# 18650 Li-ion Configuration To Power 1/4 HP 3-Phase Motor?



## PStechPaul (May 1, 2012)

For 1/4 HP at 230 VAC you would need a 300V battery pack rated about 750 mA or more. For no load and short durations you could get by with 500 mA. I bought some 18650 cells that should work for this application:
http://www.ebay.com/itm/400373810881

They are listed as 1800 mAh but are actually closer to 900, but 100 of them would give you 320 volts which is enough for a VFD, and actual energy of 300 Wh which should run your motor (even at rated load) for ovr an hour. They are about $3 each with shipping so your pack will be $300.

You can get 3.7V Li-Ion from the same company rated at 3600 mAh (but actually tested at less than 1000) for about $2.88 each, and you would only need 80 of them for 300V:
http://www.ebay.com/itm/24-Pcs-1865...geable-battery-silver-Tab-W-Tab-/151011143057

If you are not locked in to 18650 cells, you could put together a pack using batteries from Hobby King, but the shipping costs for LiPo are quite high. You might also consider using 9V 350 mAh NiMH batteries which you can get for $3.50 each including shipping. 30 of them (about $100) would give you 270 volts and 95 Wh which will run your motor at half-power for close to an hour. They are also easy to snap together in a pack and they are not as critical for charging:
http://www.ebay.com/itm/4-pcs-9V-9-0V-350mAh-Ni-MH-17R8H-Rechargeable-Battery-/380597324600

You can also get 550mAh Li-Ion 9V cells for about $8 each:
http://www.ebay.com/itm/BATTERY-x-2-9V-9-Volt-550mAh-Rechargeable-Li-ion-TWO-BATTERIES-/390466040687

But you must be aware, however, that many of these batteries are way over-rated so you may get only 1/2 to 1/4 of advertised capacity. See my thread on testing a cheap 18650 cell. I also tested some AA NiMH that were supposed to be 3000 mAh and they tested at about 900. Look at the bottom line of energy cost and you will find a range from $0.06/Wh for FLAs to about $1/Wh for LiFePO4 in small sizes.

May I ask what you are trying to do? You can get a 1 or 2 HP three phase motor for about $50 and a similar size VFD for about the same, and you can run the VFD either on single phase AC or 200-400 VDC. You can also use an automotive inverter to get 220 VAC (or 280 VDC) from a 12V or 24V battery, and a 1000 watt inverter can power a small lawn tractor, so at least you will have something useful from your experiments. Here's my EV: http://www.youtube.com/user/PaulAndMuttley/videos?query=craftsman


----------



## RaySuave (Mar 13, 2013)

PStechPaul said:


> For 1/4 HP at 230 VAC you would need a 300V battery pack rated about 750 mA or more. For no load and short durations you could get by with 500 mA. I bought some 18650 cells that should work for this application:
> http://www.ebay.com/itm/400373810881
> 
> They are listed as 1800 mAh but are actually closer to 900, but 100 of them would give you 320 volts which is enough for a VFD, and actual energy of 300 Wh which should run your motor (even at rated load) for ovr an hour. They are about $3 each with shipping so your pack will be $300.
> ...


Thanks for the info. I basically want to build a stationary rig that comes close to mirroring the set-up of the newer EV vehicles, hence the 3 phase AC motor and Li-ion cells. I want to try out some ideas I have on extending operating/driving range. I also just want to get my feet wet and get more familiar with these components and how they interact. I have been in the remote control hobby for a few years and already have experience working with lipos and brushless motor set-ups. 

Thanks for mentioning the over ratings on a lot of 18650 cells because it was confusing as to how some sellers price 5000mah cells for $2.50 each, while others have the same price for 1500mah. Glad to have an idea of the realistic specs.
http://www.ebay.com/itm/10-5000mAh-...Torch-Rechargeable-Battery-Pack-/221172886814

I want to stick with the lower HP AC motors to keep the amp draw down so the battery pack can be smaller. The motor doesnt necessarily have to be 3 phase but I would like it to still be AC. I want to stay with Li-ion cells due to charge rates but the cell type doesnt have to be 18650. The 9V Li-Ion cells seems like a good alternative in regards to making the battery pack.

What is a good source to learn more about VFD's? I have looked for information on them before like prices and how much input power they require vs their output so I can come up with a battery size, but didnt find anything but jargon I couldnt really grasp. Just to be clear, you say a VFD can convert DC (from battery) straight to 3-phase AC without the need of an inverter? From what I have read, the VFD needs sine-wave(AC) power as input.


----------



## PStechPaul (May 1, 2012)

An AC drive is essentially a switching power supply, and the first thing they do is rectify the incoming AC voltage to get what is called the "DC link", or "DC bus". This is generally the peak voltage of the AC, so 120 VAC will be 170 VDC and 208/240 will be 294/340. However, there are some VFDs that use gated thyristors on the input to achieve a "soft start" or "precharge" to the bus capacitors, but I think that is only for much larger drives.

Here is a 0.57 kVA (3/4 HP) drive similar to mine for $70:
http://www.ebay.com/itm/FUJI-VARIABLE-FREQUENCY-DRIVE-FUJI-FVR-E11-FVRO-2E22S-2-/160952025832

And an older? Fuji 2HP drive for $100:
http://www.ebay.com/itm/fuji-vfd-variable-frequency-drive-220-240-vac-3-phase-2hp-/230929761401

Here are some 3HP Yaskawa drives for $130 each. Yaskawa is a popular brand and you can get parts and service:
http://www.ebay.com/itm/CIMR-J7AU20...-Inverter-AC-Drive-CIMRJ7AU20P7-/290621312642

You should be able to find a manual for whatever drive you choose to make sure it can still be serviced and set up properly. It would also be best to get one rated for 208/240, although there are some 120 VAC single phase drives:
http://www.ebay.com/itm/110V-VARIABLE-FREQUENCY-DRIVE-INVERTER-VFD-1-5KW-2HP-7A-/260774619784?

Since most AC EVs use three phase motors I suggest you get a 3 phase setup. And you might as well get a drive capable of at least 1 or 2 HP so can use it for something useful like a small tractor or utility vehicle. You could even make something like a R/C lawnmower.

A stationary rig may not be sufficient for testing your ideas for increasing efficiency, since regeneration is usually a large part of that equation. Theoretically, you should be able to recoup most of the energy expended going up a hill when you go back down, except for the non-revoverable losses due to rolling resistance, aerodynamkic drag, and inefficiencies of the drivetrain and the electrical system. You can get an idea of what to expect by using my EV calculator:
http://enginuitysystems.com/EVCalculator.htm

For instance, a 1000 kg (2200 lb) vehicle moving at 50 k/h (30 MPH) with no acceleration requires about 4.4 HP and expends about 100 Wh/mile. That is probably a realistic lower limit of energy consumption, and if you figure an overall 80% efficiency it would be about 125. Most DIY EVs use about 200-400 Wh/mile. It is possible to make a vehicle which is totally solar powered if it is used at low speeds and not continuous highway driving:


----------



## Ivansgarage (Sep 3, 2011)

That is not a 3 phase motor.

.....


----------



## PStechPaul (May 1, 2012)

Ivansgarage said:


> That is not a 3 phase motor.
> 
> .....


True. It is almost surely a series wound DC motor, and I'm not sure what type controller it uses. A three phase IM can be as high as 90-95% efficient, while a brushed DC motor will probably be 80-90%, especially when running at low speed and high torque. I just showed the solar tractor as a way to get maximum overall efficiency, and he could probably do even better with AC. Of course, there is also the overall cost factor, and the solar panels add about $9000. An AC motor and VFD would add maybe $1000 and could cut losses by 50%, but the difference of 80% to 90% is really insignificant and probably not cost effective in this case. The big efficiency boost is from ICE (15-20%) to any electric system, which can be 5 times more efficient.


----------



## RaySuave (Mar 13, 2013)

Ivansgarage said:


> That is not a 3 phase motor.
> 
> .....


Nice catch, I linked the wrong motor...meant something like this.
http://www.amazon.com/Dayton-2N863-...1363382808&sr=1-8&keywords=1/4+dayton+3+phase


----------



## RaySuave (Mar 13, 2013)

PStechPaul said:


> An AC drive is essentially a switching power supply, and the first thing they do is rectify the incoming AC voltage to get what is called the "DC link", or "DC bus". This is generally the peak voltage of the AC, so 120 VAC will be 170 VDC and 208/240 will be 294/340. However, there are some VFDs that use gated thyristors on the input to achieve a "soft start" or "precharge" to the bus capacitors, but I think that is only for much larger drives.
> 
> Since most AC EVs use three phase motors I suggest you get a 3 phase setup. And you might as well get a drive capable of at least 1 or 2 HP so can use it for something useful like a small tractor or utility vehicle. You could even make something like a R/C lawnmower.
> 
> ...


So then I would need an inverter for the VFD. I understand your logic of why a moving test rig would be more beneficial but as of now, getting to that point would be further down the road as in Phase 2 or 3...lol

Thanks for the info again....cool informative videos BTW.


----------



## PStechPaul (May 1, 2012)

That's rather expensive for a small motor. I have found that Automation Direct has good prices for new motors ($155 for 1HP Premium Efficiency):
http://www.automationdirect.com/adc...Premium_Efficiency_(1_-_300HP)/MTCP-001-3BD18

Here are specs and information on use with VFDs:
http://www.automationdirect.com/static/specs/ironhorsetprs.pdf
and for premium efficiency:
http://www.automationdirect.com/static/specs/ironhorsemtcp.pdf

And a set of manuals which may be helpful:
http://www.automationdirect.com/static/manuals/ironhorsemanual/ironhorsemanual.html


----------



## RaySuave (Mar 13, 2013)

PStechPaul said:


> That's rather expensive for a small motor. I have found that Automation Direct has good prices for new motors ($155 for 1HP Premium Efficiency):
> http://www.automationdirect.com/adc...Premium_Efficiency_(1_-_300HP)/MTCP-001-3BD18
> 
> Here are specs and information on use with VFDs:
> ...


Do you have any links on battery pack making?


----------



## PStechPaul (May 1, 2012)

I think there were some threads a while back about DIY battery packs with 18650 cells. There is also a company on eBay selling 100 pieces of 18650 cells for $220 and they have a spot welding service:
http://www.ebay.com/itm/200824865118?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

They charge $0.30/cell:










You can also purchase a spot welder for $150 made for batteries:
http://www.ebay.com/itm/Hand-held-S...21201637995?pt=BI_Welders&hash=item3380a5226b

Another company has 100 pcs of 3.7V Li-Ion supposedly 4500 mAh for under $160. Even if they are actually only 1200 mAh as I suspect, that would be an awesome 370 VDC pack with about 450 Wh. At $0.36/Wh that's not bad. But they are unprotected and they may live up to their "UltraFire" name.
http://www.ebay.com/itm/100xWhite-U...thium-Battery-4500mAh-LED-Torch-/160891491710


----------

