Re: (ET) 12 Volt batteries!

["David Roden" <etpost drmm net>]

On 19 Mar 2007 at 16:28, Kleinbrahm, Robert wrote:

> Does anyone know the shelf life of large AGM type batteries. 

They're like any lead battery - if they self-discharge and are left 
discharged, they'll become sulfated.  There's no cure for that.

The good news is that most AGMs have appreciably lower self discharge than 
flooded or gel batteries.  Six years is a prettly long time, but as a wild 
guess, I'd say they have a 30-50% chance of retaining enough capacity to 
make them useful for light duty use.  

They'll most likely be dead flat or nearly so.  To try to bring them back, 
you'll need a moderately high voltage power supply.  Connect an automotive 
taillight in series as a current limiter and crank up the voltage until 
you 
see a little current flowing.  If you're lucky, after something between 
several hours and several days, the current will start to increase.  Then 
you can start turning the voltage down.  Once they get a bit of a charge 
on 
them, you can switch over to a real charger.

If someone offered them to me for nothing, I'd take them.  I wouldn't pay 
anything for them, though.  Hey, if nothing else, they could be useful as  
ballast in the ET weight box.

David Roden - Akron, Ohio, USA

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