EG4 6K Split Phase Inverter not powering Tesla Mobile Connector via Solar+Battery. EG4 says Inverter is bad?

[TessieRed]

Hello All. I am coming to you for help with a mystery I am having with charging my Tesla. I will try my best to make this post clear and concise.

I was successfully able to charge my Tesla Model S 75D for 3 days with Solar and battery no issues. Suddenly, I am no longer able to. As I attempt to charge my Tesla the Mobile Connector indicated high amperage and wouldn’t not allow the vehicle to charge.

I visibly observed the incoming amperage from the solar increase and decrease ranging from 18 all the way to 60A rapidly. I checked all my connections reseated the ground wire in the 240V receptacle and attempted again, this time the Tesla Mobile Connector indicated a fault within the until.

Here’s the mystery, when I switch to Utility mode as the means of power source, I charge without issue. All faults within the Tesla Mobile Connector are gone, but now I am not charging at all with solar, except for what my battery has captured.

EG4 has requested pictures of the install and believe the inverter may be bad. I agree possibly, but all other loads run fine such as my Split AC which draws about 8A or so, but 240V as well.

Even at a reduced amperage of 5A the Tesla Mobile connector will NOT charge via solar and battery. I am mystified as to if the issue is the Inverter itself or the Tesla Mobile Connector.

If the Tesla Mobile Connector is the issue, why does it charge via utility (AC Input)?

If the EG4 Inverter is bad, why is it able to power all other loads not problem?


System Details:

EG4 6K Off-Grid Split Phase Inverter

3.6Kw of Solar

5Kwh EG4 LL Server Rack Battery (48v)

Thank you in advance for your advice and assistance!

 

[timselectric]

It appears that you have lost the N/G bond, when in inverter mode.

 

[FilterGuy]

My first suspicion for any problem with a tesla charger is that there is a problem with the NG bond. That would explain why it works in passthrough mode but not on battery. However, the fact that it worked for a few days and then stopped working would imply it is not something as fundamental as not having a neutral bond.

How is the system wired? Presumably, the two hots, neutral, and ground from the grid is tied to the inverter inputs and the two hot outputs and ground are routed to the charger. Did you do anything special with the neutral output?

The EG4 6000 is a split-phase low-frequency inverter and we have had a devil of a time finding out how/if it does bonding. (EG4 and signature solar has been very poor at providing information about this) Based on measurements from several different forum members we think the inverter can be modeled like this:



Notice that this model has no dynamic bonding. If this is correct, there would be no bonding when in battery mode unless the user did something external to the inverter.

Also notice that in pass-through mode, the output transformer is acting as an autotransformer. To be compliant with NEC, the output neutral would need to be tied back to grid neutral. Some people report that they have wired the system with the output neutral tied back to the input neutral and it works, but EG4 support and Signature solar support refuse to say whether they support such a configuration.

Please measure the voltage between the output neutral and ground when in battery mode and again when in pass-through mode. If it is zero or near zero it does not tell us much. However, if it is more than a couple volts, it is a reasonable assumption the neutral ouput is floating.

 

[mlc27]

Just wondering if this got resolved successfully.I was thinking of making a similar system for my Tesla charging.
Thanks

 

[e2brindle]

Just wondering if this got resolved successfully.I was thinking of making a similar system for my Tesla charging.
Thanks

I was worried about this too - but figured it out.

I have an offgrid EG4 6k [with 3.6kw PV and LI 200aH batteries) to a Tesla mobile charger (NEMA 6-50) - and it faulted with 2 flashes - even with internal bonding.
Add a simple light bulb string light to an outlet with a circuit checker (indicating correctly wired neutral and ground) on L2 - and tada - it works.
I suspect the bond was really completed by the checker.

Its been charging without incident for a couple of days now...