ebike build from scratch

[awol]

I do like the look of that, from what I can see. What size bottle did it all fit into. That is my preferred controller hiding place too.

It's about 8 to 9 inch long and 3 inch wide. It's just a very old one I seem to have had in my garage forever and now I've found a use for it.
I got the idea from d8veh 's build
http://www.pedelecs.co.uk/forum/threads/lightweight-trekking-bike-build.28276/

 

[anotherkiwi]

A 15A controller will also fit in a B'Twin (or other) tool bottle. You might want a waterproof vent in the top to let the excess heat out.

 

[awol]

A 15A controller will also fit in a B'Twin (or other) tool bottle. You might want a waterproof vent in the top to let the excess heat out.

Oh, I never thought of heat build up.
Any ideas for a waterproof vent?

 

[Deleted member 4366]

Heat won't be a problem with a 15 amp controller unless the motor is too fast for its power, like using a 328 rpm Q100 on an MTBwith 26" wheels.

 

[anotherkiwi]

Heat won't be a problem with a 15 amp controller unless the motor is too fast for its power, like using a 328 rpm Q100 on an MTBwith 26" wheels.

I must be doing something wrong With the Mxus (260 rpm?) in a 26" wheel and the controller in a bag after climbing my typical 3.4 km hill at assistance level 5 the controller was too hot to touch and the bag smelt of hot plastic. I am not sure that temperatures so high are good for wire insulation plastic?

 

[Nealh]

If the controller gets that hot may needs repositioning for better airflow cooling. My big bear 20a controller gets very warm in 26"wheels, controller is in a saddle bag with vent holes so I have now helped cooling with a heat sink & 2 x 5v mini fans run off a pair of old laptop Sanyo 2200mah cells.

 

[Deleted member 4366]

I must be doing something wrong With the Mxus (260 rpm?) in a 26" wheel and the controller in a bag after climbing my typical 3.4 km hill at assistance level 5 the controller was too hot to touch and the bag smelt of hot plastic. I am not sure that temperatures so high are good for wire insulation plastic?

How many amps? Maybe your controller has crappy mosfets. Which one is it?

 

[anotherkiwi]

How many amps? Maybe your controller has crappy mosfets. Which one is it?

The bog standard KT 15 A sine wave controller that came with the Mxus from Ciclotek, the same as the one sold by BMSbattery. If the display is to be trusted it peaks at 14.xxA (forgotten the exact number) - about 546 W at between 38 and 40v.

 

[Deleted member 4366]

That's weird. I have the same one and it hardly gets warm at 14 amps. The KT controllers use current control, so you only draw max current on level 5. I run at 48v, so my level 4 gives the same power and torque as a 36v one on level 5. That helps, but I still use level 5 when I want to crack on or on some of our exceptionally steep hills. As you probably know, mine's packed very tightly in a bag with no ventilation.

 

[anotherkiwi]

Maybe being in a small closed black triangle bag and external temperature being in the mid 30°C range might have something to do with it? I can see those conditions plus a long climb at full power getting it up to and over +60-70°C quite easily.

So back to OPs question: I was thinking about one of those screw in plastic vents that are used on dinghy caissons or making something like this (reduced in size of course)

 

[awol]

Finished weight without battery is around 14 to 14.5kg (varies using my old weighing scales)
Just been out for a short test ride. I used the 15amp controller for now. It will pull me along at 20mph with 36v battery along the flat if I unrestrict it. Frame size appears just right for me.
Gears are very smooth pedaling and changing, steering is a bit more sensitive than my other bikes, the hydraulic brakes are awesome, I have to be careful how much pressure I put on them.
Overall very pleased.

 

[anotherkiwi]

Nice build! Doesn't that look stealthy!

 

[Neil5403]

Looks good and subtle. Is the battery in the rear seat bag?
What battery have you used?

 

[awol]

Looks good and subtle. Is the battery in the rear seat bag?
What battery have you used?

It is 6a blocks 10s lipo's at the moment. The good thing about that saddle bag is it unrolls and can fit my 10a 10s graphene lipo's when I start using it further and it will look just the same.

 

[awol]

Alternative battery holding idea's I had -
This was my favorite which I had planned a few years ago and holds 8ah graphene batteries, but unfortunately I am too short to use it (never thought of that).

Next I thought this one spoiled the look of the bike, but could have a short wire straight from the top of the bottle to the bag and was limited to 8ah multistar size batteries.

 

[Neil5403]

That battery sound very technical. For me anyhow.
I presume you made the battery yourself, as I do like the stealth look.

 

[awol]

After more riding about I decided the small 15a controller was a bit weedy so changed it for the 17a one. This brought the bike to life and gives that bit of a kick when accelerating. While only being 2a more it is physically a larger size so probably has larger components to give that extra boost.

 

[anotherkiwi]

After more riding about I decided the small 15a controller was a bit weedy so changed it for the 17a one. This brought the bike to life and gives that bit of a kick when accelerating. While only being 2a more it is physically a larger size so probably has larger components to give that extra boost.

Try two 6S Graphenes in series with that controller for a real kick! Mine were only charged to 46v the other day and I can't wait to get out with them charged to 49v

 

[awol]

Try two 6S Graphenes in series with that controller for a real kick! Mine were only charged to 46v the other day and I can't wait to get out with them charged to 49v

I will give it a go next weekend, but being a 260rpm motor, will 2x6s not make it spin too fast for it's own power and reduce torque? also as d8veh mentions above controller heat could be a problem.

 

[anotherkiwi]

That will make it a 325 rpm motor, it will work on the flat if you help it off the line. True you may have problems on the hills though Maybe 12S is better left to a 201 rpm Q100...