48V x 1000W Conversion kit on MTB in Philippines

[rbscebu]

I was originally going to use this conversion kit to electrically power a Filipino style pedicab. After posting and getting advice from members here, I realised that I had a lot more to learn so decided to postpone the pedicab project and first convert my 26" MTB to an e-bike.

The conversion kit was a done deal. I bought it on special from China on for about USD260 (including delivery to Cebu, Philippines) rather than the normal price of USD380 - no returns and no warranty. The kit arrived today. The kit consists of:

• 48V x 1000W brushless non-geared hub motor on a 26" x 1.75" alloy wheel with 6-speed freewheel sprockets
• 48V x 1000W control box
• 2 x brake levers with electronic cut-outs
• 5-magnet PSA unit
• Thumb type speed control
• Bag for batteries
• All associated wiring with 35A fuse.

I need to provide the batteries, charger and a rear carry rack for the batteries.

Overall the quality appear to be very good for the price.

The MTB this is to be fitted on has 26" wheels, alloy frame, 3 x 7 speeds chain gears, disk brakes. I also purchased this on special from China for a little under USD150 (including delivery to Cebu. Philippines).

More tomorrow on what I have discovered and some of the initial problems that (I think) I have solved.

 

[rbscebu]

So far, I have not had much free time to play with the conversion kit.

I played around with the handlebar controls and am satisfied that I can position everything to my liking.

A couple of spokes on the hub motor wheel were loose so I had my local bicycle mechanic reset all the wheel's spokes and check that the wheel was "true". He charges like a wounded bull at USD2 per hour!

I have ordered a rear carry rack (USD20 incl. delivery) that should arrive in a week or two from China. It is of aluminium alloy and rated for 35kg load so should be strong enough to support 4 x 12VDC x 20Ahr sealed AGM batteries. I also ordered a 40VDV 20Ahr lead-acid battery charger that should arrive today (USD17.50 incl. delivery).



The hub motor comes with 6 chain sprockets while my MTB is set up with 7 chain sprocket on the rear hub. I am hoping this this will not be a problem if I can suitably adjust the rear derailleur.

There is no provision on the hub motor to directly bolt on a disk brake rotor, however the left- hand side of the hub has an M35x1.5 threaded spigot. This is the same arrangement that is on my MTB. The disk brake rotor can be unscrewed from the hub on my MTB and it screws directly onto the hub motor spigot. Rather than using the disk brake rotor from my MTB, I have ordered another for USD6.50 (incl. delivery) that should arrive in a couple of weeks from China.



I am a bit concerned about using the supplied battery bag that came with the conversion kit. The day-time temperature here is Cebu are a constant 29deg C to 32deg C throughout the year. I am not sure if using the batteries in the bag will be detrimental. Your thoughts on this would be appreciated.

This weekend, I will look into sourcing the 4 x 12VDC x 20Ahr sealed AGM batteries locally and I will play around with fitting the PAS to the MTB's pedal crank.

The cost so far (in USD incl. delivery where applicable):

MTB = $133
Ebike conversion kit = $253
Spoke adjustment = $2
Battery charger = $18
Rear carry rack = $20
Disk brake rotor = $7

Total so far = $433

 

[pnop]

i ditched my bag. Too big and bulky.

 

[harryS]

I don't look forward to it, but expect a future post about the welds in your alloy rack snapping off from the weight of four SLA batteries. Good for testing the system anyway, Don't hit any bumps.

Another failure is the forward struts on the racks coming loose off the bike. Twice, I've had that happen and the racks tips backward. Part of my morning check now,

 

[rbscebu]

HarryS, thank you for the warning.

Rather than use the rear rack shown above, I purchased a different type with a higher load rating for USD20 (incl. delivery from Manila).

​

This rack is rated for a 25kg load. I loaded it to 80kg (static) without any noticeable deformation, so it should be good fo at least 25kg load (dynamic) while riding. The battery pack to be carried on the rack has a total mass of 19.2kg.

 

[rbscebu]

I have decided to change tack - again - on this project.

I originally bought an aluminium alloy frame MTB that I intended to convert to an ebike. Since then, I have set that bike up so well that I really enjoy riding it with pedals only. After a long think, I have decided to buy a cheap(er) steel frame MTB for this conversion project. Cost is USD112 (including delivery from Manila).

Having a steel frame, this new bike should be more resistant to stress cracking. It will also allow to more easily "hack" the bike while I experiment with the conversion. This steel frame bike is basically the same as my aluminium frame bike and should arrive early next week.

The batteries arrived from Manila yesterday.

The cost so far (in USD incl. delivery where applicable):

MTB (steel) = $112
Ebike conversion kit = $253
Spoke adjustment = $2
Battery charger = $18
Rear carry rack = $20
Disk brake rotor = $7
Batteries (4x12V 16Ahr) = $97

Total so far = $509

 

[indianajo]

Dozens of steel MTB frames go to the dump every garbage day. Don't you have any access to the scrap trucks driving around? Or a charity resale shop or something? I realize 2nd world countries are different, but buying common trash new is tough on the environment. I had to buy my aluminum bike new, but I've had a half dozen used MTB frames that I've ridden and ditched. I bought one new MTB in 1985, wore the sprocket totally out and couldn't buy or get off (stuck) any more to match (15 speed). Warning, the 18 speed MTB the rear axles break, axle too thin. 5 & 7 speed axles are thicker.

 

[rbscebu]

Indianajo, there is no such thing as a "garbage day" or charity shops in the Philippines like you have in developed countries. There are a few second-hand MTB's locally available (I found 15) but the cheapest was for sale at the same price as I could buy my new steel frame bike (including delivery from Manila). I decided on the new as hopefully there will be less chance of any defects.

 

[indianajo]

It's a shame your scrap merchants are so stingy. At least you looked around to try to find a recycled cycle.
I saw a MTB frame with both front and rear suspensions for $85 at Salvation Army resale Wednesday. Only, I need a stretch frame cargo bike, or I would have bought & electric converted it.

 

[rbscebu]

I NOW HAVE THAT EBIKE GRIN!

Sorry for this late post but I was overseas working for the past few weeks.

I returned home early this week and got the time to put my ebike conversion together. Now I have that grin!

I have been riding motorcycles for the past 40 years and push (peddle) bikes on and off for the past 55 years. Never owned a tin top. This is my first ebike ?.

I'll post some pics tomorrow.

 

[rbscebu]

Trying to use the steel frame MTB was not going to be easy.

1. The gear-shift\brake controls where combined units that was going to make it extremely difficult to utilise the brake controls that came with the kit (and included motor cut-out switches.

2. The rear wheel dropouts, although made of steel, where no stronger than the dropouts on my aluminium frame MTB.

3. The front fork suspension was of a much lower quality and strength than on my aluminium frame MTB.

4. The biggest problem was that my girlfriend preferred the steel fame MTB over my aluminium fame MTB. She wanted (and got) the steel frame bike.

My girlfriend convinced me to convert my aluminium frame MTB instead.

My first priority was to see if it would all go together and actually work.

Some pics of what I have so far.







What I did:

(a) I had to shorten the spacer tubes in the rear hub to get the rear disc brake to properly line up.

(b) After doing a structural analysis on the rear carried, I found that the weakest part was the mid-length connection in the tubular struts going down to the seat stays. To correct that, I filled the hollow portion of those struts with epoxy.

(c) I mounted the motor control under the rear rack using 6mm zip-ties.

(d) To help with handling the rear hub motor torque, I fitted a 10mm spanner (wrench) has a torque arm on the LH side.

Once it was all together, I charged the batteries and took it for a ride. That's when I got the ebike grin on my face!

The bike is heavy but that is to be expected with my 4 x 12V 16Ahr SLA batteries on the rear rack.

My ebike has a top speed (on the flat) of 33kph (20.5mph) with my fat arse on board 100kg (220 lb). I tried it on the steepest hill on my island (Mactan Island) and the bike had no problem going up, provided I did not start from stationary.

I then tested the bike's starting torque. I did this by measuring the maximum pulling force the bike's motor could exert when stationary. This came in at a surprising 315N (70.9 lb). On a 26" wheel, this equates to 104N.m. Torque is proportional to the current drawn by the motor so this can only be measured for a short time before the motor control cuts the power the the motor due to maximum allowable amperage being met.

I still haven't fully figured out how the cadence sensor interacts with the drive system. All I know is that, with no throttle, the motor starts powering after I rotate the peddles abut one revolution.

The main things I have to do now is build a battery box to fit on the rear rack and tidy up all the wiring. I also need to lengthen the side stand by about 25mm (1") so that it can properly support the bike. The existing stand it already at maximum length.

The rear tyre is only rated at 85kg (187 lb) load and 345kPa (50psi) air pressure. I will consider fitting a stronger tyre. I have one available that is rated at 100kg (220 lb) and 415kPa (60psi).