Do I have a battery problem?

FlyingDutchman

FlyingDutchman

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Last weekend I was on the boat for the first time since October last year.
Tha batteries have been on the boat since then with the cables disconnected.

Having read about a 'natural' discharge of about 10% per monh on this wonderful forum, I decided to charge them up with a Halfords type charger that has am ammeter, although the 'eyes' still showed green.

The charger started to charge at about 3-4 amps, but after two minutes, it showed zero. The same for the second battery.

I am now worried that leaving them unattended for so long has killed them.
I did not have a multimeter at hand, but next weekend I might go again and could measure the voltage.

Any views, as always, highly appreciated!
 
Morning-

Is the battery bank Ah rating large compared with the charger max recommendations? Some modern chargers throw their toys out of the pram if they don't detect a Mondeo on the croc clips..

Have you used this charger before, with same or different results?

Could it be , given the green indicators, that all is OK ?(we need a 'fingers crossed smiley!)

I guess you did not try starting the engine/s with this bank?

Please let us know the outcome when you next visit.

Nick (Rivendell)
 
Hi Nick,

The batteries are 'Mondeo' size (71 aH) starting batteries. The halfords type charger has always wored fine with them. The batteries are not connected, so I was not trying to charge a 142 aH bank. Besides, I don't think the Halfords type is very intelligent...

I did not try to start the engine since the boat is on the hard.

I will let you know how I get on. I really don't hope they are kaputt as they are only 2 years old...
 
10% per month sounds a little excessive for winter. The discharge rate is affected by temperature, so with cold weather over the last months, the D R is likely to be lower.

That said, I would expect any charger to work a bit longer than a few minutes under those circumstances.


What voltage readings do you have across the terminals now ?


EDIT
Sometimes a charger needs to 'get going' before it starts putting charge into a battery. Try charging again; then leaving the batt for a few minutes, and connect up again.
 
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After connecting the charger, the needle went up to 3-4 amps and after a few miutes it dropped to zero. The same thing happened after connecting the charger to the second battery. I would think that the charger is ok, but this would mean, that either the batteries have passed away or they are so good that they have hardly lost any charge over the winter. It was cold here too, but only 2 or 3 weeks.

I will measure the voltage next weekend when I am on the boat and let you know my findings.
 
I had the same issue with my Halfords charger that out out 4amp max, it very quickly went into float charge. When I connected the Ring 16amp charger it kept going for much longer.
 
FlyingDutchman said:
After connecting the charger, the needle went up to 3-4 amps and after a few miutes it dropped to zero. The same thing happened after connecting the charger to the second battery. I would think that the charger is ok, but this would mean, that either the batteries have passed away or they are so good that they have hardly lost any charge over the winter. It was cold here too, but only 2 or 3 weeks.

I will measure the voltage next weekend when I am on the boat and let you know my findings.
Click to expand...
I suspect the batteries are fully charged, the charger thinks they are charged or at 13.8v and wont put any more in!
Stu
 
I leave my batteries with a solar panel connected, Keeps them nicely topped up. Went to the boat to find a flashing light on the solar charger. Oh no what's wrong! RTFM! means batteries fully charged. Doh!
 
Assuming good quality modern batteries in good condition, in winter temperatures the self discharge rate is probably more like 2% per month. 10% is a worst case figure for old high-antimony content batteries.
So they are probably still 80-90% charged and your charger will quickly go to float voltage and little current.
If you can set your charger to manual boost at say 14.5V for a few hours it would be a good idea, otherwise leave on 13.8V float for a day or two.
 
Well, last weekend I measured the voltage of the batteries. One showed 12,45V, the other 12,43. This was after the batteries have 'rested' for 1 week. The temperature of the batteries was quite low, something like 5 deg C.
Someone please tell me they are fine?:o
 
depending on the ambient temp, that gives them a figure of approx 75% charge. They are fine, but they might like a bit more charging.
 
Is there a possibility your charger is underpowered?
If it's trying to run at full belt, it may have a thermal-type of trip, which, if left alone, will cool and reset then the charger will start to charge again, until it overheats and the cycle restarts. I have a little red Halfords/Gunson which did that until I chopped up the cover and fitted an old computer fan.
I now have an audio ammeter as well, since the fan rate varies with the voltage.
 
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