[RE-wrenches] Magnum System - Discharged Battery Bank

[jay peltz]

How long has this system been operational?

Jay
Peltz power




> On Dec 16, 2014, at 6:27 PM, Corey Shalanski <cshalanski at joule-energy.com> wrote:
> 
> 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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