspond to a particular physical quality, there is no consensus in the industry on how SoH should be determined. The designer of a battery management system may use any of the following parameters (singly or in combination) to derive an arbitrary value for the SoH.

• Internal resistance / impedance / conductance
• Capacity
• Voltage^[3]
• Self-discharge
• Ability to accept a charge
• Number of charge–discharge cycles
• Age of the battery
• Temperature of battery during its previous uses
• Total energy charged and discharged

In addition, the designer of the battery management system defines an arbitrary weight for each of the parameter's contribution to the SoH value. The definition of how SoH is evaluated can be a trade secret.^[4] "

 

 

^{https://en.wikipedia.org/wiki/State_of_health}

 

 

 

Edited October 12, 2022 by MtB

[Jen-in-Wellies]

5 hours ago, MtB said:

"As SoH does not correspond to a particular physical quality, there is no consensus in the industry on how SoH should be determined. The designer of a battery management system may use any of the following parameters (singly or in combination) to derive an arbitrary value for the SoH.

State of Health = Amps per Hour. I'm surprised the experts here know that. 😀 T

The battery tester shouldn't be quoting it as a percentage though.

[GUMPY]

I would like to think that SOH is calculated using some magic formula from internal resistance, capacitance and voltage.

The device will be on its way back to Amazon soon having fulfilled its purpose. At a minimum it measured the internal resistance and voltage of each battery showing me one had gone high resistance.