Building the best commuter (DIY) ebike.

[Raged]

I recommend running a BMS if you're running lipo as well for reliability and "no fuss" plug and play. I run a 14S 40A BMS ($50). My cables/connectors (10AWG with 5.5mm bullets) are "rated" for 90A(conservative), so it would suck to have my shit melt on me if my setup went unregulated and pulled close to the amps you were pulling.

Someone correct me, but you'd need 6 or 8 AWG wire to run 80A reliably?

 

[biohazardman]

Well I have 3,000 miles as of yesterday on my hard tail and 30mph on a flat is the norm closer to 40mph downhills. Nice seat and a good tire. I must be lucky.

Yeah man. I have like a ridiculous amount of miles on my 48v ping 9x7 bike. Well over 20k miles. Never had anything fail from vibration (a cap did pop off a controller, but that was Lyen's fault for not gluing it down properly.)

To be fair though the roads I ride on are decent, and I know the route so well I don't even have to think about dodging bumps.

I have a suspension fork for one reason alone: SAFETY. Damage mitigation against potholes and curbs if I ever lose control or make a grievous mistake.

I'm not worried about comfort. If I have to stand up and slow down when I go over a speed bump, so be it. I'm not spending an extra $1k for a decent FS frame.

Digression: The best commuter ebike would be full suspension. No arguments. I just don't think it's in the realm of DIYers.

I have well over 10K on my full suspension Giant Trance 3 commuter. I thought I had a problem with the V2S motor once ended up being a wiring problem and a loose bearing. My first commuter was a hardtail and it was hard on my tail for sure. Lower back problems made the full suspension build a must to continue the ebike commute. New bikes and frames are spendy but there are lots of seldom used units hanging in garages out there for a third the price.

 

[auraslip]

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32056 Anyone interested can browse this thread if they're interested in full suspension frames big enough for batteries. Most of them are frames from the 90s and I question the reliability of their build. It's one thing to stick some batteries in a frame. It's another thing to make it water proof and theft proof!

Someone correct me, but you'd need 6 or 8 AWG wire to run 80A reliably?

To pull it continuously, yes. Realistically, that would wreck my controller and motor quick. The 80a peak I'm seeing is in the time before the controller caps the amps. If I had updated software I could set my blocktime to 0, I could limit the amps to something lower. Probably more like 40a would be safest for reliability. Keep in mind 80a battery is not what the phase cables see. Phase cables see a bit more to do phase multiplication. Keep your phase cables as short as possible and use the biggest gauge in reason to minimize i^2r heat losses.

On this bike I'm running 8awg battery and phase cables. Not because I need them but because I already had them made from a previous bike. I just crunched the numbers on the wiring simulator I made https://sites.google.com/site/shelbyelectro/controllers-and-electronics/inter/--i-2r-power-loss-calculator-and-why-you-should-upgrade-your-wiring

At 30a the differences in losses between 10awg and 8awg is at worse 20w. In practice it's more like 5w.

Actually. I take that back. Definitely go with the thickest wires possible on ALL BIKES. 5w might not seem like a lot but if we're counting watts per dollar it's probably the cheapest way to improve your ebike. Incremental improvements add up.

I recommend running a BMS if you're running lipo as well for reliability and "no fuss" plug and play.

I'm trying to cut as much chinese crap off my bike as possible.... i would pay top dollar for a BMS I can trust. Which bms do you use, and where can I get it? It might be worth trying! I've had bad experiences with bms(battery murdering systems) in the past.

 

[Raged]

I got my BMS and charger from em3ev. The BMS is enclosed in the frame with all balance cables. Charger cable goes to waterproof saddle bag for easy access with anderson 45pp plugs. All I need is the charge cable hanging out for my daily charge.

The charger has 3 pre-sets. High (4.2v / cell), Mid (4.15/cell) and low ( can't remember what voltage ). It automatically turns off when it hits target voltage.

This is how simple it is to charge lipo for me :

14S charger : http://em3ev.com/store/index.php?route=product/product&path=37&product_id=120

14S BMS : http://em3ev.com/store/index.php?route=product/product&path=42&product_id=75

 

[auraslip]

Note:

BMS PCBS are sold without Warranty, no exceptions. BMS will be tested before shipping to confirm functionality. If a fault occurs, we will not discuss repair or replacement. If this is unacceptable, please do not order BMS from us.

lol sounds about right

Charger cable goes to waterproof saddle bag for easy access with anderson 45pp plugs. All I need is the charge cable hanging out for my daily charge.

This is what I do on my bikes too. Keep charger cable in the rear bag.

 

[Raged]

Note:

BMS PCBS are sold without Warranty, no exceptions. BMS will be tested before shipping to confirm functionality. If a fault occurs, we will not discuss repair or replacement. If this is unacceptable, please do not order BMS from us.

lol sounds about right

Charger cable goes to waterproof saddle bag for easy access with anderson 45pp plugs. All I need is the charge cable hanging out for my daily charge.

This is what I do on my bikes too. Keep charger cable in the rear bag.

Yeah that's a normal response to anything connected to batteries... especially high power ones. People do stupid things with them (like short out the cables or plug in a 12S of battery when it's a 14S BMS... hoping it will work)... Em3ev does add some little touches like fuses to each BMS line, so you dont blow the unit when you short a balance cable.

Hopefully you're getting enough ideas from my build to get you on your way. Be good to see the finished product =)

 

[auraslip]

Bike is pretty much done for the next month or so until I get my first paycheck. Right now I'm going to concentrate on tuning the controller, brakes, and fork. Also cleaning up the wiring.

I do have a long list of things I need to do once I can afford it.

I have a question for all those with experience in material science; what should I use for siding material? Home Depot sells sheets of aluminum for $25 and that seems like it would work. The current plastic sidings I have are not good. They compress under the screws and look bad. They are not rigid so do not lay flat against the box. And they don't take spray paint well. I'm fine with bare aluminum, but if I could save weight with a some sort of plastic siding that comes pre-colored I would go with that as well.

 

[Raged]

Since you're good with woodwork, some 3mm ply for reinforcement then your plastic sides on top? If your plastic is semi-see through, paint the ply black or white and put a design on there. Then cover with see through plastic?

 

[auraslip]

PROGRESS.

Got my EM3EV 18 fet this morning. After 4 hours of making the connectors compatible and trouble shooting here we are. Me doing wheelies in the back yard. 8) 8) 8)

I just can not believe how much power and therefore fun this setup produces.

The troubleshooting involved em3ev's poor documentation. Had to figure out phase/hall combos from scratch. Had to figure out XPD and mod my usbttl programing cable to be compatible with infieion 3. I had a problem where my magura throttle was tripping the throttle blowout protection that comes enabled stock. Luckily I read all the settings before I used the program.

Awesome program XDP is btw

the ebs unlimited setting works with my eb318 - it pulls about 700w of regen. very nice.

with block time at zero the controller will pass current up to the limited amount. And it goes much higher than the stock 60a. Right now it's set at 120a. 6kw Wheeeelie time.

Ok, but seriously, can I leave it set at 120a? Is the only danger overheating and blowing a fet because I know how to back off the throttle when the controller gets hot. Can I go higher to the saturation point of these motors?