48V 1500W Inverter

R

rev0

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Oct 3, 2017
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Hello All, I just purchased this inverter:https://www.ebay.com/itm/232546972210 and thought I'd post a thread to share my experiences with it and data as I go along. It's currently selling for $165 including shipping within the US (ships from California, I got it in 2 business days). It's a Reliable brand inverter, other Youtube videos I found on it show it is a pretty solid inverter, I saw a video of it operating at 1560W or so powering an electric oil heater, at an efficiency of around 82%. I plan on using it to charge my Nissan Leaf with the 120V adapter, which pulls up to 1437W. I just did a quick test with a 60V 5A bench supply to make sure it works, and it seems that it doesn't like running unloaded (the voltage display flickers and it makes unhappy noises), but with a little 7W CFL plugged in it works fine. It runs from 42V to 58.8V (up to 60V specced), which is perfect for a 14S Li-Ion setup which I intend to use. It has an awfully loud beeper that turns on below 42V, and the output shuts off below 40V. It won't turn back on until it reaches 49.1V (3.5V/cell for 14S). It appears to have a true shutoff when the switch is off, no leakage current, but I'll confirm that with a current meter later.
 
I nearly bought one of these.
I'll be following to see your thoughts
Cheers
 
Here's some data. This is all I think I can get till I build a real 48V battery which likely won't be till after the holidays,sorry guys :)


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I have this exact same inverter and have been using it since around October 2016, so I can confirm it's very reliable.

Here's a few things I noticed
- The output is 128v which is a bit high for some appliances. The UPS for my computer keeps trying to step it down.
- The output is actually 64v split phase. If you measure either leg to ground, it's 64v. So you can't use it with any transfer switch or anything like that where the ground and neutral are bonded at some point (usually breaker box). Maybe this is how 120v inverters are supposed to operate but it seems odd to me.
- It does hold load very well. I pulled a consistent 1400w from it for over an hour once with no issues at all
- I like the awfully loud beeper when the low voltage is reached. It saved me once from being a moron and overdischarging my packs, woke me up in the middle of the night.
 
Thanks, that's good info, I'll need to tie ground to neutral for the Nissan Leaf EVSE (charger) to be happy, so I guess this will have to be done externally with a cheater plug or similar.
 
rev0 said:
Thanks, that's good info, I'll need to tie ground to neutral for the Nissan Leaf EVSE (charger) to be happy, so I guess this will have to be done externally with a cheater plug or similar.
Click to expand...

I was about to connect mine to a reliance transfer switch when I thought to stick my meter on it just for the heck of it and was like "oh crap". Glad I didn't...
 
Wait, the Neutral leg is 64V hot?!? That's crazy! Or did I read that wrong?
 
Ahhhh, that alone is enough for me to not get it. That's not safe. For 120V (US), there should only be 1 hot leg and 1 neutral. If both legs are hot, there isn't a neutral. There's a reason why there's a neutral.

I bet what they did was take the 240V split phase unit and ramped down the output to make 120V split. So internally there may not be a difference between the 240V and the 120V.

Hrmm, so, I wonder if you could reprogram it to give full 240V split phase output and then you use Ground as the neutral. Now that is ok and safe.

Maybe that's why it's 64V instead. Hmm, no, cuz that'd be 256V between the hots. That's still too high for the US market.
 
Korishan said:
Ahhhh, that alone is enough for me to not get it. That's not safe. For 120V (US), there should only be 1 hot leg and 1 neutral. If both legs are hot, there isn't a neutral. There's a reason why there's a neutral.

I bet what they did was take the 240V split phase unit and ramped down the output to make 120V split. So internally there may not be a difference between the 240V and the 120V.

Hrmm, so, I wonder if you could reprogram it to give full 240V split phase output and then you use Ground as the neutral. Now that is ok and safe.

Maybe that's why it's 64V instead. Hmm, no, cuz that'd be 256V between the hots. That's still too high for the US market.
Click to expand...

They do make a 220/240V version, but there is probably some component changes to go along with it. Probably different inductor or transformer size and higher voltage rated capacitors.

I don't think it would work with just one of the legs though, it's not a true split phase I don't think, more like positive half of waveform on one side and negative half of waveform on the other. Wouldn't be sinusoidal for just half, more like a half wave rectified output. I'll try and check it on the oscilloscope tonight.
 
Scope view would be interesting :)
And I'm sure you'll do all variants of the scope connections, we like graphs/charts/curvy-lines :p
 
Here's some oscilloscope shots for you, this is in a basically unloaded condition, just with a 13W CFL plugged in. The waveform is a pretty clean sine wave, looks like it has good THD (2nd harmonic is down by 37dB), and the switching frequency appears to be around 23kHz (with 60dB rejection). I confirmed via a teardown that the chassis groundisn't connected to either neutral or hot, it's capacitively coupled to both, hence the seeing half of the voltage to each. I measured open circuit between ground and neutral/hot, and likewise between ground and input + or -. So there should be no issue connecting neutral to ground externally to make equipment happy.


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I took loads of internal pictures with my DSLR which I'll find a place to upload to spare this site the bandwidth. Looks pretty clean overall, but there's a few sloppy reworks likely by the seller to set my preferred voltage/frequency setting. Perhaps it could be modified for 50 Hz or 220, but it's a little too adventurous for me since this works for my needs.
 
Ok, so you could basically do the same as one does with the first mains panel; bond ground and neutral. That is, after you connect the inverter to a box. So, would that mean, after bonding, then you'll see the 120V one the Hot leg then?
 
rev0 said:
I confirmed via a teardown that the chassis groundisn't connected to either neutral or hot, it's capacitively coupled to both, hence the seeing half of the voltage to each. I measured open circuit between ground and neutral/hot, and likewise between ground and input + or -. So there should be no issue connecting neutral to ground externally to make equipment happy.
Click to expand...

You're way beyond my understanding/skills at this point :) If I'm seeing 64vac between ground and neutral, how is it safe to bond them at any point along the circuit?
 
mike said:
I have this exact same inverter and have been using it since around October 2016, so I can confirm it's very reliable.

Here's a few things I noticed
- The output is 128v which is a bit high for some appliances. The UPS for my computer keeps trying to step it down.
- The output is actually 64v split phase. If you measure either leg to ground, it's 64v. So you can't use it with any transfer switch or anything like that where the ground and neutral are bonded at some point (usually breaker box). Maybe this is how 120v inverters are supposed to operate but it seems odd to me.
- It does hold load very well. I pulled a consistent 1400w from it for over an hour once with no issues at all
- I like the awfully loud beeper when the low voltage is reached. It saved me once from being a moron and overdischarging my packs, woke me up in the middle of the night.
Click to expand...

Thats normal. If you get a inverter with a hard wire output it should be setup to have a bonded neutral and ground. That is a bit high on the voltage. There maybe an adjustment.
 
Just to explain the phenomena, here is the equivalent circuit simulated in LTspice. The chassis ground is tied through only a capacitor to the hot and neutral of the inverter. For DC there would be no coupling but since it's an AC signal, the 2 capacitors act like a voltage divider does for DC, so you see half the AC voltage measured with respect to the floating ground.


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Hope this makes sense. As for where to bond ground and neutral, I would logically say close to the inverter since that's the source of the power, but I'm not an authority on electrical code/safety.
 
I modified the 10s pack I build yesterday to 14s and wired it up to the inverter today. Tried running a portable air conditioner but it shut off as soon as the compressor kicked on. I was able to run a "2HP" shop vac (rated at 6A, measured 713W peak, 605W steady state) at ~89% efficiency (measured with a cheap current clamp, so accuracy isn't the best).


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I need to make an external ground/neutral bonded extension cord/power strip to try charging the car, but I'll want a second pack in parallel for that. Right now it would pull 10A per cell which isn't doableeven for a quick test with the kinds of internal resistance numbers these cells have.

Just dumped the raw images I took of the internals here:
https://imgur.com/a/ODBo6
 
Just a little new year'supdate, I got lucky and pickedup a 160W solar panel from a local solar installer for $25 (ML Solar in San Jose CA, they routinely have "surplus" panels listed on Craigslist from upgrades). SoI ordered an MPT-7210 and MC3 connectors which will arrive hopefully soon. I'll use the panel to charge a relatively small pack, maybe around 1.2 kWH, basically whatever is convenient to carry and has a reasonable charge time, which I can use with the inverter to run individual loads or add a few miles of charge to my Leaf. I think I'll add an ESP8266 to the setup to track the charge status of the battery and maybe email me when it's full so I know when to pull it out and use it.

My options as an apartment dweller are pretty limited (with this panel in my patio I think I can only get around 0.4 kWH per day)but this is still a fun proof of concept and I don't think there are many portable powerwall setups out there.


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