[RE-wrenches] AGM battery charging, more details

[Darryl Thayer]

HI Hugh and all
As Hugh knows the Outback FNDC was meant for such operation, Apollo can track 
the SOC but can not control off SOC.   

 




________________________________
From: Hugh <hugh at scoraigwind.co.uk>
To: Allan at positiveenergysolar.com
Cc: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Mon, April 25, 2011 1:27:00 AM
Subject: Re: [RE-wrenches] AGM battery charging, more details

At 15:30 -0600 24/4/11, Allan Sindelar wrote:
> The Solar Boost products actually used an external shunt option, tying to the 
>Kelvin terminals on the shunt to measure current and allow compensatory current; 
>a dip switch controlled internal/external sensing. Modern digital controllers 
>apparently rely solely on voltage variations.

Thanks Allan,

So most modern controllers cannot sense the battery current and therefore cannot 
use this as a cue to switch to floating the battery. I confess that I had never 
heard of the Solar Boost external shunt but since most of my systems have an 
element of wind and/or hydro this would not be an option for me.  Without this 
external shunt, a controller is not going to know the charging current (since 
part of the current will be going to the load).  Without knowing the current, 
how can you do a proper job of switching to float and avoiding drying out the 
battery?

I don't understand how people can use sealed batteries successfully on RE 
systems.  I avoid them when I can and I usually set the absorption voltage too 
low, for safety, if I do have to.  But I am keen to learn about a successful 
approach that does charge the battery properly without drying it out.
-- Hugh Piggott

Scoraig
http://www.scoraigwind.co.uk
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