Schneider xw pro 6848 not powering up with eg4 lithium battery

[acdoctor]

It looks like potential difference across the breaker is the control for the little board. In that case the only way to activate the per charge would be to put a load greater than the relay coil on the battery than turn on the battery breaker last. Relay closes for 4 seconds then opens before caps bleed off turn on the batteries breaker. If 4 seconds is not enough you could cycle the load breaker a couple times before the battery breaker is turned on.
If this is so I wonder if you connected all 5 batteries and close inverter breaker would you get pre charge from all 5?
Everyone has a opinion that is what I see in the pictures.

 

[RCinFLA]

The big question remains, what triggers the Pre-Charge circuit? I've asked this question probably 6 times. I'm starting to think Signature Solar doesn't know how their batteries pre-charge circuit works.

The unit's BMS cannot give up short circuit protection.

The only way to automatically engage inverter capacitors pre-charge resistor circuit is to allow the BMS to almost immediately trip off for high excessive current and then allow the pre-charge resistor to attempt to bring the voltage up. If after a small period of time the pre-charge resistor is unable to bring up the voltage, then an actual short/overload is assumed, and the pre-charge resistor relay opens to prevent pre-charge resistor from burning up. If pre-charge resistor brings up voltage, then BMS is reactivated, and you are up and running.

Some large current BMS's just allow more initial overload current time before BMS disconnects, like a slow blow fuse, long enough for inverter input capacitors charging through BMS series resistance. However, this does not help much for reducing your turn-on by circuit breaker contact stress that progressively degrades breaker contacts resistance. The BMS PCB must be robust enough to take the msec of 1000+ amp surge current without vaporizing a PCB copper runner.

 

[Mr-Sandman]

So IF I understand what the pictures is showing and you guys are saying, The Pre-Charge Resister is wired parallel to the BMS output. IF the BMS is overloaded to a point it shuts off "such as initial capacitor charging an inverter" the power will continue to flow around the BMS thru the Pre-Charge resistor to attempt to charge the capacitors. If the output voltage rises to match battery in certain period of time "we don't know this amount of time for sure", the BMS will re-connect and operate normally. IF the voltage doesn't rise to match battery on output thru pre-charge resistor in that time, it faults the battery BMS and doesn't power up.

For the Schneider or inverters that actually power up when DC power is applied and don't have an on/off switch, this is a poor design. The Schneider never quits pulling power after initial connection. seems like the Pre-charge would have trouble getting the voltage high enough for BMS to re-engage. That might explain why some are having troubles getting their inverters powered. It could possibly be fixed by shortening the pre-charge timer in the BMS that re-engages the BMS after initial surge. Leave it on pre-charge too long and the inverter will not boot due to starving for voltage.

 

[RCinFLA]

The pre-charge does not have to get totally to battery voltage, just close to it, before BMS series MOSFET switch reactivates. The act of activating the MOSFET switches in a progressive sequence of parallel MOSFET turn on is a pre-charge resistance in itself.

There is inverter power up and there is inverter control power up. Just powering up the processor control and maybe even AC pass through relay does not take a lot of current.

I would highly recommend you not allow inverter to activate directly into inverting power output when battery power is applied to inverter. It is not a safe situation to allow this. If you have a problem, the inverter can just cyclically repeat the fault shutdown and reactivation until something worse happens.

 

[Mr-Sandman]

Just powering up the processor control and maybe even AC pass through relay does not take a lot of current.

It's a lot of current when it's flowing thru the pre-charge resister circuit. The issue seems to be the pre-charge circuit initiates and the BMS doesn't kick back in soon enough to get the inverter to finish "booting up". I don't know how much they pull during the boot-up, but there's a lot of clicking and fan spooling going on "self checks" so I'm betting on more than 100watts the resistor can handle.

These people having issue aren't inverting power on start up, the inverter is in standby.

 

[RCinFLA]

It's a lot of current when it's flowing thru the pre-charge resister circuit. The issue seems to be the pre-charge circuit initiates and the BMS doesn't kick back in soon enough to get the inverter to finish "booting up". I don't know how much they pull during the boot-up, but there's a lot of clicking and fan spooling going on "self checks" so I'm betting on more than 100watts the resistor can handle.

These people having issue aren't inverting power on start up, the inverter is in standby.

That is the challenge of 'one size fits all'. Imagine if you have four large inverters being fed from the same battery array.

 

[jberger]

In looking at the video posted earlier, it seems like it is powering up the Inverter and the Midnight Solar boxes. Any chance to have the Midnight Solar stuff wait to come up after the inverter stablizes?
I wonder if the inrush of all 3 components is triggering the issue.

 

[Mr-Sandman]

I suggested that to @Koldsimer already. He says there is DC breakers to the Midnights and they are shut off during the power up. In the video you can see him flip both the DC and PV breaker on to power them to show how they will start the inverter

 

[Hedges]

That is the challenge of 'one size fits all'. Imagine if you have four large inverters being fed from the same battery array.

<---- like this? ?‍

 

[Solar Guy Richard]

Thanks for the pics. The big question remains, what triggers the Pre-Charge circuit? I've asked this question probably 6 times. I'm starting to think Signature Solar doesn't know how their batteries pre-charge circuit works.

I'm sure someone here knows the exacts. Before I shove my foot in my mouth I want to make sure I have the correct answer. That being said, since I've started helping people and answering questions on this forum I get about 100+ calls emails and PM's a day so I'm doing my best. I'll get all the answers - as fast as I humanly can.

 

[Solar Guy Richard]

Hey everyone - just wanted to update:
We have a few additional reports of inverters/other devices having issues with start up. So far, anything we've had on our bench has no issues using the batteries with default settings. Not sure exactly what that means at this point, but that's where we are.
Regarding what starts the pre-charge circuit: We are verifying this information with the manufacturer to ensure we provide a correct answer. They just came back from holiday so hoping to hear an answer soon. I will be reaching out to those who have PM'd me over the last few days and touching base as this is ongoing. At this time, it appears that the units will run systems etc, just having issues with the initial start up. Sorry I don't have more, but we only just started receiving communications back from the manufacturer this weekend.

 

[Bluedog225]

Thanks for the update Richard. I’m surprised this is as complex as it‘s turning out to be. You guys will get to the bottom of it.

 

[Mahendra Gomanie]

Well I don't want to be the bias here but I would have posted about an issue that I suspect that was caused by the new gylls on a Xantrex system.
I will update after installing the Outback Radian.
I would have emailed on this issue after no response from email or this forum I called this morning.
I would admit Signature solar support is not kool.The impression I got is that I am paying the price for not getting a growatt inverter.to go with the gyll battery.
I am not pointing any fingers I will confirm after Saturday though.

 

[Solar Guy Richard]

Well I don't want to be the bias here but I would have posted about an issue that I suspect that was caused by the new gylls on a Xantrex system.
I will update after installing the Outback Radian.
I would have emailed on this issue after no response from email or this forum I called this morning.
I would admit Signature solar support is not kool.The impression I got is that I am paying the price for not getting a growatt inverter.to go with the gyll battery.
I am not pointing any fingers I will confirm after Saturday though.

I'm interested to hear what happened here. Although we have been told that some people are running into this issue, we have been unable to duplicate (and we even ordered inverters of the exact same make/model as people have told us!) on our tech bench. Preliminary research seems to point towards pre-charge resistor timing, but in our tests we have gone out of our way to actually lengthen this (by 50% or more) and still haven't duplicated this. It's a real head scratcher that we are still working on pinpointing. That being said - once the system is started it seems there isn't any issues at all.

 

[Solar Guy Richard]

Thanks for the update Richard. I’m surprised this is as complex as it‘s turning out to be. You guys will get to the bottom of it.

It would be so much easier if we could duplicate the issue locally. We have spent thousands on buying inverters (as mentioned by users) to specifically test XXX inverter with our batteries and have never had an issue. Including when we extended the precharge timer by 50%. I'll check with the team to see if they have any update to this today.

 

[Hedges]

I'm inclined to think the problematic inverters start drawing lots of current earlier. If those customers can measure time from battery on to inverter draws current, that might show an issue.

You can lengthen turn-on time, which you've tried. Deliberately load inverters and configure the to auto-start. Connect two inverters, for double the capacitance.

At this point, I would suggest travel to customer sites would be the best approach. Consider them beta-testers. Bring your battery and your inverter, reproduce, measure, swap hardware. Maybe leave them with a functioning system and take the problematic units back for your lab.

 

[Mr-Sandman]

I think @Koldsimer is just down the road from them too....

 

[Bluedog225]

Maybe OP will swap inverters for a bit?

 

[Bluedog225]

Tie!

 

[Hedges]

Tie? No, I won by a nose!