Battery problem

[rog]

For various domestic reasons I haven't visited my boat for a couple of months so when I finally got there last weekend I did a thorough check round everywhere, obviously.

Anyway, even bothered to check my batteries and to my concern found that the 2 starting batteries needed THREE litres of distilled water although the domestic was quite OK.
Don't suppose I've checked those batteries for about a year or so (I'll know better now!)

After filling, I measured just 7 volts on the terminals with the charger off momentairily and almost 8 with the charger on immediately after - was a bit suspicious about the accuracy of the voltmeter and have since checked the thing and found it is reading incorrectly on that scale - it was probably 10 volts and slightly more with charger.

Engines started OK but anybody know what's going on - is this usual with long term shore power/charger set-up and why is it effecting the starting batteries and not the domestic?

Thanks

Roger

 

[LadyInBed]

What sort of charger, 3 stage or what?
What type and how old are the batteries?

 

[Piers]

Oops. A number of points. First, let's hope the batteries are not terminally damaged, which can happen when batteries are left to run flat, when an unremovable deposit is left on the plates.

Second, when charging, it is likely a great deal of hydrogen gas will be given off - burns on its own, explodes when mixed with air - so ensure the battery boxes can drain overboard. If not, make sure the area is well ventilated with no possible sparks around - no smoking!

Third, it will take a long time to completely recharge them, and will depend upon the charger. If they are that low, a 'normal' charger may not recharge them fully. May be worth taking them to a garage for a charge up.

Fourth (or maybe first) - check the specific gravity before even thinking of charging them. Again, a garage job if you are not sure of what to do.

Lastly - in the future, and as you have realised, check the levels regularly!

Piers du Pré
www.playdeau.com

 

[quaelgeist2]

There is hardly any terminal age in sight for most batteries - definitely not the few years that your local chandler recommends...

Leaving aside mechanical failures (e.g. from dropping it ;-) ), almost all batteries can be brought back to working conditions.

have a look here:
http://www.megapulse.net/megapulseFAQ.html
http://www.megapulse.net/

regards
chris

before you ask - I am not in any way connected to that business, it's just one of the 'secrets' the spare part industry does not like you to know... (yes, I have one and a car with a 7 yr battery, advised to be changed numerous times)

 

[andyball]

It may recover....from experience with a lot of "dead" batteries, you may be better with a very slow charge- sometimes I've been able to recover discharged batteries with a tiny (1-2 amps) charge over several days, when a faster/larger charge has had little effect.

 

[VMALLOWS]

I simply can't agree with your comment that 'most batteries can be brought back to life' (we are talking lead-acids). You can certainly get a good number of years if you look after them well. Have just managed nearly 9 years on the car battery (in a diesel as well) and the 100amp boat batteries have averaged about 6 years (they get much deeper discharge, and often have to be left less than fully charged on the mooring). When they reach their end they tend to die very quickly indeed.

I have a couple of total 'duds' if you want to proove me wrong!

 

[quaelgeist2]

I guess you haven't checked the web address, have you ?
The thing advertised there tackles the main problem of the "dead" batteries, that is the build up of an passive sulfate layer. This layer limits the capacity and at some stage you can't charge it anymore.

There are a number of people who have reactivated old/dead batteries - monitored by independent authorities / institutions. I have not had to start from zero - yet.

chris

(admittedly, a little German helps as the report is in German)

... and as I said, keep believing in the myth of dead batteries, the manufacturers want to keep the sales levels up !

 

[Bodach na mara]

I agree with Vmallows and note from the German results that they EXCLUDED from the test any batteries with short-circuited cells. In my own (limited) experience of dead batteries, the open circuit voltage was often 10 volts or less, and that cells were often short circuited.
It used to be possible to measure this directly in the days when all cell terminals were accessible and this allowed a rather brutal method of extending battery life. I once ran a car (Standard 8 in front or 10 on the boot!) that had a 10 volt battery, i.e. the positive terminal had been cut off and re-soldered to the next cell.

Ken Johnson

 

[tr7v8]

I have one of these battery maintainers for the TR7 which float charges at 350MaH or so and "preserves" the battery between runs and when out of use in the Winter.
Several of my mates have reported that using one of these they've brought back batteries from the dead. For a £ 20-40 outlay definitely worth a try in my view.

Jim
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[VMALLOWS]

Exactly! I've been running all season with the 'domestic' battery one cell down at 10v....it's sufficient to run the electronics and lights adequately. Interestingly, looking through the filler, you can actually SEE the cell that has collapsed! (obviously shorting sufficiently to allow the other cells to continue to provide power).

With the onset of the cold weather, another has gone down, so now terminal.

Having said that, I have 'recovered' quite a few batteries from beside the marina skip which have given very worthwhile life, best being a monster 180amp which gave me 4 years of useful life. (lots of very big gin palaces in the marina).