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lectric80 avatar image
lectric80 asked

MPPT 250/85 not charging batteries

Installed a new SmartSolar MPPT 250/85 Tr controller connected to 3600 watts of solar fully off grid. Currently showing 60-75 Volts coming from solar, batteries (10 24v lead acid) have dropped to very low condition since a change was made elsewhere last Thursday.

First to answer the question, last Thursday the whole system was shutdown, including the charge controller(PV first then batteries), so that 2/0 wire and 400 amp fuses could be added to the 2 Multiplus II X2 systems. This whole system was originally running a pair of AIO units which used 150 amp breakers and 6 gauge wire. The VE system was installed about 6 weeks ago and everything ran perfectly, inverters were humming nicely and charge system maintained the batteries fully. The charge stopped last Thursday when we brought it back online.

To make the change, first the PV was disconnected from the MPPT, then the battery was disconnected as well. Finally during this downtime the main negative cable (2/0 copper) was moved to the bottom of the battery array (10 24v lead acid batteries) to help balance the batteries. Cables were connected to the inverters, then the battery was reconnected to the MPPT. At this time the MPPT did NOT power on, it did not power up until the PV was reconnected.

Either way, since last Thursday the portal shows around 100w of production from the charge system. Today I went onsite and verified connections, made sure that nothing had happened up at the panels (420' up the hill). Connections at the controller and batteries are clean and tight, screws were disconnected and re-secured for all 4 8ga cables. With just batteries connected the controller does not turn on, it only powers up when PV is switched on. Voltage on the display is correct, currently 21.3v, but no more than 1 amp is ever shown.

So what can I possibly be missing? Did anything in the change cause this? I'm waiting on support from the dealer, just looking for anything I might have missed.

MPPT SmartSolar
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lectric80 avatar image lectric80 commented ·
Spoke with my dealer's support team and after doing a master reset to see if the device would wake, it is being sent back for warranty. Unknown at this point if they will simply replace, or if they will repair, as there's no way to know what exactly failed.
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nesswill avatar image nesswill lectric80 commented ·

With just batteries connected the controller does not turn on, it only powers up when PV is switched on.

This usually only happens when there is no connection to the battery (fuse blown or breaker off), any production will only be direct usage from equipment. Did you measure the volts from the battery negative terminal to the battery positive on the MPPT?

Otherwise, the MPPT could be faulty, sending it back to the dealer is a good move, good luck.

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