Electric Brompton – custom build

[benjy_a]

Wow that is some looking battery. Nice sizing for the bag. Is it made of of pouch or A123 cylindrical cells ?

Regards

Jerry

Looks good doesn't it! It's 16S 6P A123 cylindrical. Serious brick of power!

Ben

 

[benjy_a]

Chargers arrived yesterday for the cellman battery.

I went for a run with it last night and commuted on it this morning which is a distance so far of 40 miles. Cycle Analyst shows 11.7 Ah used and I'm now charging it again.

Performance is outstanding and its the strongest hill climbing ebike I have ever ridden. At 100% speed setting on the controller and 12A current limit it climbs anything at 15-16mph with little rider assistance.

I can say that this project is now complete and now into a long term reliability test phase.

I would say that 48v is absolutely required for this motor in a 16" wheel if you want to achieve the legal maximum speed.

Ben

 

[jerrysimon]

Look forward to see how it fares over time with use. The first few months I was paranoid something would fail and would panic at the slightest fluctuation in power.

The first failure I had has was after about 3 months when a wire came off my switch as the controller was bouncing around in the bag pocket and I had not put enough slack in the cabling. The second was a failed cell in my DIY pack after about a year. That was caused by me abusing the pack and running it flat every day for a year.

Now some 2 & 1/2 years later, 3700 miles and nearly 800 charge cycles its still going well. More than paid for itself and I have spares of everything still sitting unused.

Regards

Jerry

 

[benjy_a]

I am fairly paranoid about it at the moment! There is an amazing amount of torque from this motor and I'm very aware of how tiny the Brompton dropouts are! I'm trying to get used to using leg power to get it up to speed, then feed in the power gently. I think this motor has the potential to break the forks! I guess over time I will learn to trust the setup if it doesn't let me down.

I was also contemplating ordering a spare controller as I feel (for no particular reason) that if anything fails it's likely to be that. At the moment I'm also carrying with me tools to fix everything; including wire cutters, cable ties, amalgamating tape etc for electrical repairs! I really don't want to be stranded in the middle of the countryside. As time goes on I will reduce the kit that I'm carrying.

 

[cwah]

That's a nice pack Benjy, have you tried to see what's the total capacity you can use from the pack? I recommend you to do it so you'll know later the health of your pack.

What the weight on the scale also?

 

[benjy_a]

Quick update....the Brompton is going strong, daily 28 miles total cycling and no faults as yet. I'm still quite paranoid about things going wrong but apart from various bits loosening off over the first 1-200 miles it all seems quite stable now. The dropouts are holding up well with my custon torque plates, the axle nuts have not loosened at all from using regenerative braking which is definitely making my brake blocks last longer.

Today is a big test, due to the Olympic cycling routes through Surrey and the fact that there are no trains for me to get home I will be riding the Brompton all the way to work in London. This is a 75 mile round trip and I'll be charging at work for the ride home. A slight risk is that I still have not done a range check with my battery; so I could have a tough ride if I run out of juice!

 

[benjy_a]

Ok the longest journey so far in one hit; 36.7 miles, average speed 18.7mph, economy 10.6Wh/mile.

I have used just under 7Ah so my estimate for max range was way too low. I should theoretically get 70 miles from this battery so I'm very happy with the performance of the motor.

However I have a problem! My front spokes loosened off again and one seems to be bent. I didn't notice the bent spoke before so I'm guessing it's from a pothole or something. Has anybody had just one bent spoke before? Seems weird and I would have expected more than one bent or broken if it was from impact damage. Could it have been bent during the build and I just didn't notice?

I'm contemplating getting the front wheel completely rebuilt by somebody like SJS Cycles. Are there any stronger ways to build this motor into a rim? Stronger spokes or something? Any advice gratefully received!

Ben

 

[cwah]

Ask Alan (Catsnapper) to do that for you. He can do it for a good price and never had any problem with overpowered motors.

 

[JHDijkhuis]

fitting motor

Ok so yesterday I pretty much completed my Brompton build in one day. The first thing I found is that the Crystalyte G209 motor may well have a 74mm dropout spacing but it WILL NOT fit straight into Brompton forks! The only way the motor will clear the forks is by using the supplied washers which makes it effectively 10-15mm wider!

So I had to stretch the forks somewhat using threaded rod so that the wheel would go in. Incidentally there is no indication on the motor which way it will rotate either so for reference if anybody else uses this motor the wire exits on the left of the bike (which I found after getting it backwards).

Hello, I followed your posts for some time because I am trying to make an eBrompton with a Cryst. motor also. After having some problems fitting the motor (like you have) I couln't get the motor running fine. Not enough torque and speed. After ordering another motor I discovered the first one (the same as yours) isn't suitable for Brompton. The one I have now is about 5 mm. less wide and fits the front fork without stretching it.

While still testing I just wanted you to know.

Greetings from Holland, JHDijkhuis

 

[benjy_a]

Hello, I followed your posts for some time because I am trying to make an eBrompton with a Cryst. motor also. After having some problems fitting the motor (like you have) I couln't get the motor running fine. Not enough torque and speed. After ordering another motor I discovered the first one (the same as yours) isn't suitable for Brompton. The one I have now is about 5 mm. less wide and fits the front fork without stretching it.

While still testing I just wanted you to know.

Greetings from Holland, JHDijkhuis

This is interesting indeed! Although I am now very happy with the motor (very powerful and efficient) it was annoying to have to stretch the forks and I'm not at all impressed with Crystalyte as a company at all!

So far they were terrible with the original order, then sent the wrong items, have never responded to email enquiries and made several promises which were not kept.

My wheel build is not straight and now the spokes keep loosening and one is bent. I am getting the wheel rebuilt at my own considerable cost and it's only a few months old!

I would never deal with Crystalyte again if I could avoid it although the motor itself is good.

 

[dingrpdl]

Has anybody had just one bent spoke before?

Yes, I did have a problem with a bent spoke. And it stumped me for a while.

My problem was that part of the thumb-throttle unit was sticking out too far and was hitting the spoke when I swung the stem and handlebar into the folded position. However, this happened only rarely which is why I didn't realize it was happening. It all depended on what position the front wheel spokes were in when the fold was done. 90% of the time, the throttle unit would happen to fit between the spokes and all was well. If a spoke happened to be in the way, contact would be made. And I believe my bent spoke happened during one forceful folding excercise! I have since corrected that problem by adjusting the position of the throttle unit. I also found that there was very little clearance between the spokes and the shifter units.

Is it possible that your throttle unit, a shifter unit or a brake lever assembly is coming into contact with the spokes when the bike is folded?

Richard