Over the Gate

debbie · Joined: 17 Feb 2007 Posts: 1191 Location: exmoor

Anyone know how long a 12v car battery should last? Ours are two years old and are used for the pulsor for the electric fencing. Now they just won't hold a charge. they are topped up with distilled water. Any ideas? Two of the four have died.
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Justme · Joined: 10 Feb 2007 Posts: 932 Location: Pwllheli

There is a saying that car batteries dont die they get murdered.

I bet you use it till its flat. Thats SOOOO bad for a battery.

The rule is
you start with a fully charged battery (12.6v after 24 hours with no charge or load)
for each .1v drop in voltage you have used 10% of the charge
if you use 10-20% of teh charge your battery will have say 1000 recharges in its life
if 20-40% 500 charges
40-60% 250 charges
60-80% starts to realy stuff the battery
over 80% used & it wont last long at all
take a battery to 100% flat & you are lucky if it works again.

So you can see that you realy dont want to go below about 12.2v. Most 12v kit turns off at 10.5v which is far to low. Let the bat get to 0v just once & it dead.

Justme
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debbie · Joined: 17 Feb 2007 Posts: 1191 Location: exmoor

that would explain it then....new batteries it is. Thanks just me.
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www.hiddenvalleypigs.co.uk
South West Regional Finalists for UKTV food Heroes 2007 placed 2nd