Battery minimum voltage?

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Nicholas123

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I've got a battery down my boat that I am just using over winter to power the hoover while I clean up after bodging (it is actually my starter battery) & being on a swinging mooring I am not to keen to hump it ashore & peddle with it back to my hovel on my pushbike for recharging any more than absolutely necessary.So what is the minimum voltage I should let it drop down to before sulphurization becomes an issue?It's down to about 12.4 volts at the moment.
 
depending on age and number of cycles, that 12.4 could be starting to be a bit on the low side. Any chance of a small solar panel (ebay cheapies of 5W or thereabouts, go for <£15) which could be left permanently attached (no need for a regulator) ?

That would save a huge amount of transport hassle, safety in the dinghy, etc, and would keep the batt topped up pretty well over the winter. Worth it to reduce time wasted in transport, and also it would keep it in better condition for starting - which is a pretty critical activity :)
 
You should not leave any battery in any significant state of discharge for longer than necessary.

All things are relative. The closer you keep it to fully charged the better it will be. If it's 12.4 when rested and not under load it's time to recharge it

+1 for a 5 or 10 watt solar panel.
 
It largely depends. Discharging and leaving it in a discharged state is not good for it. It also increases the chance of the electrolyte freezing if we have a cold spell. I would say 12.1V but you can go lower and it will recover. At the end of the day, all batteries are sacrificial.
 
2.4 its too low; time to recharge and must keep it charged at all times if you want the battery to last a few years. Small solar panels cost very little nowadays and should keep your battery at 12.7
 
tinkicker0 said:
Used to be a ditty we learned at college:

The battery song

12.7 and I'm in heaven.

12.5 I'm still alive.

12.1 my work is done.
Click to expand...

That sounds like the song for me if I can just think of a tune to go with it as I go along my merry way ;)
Seriously,It'll do until I can get round to sorting out my solar panel & have less important things to do.
Happy Christmas one & all & thanks for your advice.
 
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I have two of these on my boat.
Last winter one of them ran down to 10V due to a stuck bilge pump...don't ask.
It recovered well and has held it's charge well ever since. I gather that it's life may now not be as long as its twin though.
 
dylan said:
I have two of these on my boat.
Last winter one of them ran down to 10V due to a stuck bilge pump...don't ask.
It recovered well and has held it's charge well ever since. I gather that it's life may now not be as long as its twin though.
Click to expand...

Looks like overkill to me Dylan since you don't now have a diesel engine to wrestle with.Have you got a sauna on board or something! ;)
 
Strongly agree with use of solar charger. If you have room for a large one from a 'domestic' supplier you can get 200-250 watt panel for similar price as a 'marine' supplier. less than half the size. Its a function of volume production. Also an MPPT controller is much more efficient at low light levels and gets round the 'voltage' issues.

kind regards
 
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