Search found 12680 matches

by fechter
Dec 09 2018 1:24am
Forum: Battery Technology
Topic: Replace Cells?
Replies: 16
Views: 293

Re: Replace Cells?

Thanks, i got it. Lucky for me my BMS has blue tooth connectivity, otherwise i would have never known. Must be people riding around out there in ignorant bliss, until.... Well, until the pack dies way sooner than expected like the one in my picture. That one had a bad BMS channel that drained the c...
by fechter
Dec 09 2018 1:22am
Forum: E-Bike Technical
Topic: Controller shunt mods
Replies: 34
Views: 4044

Re: Controller shunt mods

Those are rated for 55V and have an on resistance of 8 milliohms. For sure you can find FETs with much lower resistance. Less resistance will produce less heating. The legs will melt off the FETs around 70A, so the silicon rating is not the limiting factor. I'd just try the stock FETs and see if it ...
by fechter
Dec 08 2018 7:34pm
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2713
Views: 158241

Re: Sur-Ron - New Mid drive Bike

Nice video on the stairs :thumb: I think the Sur-ron motor and drive train can easily handle 10+kW. The battery is the limiting factor. Sooner or later they will come out with better performing cells and a battery rebuild will be pretty attractive. Stuffing the battery housing full of Lipo would be ...
by fechter
Dec 08 2018 1:45pm
Forum: E-Bike Technical
Topic: bms with canbus
Replies: 3
Views: 86

Re: bms with canbus

I am not aware of any that you could just drop in and work other than one from A2B.
by fechter
Dec 08 2018 12:04pm
Forum: Battery Technology
Topic: Pneumatic spot welder sticks to cells
Replies: 9
Views: 223

Re: Pneumatic spot welder sticks to cells

It looks like the welder can do dual pulse. Maybe they don't provide good instructions on how to program it.
Twisting the pack slightly after the weld to unstick the tips may be needed no matter what.
by fechter
Dec 08 2018 11:56am
Forum: Battery Technology
Topic: Replace Cells?
Replies: 16
Views: 293

Re: Replace Cells?

Ahhhh, clever. So the negative pin just goes into the pin with the black wire and the positive into the pin going to the low cell group? The wires have to go across the low cell. They will be adjacent holes in the BMS connector. Since the phone charger can over charge the cell, you need to babysit ...
by fechter
Dec 08 2018 11:51am
Forum: E-Bike Technical
Topic: Controller shunt mods
Replies: 34
Views: 4044

Re: Controller shunt mods

My controller has 6 mosfets, so if I increase the amp capacity of the shunt, I think i must add more mosfets. If I added 6 more mosfets, could I add them in parallel, or does this mod require a new board and controller? It depends on the FETs and how much current you end up with. Many times you can...
by fechter
Dec 08 2018 1:12am
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2713
Views: 158241

Re: Sur-Ron - New Mid drive Bike

Mine is really tight. It's hard to pull the battery out. The sides of the pack are supposed to sit against the black plastic pieces on the frame. I'd guess your frame is a little wider than normal. Maybe you could loosen the black plastic piece on the left that holds the wires and put some kind of s...
by fechter
Dec 07 2018 3:51pm
Forum: Battery Technology
Topic: Replace Cells?
Replies: 16
Views: 293

Re: Replace Cells?

The typical cheap BMS draws the power for the control circuit from cells 1-3. Over a really long time, those cells will get lower than the rest. If only one group is low, it could be a bad channel on the BMS. 3.5 is not dangerously low and when a BMS channel fails, it typically drains the cell to ne...
by fechter
Dec 07 2018 3:40pm
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2713
Views: 158241

Re: Sur-Ron - New Mid drive Bike

Nice!

I bet it won't stay that clean for very long.
You'll probably need to crank up the spring on the rear shock as they compress it for shipping.
by fechter
Dec 07 2018 2:02pm
Forum: E-Bike General Discussion
Topic: Stromer STX1 -> Hack
Replies: 6
Views: 157

Re: Stromer STX1 -> Hack

Hmmm... If there is no output from the battery, then there would be nothing to power the display or controller to send data. Seems like the BMS is bad. The BMS likely sends data to the controller telling it that it's a genuine battery and enables the controller. If you could read the data stream on ...
by fechter
Dec 07 2018 1:54pm
Forum: Battery Technology
Topic: New 14S7P & 14S5P packs need advices (to climb high mountain)
Replies: 38
Views: 1221

Re: New 14S7P & 14S5P packs need advices (to climb high mountain)

Cell balance looks great. Not a bad idea to double check those voltages with a good DVM to verify accuracy. See how the voltages look after a full charge.
by fechter
Dec 07 2018 11:58am
Forum: Battery Technology
Topic: Pneumatic spot welder sticks to cells
Replies: 9
Views: 223

Re: Pneumatic spot welder sticks to cells

About all you can do is play with the settings and do some tests. Tip geometry and material will also make a difference. I know with my Riba welder the tips would stick pretty bad when I was using a source that was too weak. When I got a higher current source battery, the weld were much better and t...
by fechter
Dec 06 2018 2:14pm
Forum: Battery Technology
Topic: Pneumatic spot welder sticks to cells
Replies: 9
Views: 223

Re: Pneumatic spot welder sticks to cells

Higher current and shorter pulse if possible. More pressure on the electrodes might help too.

I watched a guy using something like that before and after each weld, he would twist the pack a little to break the electrodes free.
by fechter
Dec 06 2018 2:08pm
Forum: E-Bike General Discussion
Topic: Stromer STX1 -> Hack
Replies: 6
Views: 157

Re: Stromer STX1 -> Hack

Not much experience with that model, but does the battery have a data connection? It may require a command to enable. The command may also just be simply a voltage applied to a line. You may need to measure on a working one to see where the signal is.

Any pictures of the battery insides?
by fechter
Dec 06 2018 1:58pm
Forum: E-Bike Technical
Topic: Noise while coasting - Bafang Max torque motor
Replies: 7
Views: 180

Re: Noise while coasting - Bafang Max torque motor

It's definitely not running when I try to stop or anything like that. I guess I've been worried that something will strip if it keeps lightly "catching" like that (if that is what's happening), or that it will get worse and eventually form a drag on my coasting momentum. I guess I'll just keep ridi...
by fechter
Dec 06 2018 11:19am
Forum: E-Bike Technical
Topic: Length of wires
Replies: 9
Views: 181

Re: Length of wires

Not much difference. They all turn on/off at the PWM frequency so any issues from inductance or resistance would be the same. If the controller is adequately rated, the relative length of the battery wires vs. the phase wires won't really matter. Phase wires will have more current, so will have more...
by fechter
Dec 06 2018 11:11am
Forum: E-Scooter and Motorcycle General Discussion
Topic: A2B throttle wiring
Replies: 8
Views: 250

Re: A2B throttle wiring

I'm gathering that the original key switch did not have the option for "both". Am I going to blow up the module when I select "both"? Yes, if the two batteries don't have exactly the same voltage when you select "both" there is a chance of destructively high current to pass from one pack to the oth...
by fechter
Dec 06 2018 9:14am
Forum: E-Bike Technical
Topic: Noise while coasting - Bafang Max torque motor
Replies: 7
Views: 180

Re: Noise while coasting - Bafang Max torque motor

So it sounds like a controller issue, not a strictly mechanical issue. It's normal for the chain to not move when you pedal backward. The motor has to be able to drive the chain without driving the pedals. To me it doesn't really sound like anything to worry about. If the motor is getting small puls...
by fechter
Dec 06 2018 9:10am
Forum: E-Bike Technical
Topic: Controller shunt mods
Replies: 34
Views: 4044

Re: Controller shunt mods

On newer designs, the op amp is built into the main MCU chip so all you see is maybe a RC filter between the shunt and the MCU. The shunt resistors are generally in the neighborhood of 1 milliohm. Making an adjustable divider on the signal is pretty easy but most people just lower the shunt resistan...
by fechter
Dec 06 2018 8:51am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 1030
Views: 44680

Re: la Nina rears her ugly head

I got about 0.3" out of the system. Sort of a dud, but need every drop.
by fechter
Dec 06 2018 12:19am
Forum: E-Scooter and Motorcycle General Discussion
Topic: A2B throttle wiring
Replies: 8
Views: 250

Re: A2B throttle wiring

I never noticed that before. That's funny. I'd guess the French guy was stoned. The positive wires go to the relays and are red. One relay is for the A battery and the other one is for the B battery. The switch logic prevents both from coming on at the same time.
by fechter
Dec 05 2018 3:46pm
Forum: Stand-up E-scooters and E-skateboards
Topic: TDPro Cheap 36v Controller 800w Modding to 70v
Replies: 7
Views: 160

Re: TDPro Cheap 36v Controller 800w Modding to 70v

It just blew the copper off the traces like a fuse. Needs more copper there. I was seriously injured when the brushed motor controller on my old Zappy shorted and stuck on full throttle. I even had a contactor and kill switch on the handlebars but I was too slow to hit it. The only good way around t...
by fechter
Dec 05 2018 3:40pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Yz-EEB *5000w, 50mph, mx style*
Replies: 19
Views: 1800

Re: Yz-EEB *5000w, 50mph, mx style*

Looks great!

I thought NYC cops hated ebikes and were confiscating them until the law recently changed. They were targeting poor food delivery riders.
by fechter
Dec 05 2018 3:27pm
Forum: E-Bike Technical
Topic: Noise while coasting - Bafang Max torque motor
Replies: 7
Views: 180

Re: Noise while coasting - Bafang Max torque motor

The Ultra motor is pretty different than the BBSHD. Possibly the torque sensing is picking up something even though you aren't pedaling. Just the weight of your feet on the pedals might make a difference. When you hear the noise, try lifting your feet off the pedals and see if it changes. Also try p...