Air Conditoner that will startup with 1400 watts 48 volt Growatt system

cwilken

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I cant get my portable AC unit (1200 BTU Edgestar 10 amp system) Because the starting burst of the AC causes my Growatt 3000 to fault out. I would like to run with 1400 watts of solar and I have even tried 2000 watts but the AC startup shuts me down. I can start it with AC bypass on the Growatt but it fails when I unplug the AC in connection.

Ive been looking at hard start and soft start for my portable AC. I have even thought of wiring in an Ametherm SL32 2R025 Thermistor somewhere on the startup line to slow the incoming surge rate on my AC unit. If I get brave I might try that today.

Plan B: Im looking for a split AC unit that will work with 1400 watts? Do you know one that will startup in that environment? I am currently using a 48 volt ebike battery for my battery. Im tring to cool my 300 sq ft porch.

 

cwilken

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Thanks MisterSandals for your reply...
My son is helping me build a bigger battery right now. Meanwhile I have the the portable AC unit apart and am studying if there is any boost I can give it to start up easier. I will also measure the high Amp surge it gets today to see what Im up against. Im also wondering what new split models out there have the lowest start surge or the best startup technologies.
 

MisterSandals

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Im also wondering what new split models out there have the lowest start surge or the best startup technologies.
This guy has been pushing small DC units here...(i know nothing about them)

 

cwilken

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Well I measured the surge amps on my 10.5 amp portable AC unit and it turned out to be 35 amps high. I will be experimenting soon with a "Inrush current thermister to see if that can get my Growat Inverter from timing out.
 

cwilken

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Thanks Rider ive studied it and am considering it. However I would hate to spend that much on it and have it not work when I could spend $800 on a modern mini split with inverter instead. My portable AC unit is 10 years old. Right now Im trying to figure out where to solder a momentary thermister onto the compressor wiring for a 1/4 second buffer of the startup. Should I try the start, run or common line to the compressor. Im hoping to bring my 35 amp surge down by half so the Growatt doesnt time out. It is a $7 experiment with a Ametherm SL32 2R025 Thermistor.
 

Supervstech

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Thanks Rider ive studied it and am considering it. However I would hate to spend that much on it and have it not work when I could spend $800 on a modern mini split with inverter instead. My portable AC unit is 10 years old. Right now Im trying to figure out where to solder a momentary thermister onto the compressor wiring for a 1/4 second buffer of the startup. Should I try the start, run or common line to the compressor. Im hoping to bring my 35 amp surge down by half so the Growatt doesnt time out. It is a $7 experiment with a Ametherm SL32 2R025 Thermistor.
I have worked with HVACand refrigeration since the 80’s post the thermistor schematic, and I can assist you hooking it up. I don’t like thermistors personally. They usually fail. A balanced starting cap kit helps more reliably.

but… if the unit starts when AC connected, won’t the growatt switch back to battery after the starting load has passed?
 

Zwy

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I cant get my portable AC unit (1200 BTU Edgestar 10 amp system) Because the starting burst of the AC causes my Growatt 3000 to fault out. I would like to run with 1400 watts of solar and I have even tried 2000 watts but the AC startup shuts me down. I can start it with AC bypass on the Growatt but it fails when I unplug the AC in connection.

Ive been looking at hard start and soft start for my portable AC. I have even thought of wiring in an Ametherm SL32 2R025 Thermistor somewhere on the startup line to slow the incoming surge rate on my AC unit. If I get brave I might try that today.

Plan B: Im looking for a split AC unit that will work with 1400 watts? Do you know one that will startup in that environment? I am currently using a 48 volt ebike battery for my battery. Im tring to cool my 300 sq ft porch.

Your problem isn't the GW3000w inverter. Your problem is the battery and most likely the BMS can't handle the load. I own 2 ebikes, each one runs a 48V 750w motor. The larger factory battery is 16Ah Li-Ion. The factory bike controllers are rated at 20a max, so you can be certain the BMS is around that area as the C rate of battery would be around 32 amps with a 2C rate of discharge but that high C rate is only for a very short time. That's 1500 watts which I'm certain the BMS will cut out before then, I've never seen mine run over 1200 watts. . You have a load of 10 amps at 120V which is 1200 watts. Plus inverter loss. Do you see the problem? And surge will be even higher.

I can easily run the 11K BTU roof air on my truck camper off a 24V 280Ah bank thru my GW3000. It draws 50 amps/24V (1200 watts) sustained and will run over 4 hours off a full charge. Inverter does generate some heat but fans in the GW really only idle along. I don't see the GW as the problem but rather you are exceeding the C rate of the battery and it's BMS.
 

cwilken

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Thanks ZWY
I am working on a larger battery as part of plan A.
 

Just John

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If I have to go to plan B after trying to modifying my old portable AC I think an inverter mini split would have a low startup amperage:
This one seems to have a claimed low max amps
Most of the "inverter" mini splits (even the cheap ones) really do stop that massive inrush current.
Like this one:


I will also add, most of the inverter mini-splits seem to work internally on 48v DC. On Alibaba and Aliexpress you can find a bunch of them that work on 48v DC as "solar air conditioner".
 
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falgsc-al

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Most of the "inverter" mini splits (even the cheap ones) really do stop that massive inrush current.
Like this one:


I will also add, most of the inverter mini-splits seem to work internally on 48v DC. On Alibaba and Aliexpress you can find a bunch of them that work on 48v DC as "solar air conditioner".
Some run on 300 or so. Looking down into the motor of my Midea U as we speak. 310v fan motor.
 

falgsc-al

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I just reset my Midea U so I could run a meter test. Peak start up was 2.71A on 122v and slowly crept up to 5.6a.

agree with Nola_castle these units are absolutely amazing
 

cwilken

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Thanks for the feedback on the minisplits!! I will buy one eventually . I do like the 12000 BTU 110 volt models as that is the highest capacity you can go without 220v. Thanks for actually measuring the intake spiking amps. I like the on Falgsc cited as it is prefilled with AC gasses. I still consider buying a 48Volt unit to increase efficiency 10%. However I don't have 100% confidence in my Growatt system, yet, to make the nightly solar-battery to grid transitions smoothly. I'm still tinkering with it.
My new homemade battery pack is almost done and my installed Ametherm SL32 2R025 Thermistors on the the old portable AC unit have brought the startup surge from 35amps to 12-15 amps. I want to see if this will work with my new battery. It still doesn't with my bicycle size battery. If it doesn't work I might try two thermistors on the AC unit. Right now I have one thermistor on each of the two power wires to the compressor. One on the run coil wire and one on the start coil wire. I put the thermistors in a heat sink. Now my ancient, grossly inefficient portable AC unit is even more inefficient with the hot thermistors modulating the startup shock! Once my experimenting is done and my savings are increased I will buy the mini split.
 
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falgsc-al

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Thanks for the feedback on the minisplits!! I will buy one eventually . I do like the 12000 BTU 110 volt models as that is the highest capacity you can go without 220v. Thanks for actually measuring the intake spiking amps. I like the on Falgsc cited as it is prefilled with AC gasses. I still consider buying a 48Volt unit to increase efficiency 10%. However I don't have 100% confidence in my Growatt system, yet, to make the nightly solar-battery to grid transitions smoothly. I'm still tinkering with it.
My new homemade battery pack is almost done and my installed Ametherm SL32 2R025 Thermistors on the the old portable AC unit have brought the startup surge from 35amps to 12-15 amps. I want to see if this will work with my new battery. It still doesn't with my bicycle size battery. If it doesn't work I might try two thermistors on the AC unit. Right now I have one thermistor on each of the two power wires to the compressor. One on the run coil wire and one on the start coil wire. I put the thermistors in a heat sink. Now my ancient, grossly inefficient portable AC unit is even more inefficient with the hot thermistors modulating the startup shock! Once my experimenting is done and my savings are increased I will buy the mini split.
You could also try a hard start kit to get your amps down. I know it sounds counter productive but they do usually bring the start amps down with a capacitor and a hysteresis relay. They are often suggested for older-tired compressors. I've also seen some soft starting kits that replace the capacitor but I have no personal experience with them.
Btw wanted to correct some terminology from your post. The Midea U is a window unit not a mini split (although one could argue it's a mini split on a common pan) and they can be had around $350 shipped for 8k btu. Every motor in it is soft starting.
 

Supervstech

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Thanks for the feedback on the minisplits!! I will buy one eventually . I do like the 12000 BTU 110 volt models as that is the highest capacity you can go without 220v. Thanks for actually measuring the intake spiking amps. I like the on Falgsc cited as it is prefilled with AC gasses. I still consider buying a 48Volt unit to increase efficiency 10%. However I don't have 100% confidence in my Growatt system, yet, to make the nightly solar-battery to grid transitions smoothly. I'm still tinkering with it.
My new homemade battery pack is almost done and my installed Ametherm SL32 2R025 Thermistors on the the old portable AC unit have brought the startup surge from 35amps to 12-15 amps. I want to see if this will work with my new battery. It still doesn't with my bicycle size battery. If it doesn't work I might try two thermistors on the AC unit. Right now I have one thermistor on each of the two power wires to the compressor. One on the run coil wire and one on the start coil wire. I put the thermistors in a heat sink. Now my ancient, grossly inefficient portable AC unit is even more inefficient with the hot thermistors modulating the startup shock! Once my experimenting is done and my savings are increased I will buy the mini split.
Why would you put a thermistor on the run wire? I would think that would waste energy and reduce compressor voltage, no?
 

Supervstech

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You could also try a hard start kit to get your amps down. I know it sounds counter productive but they do usually bring the start amps down with a capacitor and a hysteresis relay. They are often suggested for older-tired compressors. I've also seen some soft starting kits that replace the capacitor but I have no personal experience with them.
Btw wanted to correct some terminology from your post. The Midea U is a window unit not a mini split (although one could argue it's a mini split on a common pan) and they can be had around $350 shipped for 8k btu. Every motor in it is soft starting.
Start kit will not lower starting amps, but it can reduce the starting time, and help a weak compressor to start when conditions need it. They actually INCREASE the starting amps on the start winding of the compressor.
 

falgsc-al

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Start kit will not lower starting amps, but it can reduce the starting time, and help a weak compressor to start when conditions need it. They actually INCREASE the starting amps on the start winding of the compressor.
Yes the hard start kit increases the starting amps but I would argue that energy comes from the capacitor. I installed one in a 2.5ton home unit and dropped the start up peak from the line by around 25%.
 
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