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Coyote X 10-18-2008 01:06 AM

Geo Metro plug-in parallel hybrid EV - in progress
I should be filling up my car tomorrow and be back in the 50 mpg range with it hopefully this tank if nothing else unknown is wrong with it. So it is pretty much ready for normal use. My long term goals have always been to add electric drive to the car somehow though.

So my criteria for how to do it are that it needs a a small set of batteries and would like to keep the costs reasonable. Reasonable meaning I would like to stay under $5000 if possible. My car is ~1500lbs right now so with me and any random junk in it I would say a maximum load of 2000lbs as it is now. I don't have lots of room inside the car to put stuff and taking up what little room is left with batteries would suck. My goal would be able to start and run only electric drive for 5 minutes at 35mph. Any longer or faster would be a bonus but if I can do that then I'm happy.

For the motor and controller this one seems like a good setup to me Mars Brushless PMAC Motor with 250A Controller Kit and is complete for 1500 bucks. The only clue I have about what is needed is an online calculator that says it will pull 150 amps at 50mph flat ground with the weight of my car put in it. AGM batteries seem like a good choice since they are a bit stronger than regular deep cycle marine batteries. But maybe optima or some other types would be better?

With that controller I can run 48V and that is a good voltage range to modify the alternator to charge them if needed. I plan on not charging them with the gas engine most of the time but having the flexibility to be able to might be nice. A 48V charger would not be hard to either find or make to charge it at home. I could also Cover the trunk and hood with solar panels even though they would cost way more than they would be worth really.

As far as connecting the motor to the drive. I can add a sprocket to the drivers side cv axle and put the motor over top of the transmission. It would spin all the time while driving but that should not be much of an issue. I am not sure if it is possible to rig a clutch up to it to keep it from always having to spin. The suspension doesn't have much travel so the drive chain would not have any issues with binding or slack. I have read that a brushed DC motor would not work well spinning as fast as I would be driving it while under gas power. The brushless motor seems like it tolerates high rpms better according to it's specs.

So enough rambling. Does anyone think it would work or am I way off? I am not committed to buying any of the stuff I listed or even mounting it like I described. I am mainly trying to plan what to do and experiment with a spare Metro this winter and start putting it in my good Metro this spring. ٩(͡๏̯͡๏)۶

MetroMPG 10-18-2008 10:04 AM

Cool - if anyone's going to follow through with this, it would be Coyote X.

Hope you don't mind I changed the subject line a bit. It really would be a hybrid...


Originally Posted by Coyote X (Post 67905)
My goal would be able to start and run only electric drive for 5 minutes at 35mph. Any longer or faster would be a bonus but if I can do that then I'm happy.

That's totally achieveable with the parts you linked and 48v worth of either floodies or AGM batts. (Optimas are AGM.) Another benefit of AGM is you can mount in any orientation - they won't spill - so "packaging" is easier.


The only clue I have about what is needed is an online calculator that says it will pull 150 amps at 50mph flat ground with the weight of my car put in it.
FYI, the ForkenSwift pulls roughly 70-100A @ 48v to go 30-35 mph. That's with a less efficient motor, heavier (2070 lbs) car, and horrid rolling resistance (snow tires... in the summer).


As far as connecting the motor to the drive. I can add a sprocket to the drivers side cv axle and put the motor over top of the transmission. It would spin all the time
The motor & controller you linked to can do regen, so that may not be a bad thing to have direct drive, always turning. Though the rule of thumb is to expect only about a 10% range increase with a regen system.

What about a sprag/freewheeling clutch? Maybe a little less parasitic drag, and you could potentially use a cheaper brushed motor/controller.

This is totally do-able. I think about it often and want to do the same thing to the Flea, though it's further off in the future than next year if at all.

Another thought: what about using the 5th gear shafts on the end of the transmission?

ZeroFuel 10-18-2008 02:01 PM

Hey Coyote X

Good luck on your project. I would suggest if you haven't seen it yet is the link I am enclosing from the Cornell X Prize team. They have a mule that will be substantially modified, but on their first attempt they only achieved mid 40's. I'm sure your getting much more on your ICE. Weight is a big issue.

Cornell AXP Mule: PHEV Geo Metro - X Prize Cars

Christopher Jordan 10-18-2008 03:16 PM


Originally Posted by Coyote X (Post 67905)
. Reasonable meaning I would like to stay under $5000 if possible. ....My goal would be able to start and run only electric drive for 5 minutes at 35mph. Any longer or faster would be a bonus but if I can do that then I'm happy.

With that controller I can run 48V and that is a good voltage. A 48V charger would not be hard to either find or make to charge it at home.۶

Today I will make you a great deal! For $4999.99 I can sell you a 50 mph, 48V (four chargers onboard) City-el!

I finally got new tires on it and an idiot light began flashing. I took the lid off to check connections on the lower 3 batteries and darn near had heart failure; then got angry since I could not believe the wires, blocks, relays, clips, and more. MORE than a car. An electrician who saw it could not believe it! Multiplied problems many many times. I will not touch it.

I just closed the lid annoyed- with that mess. I asked at the P-A Group whether City-el will ever come to the US hoping to get another "normal" one
Everything works great, just ignore the flashing light. I'm not sure about going the classified ad route and waiting 6 months for a lowball offer. So much for that EV. I have enough trouble charging it her sneakily because the complex does not allow it.

Coyote X 10-18-2008 06:03 PM

I thought about the 5th gear shaft or using a rear wheel to drive the electric. But it pretty much came down to keeping it simple, reliable, and easy to work on. If I modify the trans and something happens later on I will have to remake a lot of parts. Or at least have a huge mess trying to take it apart when I have to work on it in the future. Same thing with finding a euro awd swift and using the rear drive. When I need a part it will take a month to get it shipped so maintaining it in the future would suck.

The main thing about attaching the drive to a cv axle is that it really won't make anything else harder to work on. At most I would have to swap the axle shaft over to a different halfshaft assembly to keep from having to remake the sprocket mount. If I do make it then it will be on a new half shaft so I should be good for 150k miles before having to deal with it. The sprockets and chain will wear about like any good O-ring chain and I figure 25k miles out of it. If I use a master link on the chain I could also just take the chain off if anything happens to the electric drive and it needs disabled to get the car home. Making the sprocket mount should be pretty easy. Just find a non cushioned drive motorcycle rear wheel hub that has an axle shaft size big enough to stick the cv axle through and center and weld it solid. The sprockets are big enough to slide over the cv joint and bolt to the hub when they wear enough to need replaced.

bbjsw10 10-18-2008 06:16 PM


Originally Posted by Coyote X (Post 67987)
Making the sprocket mount should be pretty easy. Just find a non cushioned drive motorcycle rear wheel hub that has an axle shaft size big enough to stick the cv axle through and center and weld it solid. The sprockets are big enough to slide over the cv joint and bolt to the hub when they wear enough to need replaced.

The nice thing about this as well would be sprocket selection, tons of them on the market of different teeth count.

Good luck on your project. If you get it done for Geopalooza next year you should bring it by.

metroschultz 10-19-2008 11:13 AM

What, your not done already?
When I left you had an engine and trans combo laying on the floor to use as a mock-up guide.
I thought by now you would at least have a bracket hammered out for the elctric drive and a sprocket welded to one of the half shafts just to see how it all would fit.

We all have faith that you will make it work.
"You can do eeet"

bennelson 10-19-2008 09:51 PM

Well, I have both an Electric Geo Metro, and an electric motorcycle with almost the exact same motor and the one suggested, so I will weigh in on the topic.

>Battery Weight
>Motor Gearing
>Where do you put the motor?

I think one limitation you will have is space - where the batteries go, and where the motor goes. The Etek is a very compact motor, but it still has to be spaced and mounted. You also need room for the motor controller, and charger if you want to recharge while out and about. Since you will have gas power, figuring out charging and regen braking would be pretty slick. Kelly controllers have a regen feature available. A Permanent magnet motor like the Etek RT could be used for regen.

Please keep motor gearing in mind. Electric motors want to spin fast with less load to be efficient. My motorcycle has about a 6;1 great ratio on it. It has plenty of power. I have heard of guys using higher gear ratios, and burning out their motors because of it. Faster spinning motor = less amps = better range and happy equipment.

I have 450 lbs of lead in my car, and I can go 20 miles on a charge.

I mostly have space for everything in my car because all the gas stuff is out of the way. I would be a challenge to fit everything in as a hybrid. Not saying you can't do it, just that it might be a puzzle!

You might want a higher amp controller. Keep in mind that most controllers are rated at their "peak" amperage - the power they can put through for only a minute.

Also, if you are using the electric for pulling away from stops and getting going, that's when you are pulling a lot of amps. A higher amp controller means better acceleration.

I really don't know what the best place to put the motor is, just make sure it's mounted solid and geared down well!!!

AWESOME project!

MetroMPG 10-19-2008 10:01 PM


Originally Posted by bennelson (Post 68169)
I think one limitation you will have is space - where the batteries go, and where the motor goes.

Ever seen the hood on the Volt mule?

I've thought some bodywork like that might be needed to mount a motor on top of the transaxle to drive either the 5th gear shaft or the driver's side axle.

bennelson 10-19-2008 10:16 PM

Actually, and Etek sticking up through the hood would air-cool the motor AND look pretty cool, but you would take an aero-hit at high speeds.

Coyote X 10-19-2008 10:33 PM

So what kind of amps would you guess I probably need to pull away from a stop light and accelerate at a average or slightly below average rate up to say 30mph? I can't find a lot of PMAC motor controllers that go much beyond 250 for peak amps. I am not sure how many miles a brushed dc motor can handle between rebuilds if I go that route. I typically put 15k miles a year on the car so I would like to have it last at least a year between having to mess with it.

The good thing about how the car is built if I need to I can move the passenger side firewall back to give me enough room to fit the motor up behind the engine. It won't affect the strength of the chassis.

MetroMPG 10-19-2008 10:46 PM

Good person to ask would be one of the Citi/Comutacar owners (yes, I know Ben owns one of those too, but hasn't really be driving it yet). They're fixed gear vehicles.

250A will give you less than "normal" acceleration.

When we had the 225A controler in the ForkenSwift, I measured 36 seconds to get to 30 mph - on a fresh charge, on level ground. And that's using 3 or 4 gears to keep the pot boiling just right. That'll get you honked at etc., in most places if traffic can't go around you. (The 400A controller is good for around 25 seconds to 30 mph.)

But Mike D claims acceptable acceleration from his fixed-gear e-5th wheel using a 275A Curtis & Etek PM brushed DC motor: Finding The Best Hybrid Mix - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol

If you go with a brushed DC motor... sprag clutch!

bennelson 10-19-2008 10:54 PM

That's right Darin, I don't even have a working ammeter on the Citi yet.

You all might want to check my acceleration test videos in the Metro.

Those show me accelerating away from a stop in the Metro in different gears. I am using a 400 amp controller on the car, and it pretty much tops out in that type of situation.

See it here:

MetroMPG 10-19-2008 11:07 PM

Rick's likely looking at a 48v setup. Keep in mind your 400A @ 72v = 600A @ 48v.

Coyote X 10-19-2008 11:18 PM

I have nothing wrong with going higher voltage. The main thing I was looking at was the biggest PMAC controller I could find was 48V at 250 amps max. I like the regen and less maintenance that combo listed gives me.

So what about if I doubled the motors up and ran 2 of them at 250 amps each? That is getting expensive at 3000 bucks for the pair but if that is basically my main problem then that still keeps me within my more or less arbitrary $5000 budget I picked.

I did move my spare metro up to my garage today so this week if I have time I will take a lot of the body and extra crap off it so I can start figuring out where to put the motor. I might have room to put two motors or not really have enough room for one. I will find out soon I guess :)

Coyote X 10-19-2008 11:49 PM

I guess I am getting better search terms figured out for this ev stuff how about this controller:
Kelly Controllers KBL72301 max 300A Continuous 150A Voltage 72V

bennelson 10-20-2008 12:08 AM

That controller doesn't look too bad.

I havent' heard a ton about Kelly controllers yet, but I haven't heard anything bad about them either.

I suppose the rule of thumb is to get as many amps and highest volts you can afford.

I think that controller would suffice for you.

Doubling up motors and controllers would get complicated and expensive.

Jim Husted of Hi-Torque Electric has been building some "Siamese" motors with great success, but that's kinda a wacky drag racing thing.

Coyote X 02-21-2009 01:38 AM

So the weather looks like it is finally getting better, it was below freezing most of the time for the last few weeks. The longer term forecast seems more reasonable so now it is time to actually start doing something with this idea. I figure the first step is to buy a motor and mounting bracket and get it hooked up.

I still can't find a better looking motor for what I want out of it than that AC Etek motor. It should be able to handle 5000RPM easily so that gives me a 1.3:1 ratio to let the car get to 70mph without overspinning the motor and without a clutch on it. What I need to do now is print out a copy of that bracket on robot marketplace and tape up a cardboard model of the motor and bracket and see how it fits under the hood.

If it fits without making much of a bump in the hood then next step is to figure out how to get a sprocket on the axle. Anyone ever taken a cv axle apart and still able to put it back together? I am thinking that my best bet would be to find a drive hub off a motorcycle that is about the right size to slip over the axle shaft and weld it solid. That way I can change sprockets easily as they wear. I would like to use a pretty good chain so maybe something like a 525 O-ring chain would be best. I am not sure what it actually needs though so maybe something smaller or bigger?

I planned on using AGM batteries of some sort. Is there anything out there better than that but still being reasonably close to the same price? I looked around but it looks like they are still the best price/performance ratio out there. I need to also make a box up the same size as a battery and start trying to figure out where to cram 6 of them without taking up the last bit of space I have in the trunk :)

Other than getting a sprocket on the axle this really doesn't seem up front to be a hard project. Just expensive :eek:

Coyote X 02-21-2009 07:04 PM

Looks like it will fit :)

Just have to move the MSD box and fuse box somewhere else and there is tons of room. If it is mounted exactly like shown in those pictures it will have 2-3 inches of room around it. I will probably move it closer to the strut tower but I really need the motor and other hardware before I can know for sure where it is going to mount exactly. I took one of the old axles I had laying around apart and if I can find a hub that slides up on it then adding a gear will be easy. The total movement of the axle where I plan on mounting the gear is less than an inch so that is well within the range a good chain and sprockets can handle.

Looks like it is time to buy parts now. I wonder how long it takes that Robot Marketplace store to ship stuff out. I will probably order a motor and the bracket to start with since I have no idea what it is going to take to mount something on the axle.

MetroMPG 02-23-2009 05:15 PM

This is going to be lots of fun.

Glad the nice weather's coming back where you are, Rick.

Coyote X 02-23-2009 10:44 PM

The weather isn't quite here yet but it is close... Yesterday we had a few more inches of snow and today was like 25 degrees all day. Tomorrow is going to be near 50 though so :D:D:D

I can't see anything online that is bad about the motor/controller combo I am planning on using so I am going to order the motor tonight and hopefully in the next week or two I will actually start building things. I was going to order it yesterday but I just got a copy of orange box for the 360 and it needed playing :rolleyes:

Also I took an axle to school and talked to some engineering types and I think I have a pretty easy to make plan for getting a sprocket on there. If things go smoothly I should have it done and working by geopalooza so everyone will get to see it in person.

Coyote X 02-27-2009 04:08 PM

Motor came in today. I will start messing with it this weekend and see what I can figure out. It is a bit thinner than I estimated so it should have no trouble fitting in a few different places.

I saw Kelly controllers has a 144V controller now. Is it worth spending double the money to get a 144V 650A controller instead of the 72V 300A I was planning on? I doubt I could fit 12 batteries in the car easily but I guess anything is possible. Is going to 144V actually worth it though in real day to day use? If anything I guess I could get that controller just so I have the option of going higher voltage in the future. Not sure if that Mars motor can take that much abuse though.

Coyote X 02-27-2009 04:31 PM

was looking at the dc controllers this is the one I should be looking at:

KBL12401H,24-136V,400A,BLDC Controller/With Regen

So that still lets me go to 120V 200A continuous. Still more than the mars is rated for so I am not sure it would handle it.

MetroMPG 02-27-2009 04:38 PM

So you didn't order the low voltage AC motor kit with regen? Regen would be cool. You can't coast up to every stop. :)

Daox 02-27-2009 05:09 PM

I'd recommend staying away from Kelly controllers. Just by word of mouth. We have a guy running a 144V S-10 around here. His Curtis 600A controller works better than the Kelly 1000A he used to have.

Coyote X 02-27-2009 07:22 PM

I ordered the motor directly from mars electric. That robot marketplace has insane shipping rates. I can always get that 48V controller later but from what I have seen everyone says go to a higher voltage to get more reasonable acceleration rates and top speed, plus it reduces the amps required. I am not really sure what controller to get though that is why I haven't actually ordered one yet. I always have the option of making my own but I really don't have the time to deal with it.

Just about all the AC controllers have regen braking so I will be able to use that no matter what. I have not seen anything over 48V other than the kelly controllers so I don't see a lot of options if I want to run 72V for now. I still have to get the motor mounted and a chain drive of some sort figured out so I have a few weeks at least to decide on the motor controller and voltage.

For the chain drive I have seen some specs on the motor saying it has an absolute max of 4000 rpm. So with my 175/70-14 tires I need a 3.9:1 ratio to allow the car to go 70mph without overspinning the motor. The best I can come up with is an 11 tooth 7/8 bore sprocket from that robot marketplace($18 shipping!!) and a 42 tooth from tractor supply for the axle. That is using a #40 chain so it is a bit smaller than I would like but it is about the only thing I can come up with that fits in the space. I can go to a max 3.75 inch diameter sprocket on the axle without hitting the lower control arm. That pretty much limits my options using a #50 or 525 chain since they would be a bit too big, so it looks like a #40 will have to do. Unless anyone knows a good place to order sprockets from that has a pretty good selection :)

The Metro axle shaft is 7/8 so it isn't going to be that hard to find a hub for it. The drivers side has lots of room for the motor and I could probably grind the flange on the control arm and get another quarter of an inch or so clearance if I need to go slightly bigger but it still won't let me go to something like a 38 tooth 525 without hitting. My only other option would be to put a 13-15 tooth gear on the axle and a gear reduction sprocket set somewhere to gear the motor down. That would be a lot more stuff that could go wrong long term since it would be 2 chains, 4 sprockets, and 2 extra bearings. I might have to do it though if the #40 chain won't hold up to long term use.

bennelson 02-27-2009 08:18 PM

I ordered my custom rear motorcycle sprocket from Sprocket Specialists.

I'm running a #40 chain on the motorcycle - just a plain cheap chain from the tractor aisle of the farm store. They also had pretty small sprockets at the farm store as well. I got both a 12 and 14 tooth sprockets there, and a 72-tooth from Sprocket specialists for a 6:1 gear reduction.

MetroMPG 02-27-2009 09:43 PM

Want me to rename the thread title?

I figure if you're actually spending money, it's progressed beyond "questions".

brihoo2k 02-27-2009 11:39 PM

Just a thought but how about going with a belt configuration like a cvt (constant variable transmission) you could possibly rob one off a snowmobile. I myself would not consider the size 40 chain unless it was double roller. Also are you mounting the sprocket in a stationary spot on the axle, one that doesnt move with the suspension. Does the axle have a mid bearing to keep it stable? It's been a long time since I've worked on a metro so I'm not sure.

Christopher Jordan 02-28-2009 12:03 AM

Pretty old thread; but last year I was offered a trade for an electric Metro for my City-el. No thanks, plug-n-go- I don't know. Just last week I saw that same Metro in Craigslist with an 'as-is, doesn't move' warning about motor to axle connection grinding out.

There must be an EV God :D ! City-el is way over-amped, is about 77 pounds over the limit, exceeds top speed and acceleration- so has less range, very tricky charging; but took it out yesterday on highway 1 (in-town) with no problem.

Christopher Jordan 02-28-2009 12:51 AM


Originally Posted by brihoo2k (Post 90059)
Just a thought but how about going with a belt configuration like a cvt (constant variable transmission) you could possibly rob one off a snowmobile. I myself would not consider the size 40 chain

My 'El has a higher ratio and a poly-vee belt (former owner wrote this):
Chris Jordan's CityCom CityEL
but the newer 'Els have a chain. I have no idea what a Metro conversion would use.

Coyote X 02-28-2009 01:03 AM

I guess a rename might be in order. It would save me from actually starting a new thread :)

I am putting the sprocket on the axle about an inch away from the CV joint so it gets very little movement. From full extension to full compression of the wheel is about an inch of movement at most at that point. The suspension droops a lot more than it really should with the cut springs so I will be putting limiting straps on it anyway. right now with the wheels hanging in the air the springs could possibly fall out. So fixing that problem will make the sprocket movement pretty small.

I really don't like the idea of using #40 chain for a car. It just seems small.

ANSI 29.1 roller chain standard sizes
Size        Pitch, in.        Roller diameter, in.        Ultimate strength, lb.        Working load, lb.
25        0.250"        0.130"        781        140
35        0.375"        0.200"        1,758        480
41        0.500"        0.306"        1,500        500
40        0.500"        0.312"        3,125        810
50        0.625"        0.400"        4,880        1,430
60        0.750"        0.469"        7,030        1,980
80        1.000"        0.625"        12,500        3,300
100        1.250"        0.750"        19,531        5,072
120        1.500"        0.875"        28,100        6,800
140        1.750"        1.000"        38,280        9,040
160        2.000"        1.125"        50,000        11,900
180        2.250"        1.460"        63,300        13,700
200        2.500"        1.562"        78,000        16,000
240        3.000"        1.875"        112,500        22,250

810lbs working load probably mean at best I will get 10,000 miles on a chain before it breaks. If I can get a #50 chain that will make it much better but the only way to do it would be to add a gear reduction shaft and that means more parts and more points of failure.

from a web search.

530 chain has a pitch (distance between center line of rollers) of 5/8". The roller diameter is .400" and the width (inside distance between plates) is 3/8". #50 chain has the same specifications. An O-Ring 530 will be wider #50 and 530 chain are the same in dimensions. #50 is the ANSI industrial chain designation while 530 is the motorcycle industry designation for that chain. Both have the same specifications and can be used in place of each other (other than the 530 will be slightly stronger in regular chain and much stronger in the o-ring version).overall, but still has the same critical (roller, pitch, and inside width) dimensions.
So I really need to use #50 sprockets so I can use o-ring chain like I was planning. It will last much longer. Standard Roller Chain Sprocket Diameter - No. 50 Chain shows the diameter and I have a 3.75" max radius without grinding a notch into the control arm. I might possibly get 4" if I grind everything down. If I could possibly get an 8 tooth front sprocket then it would work great. If not I will have to build a shaft to do my gear reduction. I guess I need to hunt around and see what I can find. I have a week or two before spring break so I have time to look for stuff.

Coyote X 02-28-2009 09:22 PM

From fremont supply:

That will get me a 3.92 gear ratio. I would put the 22 tooth gear on the axle. It is 4.722 inch diameter so it clears everything fine. And put a shaft somewhere using those 2 bearings and a 14 tooth gear paired with the 22 on the axle. Then put a 30 tooth gear on the mid shaft and a 12 on the motor. That won't be an ideal setup but it should work and make changing the ratio a bit easier by just swapping gears on the shaft. This is very close to where 3rd gear is in the car right now so it seems about right. The only bad part is it is going to take a lot more fabrication to get that shaft fit in there somewhere and adding a lot of extra crap under the hood and be a lot more work and expense maintaining it in the future.

The best I can do with a #50 chain direct drive with no mid shaft is a 10/36 gear set so that gives me a bit lower motor RPM but I am not sure if it is good enough to actually work. It would be much cheaper and simpler since it does away with the extra shaft and assorted mess that goes with it. It would just be the 2 gears and a chain.


at 3.92 here is my rpm/mph
rpm        288        576        1151        1727        2303        2878        3454        4030
mph        5        10        20        30        40        50        60        70
at 3.6 here it is
rpm        264        529        1057        1586        2115        2643        3172        3701
mph        5        10        20        30        40        50        60        70

I have no experience at electric drives but I really can't see how 24 RPM at 5mph is really going to matter that much to the current draw pulling out from a stop.

Also I measured a stock framed metro and a 36 tooth gear will fit the axle without any real trouble, just a dent in the control arm mounting area for clearance. So if the 3.6 or 3.4 ratio is good enough then pretty much anyone could add an electric motor to their car real easily. A kit could be fabricated that would consist of an axle that has the keyway cut into it and a bracket set for the motor. Probably a couple hour job to add to any Metro.

Coyote X 03-01-2009 12:12 AM

2 Attachment(s)
Interesting charts on that motor running at 48v and 72v

From the thread where I found those charts at:


The X axis of these motor dyno charts is almost always torque, as the way they're tested is to have the motor drive an increasing load (i.e torque) and measure how the rpm/volts/current/etc changes.

In this case I believe the x-axis units are inch-pounds, 1 in-lb = 0.113 Nm. This would make sense with the Watts Out curve where take the 160 in-lb mark for example = 18 Nm, x 2500 rpm / 60 * 2PI (converting to radians per second) -> power of 4716W, looks about right on the Watts Out curve.

Edit: Interesting though that the amps and inch-pounds happens to be pretty much 1:1 - coincidence I suspect, but hard to fault Electrocycle's assumption! (Being a permanent magnet motor, it has a constant amps to torque ratio.)
So That means I would lose 8% of my acceleration rate going from 3.9:1 to 3.6:1 assuming I am accelerating at the current limit of the controller. That chart is very hard to figure out what they are talking about so I could be wrong :) I think I will order the 10/36 gears and mount them. Trial and error is a lot more fun than research.

Coyote X 03-01-2009 10:53 PM

Found a better selection of sprockets. They are at Shoup Manufacturing Company I ordered #50 sprockets. I got a 9 tooth drive gear and a 32, 34, and 36 tooth driven gear. They are the weld on hub type so I also got an X series 7/8 hub for the axle and a V series 7/8 hub for the motor. The available gear ratios with those driven gears are 3.55:1, 3.77:1 and 4:1. That should pretty much cover any range I need keeping my 4000 RPM limit of the motor.

Now that that part looks like it is pretty well settled it is time to move on to the next part, the controller and batteries. I don't think the Mars brushless motor can take much more than 72V and still have a long life. So I am not really sure I would ever use more than that. I could always modify the controller to boost it's output if it ever comes up I suppose. So the 72V 300A w/regen controller looks like my best bet.

For the batteries it looks like it is ideal to charge them individually. That is not hard really if I just use 5 or 10 amp automatic chargers, it would just be a mess of wires and crap to hook up all the time. Another simpler option is to charge them with one 72V charger and balance them using a balancer of some sort The Balancing Act | ELECTRIC-LEMON shows a pretty simple circuit to balance the batteries over time. That should get them charging and working as long as possible. The fun part is trying to figure out what kind of battery to use. I planned on using AGM-31 but I really don't think I can fit 6 of them in the car and still have room for anything else, they are pretty big batteries and heavy. I don't really think I need that much capacity anyway. I can get a MK 8A24 79 Ah (20 Hr) AGM Sealed Battery - Batteries: Sealed Agm @ AltE 79AH battery that looks like a good size to cram in corners in the car. 6 of those would be a lot lighter at 50lbs each. I am not sure what kind of range it would give me though.

Anyone know of a better battery to use?

bennelson 03-01-2009 11:22 PM

I think any AGM battery would be a good bet for a hybrid.

The Optima Yellow Tops on my motorcycle have worked well. I have heard of some other people say they ran into quality issues with Optimas, but mine have been great.

You could also use a charger like this for whatever you end up getting.
SE-1072 - Schumacher Chargers - 877-746-2288 Live Help

It's pretty reasonably priced as far as multi-battery chargers go.

Coyote X 03-04-2009 06:52 PM

Is that a battery in your pocket or are you happy to see me?

Ended up going in a completely different direction :) Got batteries from Walmart of all places. They are deep cycle/starting batteries rated at 125A. I figure under heavy load it would be more like 50AH but for a 60lb battery that is $67 they aren't bad. I only got 4 of them, the other 2 will have to wait for more to get back in stock. I can fit 4 in the trunk and 2 behind the seats in battery boxes. Going back to uncut rear springs will get the ride height back to what it is without batteries. This setup should last me a year or more, at least until LiFePO4 batteries get a stable price and good availability.

So now I am just waiting for sprockets to come in and I need to finally order a controller. I am still leaning towards the 72V model since from trying to stuff batteries in there I really don't think it is possible to get 10 of them in the car without serious modifications. I might go ahead and order everything since I have one more week of work until spring break. That would give me a lot of time to do everything to the car at once.

MetroMPG 03-04-2009 09:38 PM

Thread title changed. Let me know if you want something different.


A kit could be fabricated that would consist of an axle that has the keyway cut into it and a bracket set for the motor. Probably a couple hour job to add to any Metro.
I like the sound of that.

Way to grab the bull by the horns on this.

roflwaffle 03-07-2009 09:19 PM

Are you attaching the sprocket to the axle hub or shaft? I've been thinking about doing this for a couple years too but the shift linkage is in the way on one side and while the other side is doable if I went to manual brakes, something I was planning on doing anyway, it's right next to the exhaust manifold which probably would require a heat shield and funky electric motor mount. My pickup would be easier since I could just shorten the driveshaft and put a double shaft motor inline, but since it has to be smogged I have to get it legal somehow and the PR person I talked to at CARB was a total bonehead. :(

Coyote X 03-08-2009 03:24 AM

I am putting it on the shaft. There is room beside the transmission with the 3 cyl to run the chain up to where the motor will be sitting.

The 72301 controller is on its way. I went ahead and ordered the 72V 8A charger they have. I picked up the last 2 batteries today also and got a pair of battery boxes for the batteries that go behind the seats. So hopefully next weekend I can start installing everything. The sprockets have also came in. I have a 9 tooth drive sprocket and 32, 34, and 36 driven sprockets. The last thing I need to find is some welding cable. I am thinking for 300 amps I probably need 2 gauge minimum. 0 if I can find it. 4 gauge is probably good for going from the controller to the motor depending on the distance. I also need to order the parts to build a battery balancer and the stuff to modify the alternator to make it output 14.4V or 86.4V depending on what I want to charge.

The instructions for the controller leaves out a few details. Like do I need to ground the 72V to the chassis or leave it floating and just connect it directly to the controller only? And is it better to put the controller close to the batteries or closer to the motor? I could easily fit it in the trunk but if it is better near the motor I could make room for it under the hood as well.

On ebay I could get 3x6 solar cells 1.75W each. So with 200 of them I could get a few amps of charging. It would peak at 4.5A@72V. So if the car was parked outside with partially discharged batteries for a while I might get enough charge to get a few more miles out of it. I am really tempted to try that out after I get this electric drive working. It is another one of those things that won\'t pay off in saving money but it would be really cool to have on the car.

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