Got twin Puma motors running and it feels good.

[cell_man]

I'm getting a few Puma (Mac) motors and I thought I'd try something a bit different, so I was thinking a double motor installation would be interesting. I had a quick play with this idea before and it felt good, so this time I ordered some higher speed motors which have a no load rpm of about 480rpm at about 38V as opposed to 365rpm for the standard winding. I figured that with a dual motor installation the motors are well within their limits but combined they will still have good power. My play with the standard winding told me that it was rpm limited in a dual motor installation and although it had great power and acceleration, the top speed was a bit limited for my liking (the standard winding is about right for a single motor installation on a 26" rim IMO). The high speed motors I've got are too high RPM for a single 26" installation but would work well on a 20" wheel I reckon. I'll have to see if they are also a bit fast on the dual motor install, but I can always go to 24" rim if I want.

So far I've installed a high speed rear, a standard speed front and am running them at 36V on dual 25A 12Fet controllers. I was a bit worried about getting both controllers running and was thinking I'd need 2 throttles, but after a little play today I found that by connecting the +5V and ground from 1 controller to the throttle and connecting the signal from the throttle to both the controllers, it worked just fine. I was thinking I might have to link the ground signal also but it's not necessary for my setup.

First impressions are really good. Top speed isn't amazing at about 46kph (fast enough for Shanghai Streets on a POS bike with bad brakes ) but once I fit the 2nd high speed motor that should improve as the standard speed motor cannot contribute much at that RPM. The thing that's most impressive for me is the acceleration and at only 36V. I'm also quite keen to keep the battery voltage low as it will enable me to fit 12S of the 15Ah prismatic cells I have in the triangle of the frame keeping the weight to as close to 5kg as possible including BMS, case, mounting etc and centralised in the bike. A bit reluctant to show pics of my little creation as it stands as it is an eye sore and you can barely see the crappy bike under the rats nest of cables, tie wraps tape and the battery pack is just sat on the rear rack

I have a couple of new bikes I can transfer the kit to when I'm happy with it. Unfortunately I don't think I can squeeze the prismatics into the frame of the dual suspension bike I have so it will be a hardtail for now. I've got lots on at the moment so the progress on this may be a little slow but I'll try to get something done and keep this post updated if anyone's interested. Be interesting to try some smaller motors and see how they feel too. The smallest of the cute motors are only about half the weigh of the Puma, but I'll get this running for now and go from there.

 

[NeezyDeezy]

show us please

 

[mr.electric]

Sounds like a great build. I like the combination of high torque and high speed motors. Do you lock it outside?

 

[cell_man]

Ok I'll get some photos up tomorrow but it really does look bad and all it is right now is a bad bike with 2 fairly big hub motors, 2 controllers and a makeshift battery pack bungeed onto the rear rack, with about a mile of random cables thrown in for good measure. I don't know if the motors will be the right speed but I'll soon see. If I can get the battery into the frame and fit it into a reasonably light frame it will be a nice bike around town I reckon and shouldn't be overly heavy, but still no lightweight.

I keep this in the apartment and will just lock it with a couple of locks and remove the battery if I need to leave it somewhere.

Even running at only 36V I still used over 26whrs/km average on a 10km trip with lots of stop/start and mostly full throttle, no pedalling. It's pulling 50A under acceleration so about 2KW. It's not lightening but it does have a nice turn of speed and gets up to speed very nicely. I've used it with dual 35A controllers at 48V and it was maxing out at about 55kph but again dual high speed motors should add to that. It really kicks at 3.5KW under acceleration though.

 

[dogman dan]

I've thought about a dual gearmotor full suspension bike for some time. How to carry enough battery on most FS bikes to power two motors is the problem. But with a backpack with 48v 20 ah of A123 pouches, BINGO!

 

[cell_man]

I've thought about a dual gearmotor full suspension bike for some time. How to carry enough battery on most FS bikes to power two motors is the problem. But with a backpack with 48v 20 ah of A123 pouches, BINGO!

That's 1 way for sure and it wouldn't be an overly heavy pack at maybe 8kg if if you were careful with weight and had a small BMS. The pack I've been using has 12S 30A BMS and it holds up just fine with the dual motors. The BMS is really compact as well. The BMS start to get kind of bulky when the current rating increases from what I've seen. Like I mentioned the 15Ah cells will fit in the triangle of a typical hardtail frame, but maybe I can find a way to get them in that FS bike too.

 

[dogman dan]

Now I've gotten stronger and prefer to just pedal a good bike on the mt trails. But two years ago when I was looking into a dual motor dirtbike, I was thinking I'd have to carry two 48v 20 ah pings. The idea of riding with 40 pounds in a backpack didn't appeal to me at all, and not much space on frames for carrying there on FS bikes. I have nowhere near the abiltiy of DR Bass to make a pack from little A123's.

But the 20 ah pouches of A123 changes everything! Everything except the I never have money thing. For now, I have my work cut out for me trying to wear out two pings. It should take a while, allowing some money to accumulate.

 

[cell_man]

Just thought I'd do a bit of an update on my dual Puma bike. I've now transferred all the kit to a full suspension bike. It's not a high end bike but it does the job and takes the sting out of the pot holes when you hit them at 50kph. I was previously running 1 standard speed motor and 1 high speed motor. I've now changed over to 2 high speed motors and also soldered the shunts on the controllers.

The suspension bike is an alloy frame so I thought it wise to knock up a torque arm for the rear motor. The forks are cheap forks with steel dropout so they will do till I get some proper torque arms/c washers made up for the better alloy forks I have. Anyway here's a couple of pics.

Here's the torque arm. It had to be a bit complicated due to the design of the rear dropout. I would have rather used thicker steel, but this will do for now. Maybe do another 1 the other side as well



Fitted



A couple of pics of the bike





I've not had it running long in this configuration but it does about 52 or 53kph on the flat no pedalling (too low geared to add anything at that speed anyways) at 36V and has very respectable acceleration. The soldered shunts seemed to have perked it up a bit and it's pulling over 60A under acceleration. At max speed the power drops off from the maximum so it seems like it isn't too high geared, but I think 24" rims would perk up a bit. I would have liked to have fitted the pack in the frame but this deign of frame will not allow it. The rear rack isn't working too hard anyways as the 12S 16Ah pack is only 5kgs. Here is the pack naked

View attachment 1



Next I'll get the alloy forks fitted with proper torque arms. I want to get some modified 6 fet controllers. Those 2 bricks tie wrapped to the frame just let the whole thing down big time. Once I get some proper controllers I'll sort the wiring and get it routed through the frame I think and lose anything I'm not using. I also want to get a disk equipped motor in the front but the standard 500W front is rim brake only. I think a rear could be persuaded to fit.

 

[liveforphysics]

Brilliant torque arm and torque arm mounting off the disk brake bracket.

Fantastic energy and power dense lightweight little pack too! Great work!

 

[dogman dan]

Yeah, really really nice work.

Bring it to the races.

 

[cell_man]

Brilliant torque arm and torque arm mounting off the disk brake bracket.

Fantastic energy and power dense lightweight little pack too! Great work!

Thanks Luke

I need to do the same for the other side and then do something to safely mount into alloy forks. It takes some time getting it all to fit right though. Even though I made a template from some thin material I still had to drill out the bolt holes as they were a little out... Yeah that little pack gives out some power alright. I'm using about 30wh/km at only 36V so it's doing a fine job and the little 30A BMS seems to be handling 60A plus under acceleration just fine. That pack hit 16Ah on my CA with a 50A limit, although I did have to nurse the last bit out of it.

Yeah, really really nice work.

Bring it to the races.

I'd love to but I have a feeling the races are a long way away and I'd be needing more than 36V I reckon. I find it squirms around a bit on the bends, maybe a better rear suspension unit would help, but that would probably cost twice the price of the complete bike from the factory. I'll throw a 16S pack on there when I get a chance. I'd hope for mid 60kph and it wouldn't be overly stressed either I reckon. I mean the dual geared hub motor setup is never gonna be the lightest (well not with these full sized motors) or the most efficient but it can take the power no problems, has very respectable acceleration, you're only putting half the power through the dropouts and it's well balanced (it's heavy both ends )

 

[GrayKard]

Sweet. Welcome back to the 2wd 2wheeler club. A very exclusive club. :wink: (no, you front motor back wheel peddlers don't count )

I'm pretty happy with my build. It ended up light (53lbs) and well balanced. It takes off like a jack rabbit and can climb almost any hill unassisted. Only place it drops short is top speed. But I have a fix for that. (delta/wye )

How much did your bike end up weighing?

 

[Mark_A_W]

That's really cool cell-man.


But why the high KV motors (super high, as the standard 365 rpm is FAST), rather than more volts?


My 365 wind will do 55kmh with pedalling, at 64v nominal. I'd prefer a 300 wind.


And you would be carrying more watt-hours at 48 or 60v (or even 72v), so potentially more range.


Your current pack doesn't look very thick, a few more cells won't hurt


What controllers are they?

 

[MitchJi]

Hi Paul,

I would have liked to have fitted the pack in the frame but this deign of frame will not allow it. The rear rack isn't working too hard anyways as the 12S 16Ah pack is only 5kgs.

Would the pack fit, edgewise where you currently have the controllers (either in place of the top controller or the bottom controller)?

I think your 12s pack is under 4" thick edgewise and you should be able to fit up to about 5" between the cranks. If the cells are mounted edgewise the height is just under 7" which looks like it would fit either above the downtube (in the triangle) or below the downtube (below the triangle).

 

[cell_man]

How much did your bike end up weighing?

The standard bike was no lightweight at circa 16kg. It's about 32/33kg all in with a 36V 15Ah pack. Motors are about 4-4.5kg a piece, battery pack 5kg, controllers, rear rack etc adds a bit too. I've got both 128 and 108 cute motors and lighter hard tail bikes that will take a pack in the frame triangle so would like to get a lightweight bike up and running sometime. Could maybe throw a small pack of A123 26650s on there if I need more volts less amps.

That's really cool cell-man.


But why the high KV motors (super high, as the standard 365 rpm is FAST), rather than more volts?


My 365 wind will do 55kmh with pedalling, at 64v nominal. I'd prefer a 300 wind.


And you would be carrying more watt-hours at 48 or 60v (or even 72v), so potentially more range.


Your current pack doesn't look very thick, a few more cells won't hurt


What controllers are they?

Thanks Mark

The controllers are the same as the 12Fet Ecity sell, but I got them from the factory direct. The software had to be modded to run the Puma, same problem you had with the phase current. I've got a couple of the 6fet controllers laying around and just ordered some IRFB4110 (genuine Mexican 1s I hope, they weren't cheap) and will get them fitted when I have a minute.

I personally felt the standard wind is just about right at 36 or 48V for single motor drive. When I tried a dual motor drive it felt a bit under geared, it just flew up to it's max speed but was severely rpm limited. I wanted to try to achieve a good max speed and power without having to go big volts and big pack. I've got these prismatic cells which will happily deliver all the amps I can pull and don't need a massive range. Even a 12S 15Ah pack has got almost 600Whrs and at sensible speeds and a gentle throttle hand (don't do that... ) the range would be pretty good. Even 16S starts to get a bit big and heavy for my liking and these cells are about as good as it get with regards to energy/power density on LifePO4. It really does have a good turn of speed for a 36V set up. At 48 it should get interesting, maybe low to mid 60s kph, at 60V it will be a bit silly I reckon. Even with the high rpm motors the bike is able to pull up to a sufficient speed where the motor power has reduced from it's max current range. So as long as there is no wind it will pull low 50s kph pulling around 1600/1700W. Soldering the shunts definitely perked it up a bit as well.

You mentioned that your motor is a bit fast for your liking. Have you thought of trying the 350W motor. At the over volts you are running it will still pull plenty of amps, the gears are the same and it's a much slower wind. I mean my motors are pulling 30A plus at 36V, if your controller wasn't current limiting god only knows what that motor would suck at 60V. I'm sure the 350W would give you all the power you have now but just do it at a slower RPM.

Hi Paul,

Would the pack fit, edgewise where you currently have the controllers (either in place of the top controller or the bottom controller)?

I think your 12s pack is under 4" thick edgewise and you should be able to fit up to about 5" between the cranks. If the cells are mounted edgewise the height is just under 7" which looks like it would fit either above the downtube (in the triangle) or below the downtube (below the triangle).

Unfortunately there is no room for the pack within the triangle edgewise. It's just a bit too long. The pack is about 81mm thick and 150mm wide. I didn't think putting it flat within the triangle would work, but maybe it will. I just thought it was a bit too wide and would get in the way. I don't really use the pedals anyway, maybe a few turns off the lights. I'll look into putting the pack in the frame sideways as you suggest. Having the pack with the frame would be much preferred although TBH it works reasonably well strapped to the seat pole rack as it's not overly heavy. The 15Ah and even the 20Ah cells should fit within the triangle of most hardtail and some full suspension frames.

 

[BiGH]

so nice. This is basically the bike i dreamed of making when i first started but the puma kits were $$$$$$$$. Congrats on a cool build. is it possible to build a dual suspension, dual motor, dual disk setup?

and your battery pack is SOO nice

 

[cell_man]

so nice. This is basically the bike i dreamed of making when i first started but the puma kits were $$$$$$$$. Congrats on a cool build. is it possible to build a dual suspension, dual motor, dual disk setup?

and your battery pack is SOO nice

Thanks

I'm still working on the dual disk but it might take a little time as I've got paying customers waiting. The standard puma 500W front is not disk compatible but the 350W is. I'm hoping the rear 500W motor with disk can be persuaded to fit in the front, but there is no guarantee. The standard 350W motor is a slower winding than the 500W and the motors I have in the bike are both about 30% faster than the standard 500W so I really want to stick with these high speed motors.

The battery pack is still being bungeed to the rack so I really do need to fix a proper case and mounting method soon, hopefully somewhere on the frame rather than out the back. I want to change the 2 big controllers for a couple of modified 6 fets and remove any unused connectors/wiring. Run the cables through the frame, get the front motor fitted with a disk and maybe try a few more volts....