Battery Life in Grid-Tie Systems [RE-wrenches]

[sunwise]

Scott's battery guy wrote:  Minimum 20% - 30% discharge on a regular
basis;
Equalize once a year if hydrometer readings don't indicate to do it more
Often.  The main (-) battery will use more water; and rotate battery
positions once a year.

Greetings -- Boy I sure wish there was more fact and less opinion about
LA batteries.  I've lived with them in my house for something like 15
years, sold them for almost as long, installed for the same period, etc.
After all these years there are still 10 times more answers than there
are questions about these critters.

So similar to this thread, how important is the "plate development" deal
with a new battery, whereby it is deeply discharged and then fully
recharged a couple times when first put into service.

Especially with smaller cabin systems without generators it seems like
it could be a bad policy to tell people to discharge a battery deeply
when first put into service (recharged when?).  The battery rotation
question also seems to have lots of answers.

Kurt Nelson
SOLutions

  

-----Original Message-----
From: Scott: Backwoods Solar [mailto:scott at backwoodssolar.com] 
Sent: Thursday, November 20, 2003 12:17 PM
To: RE-wrenches at topica.com
Subject: Re: Battery Life in Grid-Tie Systems [RE-wrenches]


Todd and Richard,

I have a 24v Harris hydro system which generates between 19 and 25 amps
depending on the number of nozzles open. It charges 8 Trojan L16HC
batteries
which are four years old. These batteries have been faithfully monitored
with an hydrometer and watered as needed with plates never being
exposed. I
have gradually lowered my bulk volt setting as regulated by a
temperature
compensated Trace C40 from 29.6 to 29.0 volts in order to reduce water
consumed. Hydrometer readings on a daily basis reach 1275+ in all
batteries.
Depth of discharge is typically 10% with a 30% discharge having occurred
perhaps 6 times in 4 years. Perhaps twice a year I have applied an
equalize
charge. A year ago, I rotated batteries in response to the battery from
which all (-) leads originated using more water than the balance of
batteries.

Last weekend, one cell in the battery which is now my main (-), not the
one
using extra water, died. It would not respond to any charging input from
the
hydro nor a backup generator while the other two cells in this battery
quickly attained a 1275 + hydrometer reading as did the other batteries
in
the bank. I spoke with a Trojan engineer at great length about this
situation and after a careful review of my entire system's parameters,
he
concluded that I did not cycle my batteries deep enough.

In summary, he said:

Minimum 20% - 30% discharge on a regular basis;
Equalize once a year if hydrometer readings don't indicate to do it more
often;
The main (-) battery will use more water; and
Rotate battery positions once a year.


So do I believe him?? and does anyone have other comments on my battery
situation?

Thanks

Scott

Backwoods Solar Electric Systems www.backwoodssolar.com


----- Original Message -----
From: "Todd Cory, Mt. Shasta Energy Services"
<toddcory at finestplanet.com>
To: <RE-wrenches at topica.com>
Sent: Thursday, November 20, 2003 6:34 AM
Subject: Re: Battery Life in Grid-Tie Systems [RE-wrenches]


> Richard Perez in a recent post about this said there is no reason to
cycle
a
> floated, wet cell battery in a grid tie system. Equalizing is still
> something worthwhile to do occasionally. Run the voltage up until all
the
> hydrocaps get the same (warm) temperature and you are done.

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