french double motors mtb needs help....

[easyvelo]

View attachment 4View attachment 5View attachment 4View attachment 7View attachment 8Hi everybody,
first i wwould like to escuse my poor english writing.....that's done.


I need some help, i will show you my toy , i hope you will like it, but the first try is how could i said, far from what i had expected, ok lets go for some picture, you have to know that i live in cassis south french riviera (...http://www.ot-cassis.com/), a pretty hilly place, so that's why i took the idea of a dual motor and because i love difficulties lol.

so here is the pics:

 

[cell_man]

I like. It looks really really cool.

So what's the problem with it? It looks nice to me. I've got some plans for a dual Puma bike if I can ever get away from these cells...

What are your impressions of how these 2 motors work together. I bet it has some great acceleration. Those little Bafang front motors have good torque even at standard volts.

 

[easyvelo]

hi cell man,

thanks for you interrest, i was looking to buy one of your best batteries, but my budget is to low now, as soon as i can, i will sale my 4 days ping for yours, but to be honnest, i have not find the good tunning and i feel i even be far to need torques arms,
so, i have to go further in my investigation to know how i have not the power i had expected, my two batteries is ok so, maybe the shit controller, may be i have to try kelly ones , i will let you know....

laurent

 

[cell_man]

Just use a 10mm spanner and some jubilee clips at first till you can get some proper torque arms. I've used this with motors putting out 1800W with no problem so far.

What controllers are you using and how many amps? Even though you have 2 motors it might not necessarily increase your max speed as I would have though your front Bafang is probably quite a low rpm model. They are only about 200rpm at 36V. The Puma is almost definitely higher rpm for a given voltage so once you get above the max speed the Bafang can pull it will not add anything to the speed and will not pull many amps from the controller as it is not loaded. Even 2 identical motors will not add much to the max speed if they are limited by the rpm they can produce. You would need dual higher rpm motors to get a significant increase in speed. Motors will not generally pull much more than about 85 or 90% of the no load or freewheel speed. See what each motor will pull with no load and let us know. That should tell us more.

If I can ever get the termination sorted I'd be happy to fix that for you

 

[boostjuice]

What is the make/model/brand of this armoured backpack? Where did you get it? I want one for my own back-pack battery setup

 

[easyvelo]

dear boot juice,

i bought it in ebaymerica this is a axio can am very cheap this is it

http://cgi.ebay.com/ebaymotors/New-Can-Am-BRP-Forza-Hardpack-Backpack-Axio-4471980090_W0QQcmdZViewItemQQhashZitem19b9020338QQitemZ110478099256QQptZApparelQ5fMerchandise#ht_2520wt_75
2

 

[easyvelo]

dear friends,

Here are some results, I purchased a speed meter properly calibrated, connected to my turnigy wattmetter, I have been in contact with my supplier , frank from das- elektrorad.de to check the connection of the rear Puma, obviously the wire color do not match between the motor and the contoller, so he gave me the good wiring

So here are the results:

I'll start by disappointing Bafang , I tried it with my two batteries, herehis the the following data:

with the ping v3 charge 53.35 V

vmax no load 31.5 kilometers per hour
meter data: 0012 AH / 0.6 WH / AH 4.78 / 52.21 VM / WP 249.5

With a load 47.1V Lipo

Vmax no load 28Km/h
Data watmettre: 0.05 AH / 0.2 WH / AH 2.04 / 46.98 VM / 95.8 WP ?????????

Now the puma with the ping v3 load 53.21V

Vmax no load 65 km/h

Meter data: 0133 AH / 6.9 WH / AH 9.47 / 50.86 VM / WP 482.9

Here, I am rather satisfied of the no load max speed of the puma, I have not been able to test on private road, however I still tank for Bafang, and in any case I have to check the load of my lipos. ...

What do you thin of it

friendly
laurent

 

[easyvelo]

What is the make/model/brand of this armoured backpack? Where did you get it? I want one for my own back-pack battery setup

hi, could you tell me how i could insert my picture in full image inside py post peae

 

[cell_man]

Hi Laurent,

The bafang is a much slower rpm than the Puma. I have both these motors and the Bafang states something like 195rpm at 36V on the case so that pretty much agrees with your data although your figures could be a little slower than that so there could be a problem somewhere. I got just the same values as you got with the puma on a fresh off the charger 48V pack. The Bafang are designed to be the best compromise for a european road legal setup in a 26" rim which they do very well but if you combine it with a much faster and more powerful motor like the Puma it will not add much to the power. It might add a little on the initial acceleration but once you get up to speed on the Puma, the Bafang can no longer keep up and will not be able to add anything to the power. During acceleration and up steep hills it will help. If you want to get more top speed from a double motor setup you will need to consider the no load RPM and either increase the volts you are going to be running at or get higher rpm motors as in a dual motor setup they will be able to pull those higher rpms that they couldn't in a single motor setup. I ordered some 30% faster winding Puma motors for just that purpose and hope to get them fitted to a bike soon to see what they will do. Dual 500W Pumas will still only pull about 50kph at 48V in 26" rims but will have great acceleration or hill climbing ability IMO.

If a motor is well specced for a single motor application fitting 2 will not increase your max speed by very much but will increase the acceleration and hill climbing ability. A motor will only pull something like about 85-90% of it's no load speed when under load. You also need to consider the voltage sag of the battery pack as well. When you check the no load rpm it's obviously at a significantly higher voltage than when under load so that percentage will likely decrease further depending on the batteries performance. So this will further reduce the loaded speed the motor will pull.

If you decided to change to a dual Pumas please be aware that the front is max 350W with a slower winding if you have disk brake. They can have the same 500W as you are running on your rear but you will need to use V brakes.

 

[easyvelo]

Dear cell man,

i am now much more happy with the puma, it was a problem of wiring color, 65 kph with no load seems ok for me, my goal is too climb the step hills, for the speed i will ba enough afraid withall the downhill lol, this is why i have two hydro 203mm disk brake, i have ordered o better controller for the bafang which is 23A mine is a 6 mofset 13 amp, i think i have to order one steell gear for the bafang, if not maybe it will broke, but i think i have to check my frot lipo because the difference is inportant, and i ordered gold plated contact and military plug, is it a good idea to incresse the size of all the wiring comming out of the bafang and generaally even from the puma, i will order steel ger for the puma as well, so understand my choice, the bafang needto help the puma in hills climbing , and because it is very lightweight it's not compromise the bike haandle to much...

thanks for you answer, it's always a pleasure to talk to you

lolo

 

[cell_man]

Hi Laurant,

Thanks You are more than welcome.

I doubt you will need the steel gear for either motor to be honest as the dual motors will be under less stress than a single IMO and you haven't gone too crazy with the volts or As. If it's not broke, no need to fix it I reckon. For what you require I think the combination you have is just right once you've got the Bafang sorted. Is there a possibility that the controller you are using for the Bafang is speed restricted? It did seem a bit slow to me from your data. You could try connecting it to controller you are using for the Puma if it's suitable (but the Bafang is probably sensorless??). 13A is pretty weedy for the Bafang but a 20A plus controller should be just about right. I found the bafang wires to be deceptively big when you look at them. They use a very thin insulation so there is more copper than it first appears. Before ripping out any cables I'd try cutting the cables down and fitting an inline plug using a bigger cable between controller and plug. However, I don't think the gains you will make will be so significant, so better just enjoy it I reckon.

Anyway, best of luck, you look like you've got it almost sorted. If I can get something put together that turns half as nice as yours I'll be happy.

 

[easyvelo]

hi everybody,

i had the idea to incluse my rear controller for the puma inside my backpack, i have one question, how many amp each 13 wires going out from the controller needs, i think to this kind of military plug

http://www.fischerconnectors.fr/htm/Products-Body-Styles-Plug-SA.htm

because i think it could suit and in case of emergency, falling or whatever...

what do you think about it

 

[cell_man]

Hi Laurent,

I don't think 13A is really enough for the motor phase wires or the power. For everything else it's more than enough. Actually much less would be fine. Colour coded Anderson connectors would be good for the motor phase and power. These are easily pulled apart if there's a problem. For the remaining connectors anything would be sufficient really as they are all low current. Are going to put your batteries in the back pack too?

 

[easyvelo]

HI CELL MAN,

yes the batterrie is in my back pack, enough weight on the bike, and by the way i have tà loose 5 kg.

the phase wire going out of the puma is very thin, much more than thoses from the controller, so ????


best regards laurent

 

[Geebee]

The speed controller in the backpack may not be a great idea as there will be no air flow and the chances of it overheating greatly increase.
I got my latest bike cheap as the owner could not work out why it kept cutting out, the controller was mounted on an aluminium box zipped up inside a bag, the fix was easy, leave the top of the bag open so the controller was out in the airflow.

 

[easyvelo]

DEAR GEEBEE

Yes it has to have airflow, so may be external aluminium radiator fix on the interior controlleur, jut to let the wire inssinde someting waterproof, will have a look right now, the other problem is the 13 wire connector with a kind of emergency unplug ???

best regards

Laurent

may be this.....

 

[cell_man]

That's also a very valid point about cooling. For sure best to just mount the controllers on the bike and if you want to run batteries in your backpack just use anderson power poles and go up a couple of sizes on the cable used due to the longer cable run. I can't see any good reason to put controllers in the backpack, batteries maybe but not controllers.

 

[easyvelo]

hi everybody,

so it seems that the bafang is made for 36V and he didn't work well a 48V so today i modify my 6S turnigy 5000 mA
in 5S a lot of laugh, here is some pic,,so i hAve now a 2S 5000mA ? SO I began an other challenge repair my sony erricson sat mobile and try to use my 2S for this purpose, we never know, maybe one day my nakamura bimotor will fly me to the moon