Hyena's e-bike builds (now with HD video)

[Hyena]

Hey guys,
I thought I'd post about my (mis?)adventures over the last year or so. I messed around with a few different ideas before I joined the forum, I could have saved myself alot of time and money had I come across this place sooner!

My first attempted build was using a 24v 300w brushed motor I picked up for next to nothing so I thought why not give it a go.


After stuffing around with bolts and brackets and failing to get it to mount properly I borrowed a mates welder and with a some donor parts from a bike I got off a junk pile I welded the motor, brackets and a tensioner directly to the frame.



No comments on my dodgy welds if you can make them out, it was my first time welding. This was evidenced 5 minutes later when I took it for a test ride to see if everything was aligned properly and the motor ripped off the frame and overtook me bouncing down the street
Back to the workshop and some heavier handed welds and it was there to stay. Sadly once it was all rock solid I found the non-geared motor didn't have enough guts, and it kept pulling the chain off.

Exit chain drive motors, enter brushless hubs.



I picked up this no-name 200w motor from a local supplier and got it home only to find it had had all these wires hanging out of it. WTF is all this I thought, then I learned about brushless motors

So back out to get a controller then whacked it on the bike with a packpack full of SLAs. It did 25km/hr which I wasnt that happy with, and again kept pulling the chain off.



After then doing more research into brushless hubs I came across a whole range of other options and ended up deciding to sell it and start again with a front wheel hub. No issues with the chain coming off then, no need to fiddle with the rear sprockets and I could keep pedalling with the back while being pulled along by the front.

Any advertisement you see on this site can infect your computer. DO NOT CLICK ON ANY ADS

[Hyena]

So enter my new front hub, a 500w golden motor kit from ebay.



The new hub did around 32-34km/hr which I was much happier with, but of course I wanted more
Mind you, after a ride through the national park down the road, even that speed was too fast over This terrain

Once I was happy with this hub I bought a new bike as the old one was now full of holes and with the remnants of old brackets and welds all over it from my early experiments.



I picked up a 37v 10ah LiMn pack quite cheap and was very happy with the weight of it after lugging around a metric kilotonne of SLAs, however my joy was short lived after I found it had a dud cell. I wired up a wattsup meter and found I was only getting around 3ah out of it. Pooey! Fortunately the guy I got it from was quite reasonable and gave me a full refund.

In the mean time I went back to SLAs, in a rack on the back this time. While it was better on my back it completely changed the feel of the bike and made the handling clumsy and very top heavy.
After hunting around for a cheap LiFePO4 pack I decided on giving lipos a go.
I found some cheap 22.2v 6S 4ah packs on ebay and decided to give them a go.


For the price of just over $50 AUD delivered, even with our crappy exchange rate they are great.
Running the packs in series they're just over 50v off the charge so too much for my stock 36v GM controller. No dramas, I quickly did the resistor mod on the controller and it now takes up to 58v before it cuts out. Although the batteries are rated at 15C they sagged pretty savagly with when trying to pull 20-30 amps out of them. The sag was minimal around 10a though and being otherwise happy with the 4ah packs I ordered another 2 for a 12S2P configuration (44.4v 8ah)

So next up, where to put them that's fairly inconspicious...
For fun I tried making a larger seat that I could build them in to, but after testing it I found it too wide and the front to comfortably pedal with.


I then thought I'd just get one of those seatpost racks and put them on that in a small neat box. After a trip to the local bike shop I find that they're sold out, so decided to make my own. Looking at how the racks are made I saw that they were a heavy piece of tube with the rack sitting on top. I wanted to make mine as stealthy and possible, so I decided to put the tube down the centre with the batteries either side to keep it all low profile.

Again with the left over parts from the old bike from the junk pile I used the seat post and mount to attach to my existing seat.



Then using some metal from an old computer case I bent up a housing to surround the batteries.



I rode it like this for a few weeks while I wait for the rest of my batteries to arrive and then decided I wanted something a bit neater and sturdier, so I made up a battery box in 2 halves from some 40mm aluminium channel. (the batteries are actually in the top part so they can be removed from the bike without removing the rack and seat)

The lipos get really hot when pulling alot of current from them, so I left the top of the rack open for cooling with some sturdy mesh (again from a junk pile )



Batteries in place



And finished in black hammer coat with the mesh insert in red to match the bike.



And how it looks at the moment



I took it for a ride this afternoon and the 8ah pack performs very well and I'm quite impressed with it for it's size and weight (~ 2kg). I tested it with my GPS and it does 40km/hr which I'm happy with. On the road I feel like I could do with a bit more but when you're belting along a narrow dirt trail you really feel like you're moving!

More to come!

I'd really like to cut the top bar out of the frame and weld in a slightly thicker one with the batteries inside that, but it's probably not worth the effort for the sake of the small rack on the back. Maybe on v4.0

[Mark_A_W]

Even though I think those forks are steel, you need torque arms.


Nice find on the Lipos - $50 each is a bargain.
Just be prepared for the fact that they will last a year, whether you use them or not...that's how long my lipo booster pack lasted (and my model plane lipos).

[Hyena]

Hi Mark,
Did your lipos die all together after that period of time or just lose capacity ?
I'll probably be riding alot over the next few months and then only occasionally after that, but it'd be nice if I could still get ~10ks out of it after a year.
I was impressed with the life of the pack today - the wattsup meter showed I'd used 7ah and it still had a bit of life left in it.

The frame is aluminium but yes the forks are steel.
After an trip over the handlebars while playing with regen braking I made up a bit of a torque arm. I'm planning to make something bigger and stronger in the future, but this is better than nothing in the mean time.

[HAL9000v2.0]

...Exit chain drive motors, enter brushless hubs...

How can you say that to Safe?

[Drunkskunk]

Nice build. WHo did you get the Lipo from? $50AUD is a great price.

[TPA]

^^ I second that, Who, Where? ^^

A-HA! I think I found them! Hong Kong and Free shipping to boot!

http://cgi.ebay.com/RC-Lab-4000mah-22-2 ... 1|294%3A50

[Mark_A_W]

Hi Mark,
Did your lipos die all together after that period of time or just lose capacity ?
I'll probably be riding alot over the next few months and then only occasionally after that, but it'd be nice if I could still get ~10ks out of it after a year.
I was impressed with the life of the pack today - the wattsup meter showed I'd used 7ah and it still had a bit of life left in it.

The frame is aluminium but yes the forks are steel.
After an trip over the handlebars while playing with regen braking I made up a bit of a torque arm. I'm planning to make something bigger and stronger in the future, but this is better than nothing in the mean time.

The lipos gradually lose capacity, and sag. They degraded to about half capacity, then they dropped dramatically. On the last ride the 11.v packs hit 3v. They turn into huge sausages. It's a bit risky...but they didn't catch fire.


They oxidise even just sitting on the shelf.

Just be prepared for a one year life.


And glad to see you've got a torque arm!!

[Hyena]

^^ I second that, Who, Where? ^^

A-HA! I think I found them! Hong Kong and Free shipping to boot!

http://cgi.ebay.com/RC-Lab-4000mah-22-2 ... 1|294%3A50

Yep, thats the place. There's also another seller on ebay selling different branded ones for much the same price. They're probably all out of the same factory but I stuck with the same seller so they were hopefully matched. I also found afterwards they also have 8000mah packs, although they dont offer them in 6S. I guess for simplicity of charging you'd be better off buying 4 3S packs, but they're a bit more expensive to buy this way.

Running one lot of 4ah batteries was a bit light on for my controller that pulls 30a peak.
The voltage would quickly sag towards 3v/cell when pulling 20-30a but running 2 in parallel they're much happier in the 10-20a range as its only around 2-3C. Cruising along at top speed on a fresh charge the voltage is around 46v.

Mark thanks for the info. If e-biking looks like it's going to be a long term thing for me I'll re-evaluate the batteries in a years time. By then LiFePO4 will be cheaper. Hopefully!

[AussieJester]

WOOT another Aussie Nice write up mate well done on the final build (and the discovery to get there hehe) They are the exact Lipos i was looking at but the seller wanted over 400 bucks to send me 8 packs...Now i understand the charging of multiple lipo packs at once i shall go hunt me down some me thinkz...

Welcome to the forum too

Kim

Apprentice Gangsta

p.s I would have persisted with a non hub motor myself

[Hyena]

Thanks Kim.
I've been following your build for a while too, on OCAU initially then here. Very impressive!

I like hub motors for their simplicity but I'd like to make another more dedicated off road chain drive bike. Basically an electric dirt bike.
I have THIS little dirt bike but can't ride it anywhere locally because of the noise. I'm just waiting for the engine to pack it in so I can convert it to electric

How are you planning to charge the multiple lipo packs ?
I'd ideally like to find a way of charing my 4 6s packs in parallel, but I'd need a charger that can belt out around 8 amps @ 25.2v in a lipo friendly fashion...

[liveforphysics]

I've played with the black shrinkwrap very cheap LiPo's on ebay. I think they are the lowest quality generation 1 lipo cells made. Voltage sags a lot, which means high internal resistance, and high internal heating leading to damage. Do yourself a favor and get some decent quality generation 2 lipos when/if you decide to upgrade. Ultra low internal resistance results in the cells never getting hot, the voltage stays solid during discharge, and the cells performance doesn't decrease much overtime.

Fun story with your build thread, and I liked the progression of different designs.


Best Wishes,
-Luke

[AussieJester]

Thanks Kim.
I've been following your build for a while too, on OCAU initially then here. Very impressive!

Cheers mate

I like hub motors for their simplicity but I'd like to make another more dedicated off road chain drive bike. Basically an electric dirt bike.
I have THIS little dirt bike but can't ride it anywhere locally because of the noise. I'm just waiting for the engine to pack it in so I can convert it to electric

Nice lil bike, pitty theres no areas you can ride it though FrankG from here on ES has done a nice job converting a RM125 Suzuki 'on the cheap' if you havent already check out his thread in the motorcycle section its an excellent worklog, very clever fella he is

How are you planning to charge the multiple lipo packs ?

Alot like this if i do..

http://www.rcgroups.com/forums/showthread.php?t=932319

Methods tried to explain using a power supply but its above my limited electrical skillz and i would end up burning something expensive down LoL... You could prolly use the charger you have, just need to make some balancing leads up set the charger to the max ah of the batteries when they are in parallel config....all explained in the above link anyway

Best of luck...

Kim

Apprentice Gangsta

[Hyena]

Yeah I've been watching a few of those "big bike" builds - very cool, bit a bit too complex in the fabrication for me at this stage! And to think, I started playing with ebikes because I wanted to make an electric car but thought I'd start on a small scale.

I've got the parallel charging thing sorted for my lipos, but my issue is getting enough current from a charger without spending hundreds.
Would you happen to remember what thread it was where methods was explaining using a power supply as a charger ? I'm keen to give it a crack.
I'd just buy 2 cheap B6 chargers and charge 2 packs each with those, but after my last one went up in smoke after only a dozen charges I dont want to waste any more money on them.

[AussieJester]

Would you happen to remember what thread it was where methods was explaining using a power supply as a charger ?

Was actually in the messenger here on ES matey...there is a a brief explanation on my thread around page 30-31 i think, he didn't really explain the whole balancing method however...

Here's the relevant info he laid out for me in PM anywayz-->

Lipo charger works it is simply a CC/CV charge mode
First you hit the constant current equal to the C rating of your pack, say 2.2A
Then, as the voltage comes up, you hit a constant voltage, which is the Fully Charged voltage of your pack

CC/CV
CC= AH rating
CV = Fully charged voltage

For your 22.2V 4Ah pack this would be a power supply that:

CC = 4A
CV = 25.2V

That would be a 24V power supply that can source 4A
This is a standard 100W 24V supply.
There will be a small screw to set the voltage just so
(notice I said SUPPLY, not CHARGER)

CC could be anything less than 4A
For a high quality pack (20C or better) then CC could be 6A or 8A or even 10A depending on how low the internal resistance is.

I have a $20 balancer that will actually cut off the charge current if it gets too high too. Unfortunately it is set to 4.25V, but that can be modified.

Perhaps PM him or Fletcher as Methods did mention Fletcher was the one that informed him of the charging method... see if he can explain it to you, hes a very clever fella and super helpful, without Methods my trike prolly wouldnt be running right now he sorted the connection out for my new kelly speed controller Personally i would go with a couple of chargers as you planned ALOT safer perhaps better quality than the B6 'clones' though? I know they are expensive i had a Hyperion when i was flying RC Helis and they are up near 300 bucks a pop :-S

Soz cant be of more help, i dont know the exact method Methods uses aside from the power supply and i wasnt able to find much info Googling either :-S ...the balancing and monitoring of the packs wasnt really explained he didnt think it was wise i went down the path of using PSU for charging I guess i'm not bright enough to grasp the whole process... so i gave up on the whole idea, the expense and complication of batteries/BMS/chargers etc has all but turned me off electric bicycles i wish i had just gone with a lil sub 50cc ICE motor now would have cost a shit load less $$$ than i have spent on this trike now :: sigh :: live and learn i guess Live and Learn...

Kim

Apprentice Gangsta

[Hyena]

Thanks for the info mate.

I've been riding to work every day this week - 29ks return and I JUST make it off a single charge from the 8ah pack so I'm pretty happy with that. I was intially charging at work but after my 2nd charger (one of THESE ) died after only 4 charges I had to risk the return trip on a single charge. Luckily the shop I got it from gave me a full refund so I can now go done a more gangsta path

I've been speaking with methods and am going to make up something similar to what he's doing with his high powered onboard charger, but on a smaller scale of course. I'm going to get THIS 24v 6a power supply. It has a +/-10% variable output, so I'll set it to 25.2v and pour 6 amps into my 4 6s 4000ah lipos packs in parallel. That's around 1.5a each which is under 1/2C so should be nice and safe and hopefully I'll get the most life from the batteries. The manufacturer recommends charging at 1a and 2a max which seems pretty low, but I dont want to be too daring with high current charge rates on these cheap no name packs given I often charge them indoors. Besides, a charge time of 2.5-3hrs is quite acceptable for my needs.

The only problem now is I think I need a better bike, or atleast suspension!
Travelling at 30-40km/hr along sections of bumpy footpaths and crappy access roads along the side of the highway on the way to work makes for a bone jarring ride! It's only a cheap bke so I can't expect too much, but I dunno if upgrading the front shocks alone will make it much better. If I have to replace too much it might be easier to get a better new bike. Either that or up the voltage some more so I can keep up with the cars and ride on the road

[GGoodrum]

Re: the rough ride, one thing that help me a lot was switching to big balloon-type tires, inflated to about 30-35 pounds. That really smoothed out the ride.

[Hyena]

Thanks for the tip mate. I did noticed the ride was harsher after switching from the standard mountain bike tyres to the semi-slicks I have on it now (a touch wider at 1.9" vs 1.75) so I'll try letting the pressure down a little and see how they go. I have been abusing it too I suppose, riding it fairly fast on some rough trails and taking a few jumps. The suspension has become quite noisy so I don't know if it's just made with the cheapest of cheap components and/or I've buggered it.

[Almasi]

So those cheap lipo work fine?

Do they heat up with your setup?

Do they deliver their full Watt/Hr rating?

I'm thinking about them for my nex setup!

Robin

[Hyena]

Yep they work fine for my application and deliver close to their rated ah capacity.
As I think I said previously I got around 7ah from a supposed 8ah pack, so that's pretty good. It still had life in it but not running a BMS I didnt want to run the cells too low. If you were just cruising on flat ground or using it more for assist I reckon you'd get very close to the claimed ah rating. Where I live is quite hilly though so I'm often pulling 20+ amps.

They do sag a bit with higher current draw, but pulling around 2C they're fine. Although they're rated at 10-15C I wouldn't try and run a single 4ah pack by itself unless you've got a 12amp controller or there abouts. Pull around 6C from them and the voltage quickly sags to dangerous levels for lipos. (ie around 3v or less per cell)

As for heat, again if you're pulling high current they get hot - when I was testing just the 4ah pack it was reaaaally hot when I retuned - like holding onto a hot cup of coffee. Running the 8ah pack though it's only warm to the touch afterwards. My aluminium ventilated box probably keeps them pretty cool though too.

edit: I haven't been able to use my bike lately due to the above mentioned blowing up of chargers, but the bits I've ordered should arrive soon so I can get back into it them.

[Mark_A_W]

Almasi, just be aware that Lipos (particularly cheap ones) last about a year, maybe two at the outside.

They die just sitting on the shelf.

My lipos booster pack lasted 14 months. Balanced at every charge, discharge was around 3c peak (they were supposed to be 15c).

[Almasi]

Almasi, just be aware that Lipos (particularly cheap ones) last about a year, maybe two at the outside.

They die just sitting on the shelf.

My lipos booster pack lasted 14 months. Balanced at every charge, discharge was around 3c peak (they were supposed to be 15c).

Thanks for all this info to all of you!

I may use those lipo for my next built...but 1 year life when you only ride your bike 4 or 5 month a year...hmmm but 1/2 the weight of A123 cell for same Watt/Hour then maybe it's woth it

[AussieJester]

I may use those lipo for my next built...but 1 year life when you only ride your bike 4 or 5 month a year

Nothing stopping you from discharging/charging during the months you dont ride to prolong their life rather than just leave them 'sitting on a shelf'

[Almasi]

I may use those lipo for my next built...but 1 year life when you only ride your bike 4 or 5 month a year

Nothing stopping you from discharging/charging during the months you dont ride to prolong their life rather than just leave them 'sitting on a shelf'

So if I discharged them and charge them every month it will help them live longer, is that right?

[Mark_A_W]

So if I discharged them and charge them every month it will help them live longer, is that right?

No.