Batteries

A fair sized van battery is only about £100 from halfords and just as good as one sold down chandlers. Time being money if it doesnt work just swap it out. They are guaranteed for 2 years but generally last at least 5 and one of my boats has a 10 year old one thats fine though only use ocassionally.
 
moomba said:
I had my Perkins 4236 fully serviced , as new boat to me in the Spring ,and she did not turn over the engineer looked at the batteries and all read 13 volts (etc) then opened them up and took fluid form each cell in the battery and put it into an eye glass/ small microscope and let me look through it.
He explained and I Seen for myself through the indicators that one of the cells in the battery was gone, but the other cell was still taking a charge and this can show on a multi meter as a charged battery , but there was not enough juice to turn over my engine,
This was one cell in 2 batteries 24v and the engine didn't even turn over. One battery changed over and turned first time.
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You seem to be saying that you had 13V from a 24V battery and the engine would not turn over, not exactly unusual. Unless I've not understood you correctly. Were they 2 12V in series with one dud cell (effectively knackering the circuit for any decent current level)?

What exactly did you see through the microscope? Cloudy liquid with suspended crystals?
 
Mistroma said:
You seem to be saying that you had 13V from a 24V battery and the engine would not turn over, not exactly unusual. Unless I've not understood you correctly. Were they 2 12V in series with one dud cell (effectively knackering the circuit for any decent current level)?

What exactly did you see through the microscope? Cloudy liquid with suspended crystals?
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sorry for confusion. yes 2 12 volts battieries , in series , one cell out of 4 was a dude , stopping the circuit ,
Hes was checking the Specific gravity is the density of the electrolyte fluid compared to water using a hydromenter
accoriding to him if If a cell goes dead, the battery may appear to fully charged but won’t function properly. Once a cell goes dead, the battery is bad and must be replaced

Repeat the specific gravity test for each cell of the battery. Compare the readings. If any cell shows a specific gravity more than 0.05 less than the others, the cell is dead and the battery will have to be replaced. For example, if five cells read 1.260 and one reads 1.254 (a difference of 0.06) the cell is dead.
 
moomba said:
If any cell shows a specific gravity more than 0.05 less than the others, the cell is dead and the battery will have to be replaced. For example, if five cells read 1.260 and one reads 1.254 (a difference of 0.06) the cell is dead.
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1. I wouldn't be quite as categorical as that, although I would be concerned. At the very least, with a 0.05 range, I'd give them an equalize and see how they performed during and afterwards.

2. Your sums are wrong in your example. 1.26 minus 0.06 is 1.20, not 1.254. The cell at 1.254 would be far from dead.
 
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macd said:
1. I wouldn't be quite as categorical as that, although I would be concerned. At the very least, with a 0.05 range, I'd give them an equalize and see how they performed during and afterwards.

2. Your sums are wrong in your example. 1.26 minus 0.06 is 1.20, not 1.254. The cell at 1.254 would be far from dead.
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The Batteries were all fully charged and showing a full charge on the meter but there was no crank to the starter
completely dead , after checking the 2 batteries with a hydrometer he found one cell dead , which affected all batteries
Sorry the sum is correct to 4 decimal points as this is needed for small amounts of data
1.2600 -1.2540 is in fact 0.060
a scientific calculator or excel sheet adjusted to 4 decimal points will give you this answer hope this helps
 
Still no nearer to understanding if I should bin this batt. Still 13.3v showing this morning. I can't for the life of me get into it to check the spec grav. I have never known a battery read this after standing for so long. Just to be double sure I used a different meter. Still the same reading.
 
chrishelen said:
Still no nearer to understanding if I should bin this batt. Still 13.3v showing this morning. I can't for the life of me get into it to check the spec grav. I have never known a battery read this after standing for so long. Just to be double sure I used a different meter. Still the same reading.
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You can now be pretty certain you have two faulty meters.
 
chrishelen said:
Still no nearer to understanding if I should bin this batt. Still 13.3v showing this morning. I can't for the life of me get into it to check the spec grav. I have never known a battery read this after standing for so long. Just to be double sure I used a different meter. Still the same reading.
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I'm sure that the battery is fine Chris. However, the only way to be certain, is to see if it can deliver a high current, most easily DIY tested by using it to start a car or boat.

If it spins over the starter motor with the usual gusto then it sounds good.

Richard
 
put a heavy wire breifly between terminala just like the garages used to do. if there is a bloody great spark it ok. if little spark but wire gets hot its flat, if no spark its dead. The garage has a more sophisticated device which measures the current while shorting the battery but basically the still short the battery. If both batteries ok individually, try shorting across the pair just in case crap connection between the two. If pair batteries ok check connection to starter. if connection to starter ok suspect starter.

I still think its possible you have defective cell in one of the batteries so you need to start bottom up and check each item in turn. If one cell was shorted you would have 22v for pair and it would probably still go. If one cell has high resistance however, then volts would be ok but it could deliver no current.
 
RichardS said:
I'm sure that the battery is fine Chris. However, the only way to be certain, is to see if it can deliver a high current, most easily DIY tested by using it to start a car or boat.

If it spins over the starter motor with the usual gusto then it sounds good.

Richard
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I think that's the way to go Richard. I shall report back ASAP.
 
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