lead acid battery issue

Newish car battery employed to power pony field electric fence. Likely to have been left connected well beyond the fully discharged state and possibly exposed to overnight frost.
Won't take a charge! Yes, I know, throw it away. However, horse person has gone off with my sound spare. Is *over* discharging an issue>? or...?
regards
--
Tim Lamb

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On 10/05/2012 21:03, Tim Lamb wrote:

Car batteries are designed to deliver lots of cranking amps. They are generally destroyed by a deep discharge, or the very least have their capacity severely reduced.
Use a leisure battery which is more rugged and can cope with deep discharge, or should I say are less damaged by a deep discharge. I'm pretty certain you can get devices which switches off a load once battery volts get below 11V.
There is a thought that leisure batteries can be part recovered by charging at 15V or so to reverse sulphation, but I don't have any experience of this or if applies to car batteries. My experience of car batteries is that unless they stay fully charged, they are relatively fickle beasts.
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On 10/05/2012 21:23, Fredxx wrote:

Any boat store will sell these - they cut your battery to make sure you have enough power to start engine
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Rick Hughes wrote:

and then the ponys get out..
buy a trickle charger and a waterproof pot...
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Or a mains energizer! Actually these seem to *tick* on medium wave radio reception.
Escaping ponies only an issue with a stranger as the regulars avoid the tape whether it is energised or not. Hence the probably flat for weeks battery:-(
regards
--
Tim Lamb

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On 11/05/2012 09:10, Tim Lamb wrote:

Or a PV panel and/or a Rutland Windcharger, if it's too far away from the mains.

That's guaranteed to kill any type of Pb-acid battery IME. NiFe, NiCd and NiMH don't suffer that way, provided you don't allow individual cells to become reverse-charged.
--
Andy

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On 11/05/2012 10:17, Andy Wade wrote:

I used a Rutland windcharger for years with an electric fence, but they're not cheap and a fair bit of hassle to install - a PV panel would probably be the best bet. Having said that, electric fences don't draw too much current - and if the batteries are swopped over every week or so and then recharged they should be fine.
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Farmer Giles wrote:

Can anyone think of any other application where the presence of electricity rather than its consumption is the primary function? After all, apart from inefficiency the device should have zero consumption unless something puts its nose on the wire.
Bill
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On 12/05/2012 09:58, Bill Wright wrote:

The old grid bias battery
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On 12/05/2012 09:58, Bill Wright wrote:

The battery powers the fence unit, which (to put it at its simplest) is usually some sort of switching across an inductor. Whether something touches it or not, it doesn't run on fresh air.
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Farmer Giles wrote:

No but the power it uses does no useful work until someone touches the fence. So it is inefficiency, like I said.
Bill
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On 12/05/2012 16:37, Bill Wright wrote:

You might as well say that about a burglar alarm. The fence unit does its 'useful work' by generating a high voltage from a 12 volt source, and providing a barrier. The animals don't have to keep touching it, having touch it once and got a shock from it they will keep away - and be contained. That is its job, and it generally does it very efficiently.
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Farmer Giles wrote:

Yes you're right. A burglar alarm. That's two things then.
Bill
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"Bill Wright" wrote in message

I suspect that more energy goes into the conduction to ground via blades of grass and other foliage than is used shocking the stock. Thankfully now I'm down to only one electric fence (keeping my sows in) but it's still a daily check to make sure that the green light is flashing when I feed them. I think a solar panel of the sort intended to top up a long standing car is probably the best way to keep the battery ok, but I managed to run over mine in the last snow with my tractor. They tend not to work after that!
AWEM
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Umm.. Can't quite get my brain round that one. Assuming perfect insulation for the fence and no radio transmission, I can see your point.
There must be losses in the induction coil primary and the timing/switch circuitry but not much.
Anyway, the plan is to retrieve my battery after a couple of weeks when the new horse will have learned to avoid white tape:-)
regards
--
Tim Lamb

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Tim Lamb wrote:

Imperfect insulation would allow electricity to be used but it would not do useful work.

Losses yes. Useful work no.
Bill
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On Thu, 10 May 2012 22:33:04 +0100, Rick Hughes wrote:

Any half decent boat doesn't use the engine battery for general "house" electricals. But such a device is still a good idea with deep discharge batteries.
As for Mr Lamb's battery it's dead, it's not worth the faffing about trying to resurect and even if it can be brought back it will still be unreliable. Weigh it in.
--
Cheers
Dave.




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On 10/05/2012 21:03, Tim Lamb wrote:

Provided you don't overheat it and keep it topped up, an extended charge at a few amps might recover it, although I wouldn't be that hopeful.
It is *really* worth using leisure (deep discharge)rather than car batteries for electric fencers. It just isn't worth the trouble trying to manage with ex-car batteries, in my experience.
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Tim Lamb wrote:

In this case charge them double. Swine.

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The Natural Philosopher wrote:

Car batteries aren't suitable. Use a deep discharge battery, as sold for golf buggies, caravans, etc. ('Leisure' batteries).
Bill
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