At 22:38 -0500 26/4/11, William Dorsett wrote:
OK, I can see how you could input the amphr capacity of a given set
of new batteries, but would someone explain how a controller which
counts amps can adjust as the battery bank ages? As the capacity of
the bank drops over time, and this varies by different
manufacturers, it still seems that a controller which measures
voltage would track the SOC of the bank better than current counting.
Keeping track of SOC by counting Ah is a challenge in itself, but the
battery manufacturers' instructions don't require this. Fullriver
and Surrette require the you make a transition between Absorption and
Float charge regimes/stages at a certain point where the charging
current drops to a given level (although the Rolls FAQ is puzzling in
its wording there - suggesting that you can charge at 0.25 x C20
indefinitely!). Most stand alone RE system controllers do not
possess the ability to monitor the battery current, so they cannot
follow these instructions. This is my concern.
At 10:54 -0700 26/4/11, Rick Cullen - Blue Sky Energy, Inc. wrote:
There has been some discussion in the past few days regarding AGM
batteries and charge control switching to Float based on net battery
charge current matched to battery size and that our IPN-ProRemote
product can provide this.
Rick's Blue Sky product fits the bill but it seems expensive in the
context of very small systems. Phil Smith of Barden Batteries in the
UK has told me that a correctly programmed Tristar controller will do
a good job even though it does not 'know' the battery current. This
is good news.
I am still deeply puzzled about sealed batteries as I learn that you
must not make them gas but you have to be sure to charge them well
(like any other lead acid battery) or they will fail prematurely.
That's why I would like to be able to fit controllers that monitor
the battery current and use this to determine the transition to a
float charge.
Maybe it would help if somebody told me what sort of charging would
actually damage a sealed battery. Then I would simply charge them as
hard as the wind/sun allows while avoiding doing that.
--
Hugh Piggott
Scoraig
http://www.scoraigwind.co.uk
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