Repair your mppt scc

[ghostwriter66]

sure, never work on a live device.

But not required… Turn off the solar panel… Disconnect the battery from the solar charge controller… Then it safe to work on the solar charge controller… There is no need to shut off the inverter since the inverter is not connected any longer to the solar charge controller ... Yes if it was me I would shut everything off… But if he’s got something that needs to run all I’m saying is that he can work on the solar charge controller and also draw current from the inverter as long as the solar charging controller is separated from the battery and the solar panels are oFf ...YES if it was me I would shut everything off… But if he’s got something that needs to run all I’m saying is that he can work on the solar charge controller and also draw current from the inverter as long as the solar charging folder is separated from the battery and the solar panels are off

 

[OldLett]

The inverter runs from the battery… It does not run from the solar charge controller… I’m a little lost in your explanation

The original discussion concerned an MPPT charge controller damaged by disconnecting it's output while
the PV supply was connected. My simple reply did not go into the hi volt, low amp input being converted
to the lower battery voltage higher current. This being done by SWITCHING INDUCTOR ( usually torroid )
step down converter. With PV input connected and NO load connection 100's to 1000's of watts have no
where to go and will cause damage. The kick from stored power can be huge.
Every MPPT manual insists on battery connection first.
My mention of leaving the inverter connected was to provide SOME safety load ( input caps, etc.)for the MPPT.

 

[Dzl]

I disconnected my battery before disconnecting solar panel and burned out component. Has anyone figured out how to repair ?

I mean no offense but I think you need to slow down a bit. Two days ago you seemed to be fundamentally unclear on the purpose and difference between a Battery Management System (BMS) and a Solar Charge Controller (SCC).

Now you believe you may have burnt out your SCC. I think taking things a bit slower, and doing some research first would probably save you quite a bit of money in the long run.

Also, it sounds like Will and a few other more experienced members here would lend a little advice if you follow through and post pictures of the burnt out SCC, or at the very least provide the model and the symptoms and share a bit about your system.

 

[efficientPV]

Curious what your array voltage and battery are? What was the maximum input voltage of controller? Some controllers state higher input voltage with a higher battery voltage. Can't say I've worried that much about disconnecting the battery. It is a pretty poor design that would allow them to fail in that circumstance. Not that there aren't a lot of poor controllers out there. Almost all of my controllers were bought broken. Good deal for me nobody fixes them.

 

[TomTilly]

I have some experience in troubleshooting "random" electrical/electronic failures and it usually comes down to current. Perhaps the reason some of these SCCs fail and others don't when no battery is connected is that the panels aren't supplying power at moment the battery is disconnected or reconnected. I agree with Will that it is always a good idea to follow the manufacturers instructions, but their instructions are usually for the worst case scenarios. If you have six series connected panels giving 130 volts at high noon with max current when the circuit is completed by connecting the battery that might cause a failure (or accumulate damage to components is more likely) when the same system might be just fine early in the morning when making little power. So as usual "it depends". Buy quality equipment and do your best to follow the recommended procedures.

 

[HaldorEE]

The problem with disconnecting charge controller output while receiving PV input has been discussed
on other forums. It is caused by a maximum power point controller trying to switch the inductor stored
energy into an open circuit. Could be 100's of watts with no place to discharge except internally.
Magic Smoke. BUT , if the inverter is still connected, it's input circuitry can absorb that.
So, disconnecting all outputs from a MPPT can damage most of them. Disconnecting only battery is safe,
as long as inverter is on.

Right, the scenario you describe could easily cause an overvoltage condition. Anyone familiar with how old school ignition coils and points turned 12V in tens of thousands of volts?

The answer to the problem is not hard, a TVS diode to ground should shunt the overvoltage condition just fine.

I imagine most charge controllers have forward biased diodes connecting input to output to protect against overvoltage spikes on the inputs, but without a battery connected to the output, there would be no place for that overvoltage to go either. A TVS diode to ground on the output would do double duty there.

It is hard to imagine anyone being too cheap to add a TVS diode. Perhaps they used an undersized diode and it failed shorted (which is how TVS diodes often fail). That would render the charge controller inoperable. Should be easy to diagnose and fix if that happened.

Is the output shorted to ground?