[RE-wrenches] Magnum System - Discharged Battery Bank

Steve Higgins steve at surrette.com
Fri Dec 19 07:40:07 PST 2014


Keep and eye on the batteries... when they allow this far of a discharge and go into cell reversal often they are much weaker than the rest of the batteries.   I would have the customer cycle them once or twice a week to the 85-90% SOC, just to test how healthy the battery bank is.

To do so, disconnect the AC input to the inverter and let the inverter power some loads until the Magnum says they are 10-15% down... Then reconnect the AC input.   I would do this for 4 weeks.

After about a month,get them charged up to what you think is full then do a load test, find out what the C/10 discharge rate is and apply that amount of DC current load,  you should get that amount of current for at least 5 hours before the voltage drops below 2.0 volt per cell. (50%) state of charge.     Measure each battery every 1/2 an hour with a volt meter... battery voltage shouldn't drop near (assuming 12v cells) 12 volts for at least 3.5 to 4 hours.

You will need a current meter to monitor the amount of current you're drawing from the battery.

Variance can be +/- 10 to 15% depending on the type of loads you place on the battery bank, this is why it's nice to have a linear load tester...  Good ones run about $15-20K...

My guess is you have a couple of failed, or weak cells, that are aggravating the overall issue.

Hope this helps...

________________________________
From: RE-wrenches [re-wrenches-bounces at lists.re-wrenches.org] on behalf of RE Ellison [reellison at gmail.com]
Sent: Friday, December 19, 2014 7:16 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Magnum System - Discharged Battery Bank

First time I ever saw one of the bank of 80 cells are just about put me in a panic

Had no idea they could do that either


Bob Ellison


Steve Higgins
Technical Services Manager
P: +1.902.597.4020
M: +1.206.790.5840
F: +1.902.597.8447
Surrette Battery Company
Exclusive manufacturer of
[cid:rolls7dbc5a]<http://www.rollsbattery.com>

On Dec 19, 2014, at 9:48 AM, Corey Shalanski <cshalanski at joule-energy.com<mailto:cshalanski at joule-energy.com>> wrote:

Update on my investigation:
I visited the customer's house yesterday to set up a pulse charger. Much to my surprise the three batteries that originally registered negative voltage are now reading positive. Does this make sense - are batteries able to shift between negative and positive voltages at such a low charge level?

I do not see any evidence of distorted cases.


On Thu, Dec 18, 2014 at 7:58 AM, <jay at asis.com<mailto:jay at asis.com>> wrote:

I second tump.
Most likely a bad /cell battery took out the system.
As these are VRLA batteries, I'm curious do,the cases look damaged such as expanded or sunk in?

Jay
Peltz power
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