[RE-wrenches] Magnum System - Discharged Battery Bank

Jarmo.Venalainen at schneider-electric.com Jarmo.Venalainen at schneider-electric.com
Wed Dec 17 11:27:33 PST 2014


Hi:

Figuring out what happened after the fact is a very big challenge and 
always involves a lot of cost for both time invested and ultimately the 
new batteries.

Things can be made a lot simpler, even preventative, by using a small 
battery monitor which remembers battery V, I, SOC, etc........ for up to 
10 years.

If you want more info, please contact me off-line.

JARMO
_____________________________________________________________________________________ 


Jarmo Venalainen  |   Schneider Electric   |  Solar Business  |   CANADA | 
  Training & Development Specialist - Senior 
Phone: +604-422-2528  |   Fax: +604-420-1591  |   Mobile: +604-505-0291 
Email: jarmo.venalainen at schneider-electric.com  |   Site: www.SEsolar.com 
|   Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 


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From:
Corey Shalanski <cshalanski at joule-energy.com>
To:
RE-wrenches at lists.re-wrenches.org, 
Date:
12/16/2014 06:27 PM
Subject:
[RE-wrenches] Magnum System - Discharged Battery Bank
Sent by:
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>



Wrenches,

I visited a customer today whose grid-tied battery backup system suffered 
some sort of catastrophic failure, and now I'm trying to play detective to 
figure out what happened and whose equipment/design is to blame.

Here is what I know so far:
- System is ac-coupled with a Sunny Boy 7000 (7.85kW array), Magnum 
MS4448PAE (x2), 3 strings of 4 12v batts (705Ah total)
- Site visit was triggered by the Sunny Boy registering zero output via 
online monitoring.
- SPST Solid state relay installed on Sunny Boy output, controlled via 
Magnum router, serves as secondary overcharge protection to Magnum's 
frequency shift feature. Technician who initially responded claims he 
measured 240v across the relay's terminals - relay manufacturer claims 
this is "100% impossible". We removed the relay from the circuit, and the 
Sunny Boy is again operational.
- On arrival I found the Magnum display showing a "Low Battery Charge" 
message with the bank measuring ~4Vdc. The individual batteries were in 
various states of charge, ranging from high of 6.3v to low of -2.6v. These 
measurements were taken at rest, all battery cables disconnected, and yes 
three of the batts were registering a negative voltage.
- Customer reports that he was not aware of any recent prolonged power 
outages.

The three potential suspects would seem to be:
- SS relay: The customer is convinced that this is the weak link in the 
system and somehow triggered this failure. I am not so convinced but would 
be interested to hear recommendations for properly testing its 
functionality.
- Magnum equipment: Since there is low-battery-cutout protection, why 
would this feature not have activated and prevented the batteries from 
draining so low?
- Batteries: I am not very familiar with modes of failure, but our 
distributor suggested that an internal short could be a possibility - what 
might have triggered this?

Clearly I am fishing for potential leads here, so any suggestions are 
welcome.

Thanks!
--
Corey Shalanski
Joule Energy
New Orleans, LA
ᐧ

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