Converting a gas Quad to AC

Technical discussion on converting internal combustion to electric
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Johny
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Converting a gas Quad to AC

Post by Johny » Tue, 29 Nov 2011, 16:07

With that gearing and wheel size you are down to just over 2300 RPM (motor) at 60km/h. If you retain those wheels then you will want to bring the gearing from 3.334:1 (40:12) to closer to 6.5:1 which means about 78 cogs on the big gear. If you can't get 78 (or it's just too large), then as many as practical.

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Converting a gas Quad to AC

Post by peskanov » Fri, 02 Dec 2011, 02:45

With a 6.5 gearing, I get 3900 RPM at 60 km/h.
Are you thinking 36VAC or 48VAC, here?

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Post by Johny » Fri, 02 Dec 2011, 15:11

Hi Peskanov
Looking at the Quad bike I'm think it would be pretty dangerous over 60km/h (but I've never ridden one). The lower the top speed (higher motor voltage - max. 50V), the better the low end torque as the whole unit becomes less controller limited.

With that gearing:
36V climbs a 1 in 3.1 gradient and makes 60km/h in 12 Sec.
48V climbs a 1 in 2.4 gradient and makes 60km/h in 12.5 Sec.
Both have similar times to 45km/h (4.9 Sec).

Vehicle weight to get these figures is 350kg.
Major weight contributors:
- 180kg frame and wheels
- 60kg batteries
- 30kg motor
- 80kg rider

I kind of guessed the wheel size to get the 6.5 gearing.
Getting the motor RPM up to 4500 at 60km/h improves things a little but not that much. 1 in 2.2 instead of 1 in 2.4 climbing at 48V.
1 in 2.9 climbing instead of 1 in 3.1 for 36V.
The above (7.5:1) would be better but that's a 90 tooth cog and is only marginally better than 78 tooth.

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Post by peskanov » Sun, 04 Dec 2011, 15:10

Weekend update!
We got the Kelly running with our test motor.
As we still don't have the final battery, we tested the controller with whatever we had at hand: a 24V LiFePo Ping battery + 12V Car starter battery.

Image

Heresy! Image

This Frankenstein setup worked at 1st try, so as you can guess we are quite happy now. Speeding up the motor, as you probably know, is quite adictive for some reason.

Image

The whole thing runs incredibly silent. We only got some vibration at 3000 RPM (I think).


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Converting a gas Quad to AC

Post by peskanov » Sun, 04 Dec 2011, 15:14

Johny,
Wheel diameter is 18" or 46 cm.
180 KG is the original weight, motor included (empty tank).
I think removing the motor and its complements will lighten the vehicle 35-40 KG, but that's still untested.
My estimation is: 140 (vehicle) + 35 (motor & extras) + 4 (electronics) + 55 (battery) + 70 (driver, Spaniards tend to be skinny Image ) = 304 KG.

We will use new gears, both of them, so we can get the best gearing.
Using a pinion with few teeth (8,10) would make 1:6.5 easier.
Do you think that's a good decision? Are small pinions problematic or inefficient?

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Post by Johny » Mon, 05 Dec 2011, 17:10

From what I can google the recommended minimum is around 15. So I would stay with the 12 and not go to less teeth. I'm not an expert on this though.
The lighter vehicle (due to Spaniards being so skinny Image) doesn't change the preferred ratios.

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Post by peskanov » Tue, 17 Jan 2012, 04:37

Some updates for those interested:
The Quad is now fully restored. Cracks in the plastics were fixed with fiberglass, many cracked bearings replaced, brakes fixed and new brake discs installed, plus inner tube installed on rear tires.

The motors offered to us are now out of the game. The seller was not able to produce them, I don't know why. I think they got the motor specs from some manual, but they were not able to fit the windings.
We are still talking with this company, but I am pretty sure we will be forced to buy an old motor an rewind it ourselves.

We are now looking for batteries and a cheap BMS.
We are looking at evassemble BMS products. Also, I found this:

http://www.aliexpress.com/store/202665/ ... 6cell.html

I think we could try, but they sell the 12 cells version only in bulk order. We need BMSs for 24 cells.

Could it be possible to use a 16 cells BMS in a 8 cells setting? I am thinking in pairing the wires, using 2 cables for each cell.
That way I could use a two 16S BMS, one working normally and the other working with the reamingin 8 cells.

Does anybody think that's possible?




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Post by peskanov » Fri, 11 May 2012, 09:45

Hello there!
A few things happened on out project these last few months. I am posting an update, and many pictures.
Parts collection is finished, many lessons were learned, and many pieces are different from the original plan. I thinks that's probably usual in EV conversions. :D

As I said, we first tried a small project to test the Kelly inverter and learn to use it.
Here is out "testing mule". We used a new (non modified) 1500W, 48V/83V motor and a pack SLA batteries from a junkyard (5 batteries of 12V=60V, 14AH).

Image

first try video

second revision video

I think I will start a new thread about our experiences with this beast and the kelly KIM. Some problems still persist after 2 months of ironing problems.
Last edited by peskanov on Thu, 10 May 2012, 23:47, edited 1 time in total.

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Post by peskanov » Fri, 11 May 2012, 10:00

While testing and learning to handle the inverter, we also looked for the transmission.
6:1 relation was too difficult, and finally we settled for this:

Image

Image

Old Quad sprocket (aluminum, 36 teeth) vs new one (steel, 45 teeth).

Image

The weight difference is impressive. Of course, the new sprockets come from industrial equipment suppliers instead of car/motorcycle part suppliers. The new one ones are heavy and sturdy.

Now relation is 11:45, quite far from the 1:6 we were looking for. Anyway, the motor is also quite different from the one we were looking for :)

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Post by peskanov » Fri, 11 May 2012, 10:12

Now about the motor. That one has been difficult.
Our aim was to get an industrial 4-5 KW motor in a 112 frame. As I told previously, we got several quotes from local suppliers.

Well, after some weeks it became clear that none of the knew what were they selling. One backed off and said "it was not possible". Other asked too much (or that's what we though).

After that experience we decide to try the rewind path, and went to search a junkyard motor. We settled for this:

Image

Image

This old warrior (I think it's 30 years old) is a Leroy-Somer french motor, still working (well, partially). 4 poles, 4 kw, 220V/380V. It weights 32 Kg, made of aluminum. We got it for 70 euros (90 AUD).
A pic of the stator back then:
Image
And the rotor:
Image
Last edited by peskanov on Fri, 11 May 2012, 00:35, edited 1 time in total.

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Post by peskanov » Fri, 11 May 2012, 10:34

After getting that motor, we started to look for a professional rewind.
One shop asked 300 Euros (384 AUSD) for the change to 48v/83v. I thought that was too much (failed assumption!).
I started to look for all the rewind services around my city and nearly all of them told me I was asking for something impossible or ridiculous.

After a few weeks one technician, who looked quite competent, told me he could try. He asked some money for studying the motor, perform calculations and try to do one coil at least.
To facilitate the process, I told him he could modify the voltage requirements a bit. After all, the inverter will accept any voltage over a range...
The answer was that he could do the work, but choosing the unheard-of voltage of 63V/110V :D
Also, the cost of the rewind raised from the usual 190E to 290E!

Tired of looking for options, I made some calculations and decided to get the motor rewound there.

Image

It's rewound with 6 parallel wires. Original coils had 2. The technician told me calculations asked for 6.5 wires, but he was not able to insert the last "0.5" wire coils. As a result, voltage rating is probably slightly incorrect.

Image

A picture of the current state of the motor. As you can see now I am cleaning it.
Image

And that's the point where we are...this weekend we will test the motor and will start to think about mounting it in the Quad frame, and the hard problem of cooling it.
Current is going to be high in this motor! Any ideas about cooling it are welcomed. I am even thinking about some kind of internal air cooling...
Last edited by peskanov on Fri, 11 May 2012, 00:38, edited 1 time in total.

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Post by Johny » Fri, 11 May 2012, 15:40

I love the rotary digger. I'm also amazed the the controller held up with all the shaking (having used one with ony 4 blades).

Assuming 63 volts Delta it doesn't look too bad. Yellow column is in km/h. Green column is seconds. The model says you will not get to 80km/h but that shouldn't be an issue.
Image

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Post by Johny » Fri, 11 May 2012, 15:43

On cooling. Internal cooling - my belief is that you would not get enough air along between the rotor and the stator to make it worth it. Just cool the outer case with whatever external fan you can rig up.
If you will be keeping revs pretty high (not grinding up slopes slowly) the original cowling fan might be fine.
Last edited by Johny on Fri, 11 May 2012, 05:44, edited 1 time in total.

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Post by Richo » Fri, 11 May 2012, 20:50

Even 300Euro for a rewind sounded ok.
32kg is quite light for a 4kW ali motor.

Most don't want a custom voltage from new as it may not meet MEPS.
Always cheaper to get a motor rewound.
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Post by peskanov » Mon, 14 May 2012, 13:45

Johny,
I think rotary diggers shake less the wider they are, so a 4 blade one probably shakes a lot. But yes, we had troubles with all the shaking and jumping in our 1st try. On one ocassion a pair of batteries jumped offboard! Image
Unfortunately we were so cheap on the batteries the poor machine only works for 15 minutes.

As always, thanks for your speed curve chart! The internal cooling idea is something I am pondering because of a space problem. Check these pictures:
Image
Image

As you can see we are trying to place the motor in the same place the ICE originally was located. This space is too narrow for the original fan, and we were planing to add 3 o 4 small electric fans on the sides of the motor instead.
However, a Quad collects a lot of dust and that's a killer for small fans.
That's the reason I am thinking about extracting the heat from the interior using a little air pump and some tubing.

Richo,
I went for the lightest 4KW I could find in the junkyard. I guess I was lucky!
Imho, 300E is a bit high for a 4KW motor. Most shops quoted me 200E (150+vat) here in Spain, but later refused to do the work anyway.
I considered buying the motor rewound in Bulgaria. I have seen rewind services priced very cheap on the web. But at the end I thought it was too much of a hassle.


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Post by peskanov » Mon, 14 May 2012, 14:03

Motor testing: this weekend we connected the new motor to the inverter and spun it a little (without load).

Image

We just changed the settings of the KIM from 48v to 63v, and set up a rotary encoder at the axis back end (well, we just kept the thing in place using our hands).

First thing we noticed: one of the wires was shaking a little due to the slow pulsating field (we started slow). Also some metallic dust danced on top of the motor (kind of funny).
The current clamp in one of the phases showed 30A as maximum. Revving up, amps went down to 6A. That was at 3200 rpm, we didn't try higher revs as the motor is very old and just 4 poles 1500 rpm.

The are are 2 speed points were vibrations increases and get noticeable. One happens near nominal rpm (~1420). The same thing happened with a commercial 1500W 48v motor we tested previously. That behavior does not appear when the 1500w motor works under load.
We don't know if that vibration is normal using ac motors and inverters, or it's just a kelly KIM thing.
The motor didn't get hot in those tests.

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Post by peskanov » Sun, 08 Jul 2012, 23:47

It's alive!
Having all pieces, we assembled the thing. It took about 4-6 weekends to get it to working state.
Some pictures of the process...
Steel battery boxes, welded to the chassis:
Image
Another view; we distributed the pack in 4 boxes. The front one was a bit of an ugly fix, as we ran out of space:
Image
Copper bars. We cut them from a large one we got for free. I know this shape is far from perfect, due to battery expansion; we drilled the holes a bit larger than necessary to allow some movement.
Image

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Post by peskanov » Sun, 08 Jul 2012, 23:57

Fitting the cells. The bracing mechanism is somewhat ad-hoc.
Image
Wiring of the first box; red wires go to bms & cell monitoring:
Image
Charger plug; we chose to implement the RC cell balancing model. BMS is external and connect to the pack through this industrial 24 pins plug.
Image
View of the wires. Red wires will be connected to the cells and reach the BMS plug; orange wires are connected in the same plug and feed the cell monitors.
Image
All cells:
Image
With cell monitoring:
Image

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Post by peskanov » Mon, 09 Jul 2012, 00:09

After the pack, we fitted the KIM controller:
Image
Controller fans:
Image
And the motor. We are using a cheap Chinese encoder, plugged to the shaft using a rubber joint (comming from an old VHS recorder Image ). I think the mounting is a bit too rigid...We will see how it stands the vibrations.
Image
Cooling is still pending. We tried the Quad without it, but only for a few short runs.
Assembly view:
Image
Image

So, the machine is working, AC motor regen braking felt incredible and the famous EV grin was present as usual. Image
We still have a lot of work to do in order to finish it, and then play with the controller settings. I will post our experiences soon.


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Post by Johny » Mon, 09 Jul 2012, 04:23

Well done and great pictures.

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Post by peskanov » Fri, 13 Jul 2012, 05:15

Yesterday we built our experimental internal air cooling system.
I hope these pics will explain the idea better than my broken english Image
That's the motor back cover, drilled to place air inlets:
Image
Another view:
Image
We used 4 inlets trying to open an area similar to the pump air inlet. Each small air inlet will be conected to a bigger tube, and finally to a dust filter.
That's the air pump, a common and cheap 12v battery powered inflatable bed pump:
Image
We used a thermistor and an small circuit to power the pump, but it was unnecesary: on the first trial, the pump went to maximum output pretty soon and remained there.
Image
Cooling system setup: we extract the air from the motor conections box, as there is a big hole already there connecting to the rotor chamber. Thermistor is located under the coils of the stator.
Image

We made a short test of the system but (lacking a temperature probe) it's too early to say how good it works.
The pump seems to work well, but it's too noisy. Really, really noisy. If we keep this cooling system, we will have to find an alternative pump, as this noise level is unbearable.
After a few minutes running the Quad, the pump went to it's maximum output and expelled quite hot air. The case of the motor heated slowly, and reached some stability at 40-50o centigrades (remenber, we don't have external cooling at all).

We have to perform some further testing using a temperature probe, but right now I am very confused about the whole idea.
Pros:
- It removes the heat from the core of the motor, where it's generated. That looks efficient.
- External fans get dusty and fail, and a Quad is a very dusty vehicle.
Cons:
- High pressure air pumps are horribly noisy!
- I think the air flow we got is not enough for this application.

Any comments about our little experiment is welcome...

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Post by thingstodo » Tue, 17 Jul 2012, 21:13

Very interesting build! Well documented with pictures. Thank you for sharing.
peskanov wrote:...
The current clamp in one of the phases showed 30A as maximum. Revving up, amps went down to 6A. That was at 3200 rpm, we didn't try higher revs as the motor is very old and just 4 poles 1500 rpm.


Was the current clamp set to peak or you were reading 30A maximum?

If the peak was 30A and that was for less than a second, then that is likely OK.

If you saw 30A on the clamp display for a few seconds as you were speeding up, something is not matching between the Kelly and the motor. No load, the motor should not be pulling 30A. The Kelly output voltage is too high at low speeds. This should cause rapid heating in the motor.

I have no experience with the Kelly, so I'm not much help with the specifics. On industrial controllers the current does not go above 35 - 50% as you accelerate slowly (10 - 15 seconds from 0 - 100% speed) with no load. The voltage rises pretty close to proportional for the speed.
peskanov wrote:...
The are are 2 speed points were vibrations increases and get noticeable. One happens near nominal rpm (~1420). The same thing happened with a commercial 1500W 48v motor we tested previously. That behavior does not appear when the 1500w motor works under load.
We don't know if that vibration is normal using ac motors and inverters, or it's just a kelly KIM thing.
The motor didn't get hot in those tests.


Motor vibration is not normal near rated speed. Again, I'll blame the Kelly and a setting of some kind for that. When you are starting up a bit of vibration (when you are turning less than 50 rpm) is normal and is called cogging.

Did I read that right - no motor heating when you had 30 amps going through that motor?

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Post by Johny » Tue, 17 Jul 2012, 21:36

The current clamp meter is unlikely to be able to accurately read the PWM signals that are being fed to the motor phases.

When you revved up, the PWM became closer to a normal steady waveform so the meter may have seen this "more correctly".

I would not take much notice of motor current as read by a clamp meter - unless you knew it was OK with PWM.

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Post by thingstodo » Tue, 17 Jul 2012, 21:47

peskanov wrote:...
The pump seems to work well, but it's too noisy. Really, really noisy. If we keep this cooling system, we will have to find an alternative pump, as this noise level is unbearable.
After a few minutes running the Quad, the pump went to it's maximum output and expelled quite hot air. The case of the motor heated slowly, and reached some stability at 40-50o centigrades (remenber, we don't have external cooling at all).


This document does a pretty good job of explaining the information on the motor nameplate.

www.pdhonline.org/courses/e156/e156content.pdf

I read on the picture of the motor nameplate - class B insulation. The rewind should have been at least that high. That should give you long life (10,000 to 20,000 hours) up to 130C which is a lot higher than you were in testing.

Ambient is rated at 40C which is normal for an industrial motor. This means that the motor can still cool itself properly (with the fan that you used to have on it) when it is sitting in 40C air.

The case looks totally enclosed, fan cooled by the ribbing on the outside. Did I miss holes in the end bells where you can see the rotor?

I think that external cooling only would work for you. If you go with external cooling only, you can use a larger diameter fan so the noise goes down but the amount of air that it moves goes up. If you are driving at 60 kph I don't think the motor would even need a cooling fan. At 10 kph, yes I think it would. Perhaps use 2 or 3 of the 12V computer fans with plastic blades, but real bearings.

Just my opinion, but that's the cooling I'd go with.
peskanov wrote:...
We have to perform some further testing using a temperature probe, but right now I am very confused about the whole idea.
Pros:
- It removes the heat from the core of the motor, where it's generated. That looks efficient.
- External fans get dusty and fail, and a Quad is a very dusty vehicle.


If the motor is TEFC like I think it is, there is heat in the rotor and in the stator. If the only cooling used to be the fan on the end bell, the motor is designed to get rid of the heat through the outside surface only.

I agree that external fans get dusty and they fail. If the motor gets up to 130C you will be able to tell from the heat you feel on the inside of your legs as you ride it!

I use an infrared gun to show temperature on the outside of the motor case.

At the mill where I work we have larger motors (100 HP and up) that regularly reach 100 - 120C during the summer months. The insulation is rated at class F (155C) so we trip the motor on overload at 140C. The motors run for years this way.

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Post by Johny » Tue, 17 Jul 2012, 22:01

If you are worried about a fan in a dusty environment use a 6-8 inch car radiator cooling fan. While your internal cooling was an interesting idea, it means that you a blowing rubbish (even if filtered) into the inside of the motor. I'd seal it up again and cool externally as thingstodo suggested.

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