Search found 11619 matches

by fechter
Jan 15, 2018 10:41 pm
Forum: E-Bike General Discussion
Topic: Marin County, San Francisco Bay Area?
Replies: 19
Views: 240

Re: Marin County, San Francisco Bay Area?

Hmm... That's me.

It would totally suck if they prohibit ebikes on the open space trails. I don't think I'd be able to attend their meeting though.
by fechter
Jan 14, 2018 7:42 pm
Forum: Battery Technology
Topic: BMS Canbus data
Replies: 14
Views: 186

Re: BMS Canbus data

What kind of BMS is it?
by fechter
Jan 14, 2018 7:30 pm
Forum: E-Bike Technical
Topic: Using a 13S BMS for a 11S battery
Replies: 2
Views: 95

Re: Using a 13S BMS for a 11S battery

Which last two did you connect? You should connect the B11, B12, and B13 lines together.
Also try measuring the cell voltages at the BMS to make sure all the wires are working.
by fechter
Jan 14, 2018 7:21 pm
Forum: Items Wanted
Topic: A2B Metro Swingarm UK/EU
Replies: 13
Views: 544

Re: A2B Metro Swingarm UK/EU

I don't think there was a factory version of the shorter ones. Cutting it shorter is very easy. Hmm... I think you may be correct here. Still looking for the older stem though. Any advice on getting a nice clean cut on the fender? Should some ginger Dremel work and fine-grit wet sanding suffice? I'...
by fechter
Jan 14, 2018 7:14 pm
Forum: Battery Technology
Topic: Are my charged cells within ok range of balanced?
Replies: 19
Views: 360

Re: Are my charged cells within ok range of balanced?

Target voltage for those cells is around 3.65v. The higher ones should bleed down after a day or so.
by fechter
Jan 13, 2018 12:29 pm
Forum: Battery Technology
Topic: Are my charged cells within ok range of balanced?
Replies: 19
Views: 360

Re: Are my charged cells within ok range of balanced?

That looks much better. If they sat around for a long time, they might have gotten out of balance due to uneven self discharge. If you fully charge the pack, then discharge it slightly and repeat, you can bring it back into balance, but those numbers look pretty good now. I would do a full charge an...
by fechter
Jan 13, 2018 1:57 am
Forum: Battery Technology
Topic: Vibration is killing your cells!
Replies: 8
Views: 499

Re: Vibration is killing your cells!

Well for cylindrical cells, X and Y are identical - and it's fairly snug in that dimension. But the Z has the mass of the jelly-roll moving about a central mandrel. There is nothing holding the roll together other than tension, so I can see how the active layers could start to wear down. I think mo...
by fechter
Jan 13, 2018 1:55 am
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 664
Views: 51484

Re: Active pre-charge/inrush control

For sure you wouldn't want to turn it on with a load. During the ramp up, the transistors would be dissipating a huge amount of power. Most inverters wouldn't let you do this anyway, so it should be pretty bulletproof. 44C isn't bad, but I'm sure this still assumes free air, not inside some enclosure.
by fechter
Jan 12, 2018 3:05 pm
Forum: Battery Technology
Topic: Vibration is killing your cells!
Replies: 8
Views: 499

Re: Vibration is killing your cells!

I guess it would be good to know which axis is the most sensitive. Most of the vibration on a bike is in one axis.
by fechter
Jan 12, 2018 3:02 pm
Forum: Electric Aircraft
Topic: Bell Helicopter electric flying taxi
Replies: 4
Views: 130

Re: Bell Helicopter electric flying taxi

I didn't see any rotor blades. I wonder how that works?
by fechter
Jan 12, 2018 3:00 pm
Forum: Battery Technology
Topic: Are my charged cells within ok range of balanced?
Replies: 19
Views: 360

Re: Are my charged cells within ok range of balanced?

alpharalpha wrote:
Jan 12, 2018 9:20 am
It's been several days now since I charged them and they read

3.49
3.66
3.54
3.52
3.39
3.44
3.52
3.37
3.60

Thanks.
Are those LiFePO4?

Either way, not very well balanced. You might want to also measure immediately after charging to see if some have a high rate of self-discharge.
by fechter
Jan 12, 2018 2:47 pm
Forum: Items Wanted
Topic: A2B Metro Swingarm UK/EU
Replies: 13
Views: 544

Re: A2B Metro Swingarm UK/EU

I have 3 Metros. All of the originally had the rear fender that wraps all the way around. I cut them off like the one in the picture on all of mine. I don't think there was a factory version of the shorter ones. Cutting it shorter is very easy.
by fechter
Jan 12, 2018 2:37 pm
Forum: Battery Technology
Topic: Cool student project!
Replies: 18
Views: 516

Re: Cool student project!

Seems like a silly requirement. I'll bet a Tesla doesn't have nearly that many temp sensors. I guess they are doing this in the interest of safety. Using larger format cells so you can run 1p would be an advantage here.
by fechter
Jan 12, 2018 11:00 am
Forum: Battery Technology
Topic: MeanWell HLG vs ELG as charger
Replies: 16
Views: 261

Re: MeanWell HLG vs ELG as charger

For years I've used various Meanwell supplies for charging. On something like a S-400, there is a small LED that indicates power output. If the supply was connected to the pack but unplugged from AC, this LED would drain about 4mA. On a 10Ahr pack, this would take something like 100 days to complete...
by fechter
Jan 12, 2018 10:24 am
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 664
Views: 51484

Re: Active pre-charge/inrush control

I wouldn't worry about the heat generated during the precharge since it happens so fast. Just worry about the steady state current. 0.5w per device is close to not needing a heat sink, but I would suggest at least some kind of sink, especially if it's inside some kind of enclosure. In real life, you...
by fechter
Jan 11, 2018 10:41 pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Electrical diagrams EVT 168
Replies: 5
Views: 116

Re: Electrical diagrams EVT 168

If you can't find any diagrams, it should be possible to figure out most of them with a voltmeter, etc.

I found a service manual:
https://www.manualslib.com/products/Bra ... 04104.html

These guys may have information also:
http://bravoelectricvehicles.com/Electr ... o-EVT-168/
by fechter
Jan 11, 2018 10:30 pm
Forum: E-Bike Technical
Topic: 72v Lithium Battery Maximum Charge = 88.2v?
Replies: 7
Views: 214

Re: 72v Lithium Battery Maximum Charge = 88.2v?

The BMS should slowly bring the voltage down, but it's real slow. Might take days. It's really bad (and dangerous) for the pack to sit at that voltage. Best to find a way to drain it part way. Of course ebikes are the best load, but if that's not an option, a large incandescent light bulb made for 1...
by fechter
Jan 11, 2018 3:45 pm
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 664
Views: 51484

Re: Active pre-charge/inrush control

I'd recommend 12v zener diodes from source to gate on M2 and on the bank of M3-M6. In theory they would not ever do anything but in practice you can get some capacitive coupling between parts and the gates are pretty easy to blow up. They're cheap insurance. The FETs will be throwing off a bit of he...
by fechter
Jan 11, 2018 10:56 am
Forum: E-Scooter and Motorcycle General Discussion
Topic: Electrical diagrams EVT 168
Replies: 5
Views: 116

Re: Electrical diagrams EVT 168

If you can't find what you're looking for, you might try asking the people at Electric Motorsport. They used to be EVT 168 dealers back then. Not sure if anybody there dates back to that time. http://www.electricmotorsport.com/ I remember they changed the clock crystal on the controller (overclocked...
by fechter
Jan 11, 2018 10:51 am
Forum: Battery Technology
Topic: Cool student project!
Replies: 18
Views: 516

Re: Cool student project!

Wow, that's a crapload of wires coming out of the battery. Seems like way more than you would need for 22s. Hope all of them get hooked up to the right spot. :shock:

Nice pack design otherwise.
by fechter
Jan 11, 2018 10:46 am
Forum: E-Bike Technical
Topic: Carbon Frame and BBSHD
Replies: 7
Views: 227

Re: Carbon Frame and BBSHD

They make a 100mm BBSHD for fat bikes. This could work with a spacer.
by fechter
Jan 11, 2018 10:42 am
Forum: General Discussion
Topic: Help, new controller, motor not stopping
Replies: 4
Views: 73

Re: Help, new controller, motor not stopping

There must be some throttle input. Try disconnecting the throttle. If still runs, make sure you really have the right wires going to the throttle. It's suspicious the brake input doesn't stop it though. If disconnecting everything except the motor doesn't stop it, then the controller must be bad. If...
by fechter
Jan 11, 2018 10:38 am
Forum: Battery Technology
Topic: MeanWell HLG vs ELG as charger
Replies: 16
Views: 261

Re: MeanWell HLG vs ELG as charger

The HLG is IP67 rated, which means you can use it in the rain (water resistant). Not sure about the ELG. Otherwise, the specs look the same and both look like they should work fine.
by fechter
Jan 11, 2018 10:08 am
Forum: Battery Technology
Topic: Building many smaller A123 packs (NO BMS) and add them together
Replies: 12
Views: 209

Re: Building many smaller A123 packs (NO BMS) and add them together

It would depend on your charger. Lipo is a different voltage than your A123 cells. If the charger has a LiFePO4 setting, then it would work.

36s 10p would be a very large, heavy pack. 131.4v at full charge.
by fechter
Jan 11, 2018 9:07 am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 621
Views: 21048

Re: la Nina rears her ugly head

Got almost 2 1/2 inches from the storm, bad news for Montecito fire victims as mudslides kill at least 17. :cry: They said there was over 1/2" of rain in 5 minutes that triggered the mudslides. That's an extreme rainfall rate. Luckily up in burned areas of the wine country, the rain was a bit more ...