[RE-wrenches] unique battery bank design question

[Jason Szumlanski]

1a x 12V x 24hrs = 288 watt-hours on a 48,000 watt-hour battery. My math
shows 0.6% of the nominal capacity. And that assumes there is no
charging source present.

That being said, I would agree that avoiding it altogether is the wise
decision, but there has to be a level at which the tapped load is
inconsequential. I'm just curious what that level is! 

Jason Szumlanski
Fafco Solar


-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Hugh
Sent: Thursday, September 01, 2011 4:21 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] unique battery bank design question

At 15:57 -0400 1/9/11, Jason Szumlanski wrote:

>  A 1A @ 12V fan on a 1000aH @48V battery bank can't make any real 
>difference. Correct me if I am wrong!
>

Yes that is wrong, because after 4 days you have removed 10% of the 
nominal capacity or about 20% of the usable capacity.

Tapping off batteries is bad practice as universally agreed.  One way 
to mitigate it could be to use separate shunt regulators (diversion 
load controllers) for each 12-volt portion.  This would probably be a 
healthy feature for 'balancing' any 48 volt battery and would 
possibly rescue a tapped battery, given enough surplus energy 
availability (which is usually the key thing for battery health).

Just a thought.

The snag is the cost.  ho hum.
-- 
Hugh Piggott

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