[RE-wrenches] Magnum System - Discharged Battery Bank

[Drake]

One issue I see is that a 4.4 kW inverter is 
being fed 7 kW. I don't know if this would 
account for all you are seeing. Could the Magnum 
could be shutting down on overcurrent?

At 09:27 PM 12/16/2014, you 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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