Search found 11600 matches

by fechter
Jan 19, 2018 8:38 pm
Forum: E-Bike Photos & Video
Topic: A2b metro gti
Replies: 73
Views: 4724

Re: A2b metro gti

I have a 14s, 9p pack I put on the back of my A2B. It weighs about 13.5lb. The weight on the rear doesn't really seem to bother the handling much. If I'm just running to the store or a short trip, I use the frame pack, but for longer rides I put the big battery on the rear and have two batteries. 50...
by fechter
Jan 19, 2018 8:30 pm
Forum: Battery Technology
Topic: Chilwee lead-graphene battery
Replies: 4
Views: 74

Re: Chilwee lead-graphene battery

I've never heard of those before. ADVANTAGES * Capacity has been increased 10 - 16%; * Cycle life has been increased 50% more; * Low/High Temperature performance has been improved 30-40%; * Water Loss rate has been decreased 40%; * Large power discharge capability has been increased 15%; * Special c...
by fechter
Jan 19, 2018 8:04 pm
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 659
Views: 51299

Re: Active pre-charge/inrush control

If you look at the SOA graph for your FETs, you'll probably find this application put them outside of the envelope, but since it's a single event, they seem to survive. The die can absorb some of the heat. The early precharge circuits just used a RC on the gate to slow the turn on, with no feedback ...
by fechter
Jan 19, 2018 7:57 pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: R Martin EVD Moped with HubMonster
Replies: 24
Views: 290

Re: R Martin EVD Moped with HubMonster

6.5v on the lead battery isn't a good sign. Time to recycle. A 50Ahr lithium battery will probably give about twice the range as a 50Ahr lead acid battery. Less weight combined with less Peukert effect. Just for reference, here's the dimensions of a Nissan Leaf battery module. These are 2s each, rat...
by fechter
Jan 19, 2018 3:21 pm
Forum: Motor Technology
Topic: Cromotor issue... bad sound and lack of power
Replies: 4
Views: 49

Re: Cromotor issue... bad sound and lack of power

It sounds like all the magnets broke loose. They can spin around on the inside of the hub, only held on by magnetism. If the glue gets hot enough, it weakens significantly. Ferrofluid could possibly be a factor, but most glues used to stick magnets to the motor should be compatible with it. It would...
by fechter
Jan 19, 2018 3:06 pm
Forum: E-Bike General Discussion
Topic: Marin County, San Francisco Bay Area?
Replies: 15
Views: 179

Re: Marin County, San Francisco Bay Area?

They don't like wind power either. Birds get killed by hitting the blades.

I guess they think it's OK when the birds get killed by global warming instead.
by fechter
Jan 19, 2018 3:04 pm
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 659
Views: 51299

Re: Active pre-charge/inrush control

That looks a lot like one of our earliest versions. Lots of blown FETs unless you make it super slow.
by fechter
Jan 19, 2018 9:38 am
Forum: E-Scooter and Motorcycle General Discussion
Topic: R Martin EVD Moped with HubMonster
Replies: 24
Views: 290

Re: R Martin EVD Moped with HubMonster

You might be able to fit some Nissan Leaf batteries in there. Even if you fill the entire battery compartment with lithium batteries, it will weigh about 1/3 of the lead batteries.
by fechter
Jan 19, 2018 9:16 am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 617
Views: 20939

Re: la Nina rears her ugly head

0.1" here yesterday. Just sort of drizzled all day.
by fechter
Jan 19, 2018 9:08 am
Forum: E-Bike Technical
Topic: What could be wrong with my bike?
Replies: 18
Views: 363

Re: What could be wrong with my bike?

When I had the connector on the black and blue it would switch between 0.02v and 4.97v as I turned the wheel. The exact same values were there for the black and green. The black and yellow combination went from 0.02v to 4.89v. That sounds pretty normal. I don't think that much difference is a probl...
by fechter
Jan 18, 2018 10:28 pm
Forum: E-Bike General Discussion
Topic: Active pre-charge/inrush control
Replies: 659
Views: 51299

Re: Active pre-charge/inrush control

Food for thought; another possible approach to this problem is to switch the main FETs on hard instead of slowly ramping things up. You'd still need a time delay in the case of not using a switch. Based on what I've seen with the spot welder circuits, I think the FETs would be OK with a fast turn-on...
by fechter
Jan 18, 2018 5:11 pm
Forum: E-Bike General Discussion
Topic: Marin County, San Francisco Bay Area?
Replies: 15
Views: 179

Re: Marin County, San Francisco Bay Area?

After a little more research, it seems it was the hard-core tree huggers that were against the electric bikes, not the MTB gods. The original article states: County supervisors Jan. 9 also approved, on first reading, an ordinance that would amend Open Space District regulations. Several environmenta...
by fechter
Jan 18, 2018 3:08 pm
Forum: E-Bike General Discussion
Topic: looking for tire recommendations for 1200 watt bike
Replies: 6
Views: 126

Re: looking for tire recommendations for 1200 watt bike

Your tire failure sounds like maybe the tire was quite old, possibly sat around on a shelf for too many years. Many people have given favorable reports on the Big Apple tires. If you want really tough tires and are willing to trade off for extra weight and a lot more rolling resistance, you could go...
by fechter
Jan 18, 2018 2:07 pm
Forum: E-Bike Technical
Topic: Replace hall-sensor on throttle?
Replies: 4
Views: 56

Re: Replace hall-sensor on throttle?

The whole throttle is not very expensive in most cases too.

We'd be guessing at the Gauss range. If the range is wrong, the throttle active range might change. Most of the ones I've seen have a pretty high range, like 750 to 1000. One that has a range of 5 Gauss probably won't work acceptably.
by fechter
Jan 18, 2018 2:03 pm
Forum: Battery Technology
Topic: Battery problem, voltage but no current
Replies: 4
Views: 96

Re: Battery problem, voltage but no current

Joachim wrote:
Jan 18, 2018 12:34 pm
the bms doesnt like the current peak to charge the empty controller caps....a smal coil between battery and controller will wurk.
That can happen sometimes too. You'd see a pretty good spark when you make the connection if this was the case. If the BMS is already tripped, you would get no spark.
by fechter
Jan 18, 2018 9:45 am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 617
Views: 20939

Re: la Nina rears her ugly head

Glad I don't live in Siberia: Though the official temperature was "only" 74 below on Tuesday, some residents recorded temperatures as low as 88 below at their homes, the Siberian Times reported. This isn't far from 89.9 degrees below, the coldest-ever officially recorded for a permanently inhabited ...
by fechter
Jan 18, 2018 9:39 am
Forum: E-Bike Technical
Topic: Replace hall-sensor on throttle?
Replies: 4
Views: 56

Re: Replace hall-sensor on throttle?

There are probably many that would work, but you need the right type. The ones found in motors, for example, would not work. You want a linear, ratiometric sensor with a gauss range of about +/- 1000. A Honeywell SS49E or SS496B should work. It would be best to look up the number on the old one to s...
by fechter
Jan 18, 2018 9:20 am
Forum: Battery Technology
Topic: Battery problem, voltage but no current
Replies: 4
Views: 96

Re: Battery problem, voltage but no current

Right, it sounds like the BMS is doing its job and it's tripped. When it cuts off the output, you will still see voltage if measured with a voltmeter, but it will drop to zero with a load. You need to check all the individual cell voltages. Most likely there is one that is out of range. I do this by...
by fechter
Jan 17, 2018 3:31 pm
Forum: Electric Watercraft
Topic: Safety & charging in the water?
Replies: 2
Views: 56

Re: Safety & charging in the water?

A GFCI on the AC line is usually the first like of defense. Not sure if a standard EVSE has this. The GFCI senses the current going down one wire and coming back on the other. If the difference is more than a tiny amount (indicating an unintended current path), it cuts the AC power. The second line ...
by fechter
Jan 17, 2018 1:48 pm
Forum: Stand-up E-scooters and E-skateboards
Topic: motor wires interfere with reciever?
Replies: 5
Views: 43

Re: motor wires interfere with reciever?

It depends on the type of radio and the frequency. The BMW i3 electric car doesn't even have AM on the radio due to interference issues. At higher frequencies, like WiFi, it should be no problem.
by fechter
Jan 17, 2018 1:35 pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: R Martin EVD Moped with HubMonster
Replies: 24
Views: 290

Re: R Martin EVD Moped with HubMonster

If the lead acid batteries are sulfated, it's common to get zero charge current. If you leave the charger on for a long time (overnight), it might start taking some charge.
by fechter
Jan 17, 2018 9:17 am
Forum: E-Bike General Discussion
Topic: relation between Motor power and battery power
Replies: 3
Views: 104

Re: relation between Motor power and battery power

The controller will limit how much goes to the motor. The battery needs to be able to supply more than that.
10Ah is the capacity of the battery, not the output current rating. Most batteries of that size should have no problem driving a 250W motor.
by fechter
Jan 17, 2018 9:14 am
Forum: E-Bike General Discussion
Topic: Challenge with brakes
Replies: 5
Views: 124

Re: Challenge with brakes

Maybe post a picture of the rear wheel. Is the frame steel?
by fechter
Jan 17, 2018 9:07 am
Forum: Battery Technology
Topic: Are my charged cells within ok range of balanced?
Replies: 17
Views: 306

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

Another way is to use a constant current power supply that puts out less than the balancing shunt current. Even a simple resistor or light bulb in series with a fixed supply could do this. Then just let it go for a few days. Typical balancing shunts are 100mA, but this varies. You can calculate it b...
by fechter
Jan 16, 2018 10:44 pm
Forum: E-Bike General Discussion
Topic: Potential Catastrophic Frame Failer Averted ….sort of.
Replies: 90
Views: 1072

Re: Potential Catastrophic Frame Failer Averted ….sort of.

If you want an option that really works, after acetone cleaning and sanding, wrapping a few rolls of urathane casting tape tightly around that head tube assembly in a lashing style of pattern can make a permanent solution, and is possible to assemble a strong frame from scratch that way using no we...