# Quick and dirty Honda Spree conversion



## DeadFlorist (Sep 18, 2008)

Addedum, if there were a way to do this 12v style even (perhaps a pair of 6v golf cart batteries connected in series), that would be awesome. Easy charging and not too too heavy.


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## Little Rhody (Jun 17, 2008)

DeadFlorist said:


> My questions are two:
> 1. Any problems with this design?
> 2. What sort of motor/controller setup should I go with?
> 
> ...


I don't know what kind of space you have to work with in the motor area, but im guessing a pancake style motor might a good choice as the size, weight and gearing would lend it self nicely. Look at an "E-tek-R Motor" or "Perm Motor PMG-132". The only problem I see is that you would have to run a minimum of 24V for either of these motors. 

LR


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## DeadFlorist (Sep 18, 2008)

Thanks for the reply, LR. First, I have no meaningful space restrictions given the positioning of the motor. Second, your suggestions seem pretty powerful (and expensive). I guess I should note that the scooter I am converting weighs 92 lbs from the factory. Even with a pair of 12 v lead acids, its going to be pretty light. I think even something like this might be too much motor: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=230291463914

I am considering making a basic two speed contactor controller like this one (and everyone feel free to weigh in on this idea too): http://www.aaroncake.net/Circuits/cntctcon.asp

It has the advantages of being simple, cheap and efficient, and I think the centrifugal clutch will moderate the choppy motor speed changes [?].


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## TX_Dj (Jul 25, 2008)

First of all, for efficiency and range, you will definitely want a PWM controller, and not something like a contactor controller.

Second, there will be no need for the centrifugal clutch- it's purpose is soley to stop the ICE from stalling at a stop light. You *want* the electric motor to stall, because that's where it gets its best torque output, and you don't want to wast energy having it spin when you're not in motion.

Third, the final ratio may be all the reduction you need. That will all depend on the tire/wheel size. Can you get me the dimensions (listed on the sidewall) for the stock tire? Knowing the ratios and tire size, we can figure out what the stock motor's RPM is at top speed, and also consider what sort of motor RPM you'll need in the conversion.

Fourth, are you sure this will be viable? I'd imagine the Spree in stock form has about 150 lbs max payload weight, including rider. Your suggestion of possibly using 2x 6v golf cart batteries in a 12v configuration will come darn close to exceeding that. We certainly don't want to see you go to all the effort and expense working this scooter over, only to have it crack the frame in half the first time you take a big bump.

Next, voltage = speed. Without voltage, you'll never spin the motor fast enough to acheive the speed. In my experience, 24v is good for about 15 mph without overloading the motor, and you'll get good acceleration at that. I'm currently in the process of converting my powerboard scoot to 36v, and I expect to gear it for about 22-25 mph top speed, and expect the acceleration to be comparable if not quite a bit more snappy.

Finally, the higher your voltage, the less amps you have to draw from the pack to make things happen, because there are less losses in the system, and the more range you experience as a result.

Whereas my powerboard at 24v had a capacity of 12 Ah (288 Watt-hours), my upgrade at 36v will also have a capacity of 12 Ah (but it's 432 Watt-hours!) so I expect almost 1.5 times the range, even at the slightly greater speed.

Hope it helps


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## DeadFlorist (Sep 18, 2008)

Thanks for the reply TX_Dj!

1. Re: contactor controller. I thought contactor controllers were MORE efficient because the controller itself does not dissipate any energy. I thought the downside of contactors was the lack of flexability (i.e. you'd better want to go at one of the two speeds it has). Not so?

2. The stock tires are 2.50-10. I have been using 3.00-10 tires on my gas Spree, and would probably want to use them on the electric due to increased weight.

3. Re:weight. I weigh 230 lbs and the gas Spree carries me with no problem. I have at various times had almost 400 lbs on it. It is slooooow, but it hauls it. Also, I was planning on reenforcing the frame, namely over the top of the floorpan/battery box.

4. I suppose the golf cart batteries would only be viable in a 12 v system. For a 24v system, I would have to use deep cycles, and I have no idea how I would carry batteries for a 36v system.

5. If I can get good acceleration to 15 mph at 24 volts, can I not get crappy acceleration to 25-30 mph with taller gearing (crappy acceleration to 25-30 mph is par for the course for gas Sprees. Why mess with success)?


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## TX_Dj (Jul 25, 2008)

Contactor controllers are efficient, due to their simplicity- but like you mentioned, you better want to go at one of the two or few speeds that it will provide. Also, contactors are relatively expensive, but so are decent PWM controllers. Contactors also have a tendency to weld their contacts together if they are switched on and off under load, which puts you in a "stuck throttle" condition. PWM controllers can be 95+% efficient in some cases, and that little percentage may be equivalent to the resistive losses from the contacts and extra cabling required to build the contactor controller, plus you gain fluidity in speed control.

With 3.00-10 tires, you're looking at a 48.71 tire circumference, give or take (High Floatation sizes like that don't specify the aspect ratio, though they are typically 92%). Knowing this, we can estimate that at 30 MPH your wheel speed will be ~ 650 RPM, and going backward thru the geartrain, this puts your motor crankshaft at ~ 7500 RPM.

If you eliminate the primary drive of 1.8:1, then the electric motor could run at ~ 4200 RPM, which may be doable.

Re-inforcement is definitely a good idea. Like I said, I was just taking a stab at what the payload capacity is, I don't know for sure.

Since battery placement space will be premium on a small scooter like that, you may want to check out some of the more dense technologies like AGM, Gel, Lithium, etc. There are some reasonably inexpensive AGM/gel (compared to lithium) solutions that are lightweight, and pack a punch for their size.

As for your question about gearing, it all depends on your motor and controller. The higher you gear, the more amps it will take at the motor to get you rolling. Additionally, the slower you go, the more amps are required to maintain that slow speed. 

For example, if you did as I mentioned before, and eliminated the primary reduction and went direct to the final drive, you'd need about 4200 RPM at the motor shaft to do 30 mph. At 10 mph, your motor speed will be half of that (due to the way the final/tire size ratio works), so it stands to reason that your motor volts will be half and amps double at the lower speed. More amps = more heat. More heat = more wear. More wear = less reliability over time.

Chances are, however, that it will be difficult to find an economical motor of the correct voltage which spins at 4200 rpm. 3500 rpm is more do-able in that size, which if the primary reduction is removed, and you retain the same tire size and final ratio, you'll have a 25.45 max speed.

More or less.


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## DeadFlorist (Sep 18, 2008)

Wow, thanks. One more question then: The one on ebay I was looking at has these specs:

4 HP 24 VDC ELECTRIC MOTOR 
45 AMPS NO LOAD
140 AMPS FULL LOAD
8000 RPM FULL LOAD
32 INCH POUND OF TORQUE
¾” DIAM. X 1 ¾” SHAFT WITH KEYWAY
MOTOR DIMENSION 4” DIAM. X 7 ¾” 
SHPG 24 LB (ESTIMATED)

My initial thought was that this was too much motor. Do you think it might actually work? At 8000 RPM I can leave the primary reduction in, so I'll have the best of both worlds, good acceleration, good top speed?


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## frodus (Apr 12, 2008)

Just to clarify.... contactor controllers are more efficient CONTROLLERS, but they do NOT run the MOTOR more efficiently. The motor can suck some major amps from the batteries... as much as it wants, there's nothing to limit power and the batteries can get toasted. 

Contactor controllers, even if 2 speed, are going to see that motor as a short and just pour the amps to it if you can't limit current. Using a PWM controller adds some inefficiency, but lots of FET and IGBT controllers are above 94% eff.... and helps increase the motor efficiency by controlling the volts and amps that its feeding it..... as well as save the batteries from excessive peukert effects.


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## TX_Dj (Jul 25, 2008)

Thanks for that, frodus. I knew there was some other reasons, but completely forgot about current limiting. 

DeadFlorist- check out frodus' youtube vids about his eVFR. http://www.youtube.com/user/frodus17

Frodus, I dunno if I said it before, but that is one sweet bike.


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## frodus (Apr 12, 2008)

Once I get the BMS and LCD dash installed its gonna be even sweeter....

Deadflorist: What part of the Country are you?


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## DeadFlorist (Sep 18, 2008)

Hey, sorry I haven't replied. I was out of town and then busy.

That is, indeed a nice bike frodus. To answer your question, I am in central Illinois.

I have removed the clutch and I am left with a bare spindle going into the final reduction. I have a (what I think is a) 1 horse 12v motor that I borrowed from a buddy. I think, as a proof of concept, I am going to do a rubber hose spindle to spindle attachment with this motor and see if I can get the scooter at least moving under electrical power.

As far as motors go, several of the motor I was talking about above are still available from the same ebay-based dealer for a bit north of $200 apiece. It seems like, based on TX_Dj's calculations, 8000 rpms at 24v would be plenty for this project. Agree? Disagree?


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## TX_Dj (Jul 25, 2008)

Should be. Be absolutely certain that the motor you select is capable of spinning that fast at 24v. Most are not.

Also, make sure that if that is the maximum speed of the motor that you do not exceed the ground speed that matches that motor RPM (I.E. going downhill) lest you find out what it means to grenade the motor. 

I was hoping, seeing your response here, that you'd have a dozen pics of how the conversion is coming along. Ah well, I'm a patient man! Next time send us some pics!


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## DeadFlorist (Sep 18, 2008)

Sorry, no pics yet. The fact that I do not own a digital camera complicates matters on that front.

Two elements of good news, though. First, I scouted battries and I found a 12v deep cycle of dimensions such that I believe I can stack two nicely in the former floor pan. Second, I bought the 24v 4hp 8000 rpm motor. Now, I need a controller. On this subject, I am absolutely clueless. Any ideas?


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## TX_Dj (Jul 25, 2008)

DeadFlorist said:


> Sorry, no pics yet. The fact that I do not own a digital camera complicates matters on that front.
> 
> Two elements of good news, though. First, I scouted battries and I found a 12v deep cycle of dimensions such that I believe I can stack two nicely in the former floor pan. Second, I bought the 24v 4hp 8000 rpm motor. Now, I need a controller. On this subject, I am absolutely clueless. Any ideas?


In that case, you'll get no further hazing about lack of pics from me, but do try to borrow someone's camera sometime so we can see what's going on with your project. 

What kind of motor (i.e. how is it wound?). What is its max acceptable amperage? Those factors will help determine what kind of controller you'll need.


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## DeadFlorist (Sep 18, 2008)

Here is the motor I got:

http://cgi.ebay.com/4-HP-24V-DC-VEH...ryZ26226QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## Little Rhody (Jun 17, 2008)

DeadFlorist said:


> Here is the motor I got:
> 
> http://cgi.ebay.com/4-HP-24V-DC-VEH...ryZ26226QQssPageNameZWDVWQQrdZ1QQcmdZViewItem




The only problem I see is the torque produced. 
32 "inch lbs" = 2.66 "foot lbs"
So if you run a 6:1 reduction that would still only give you 15.96 ftlbs at the rear wheel. A 5:1 gear ratio would only be 13.30 ftlbs.

I hope your a light weight person and plan on running real stiff tires for low rolling resistance. LOL

LR


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## DeadFlorist (Sep 18, 2008)

Unfortunately, I am not a light person. I figure total weight with rider will be about 420 lbs.

Bigger reduction, then? What if I use the original 1.8:1 gear reduction in addition to the final 6.345:1 final reduction? That's over 30ftlbs of torque and it should still be able to exceed 30 mph at 8000 rpm if my math is right.


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## Little Rhody (Jun 17, 2008)

DeadFlorist said:


> Unfortunately, I am not a light person. I figure total weight with rider will be about 420 lbs.
> 
> Bigger reduction, then? What if I use the original 1.8:1 gear reduction in addition to the final 6.345:1 final reduction? That's over 30ftlbs of torque and it should still be able to exceed 30 mph at 8000 rpm if my math is right.


The more gearing you can give it the bettor off you will be. ( to get it off the line from a stand still) The only other advantage you might have is having a smaller diameter tire. This also increases your gear reduction ratio. it would be nice to see the the motor make at least 15 to 20 ftlbs, and then go into the gear reduction. 

Well what do you have to loose?? you got a good price on a motor, if it doesn't work out put that motor aside for another project and upgrade to a stronger motor. This is all about having fun and learning anyway, Correct???

LR


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## TX_Dj (Jul 25, 2008)

Yeah, very little torque from that.

If it were 15 ft lbs at the shaft, that'd be well in excess of the stock motor.

Instead, it appears it will be well less than the stock motor.

Nonetheless, you should be able to mate it to the primary and get the same sort of expectation from it you would have from the ICE. I don't know what the torque output of the stock motor is, but it's probably not much more than that motor.


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## DeadFlorist (Sep 18, 2008)

Well, it seems to me that a 4 horse electric should be more powerful than the stock motor. This model seems to have more revs and less torque. Be this as it may, it seems like I should be able to find the "right" gear ratio to make it work. I suppose I'll start with the stock ratio all the way through and see what happens.


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## Little Rhody (Jun 17, 2008)

DeadFlorist said:


> Well, it seems to me that a 4 horse electric should be more powerful than the stock motor. This model seems to have more revs and less torque. Be this as it may, it seems like I should be able to find the "right" gear ratio to make it work. I suppose I'll start with the stock ratio all the way through and see what happens.


Ya, this is probably a good start. If you can keep the stock reduction, it will be in your favor. 

LR


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## DeadFlorist (Sep 18, 2008)

Would a Curtis model 1204 24-36v 275 amp controller work well for this application? I am maxing out at 140 amp at 24v. If so, how much would you expect to pay for one new/used?


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