question

I just experienced an Error #39 an hour ago. I was cleaning up some wiring mess and accidentally bumped into a circuit breaker that disconnected my battery bank from one of my charge controllers. #39 comes from the MPPT preventing overcharging and it shuts down the PV array(s) attached to it to prevent damage to the batteries.

I had to go through and rematch my charge controller settings and then go through a proper restart: PV - off, MPPT - off...then turn on the CB to the MPPT from the battery bank and let it cycle up and network with the other MPPT. Once that was done then I turned on the PV array and it took about 2 mins to cycle up and network with the other MPPT. Then all was fine. Maybe 3 mins.

It looks as if Error #87 shows the same thing. MPPT preventing overcharging and it shuts down the PV array(s) attached to it to prevent damage to the batteries.

The Error #67 looks as if you have a BMS controlling the MPPT. And the BMS and MPPT lost communication. So the MPPT shut down so as not to overcharge the battery bank.

The low battery alarm appears to validate that the BMS stopped working and your batteries are showing a low SOC...or potentially the BMS lost its settings and the settings now contradict with the MPPT so the MPPT shutdown in order to protect the battery bank from overcharging.

And one more tidbit...the array that was attached to the MPPT that did the Error #39 also was showing no amps...just volts. Once I went through the restart it came back up with volts AND amps :)

I think you will find something went haywire in the BMS or the communication between the BMS and MPPT.

Also, I think your Lynx Shunt will be just fine once the BMS/MPPT issue is resolved. Why? Because I also have a Lynx Shunt in my system and it came back up with no issues.

Please post what you do and how it turns out...would be interesting to hear.

It did that 3 times to me.

I am sorry if I didn't mention it, but I also reset both MPPTs on the last time. Killed the incoming PV power, then killed the battery power to them. Then reversed the process to start up the good one first, then the second (one with problem), then turned on the PV power. Before the last start-up effort I let them sit for 1/2 hour. I read that the error had to clear in the MPPTs before they would reengage without error. Also, on the last try I let the first MPPT run for about 5 min before starting up the 2nd MPPT(one with problem). Did your second MPPT ever give a "incompatible device" error?

At first on the last try it showed 0 amps coming in but the correct voltage, the problem MPPT was on. It took several minutes but the amps finally registered and all was good.

But remember, I had to go through and do a reset on all the MPPT battery values in the ssettings, in both MPPTs. I abandoned my "User Defined" and went with a "preset" for LifePO4.

If your BMS is shot, or a cell is bad, it may be sending wrong/bad battery info to the MPPTs. That is the main difference between what happened to you and me. And I can't help you with that one...I just don't know anything about BMS's running MPPTs.

I've lost count of how many times I've reset it now. Following the same process. I've tried it both connected to the Cerbo GX and smart network and disconnected acting standalone.

I've also tried resetting it while alternating each string of the array disconnected and no luck. I've also tested the solar panels and they seem perfectly fine, with identical numbers to the array connected to the working charge controller.

I've been through the BMS logs and it seems the cell imbalance occurred after the BMS detected an overcurrent. The erroring MPPT shows the following battery voltage of over 70v both today and yesterday.

An identical charge controller which is working perfectly fine, connected and configured in exactly the same way shows the following.

I'm starting to think not only is the charge controller faulty, but this issue was caused by this charge controller either putting out or detecting it was putting out 70v. I think it might be the former as my Lynx Shunt is completely dead.

I think I'm going to need to speak to my distributor and get some advice on how I can get some support and advice from Victron, as there's not a lot else I can do/test. Fortunately I still have one working array/Charge controller and the battery has been operating perfectly since the charge controller that has been experiencing issues has been disconnected.

Fun and games. :)

Dang, those are some strange readings.

The first shot shows the MPPT doing its job by shutting down the output and that generates your #39 error. But the 70's and 20's voltage readings are weird. Especially since they are not connected to the BMS.

The 2nd shot shows the MPPT doing its job with battery readings that make more sense...except the 45.19v which indicates an almost dead battery reading. The other 3 readings show essentially a fully charged battery.

Unfortunately one of the Error #39 resolution suggestions is a faulty charge controller.

How have you concluded that the shunt is dead?