What is my battery SOC?

[Rebotco]

I'm assessing my 110Ahr open cell FLA starter battery condition.

I have charged it at home for over 24 hrs and left it stand without load for 12 hrs.

The temperature is 18 Centigrade and the hydrometer readings for the 6 cells vary from 1.250 to 1.201.

Suspect its close to knackered, but what do the electrickery gurus think?

[Alan de Enfield]

I'd suggest you are correct.

Look at the right hand column of this chart.

 

Your cells vary from just under 90% SoC to ~65% SoC.

 

It's boogered

 

Edited June 4, 2021 by Alan de Enfield

[Sir Nibble]

I like the way SG is annotated "per cell". Gives the impression that whoever compiled the chart has no idea what specific gravity is. Do they imagine that adding the SG of each cell will arrive at any valid information at all?

[Tracy D'arth]

I would think that for a starter battery there is life in the old dog yet. Depends what you are trying to start really.

 

Do flat batteries take up less space?

 

 

Edited June 4, 2021 by Tracy D'arth

[Murflynn]

13 minutes ago, Sir Nibble said:

I like the way SG is annotated "per cell". Gives the impression that whoever compiled the chart has no idea what specific gravity is. Do they imagine that adding the SG of each cell will arrive at any valid information at all?

 

or they meant what OP is saying - but they should have used the words "each cell".

 

32 minutes ago, Rebotco said:

I'm assessing my 110Ahr open cell FLA starter battery condition.

I have charged it at home for over 24 hrs and left it stand without load for 12 hrs.

The temperature is 18 Centigrade and the hydrometer readings for the 6 cells vary from 1.250 to 1.201.

Suspect its close to knackered, but what do the electrickery gurus think?

 

what was the water/acid level in each of the cells?

[Rebotco]

18 minutes ago, Murflynn said:

 

or they meant what OP is saying - but they should have used the words "each cell".

 

 

what was the water/acid level in each of the cells?

 

 

They were all above the plates, but I did top up 2 cells with about 2 tablespoons of distilled water before charging.

They remain full now.

[Tony Brooks]

I was taught that a difference of more 0.03 between any two cells indicates a faulty cell. Lucas said 0.025. You seem to have a 0.05 difference so are likely to have a faulty cell.

[Tracy D'arth]

Its now a metric battery...........................................................................................................................................................................10v

[Rebotco]

5 hours ago, Tony Brooks said:

I was taught that a difference of more 0.03 between any two cells indicates a faulty cell. Lucas said 0.025. You seem to have a 0.05 difference so are likely to have a faulty cell.

 

Thanks. That was my gut feeling.

Its good to have a numerical confirmation.

[Ronaldo47]

Was the battery gassing freely when charging ended? My now rather elderly 1940's  textbook on accumulator charging explains that gassing occurs as the battery approaches full charge.  When most of the lead sulphate that was produced during discharge has been converted back to spongy lead and lead peroxide,  hydrogen and oxygen gases progressively begin to be evolved. When no more unconverted sulphate remains, all the charging energy is expended in producing these gases and there is no point in continuing charging any further. This description relates to traditional chargers that used a high voltage source and a series load to limit charge current and required human intervention to prevent over-charging. Modern sophisticated chargers using electronic control probably prevent excessive end of charge gassing. A charged +ve plate should be a dark chocolate brown, and a charged -ve plate, grey spongy lead. 

 

The book says that a properly treated battery should exhibit no more than a  difference of 15  to 20 points (1 point = 0.001 s.g) between cells,  and yours is more than this. However,  as your readings indicate incomplete charge, a further charge until gassing freely is observed, might be beneficial to bring up the more heavily discharged cells.

 

 You might need to use an old fashioned unintelligent charger for this. Modern intelligent chargers are fine for batteries in good condition, but are often not smart enough to know  the difference between a high terminal voltage due to all cells attaining full charge,  and one caused by one or two fully charged cells developing higher-than- normal voltages while other cells are still not fully charged. 

 

Other posts on this forum have reported how, when returning their boats to use after months of non-use , with batteries kept topped up by solar panels, the performance of their batteries had improved significantly. This could be attributed to the long period of charge (without discharge)  which had allowed all the lead sulphate to be converted back to peroxide and spongy lead right through the plates rather than just the stuff near the surface (which is what you get when using a fast charger: it takes time for battery acid to diffuse into the interior of the plates, so the interior active material can suffer incomplete conversion).

 

 

 

 

[Rebotco]

19 minutes ago, Ronaldo47 said:

Was the battery gassing freely when charging ended? My now rather elderly 1940's  textbook on accumulator charging explains that gassing occurs as the battery approaches full charge.  When most of the lead sulphate that was produced during discharge has been converted back to spongy lead and lead peroxide,  hydrogen and oxygen gases progressively begin to be evolved. When no more unconverted sulphate remains, all the charging energy is expended in producing these gases and there is no point in continuing charging any further. This description relates to traditional chargers that used a high voltage source and a series load to limit charge current and required human intervention to prevent over-charging. Modern sophisticated chargers using electronic control probably prevent excessive end of charge gassing. A charged +ve plate should be a dark chocolate brown, and a charged -ve plate, grey spongy lead. 

 

The book says that a properly treated battery should exhibit no more than a  difference of 15  to 20 points (1 point = 0.001 s.g) between cells,  and yours is more than this. However,  as your readings indicate incomplete charge, a further charge until gassing freely is observed, might be beneficial to bring up the more heavily discharged cells.

 

 You might need to use an old fashioned unintelligent charger for this. Modern intelligent chargers are fine for batteries in good condition, but are often not smart enough to know  the difference between a high terminal voltage due to all cells attaining full charge,  and one caused by one or two fully charged cells developing higher-than- normal voltages while other cells are still not fully charged. 

 

Other posts on this forum have reported how, when returning their boats to use after months of non-use , with batteries kept topped up by solar panels, the performance of their batteries had improved significantly. This could be attributed to the long period of charge (without discharge)  which had allowed all the lead sulphate to be converted back to peroxide and spongy lead right through the plates rather than just the stuff near the surface (which is what you get when using a fast charger: it takes time for battery acid to diffuse into the interior of the plates, so the interior active material can suffer incomplete conversion).

 

 

 

 

 

Thanks for that.

Yes all the cells were gently bubbling on completion of the charging session.

I was using a halfords (semi - smart) 3 stage charger.

I take your point about the possible benefit of a further charging sequence and will try that.

I suspect the charger will go into float too soon though, and I don't think I can override that.

I will let you know the outcome in a day or two.

[Tony Brooks]

Re Ronaldo47's post. Low Sp.Gr. readings may not mean the battery is not as fully charged a sit could be. In this case it's more than likely its indicative of suffering from excess sulphation locking the sulphur into the plates (sulphation) and out of the acid.

 

23 minutes ago, Rebotco said:

 

Thanks for that.

Yes all the cells were gently bubbling on completion of the charging session.

I was using a halfords (semi - smart) 3 stage charger.

I take your point about the possible benefit of a further charging sequence and will try that.

I suspect the charger will go into float too soon though, and I don't think I can override that.

I will let you know the outcome in a day or two.

 

Just turn the charger off for a few moments and on again. You may have to do this  a number of times.

[Rebotco]

46 minutes ago, Tony Brooks said:

Re Ronaldo47's post. Low Sp.Gr. readings may not mean the battery is not as fully charged a sit could be. In this case it's more than likely its indicative of suffering from excess sulphation locking the sulphur into the plates (sulphation) and out of the acid.

 

 

Just turn the charger off for a few moments and on again. You may have to do this  a number of times.

 

Good tip - thanks!

[Richard10002]

13 hours ago, Rebotco said:

 

Good tip - thanks!

My Sterling inverter charger had an algorithm which meant that it would almost always revert to float after only an hour. I would have to set a timer so that I remembered to reset it every hour, until the amps being drawn, (as viewed on a NASA BM2 Monitor), were low enough.

 

It was truly irritating and I can imagine many people assuming that, "if the charger goes into float, the battery bank must be full", to their peril  

[Tony Brooks]

7 minutes ago, Richard10002 said:

My Sterling inverter charger had an algorithm which meant that it would almost always revert to float after only an hour. I would have to set a timer so that I remembered to reset it every hour, until the amps being drawn, (as viewed on a NASA BM2 Monitor), were low enough.

 

It was truly irritating and I can imagine many people assuming that, "if the charger goes into float, the battery bank must be full", to their peril  

 

Too true, but its the price you pay for relatively safe unattended battery charging. I think modern solar controllers do the same. If you left it at absorption voltage for days on end then the batteries would suffer and may be ruined. A switch to force it into absorption would be a good thing, but then the makers would get numpties suing them for new batteries.

[Rebotco]

UPDATE

As advised I put the battery on charge for a further 20 hrs.

But it kept going into float within 2 mins. I switched it off and on at least 10 times, but it thought it knew better than us and quickly returned to float.

Nevertheless, the differences in SG between the cells seems to have closed up a bit.

After leaving for a further 12 hours the no load voltage is 12.56v and the SG readings vary from 1.225 to 1.250.

So I think its got a bit of life left in it, but its not very healthy!

Am I right?

[Alan de Enfield]

13 minutes ago, Rebotco said:

After leaving for a further 12 hours the no load voltage is 12.56v

 

Based on the voltage it is still only 80% SoC, and around 75% SoC based on SG

 

It is decidely (more than) unhealthy.

I wouldn't want to rely on it for starting my engine. make sure you have a Jump-Lead ready.