Good day all,
So I'm on my third electric bike build.
First was a 1kw home build using a generic Chinese kit build on a mountain bike. With a front hub motor, 20AH LiPofe4 2V battery.
After breaking the first controller - I upgraded to a Kelly Controller. this was a 24-42V 40amp controller. If anybody hasn't seen these controllers they are AMAZING, tiny and super-efficient.
Next up I sold that controller and moved to a 24 Vto 90V version of the same. this controller, which is the size of a coke can, does 40amps continuous and 100amps for 30s boost. Yep, that's 2.8KW cruse and 7.2KW boost.
I next broke (cracked) the front hub motor and so got a crystallite rear hub motor. Which I had to add in my own Hall sensors to.
This went on to the next dual-suspension mountain bike, with FOX RC40 front shocks.
And Finally
Now I'm building a Puch Maxi into an electric bike. I got an old frame for free. Stripped the paint (and the overpaint)off it. Electrolysis the rust off it. Re-sprayed in black.
The plan is to run 30AH 72V home-built battery pack on it, with the same controller, RC40 front shocks and rear hub motor.
SO far it looks like this.
So much still to do..
Front shocks need painting. I need to find hydraulic front brake leaver with cut off switch in it (motorbike ones look about right)
The Battery.
Having ordered a lot of different cells from AliExpress and testing them I've settled on the HG2 copies. Hold 3ah each. Will draw 60amps when shorted and don't blow up. Will do 1AH at 20amps and the full 3AH at 15amps continuous. At less than £1.6 a cell delivered they are exceptional value. This is the same capacity as the official LG HG2s but at about 5amps less on the draw for the same capacity. Since LG cells are over £5 each, it's still cheaper to get way more of these cells and draw fewer amps to get the full capacity than to get official LG cells. So that's the plan, to cram 200 cells or more onto this bike.
Now 20s BMS are expensive, as are 72V(84V) chargers, but 32V BMSs and chargers are CHEAP. Thus I'm building 4 x32v batteries. Thus with a quick switch of a cable, I can go between 72V 30AH to 32V 60AH battery, with my controller able to handle either.
I'm planning on mounting batteries on the rear panier and in the frame, where the ICE motor once was. Thus they will be exposed. Now shrink wrapping batteries looks well sh*t and rarely completely waterproofs them. So I am potting them in Polyester resin.
At first, I was just going to set each end, but ended up just making a solid block.
First-ever attempt at potting. so my mold (its just polypropylene sheet as that doesn't stick to any resin) is WAY to big. I shall refine it for the next battery. But a LOT of cutting off excess with a multi-tool and a LOT of sanding later, it looks presentable.
The bottom contains the BMS rated to 60amps and combined charge and discharge cables.
It is now fully submersible. Yep, I've tested that.
The downside is if it breaks, it is going to be hard to impossible to fix. Its also just over 3kg in weight now, but I think i can get that down to 2.5KG with a lot less polyester resin used on the next attempt. Puttin the BMS wires in between the cells will reduce the need for a think layer on that side. As will the power wires coming out directly.
I hope the polyester resin, whist way more heat conductive than air, won't result in me cooking the cells. But as I'm drawing 1.4C at 2.88KW max continuous, I'm hoping it doesn't get too hot. In my testing, I couldn't detect a temp rise when discharging at this low rate. Discharging at 20amps from full to DEAD (not empty but totally dead) the cell only got to 60C.
Up next is mk2 potted battery.
The next 50 cells are on there way.
A lot of wiring to go.. a LOT,
I have my old 20-60V down to 12V to power lights and such. throttle, indicator switch bit no indicators or lights yet...
Anyways thoughts on this project and comments recommendations always welcome.
So I'm on my third electric bike build.
First was a 1kw home build using a generic Chinese kit build on a mountain bike. With a front hub motor, 20AH LiPofe4 2V battery.
After breaking the first controller - I upgraded to a Kelly Controller. this was a 24-42V 40amp controller. If anybody hasn't seen these controllers they are AMAZING, tiny and super-efficient.
Next up I sold that controller and moved to a 24 Vto 90V version of the same. this controller, which is the size of a coke can, does 40amps continuous and 100amps for 30s boost. Yep, that's 2.8KW cruse and 7.2KW boost.
I next broke (cracked) the front hub motor and so got a crystallite rear hub motor. Which I had to add in my own Hall sensors to.
This went on to the next dual-suspension mountain bike, with FOX RC40 front shocks.
And Finally
Now I'm building a Puch Maxi into an electric bike. I got an old frame for free. Stripped the paint (and the overpaint)off it. Electrolysis the rust off it. Re-sprayed in black.
The plan is to run 30AH 72V home-built battery pack on it, with the same controller, RC40 front shocks and rear hub motor.
SO far it looks like this.
So much still to do..
Front shocks need painting. I need to find hydraulic front brake leaver with cut off switch in it (motorbike ones look about right)
The Battery.
Having ordered a lot of different cells from AliExpress and testing them I've settled on the HG2 copies. Hold 3ah each. Will draw 60amps when shorted and don't blow up. Will do 1AH at 20amps and the full 3AH at 15amps continuous. At less than £1.6 a cell delivered they are exceptional value. This is the same capacity as the official LG HG2s but at about 5amps less on the draw for the same capacity. Since LG cells are over £5 each, it's still cheaper to get way more of these cells and draw fewer amps to get the full capacity than to get official LG cells. So that's the plan, to cram 200 cells or more onto this bike.
Now 20s BMS are expensive, as are 72V(84V) chargers, but 32V BMSs and chargers are CHEAP. Thus I'm building 4 x32v batteries. Thus with a quick switch of a cable, I can go between 72V 30AH to 32V 60AH battery, with my controller able to handle either.
I'm planning on mounting batteries on the rear panier and in the frame, where the ICE motor once was. Thus they will be exposed. Now shrink wrapping batteries looks well sh*t and rarely completely waterproofs them. So I am potting them in Polyester resin.
At first, I was just going to set each end, but ended up just making a solid block.
First-ever attempt at potting. so my mold (its just polypropylene sheet as that doesn't stick to any resin) is WAY to big. I shall refine it for the next battery. But a LOT of cutting off excess with a multi-tool and a LOT of sanding later, it looks presentable.
The bottom contains the BMS rated to 60amps and combined charge and discharge cables.
It is now fully submersible. Yep, I've tested that.
The downside is if it breaks, it is going to be hard to impossible to fix. Its also just over 3kg in weight now, but I think i can get that down to 2.5KG with a lot less polyester resin used on the next attempt. Puttin the BMS wires in between the cells will reduce the need for a think layer on that side. As will the power wires coming out directly.
I hope the polyester resin, whist way more heat conductive than air, won't result in me cooking the cells. But as I'm drawing 1.4C at 2.88KW max continuous, I'm hoping it doesn't get too hot. In my testing, I couldn't detect a temp rise when discharging at this low rate. Discharging at 20amps from full to DEAD (not empty but totally dead) the cell only got to 60C.
Up next is mk2 potted battery.
The next 50 cells are on there way.
A lot of wiring to go.. a LOT,
I have my old 20-60V down to 12V to power lights and such. throttle, indicator switch bit no indicators or lights yet...
Anyways thoughts on this project and comments recommendations always welcome.
