net metered system question [RE-wrenches]

[Bill Brooks]

Great question--you are exactly right about our experience with off-grid
systems. You almost have to forget everything you ever learned about
off-grid batteries when considering an on-grid system. I am a firm believer
in Absorbed Glass Mat (AGM) batteries for on-grid systems for two major
reasons.

1. On-grid people will normally not mind their batteries (they don't check
the oil in their SUV so how are you going to expect them to maintain
batteries).

2. More importantly, Lead-Antimony (golf cart, L-16 type) batteries have a
high self discharge rate. This causes higher losses at float than AGM
(lead-calcium grids).

To answer your question, wrenches should be using AGM batteries in float
application. These batteries should not be equalized and are designed to
stay in float all the time. This is another reason that it is not advisable
to use Bulk charging since it is possible to gas a VRLA at Bulk voltages.

Bill.


> -----Original Message-----
> From: Allan Sindelar, Positive Energy, Inc.
> [mailto:allan at positivenergy.com]
> Sent: Friday, March 02, 2001 6:07 PM
> To: RE-wrenches at topica.com
> Subject: Re: net metered system question [RE-wrenches]
>
>
> Bill,
> Do you then depend on regular EQ to gas the batteries and stir the
> electrolyte up?
>
> And a bigger question for you and wrenches: Most of our battery
> care advice
> is for off-gridders, who cycle their cells routinely.  What is proper care
> for batteries that sit in float all the time on grid-backup systems? How
> often should they be equalized, if at all? And what is their life
> expectancy
> in relation to mfgr's rated cycle life, and also to their real-world
> expected life?
>
> Allan @+E
>
> ----- Original Message -----
> From: "Bill Brooks" <billbrooks7 at earthlink.net>
> On grid-connected systems I don't believe in going to Bulk. Since they can
> > absorb for an indefinite period, it's not necessary to go through that
> > process. After an outage at night, the inverter simply returns
> the system
> to
> > float voltage. It will take longer to go through absorbtion, but it does
> > away with the problem of the unit not dispatching to the grid
> during Bulk
> > charge. Since the timer is set to 0:00, it doesn't matter what
> you set it
> > to. I usually set it to 54 Volts like the float.
> >
> > Bill.
>
>
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 www.homepower.com

For info contact list moderator by email:
 michael.welch at homepower.com

____________________________________________________________
T O P I C A  -- Learn More. Surf Less. 
Newsletters, Tips and Discussions on Topics You Choose.
http://www.topica.com/partner/tag01