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Thick_Piece t1_irfoz6g wrote

Reply to comment by Real-Pierre-Delecto2 in GMP powerwall customers…feedback? by slightlyrottensalmon

As far as using your generator to charge it, I have a kill switch in my electrical box so I can directly connect my generator with a 220 plug.

Would it know the difference? I am curious as I wanted to get those batteries and figured I could just cycle back and forth. Use the battery until it is dead, start generator, charge batteries and have the house running on the generator.

I honestly have no clue how they work but they must know when the power is coming through the lines instead of a generator?

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Real-Pierre-Delecto2 t1_irfrr5d wrote

Sadly yes it does. And for disclaimer reasons don’t do this don’t try it ever unless you really understand what you are doing. It looks for a very stable frequency on the mains before it connects so you would have to have a real nice genny preferably an older very large 1600rpm unit that is more stable with lots of rotating weight. When the initial draw of about 4k comes to bear the genny will slowdown a bit until the motor catches up this causes the frequency of 60hz to drop and the Powerwall thinks that's the start of an outage and disconnects.

Also the way the unit is wired in you would have to add yet another disconnect because you would put the genny wires upstream of the Tesla box and without that you would be back feeding into the utility lines which is a big no no and can kill workers who might be in the area not expecting power to be on a line. It's not just the battery box there is also the "gateway" where the relays and brain are stored.

I want to do just as you suggest but I am not quite there yet.

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Thick_Piece t1_irftide wrote

I will take your disclaimer to heart as I have no knowledge on the matter. I was thinking of trying to figure out how to do the same with the standard deep cell marine batteries as I figure my electrician could figure out how to transfer some of the generator power over to the batteries or simply use a battery tender to do the same. Then Tesla came out with these batteries and I wondered if it was an option.

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Real-Pierre-Delecto2 t1_irfvkq5 wrote

Ya I hoped for that as well. The thing is very sensitive to power fluctuations which actually makes it work really good especially in my area. Where I live the mains have auto-breakers so if a tree or something touches the line they will trip but then re-engage a few seconds later to see if the fault has cleared. They do this up to about 5 times and it creates a huge surge in the house on-off on-off etc it's horrible for sensitive electronics. Use to have to run across the room and shut off the tube amps and other radio gear I have on. That never happens now as the Powerwall switches over so fast and wont switch back until it has about 5 mins of constant mains power.

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