[RE-wrenches] Troubleshooting Off-grid PV.. battery

Tue May 29 16:56:21 PDT 2012

Eric,

I have not been following this at all & here is my .02  - 

Load test

Specific gravity test per cell.

Volt per cell measurement at rest.

Volt per cell measurement under as big a load as you can impose.

Volt per cell measurement with as big a charge as you can impose.

The voltage will drop off on bad or dying cells severely and out of line and
in comparison with "good cells" & the voltage will jump up severely under
charge.

If you line up the measurements - SG, VPC/ rest, VPC/ load, VPC/ charge.

It become visually clear if one or more is out of line. If your SG is 1000 -
1100 & all cells do not improve even after an EQ charge on the bank you
probably are looking at replacement.

****Try a refractometer instead of a hydrometer easier, cleaner, less acid
to play with unless you are so inclined, much more accurate, best of all
refractometers do not break in the truck on the road or if someone tosses a
tool in on top of them. 

Good luck!

Dana Orzel - Great Solar Works, Inc -  E - dana at solarwork.com -  V
970.626.5253

F - 970.626.4140     C - 970.209.4076     web - www.solarwork.com  

"Responsible Technologies for Responsible People since 1988"

Please consider the environment before printing this email   NABCEP #
051112-136

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Chris Mason
Sent: Tuesday, May 29, 2012 5:16 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Troubleshooting Off-grid PV...second try with
server up

If you suspect the batteries are floating high and not taking charge, why
don't you load up the inverter and see how much power you are getting from
the PV system when there the inverter is fully loaded? If the PV output
loads up nicely, then your batteries are gone.

On Tue, May 29, 2012 at 3:07 PM, Larry Crutcher, Starlight Solar Power
Systems <larry at starlightsolar.com> wrote:

Eric,

To see the responses to your original post, go here:
http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/

Larry Crutcher

Starlight Solar Power Systems

On May 29, 2012, at 9:03 AM, SunHarvest wrote:

Sorry. I have to re-post this as my local, small-town email provider's
server crashed the day I sent this out. I couldn't receive any responses.

Hi Wrenches,

I inherited an off-grid PV system that seems to be significantly under
producing. I have:

12 KC120's (~19V 7A each) paired up 2 in series, for 6 strings terminated on
new 15A breakers in a new Midnite combiner,
Output of combiner passes through a 60A breaker into a RV SolarBoost 50
charge controller. An SW4024 ties in the CC, a Kohler 8.5 Gen set, and a
Yuasa 24V battery bank.

My problem is that I never see more than about 5A (displayed at charge
controller) coming off the array, even in full sun, regardless of the state
of charge of the batteries. I figure I should see, at least once in a while,
closer to between 20-30A. Batteries are, admittedly, passed their life
expectancy as the system was installed in '02 and I am sure this is part of
the problem. I'm thinking that if the batteries are at about 1/2 capacity
(don't own a hydrometer...yet), the controller senses the batteries are near
full SOC even at lower voltage (~24V) and is therefore attempting to trickle
charge even in the bulk stage. Though this is not how the CC is supposed to
function in bulk, obviously, I'm assuming the old batteries are altering the
standard operating conditions of the system. I've adjusted the Bulk set
point on the CC but that doesn't seem to make a difference.

I doubt this is part of the problem but the generator is problematic as well
(it has it's own array of maladies).

Any insight is greatly appreciated. Thanks!

Eric Stikes
Owner
SunHarvest Solar
+1 (530) 798 - 3738 <tel:%2B1%20%28530%29%20798%20-%203738> 
www.harvesthesun.com

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-- 
Chris Mason

President, Comet Systems Ltd

masonc at cometsystems.co

www.cometsystems.co

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