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Bonding neutral to ground?


Kbeck
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I have an evse that checks to see if the ground is good. On my current inverter I had to bond the neutral and ground for it to work correctly and start charging my car. Do I need to do that to these inverters or do I just need to ground the unit? Looking to grab one of these units that would be running in a 60°f basement so I am hoping I can run 7.2kw for a few hours a day to charge my chevy bolt. Charging on 110v is killing me here! Already 100% off grid w/ a 24kwh battery bank (adding another 40kwh min), currently 6s lithium ion but will be changing to 12s. I have 5kw in solar but expanding that to 10kw as well. Almost everything I run is 12v-24v dc with the exception of a few 110v cooking appliances, washing machine, and dishwasher. Another big thing that is super important to me is keeping the unit off when not required as I have found inverters can be a power hog sitting doing nothing. I don't see any remote function on it so I will probably be adding a wireless relay to the power switch. Maybe a feature that should be looked at as I noticed others needing the same function.

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4 hours ago, Kbeck said:

I have an evse that checks to see if the ground is good. On my current inverter I had to bond the neutral and ground for it to work correctly and start charging my car. Do I need to do that to these inverters or do I just need to ground the unit? Looking to grab one of these units that would be running in a 60°f basement so I am hoping I can run 7.2kw for a few hours a day to charge my chevy bolt. Charging on 110v is killing me here! Already 100% off grid w/ a 24kwh battery bank (adding another 40kwh min), currently 6s lithium ion but will be changing to 12s. I have 5kw in solar but expanding that to 10kw as well. Almost everything I run is 12v-24v dc with the exception of a few 110v cooking appliances, washing machine, and dishwasher. Another big thing that is super important to me is keeping the unit off when not required as I have found inverters can be a power hog sitting doing nothing. I don't see any remote function on it so I will probably be adding a wireless relay to the power switch. Maybe a feature that should be looked at as I noticed others needing the same function.

Well these can have a relay cut off switch put on if requested.  Far as the ground and nutral bounding that is going to be something Sid will have to say, I know your main power box has those bonded. so if your running it not on the breaker box, then chances are you got to bond it.

 

 

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7 hours ago, Kbeck said:

I have an evse that checks to see if the ground is good. On my current inverter I had to bond the neutral and ground for it to work correctly and start charging my car. Do I need to do that to these inverters or do I just need to ground the unit?

GS inverters with the Rev. B control board have an internal 50-amp neutral-ground bonding relay that can be configured to "always on", "inverter only", "AC Mains only", or "disabled."  This is all GS inverters on the 2nd shipment and moving forwards.  Would that work for you?

(please note, this is the Neutral leg on 240v split-phase inverters.)

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1 minute ago, Sid Genetry Solar said:

GS inverters with the Rev. B control board have an internal 50-amp neutral-ground bonding relay that can be configured to "always on", "inverter only", "AC Mains only", or "disabled."  This is all GS inverters on the 2nd shipment and moving forwards.  Would that work for you?

(please note, this is the Neutral leg on 240v split-phase inverters.)

Uhm, the first version are they bonded or not bonded?  Cause I know my main is bonded. . .

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7 hours ago, Kbeck said:

Another big thing that is super important to me is keeping the unit off when not required as I have found inverters can be a power hog sitting doing nothing. I don't see any remote function on it so I will probably be adding a wireless relay to the power switch. Maybe a feature that should be looked at as I noticed others needing the same function.

Power save mode?  No-load on the 6kw should be <600mA @ 24v.  (Please note that 6S is a difficult size to efficiently run an inverter at; I would recommend 7S for Li-Ion.  For 12S, I'd almost recommend a 36v GS inverter.  A bit high for it, but it'll run a lot better than a 48v, where that's quite low.)

Yes, it looks like we may need to add a "remote switch jack" to the inverters.  Relay contacts would be nice, but an optoisolated safety switch would be good as well.  But then it would require a voltage signal to turn on.

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32 minutes ago, The Blind Wolf said:

Does that mean any problem with it being put in a main box witht he main breaker off?  since  I'm guessing the main has already a ground rod even with the breaker switched off.

The ground rod in the dirt isn't what is important. What is important is that there exist a low impedance circuit for fault current to flow through. Your main service probably has a main bonding jumper, so the house circuits are grounded, but the inverter case itself needs to be grounded too. So if you have a 120/240 volt inverter, it needs 4 wires. This is true whether the neutral/ground bond is in the inverter or the panel. The difference is that in one instance, fault current travels along the ground conductor back to the inverter bond, while in the other instance fault current from an energized inverter case travels to the panel.

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Well, I got a 10/3 wire with only two wire for the slave per Sid wireing, a 10/4 for the master, the only wire I didn't hook up on it was the groudning wire, but, if it needs to be wired with the neutral bar and the ground wire tied to the outside equipment ground lug, then I can have somebody come back over to hook the ground wire up this week.

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23 hours ago, Sid Genetry Solar said:

Power save mode?  No-load on the 6kw should be <600mA @ 24v.  (Please note that 6S is a difficult size to efficiently run an inverter at; I would recommend 7S for Li-Ion.  For 12S, I'd almost recommend a 36v GS inverter.  A bit high for it, but it'll run a lot better than a 48v, where that's quite low.)

Yes, it looks like we may need to add a "remote switch jack" to the inverters.  Relay contacts would be nice, but an optoisolated safety switch would be good as well.  But then it would require a voltage signal to turn on.

Doesn't power save mode still pulse looking for the load? So the .6amps is the average including the pulses? My 6s voltage range would almost be the same as lead acid under load. 21v-24.6v is the range I keep it at. Double that for the voltage range at 12s. Nissan leaf modules are a pain to separate the internal 2s connection so I am working with what I have as they sit. Could do 10s for a perfect 36v system but I need the higher voltage so I can take advantage of my charge controller limits. Would 42v-49.2v actually work on the 36v inverter? Also I don't want to waste modules. I have 48modules(full Nissan leaf pack) so the ideal combinations are 4s(12v), 6s(24v), 8s(in between 24/36), 12s(48v), 16s(in between 48 and 60v). Could I get an inverter that can do 56v-65.6v range? That is the next perfect step up that I can do.

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On 3/8/2021 at 7:53 AM, Sid Genetry Solar said:

GS inverters with the Rev. B control board have an internal 50-amp neutral-ground bonding relay that can be configured to "always on", "inverter only", "AC Mains only", or "disabled."  This is all GS inverters on the 2nd shipment and moving forwards.  Would that work for you?

(please note, this is the Neutral leg on 240v split-phase inverters.)

Yup. Should work perfect.

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9 minutes ago, Kbeck said:

Doesn't power save mode still pulse looking for the load? So the .6amps is the average including the pulses?

The 0.6 amps is no-load condition, always on.  Power Save should be far less than that; "off state" should be <100mA (WiFi enabled, LCD backlight on).

Power Save Mode is a (configurable) on "load check" (1-15 seconds), looking for a (configurable) minimum load...which if not detected, is followed by a (configurable) "off time" of up to 225 seconds.

 

13 minutes ago, Kbeck said:

Would 42v-49.2v actually work on the 36v inverter?

Much better than 6S on a 24v 😉.  That's getting a smidge high, though.  The equivalent Lithium sizes corresponding to lead-acid basis are: for Li-Ion, 24v is 7S, 48v is 14S.  LFP: 24v is 8S, 48v is 16S.

It falls into a technical challenge to get the transformer specification just right; I'd like to reduce the transformer voltage some (to allow better operation at lower DC input voltages), but our efforts thus far haven't exactly been stellar (extreme EMI, etc.)

Basically, we currently use a 16v primary voltage for 24v inverters.  16vAC * 1.414 (square root of 2) = 22.624vDC absolute minimum input voltage AT NO LOAD for a pure sine wave.  Anything less than this, and the wave will start to flatten at the top--and if you dump a load on the inverter, it'll get considerably worse (due to transformer losses).  Low-range DC input will result in very low surge capability and quasi-square wave output. 

Going too high on the DC input range seems to cause weird behavior, extreme heat, low efficiency--and/or smoke.  Haven't pinpointed exactly why, though I do (now) have a pretty good suspicion why...

 

18 minutes ago, Kbeck said:

Could I get an inverter that can do 56v-65.6v range?

That's definitely unique...at least as of right now we don't have transformers wound for that specification.  Not saying it's impossible, just not tested and/or proven.  Definitely something we may want to look into.

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32 minutes ago, Sid Genetry Solar said:

The 0.6 amps is no-load condition, always on.  Power Save should be far less than that; "off state" should be <100mA (WiFi enabled, LCD backlight on).

Power Save Mode is a (configurable) on "load check" (1-15 seconds), looking for a (configurable) minimum load...which if not detected, is followed by a (configurable) "off time" of up to 225 seconds.

 

Much better than 6S on a 24v 😉.  That's getting a smidge high, though.  The equivalent Lithium sizes corresponding to lead-acid basis are: for Li-Ion, 24v is 7S, 48v is 14S.  LFP: 24v is 8S, 48v is 16S.

It falls into a technical challenge to get the transformer specification just right; I'd like to reduce the transformer voltage some (to allow better operation at lower DC input voltages), but our efforts thus far haven't exactly been stellar (extreme EMI, etc.)

Basically, we currently use a 16v primary voltage for 24v inverters.  16vAC * 1.414 (square root of 2) = 22.624vDC absolute minimum input voltage AT NO LOAD for a pure sine wave.  Anything less than this, and the wave will start to flatten at the top--and if you dump a load on the inverter, it'll get considerably worse (due to transformer losses).  Low-range DC input will result in very low surge capability and quasi-square wave output. 

Going too high on the DC input range seems to cause weird behavior, extreme heat, low efficiency--and/or smoke.  Haven't pinpointed exactly why, though I do (now) have a pretty good suspicion why...

 

That's definitely unique...at least as of right now we don't have transformers wound for that specification.  Not saying it's impossible, just not tested and/or proven.  Definitely something we may want to look into.

I figured the 49.2v would be outside of the design voltage of your 36v inverter. Aren't they usually only good to 45-46v? If I can get away with 10s then that works out great. The batteries have 80-85% of the capacity in the 3.5-4v range per cell. Higher nominal voltage than normal so most of the time it should be at 45v+.

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13 minutes ago, Sid Genetry Solar said:

The 0.6 amps is no-load condition, always on.  Power Save should be far less than that; "off state" should be <100mA (WiFi enabled, LCD backlight on).

Power Save Mode is a (configurable) on "load check" (1-15 seconds), looking for a (configurable) minimum load...which if not detected, is followed by a (configurable) "off time" of up to 225 seconds.

 

Much better than 6S on a 24v 😉.  That's getting a smidge high, though.  The equivalent Lithium sizes corresponding to lead-acid basis are: for Li-Ion, 24v is 7S, 48v is 14S.  LFP: 24v is 8S, 48v is 16S.

It falls into a technical challenge to get the transformer specification just right; I'd like to reduce the transformer voltage some (to allow better operation at lower DC input voltages), but our efforts thus far haven't exactly been stellar (extreme EMI, etc.)

Basically, we currently use a 16v primary voltage for 24v inverters.  16vAC * 1.414 (square root of 2) = 22.624vDC absolute minimum input voltage AT NO LOAD for a pure sine wave.  Anything less than this, and the wave will start to flatten at the top--and if you dump a load on the inverter, it'll get considerably worse (due to transformer losses).  Low-range DC input will result in very low surge capability and quasi-square wave output. 

Going too high on the DC input range seems to cause weird behavior, extreme heat, low efficiency--and/or smoke.  Haven't pinpointed exactly why, though I do (now) have a pretty good suspicion why...

 

That's definitely unique...at least as of right now we don't have transformers wound for that specification.  Not saying it's impossible, just not tested and/or proven.  Definitely something we may want to look into.

If you could do one in the 64VDC operating range ( Max 72VDC ) then you might get a railroad supplier interested. Locomotives use a 64 Volt nominal battery system and some of them have what are basically RV A/C units on them for cab cooling. A plug in at night unit where they can keep the engine warm and powered instead of having to rely on the batteries to start the engine to recharge the power drawn by the engine heating system would be useful to some ( US Army for one ). One of our former Gov't locos had crankcase heaters that required being plugged in to work. And as we were planning to run our steam engine on the coldest day of the year, they weren't plugged in. The steam engine had a couple leaks so it was down upon putting water in the boiler so the Diesel needed to run. It did, barely. Exhaust smoke when up the exhaust, fell down on the hood, fell down on the running boards, fell down on the ground. It took 2 hours to get the engine up to operating temp. Many railroads ( shortlines  ) shut theirs down for extended periods  when they don't have traffic so they either use a Kim HotStart  unit run off the batteries or have to plug them in to keep them warm. One on eBay = https://www.ebay.com/itm/164583061072  which is a plug in model.

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3 hours ago, Waterman said:

If you could do one in the 64VDC operating range ( Max 72VDC ) then you might get a railroad supplier interested.

The 12kw GS inverter will support 24, 36, 48, 60v nominal (absolute max system voltage 75vDC).  If we dropped 12v support on GS 6k inverters (nobody wants to spend $3k on enough MPPTs to provide 550A of charge current), we could use the same transformer method there and sorta support 60v systems across the board.

 

3 hours ago, Kbeck said:

I figured the 49.2v would be outside of the design voltage of your 36v inverter. Aren't they usually only good to 45-46v?

Needs to be tested.  Ideal max range is up to 16v (12v), 32v (24v), 48v (36v), 64v (48v)--however, that's "ideal", not that we've run them through their paces up there.  Nor that they're going to run most efficiently up there either.

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