My first entry into the world of E-Bikes

[john]

rust

I'm no fan of this move to Aluminium and carbon that everyone is going for. The only advantages that they have over steel is weight as far as I can see.

They also don't rust

 

[OneWayTraffic]

How many steel frames have been lost to rust? Derailers, chain and sprockets I can buy, but I've never had actual rust on a frame that wasn't simply cosmetic. I'll take that over the possibility of a sudden failure; I had an alloy stem (Al I guess) fail on me once. Fortunately I wasn't going fast.

 

[NRG]

I've been slowly building the miles up on the 'beast' and I'm starting to feel more comfortable with its capabilities. Despite the direct drive motor and weak SLA's it pulls well enough up hills for me and this week with the strong winds its proven it's self into some strong headwinds.

My Lipo battery packs have arrived in the country so just waiting for customs clearance and delivery.

Also been in touch with Conhismotor and a more powerful motor and higher voltage controller are well within budget...hmmmm....

 

[NRG]

Update: See first page, post 2 & 3 for update on battery...

 

[jerrysimon]

Nice job on the batteries. I have used these a lot in the model RC world. I am going to go for A123 cells though as Lipos have to be treated with a lot more respect in terms of balancing or over charging.

There are also some potential hazards with them catching fire though if you treat them well they should be ok. Also in the ebike application they probably won't be subjected to the same abuse in terms of high discharge and fast charging that they get in the RC world.

You seem to be taking extra care as well in terms of monitoring their voltage.

Regards

Jerry

 

[NRG]

Hi Jerry, yes, as I read it if the cell voltage falls too low (<2.7v absolute minimum) they can be damaged and cause problems when you come to charge them. The charge voltage should also be kept below 4.2v / cell to extend the life.

Anyhow, I managed to get some miles on the bike this afternoon and the new batteries are great. There's an increase in torque and the top speed has increased to 21mph with a bit of assistance....in fact I've now reached the gearing limit on my bike! Not that I really want or need to go any faster. Hills are taken at a faster pace and with far less effort from me, I found myself 'coasting' uphill under power much to the surprise of a few passing cars! The voltage stays up with very little sag under load unlike the SLA's.

A good result so far!

 

[daniel.weck]

Great DIY build-log !
I love the custom-made battery pack !

I've got one finished build and one that will soon start. My main interest at this stage is in cheaper smaller battery packs, possibly hand-assembled like yours (although like Jerry, I'm thinking about getting A123 cylinder cells, which are based on LifePo4 chemistry but with different characteristics than a bigger pack made with pouch cells). I've got lots to learn about batteries, so I'm all ears ! Keep up the good work and continue to letting us know

Cheers, Dan

 

[NRG]

Small update, I've moved the controller into a side pocket of my rack bag and it seems to run a bit cooler than before in the padded section plus I've made up this 3s+4s = 7s balancer lead so I can balance charge each battery pack pair...seems to work OK and I've not blown anything up...yet

Well thats not strictly true....I had my first puncture today...the rear inner tube exploded! Strangely just as the odometer had gone past 100 miles Anyhow, I was only traveling at 14mph or so down hill and there was a very loud bang followed by an emergency stop. So I had to perform my first road side repair, just as well I had remembered a 21mm spanner for the axle nuts and some tie wraps for the wires. Took about 15~20mins to put in an old spare tube I carry that has a Presta valve not a Schrader so it would only be a temporary get-you-home measure.

I stopped of at my local independent BS and showed the blown inner tube with new 4" split, seems I may have pinched it putting the Marathon Plus tyre on but I'm sure I checked it properly...he also said the inner tube was too big so supplied me with a Schwalbe AV17 which does fit better.... and I was told to use some proper wheel rim tape Lesson learnt, the bike is now back together and I hope it doesn't happen again!

 

[emissions-free]

Small update, I've moved the controller into a side pocket of my rack bag and it seems to run a bit cooler than before in the padded section plus I've made up this 3s+4s = 7s balancer lead so I can balance charge each battery pack pair...seems to work OK and I've not blown anything up...yet

Looks really good. I'm gonna have to get a few of those to play with. I've got a really tiny little 24V 6Ah (claimed) pack here that I took out of a small folder. It weighs 700gms Will have to see what is does when I connect it to the resistive loads I've got here. Got 2 * 2ohm 750W resistive loads, so these can be connected to give 1ohm (parallel), 2ohm (1 unit) or 4ohm (in series). I have to put a fan onto them to keep them from getting too hot and also helps to maintain a more stable current as the resistance will increase with heat. I just monitor the voltage and current and record them every minute to check the capacity. Everything gets pretty hot when they're working near their max for a continuous time. Plan to get a discharger and a little USB scope (their great, once you go USB scope, you will not go back)very soon.

I've got a 36V 9Ah pack made up of 26650 3Ah lifepo4 cells that I'm gonna take apart to build maybe a 36V, 6Ah pack. Will let you know how I get on. It's already got tabs welded onto the cells, so I'm just gonna cut the tab leaving some spare and join them together either by soldering onto the tab (need to be careful as excessive heat will damage the cell) or just put a small hole and bolt crimped cables to join them. Hopefully getting a spot welder soon, to do it properly. If anyone knows of a good place to get a good quality spot welder at a reasonable price, please let me know.

Well thats not strictly true....I had my first puncture today...the rear inner tube exploded! Strangely just as the odometer had gone past 100 miles Anyhow, I was only traveling at 14mph or so down hill and there was a very loud bang followed by an emergency stop. So I had to perform my first road side repair, just as well I had remembered a 21mm spanner for the axle nuts and some tie wraps for the wires. Took about 15~20mins to put in an old spare tube I carry that has a Presta valve not a Schrader so it would only be a temporary get-you-home measure.

Just happened, to have a 21mm spanner handy....

 

[NRG]

Call me paranoid LOL! When I first test rode the bike I hadn't done the nuts up tight enough, 1 mile from home and the first hill I attempted to climb the motor pushed the wheel out of the dropouts and jammed solid!

Had to call home and get the wife to bring me the spanner!

 

[emissions-free]

Call me paranoid LOL! When I first test rode the bike I hadn't done the nuts up tight enough, 1 mile from home and the first hill I attempted to climb the motor pushed the wheel out of the dropouts and jammed solid!

Had to call home and get the wife to bring me the spanner!

Front wheel? Lucky you didn't trash the cable or worse You have to be so careful with these motors, moreso the more powerful you go. What sort of torque arm are you using?

 

[NRG]

Hi EF, no rear wheel, see post #2. The torque arm is a tab washer located in the dropout. I've not had any issue in this respect since tightening them up correctly...

 

[emissions-free]

Sorry, didn't look properly and hope I didn't come across rude, as it wasn't my intention

That looks like a fairly powerful motor you've got there. I'd be tempted to put a more substantial torque arm on there just in case. A cheap 10mm spanner does the job if you've got something to brace it against.

Anyway, good job on the packs, keep us informed. I'll have to get a few sometime and have a play.

 

[NRG]

No problem EF!

Update on the packs: Firstly they have kept balance very well, I think a balance charge every 10 or 15 battery cycles would be OK, I don't think I would need to do it any sooner on the evidence so far.

The BM6 battery monitors are on the whole accurate but I've now got two that seem to be playing up reading a cell higher than it really is so replacements ordered....

I've not managed to test the full range yet but I seem to be getting 8.5w/km so I estimate a range of 50Km or 31miles more or less, not bad.

 

[NRG]

Decided to re-do the wiring today as the weather was so poor.

All wiring is now 30amp, the fuse replaced by a 30amp cct breaker and the IEC socket replaced with some 30amp power connections. I also replaced the motor bullet plugs as I'm never quite sure if they are making a good connection:

These had to go:

Replaced with 19amp 3 way connectors from Farnell:

 

[NRG]

....and the main power IEC and fuse replaced with these power connectors:

30amp cct breaker:

 

[daniel.weck]

I like the breaker. I'm fitting one of these on mine, as I've got tons of blade fuses to use:

 

[NRG]

Was using one similar to that Dan and it got warm under load! The fuse was never a secure fit in the holder.

 

[daniel.weck]

Was using one similar to that Dan and it got warm under load! The fuse was never a secure fit in the holder.

Ok. Well, I haven't received mine yet, but it's rated at 30A. I'm not sure the photo is what I'm actually getting (the wires look a bit thin):

 

[jerrysimon]

Guys some great stuff here. Really neat work.

What is the top bit on that 30amp cct breaker NRG it looks like a connector or something ?

Regards

Jerry