Re: (ET) AGM

["David Roden" <etpost drmm net>]

On 4 Feb 2013 at 10:37, Robert wrote:

> If you charge them over their max rate the one way valve can open from
> the heat developed to relieve the pressure and the battery is toast. 

One thing more.  A little too much finishing current now and then isn't 
likely to ruin an AGM or gel battery, though it won't help it.  

When the valves open, water from the electrolyte is being lost.  
Eventually 
this causes the electrolyte's SG to rise.  This can cause premature 
positive 
grid corrosion, and/or allow overdischarging of a starved-electrolyte 
battery.  This isn't instant death for the battery, though it might indeed 
mean a shorter service life.

It's not a bad idea to weigh your battery when it's brand new and record 
the 
value.  Later, if you think you might have had some water loss, you can 
(carefully!) drill holes in the battery, add distilled water with a 
syringe, 
and reseal the holes.  I've not tried this myself (yet), but have heard of 
people getting months to years of extra service out of AGMs this way.  


David Roden - Akron, Ohio, USA

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