Re: (ET) Batteries

["David Roden" <etpost drmm net>]

On 28 Apr 2014 at 18:18, Jeff Antonucci wrote:

> Have you looked at the Soneil 36V charger?
> http://soneil.com/content/3610sr 

That's really too small - its output is only 4.5 amps.  I'd recommend a 
charger that can deliver 0.15C to 0.2C, with 0.1C as an absolute minimum.

Thus, for a 220 amp hour golf car battery, a 16-22 amp charger is 
reasonable.  I wouldn't go below 11 amps.

Part of the problem is the time a small charger takes to get the battery 
full.  On a 220ah battery, just to get from 20% SOC to 80% (bulk charging) 
would take that little 4.5 amp guy almost 30 hours!

That may not seem like such a big deal with a tractor you use only once a 
wkee, but there's also the fact that lead batteries sort of get lazy if 
they 
don't get that initial "kick" when they're charged.  Some need it more, 
some 
less, but they all need it to some extent or they really do lose capacity.

I'm not an electrochemist, far from it, and I've never understood the 
science behind this.  I've heard it explained as "you need to blast the 
lead 
sulfate off the plates" and similar images, but I don't think that's what 
high initial current literally does.  

One way you could use a low power charger like that would be to use the 
blunderbuss GE charger for most of the bulk phase charging (to 70% or 80% 
SOC), then let the little guy take over and treat the battery nicer where 
it 
counts.  The only problem with that is how to automate the changeover, 
because if you're like me, you WILL forget to do it manually.


David Roden - Akron, Ohio, USA

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