Search found 12713 matches

by fechter
Dec 14 2018 1:35pm
Forum: Stand-up E-scooters and E-skateboards
Topic: Stand-up scooter "VOSTOK 1"
Replies: 15
Views: 267

Re: Stand-up scooter "VOSTOK 1"

Looks great.

A sine wave controller will make it almost silent. If you get one with field weakening, you can get a higher top speed depending on load.

Any estimate on the total weight?

Are you compressing the cells?
by fechter
Dec 14 2018 1:30pm
Forum: Battery Technology
Topic: Any advantage of one layout over the other?
Replies: 19
Views: 769

Re: Any advantage of one layout over the other?

That should work well. Depending on your cells, you might be able to run 10kW without overheating. A 80A fuse or breaker is supposed to handle 80A all day and will only trip or blow when it gets somewhat above that. I like the solar circuit breakers but they are large. Yes, you can program the batte...
by fechter
Dec 14 2018 12:14am
Forum: Battery Technology
Topic: Replace Cells?
Replies: 33
Views: 539

Re: Replace Cells?

I agree with your assessment. Sucks to have an expensive battery damaged.

Your options are DIY repair with no guarantee of success or replace the pack. Cells that get damaged in that manner may be more prone to catching on fire later. Always charge in a fire safe location.
by fechter
Dec 14 2018 12:11am
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2764
Views: 160740

Re: Sur-Ron - New Mid drive Bike

I didn't know they existed. Sounds like a good option. There are advantages to having the hall sensor in a pot box where it can't get smashed or wet so easily.

Can you post a link?
by fechter
Dec 13 2018 3:30pm
Forum: Items for Sale - New
Topic: JP spot welder
Replies: 1130
Views: 141030

Re: JP spot welder

I was thinking about use some server Power supply in parallel. Do you think they can handle? If not, what about use 48v as a DC source? I can get a lot of power supplys for free they are 48v 50A, 2400w... I can parallel them, bit not sure if 48v is too much. 48v is too much. 12v is about the maximu...
by fechter
Dec 13 2018 3:25pm
Forum: Battery Technology
Topic: Generic-Chinese-Bluetooth-BMS-communication-protocol
Replies: 21
Views: 1442

Re: Generic-Chinese-Bluetooth-BMS-communication-protocol

I don't know of any way you can get the Atmel processor that runs the BMS boards to send 'raw' commands to the TI chip. You could remove or disable the Atmel chip and talk directly to the TI chips via I2C bus if you wanted to. Simon I see, there is an intermediary Atmel that talking to the outside....
by fechter
Dec 13 2018 3:20pm
Forum: Battery Technology
Topic: Any advantage of one layout over the other?
Replies: 19
Views: 769

Re: Any advantage of one layout over the other?

MJSfoto1956 wrote:
Dec 13 2018 12:57pm
I'm aiming for a 20s20p 72V 68Ah pack (the diagram shown is just 1/4 of the whole battery)

M
How many amps?
by fechter
Dec 13 2018 3:14pm
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2764
Views: 160740

Re: Sur-Ron - New Mid drive Bike

Most of those style dc-dc converters have some kind of current limiting so should be hard to blow up. I'm not sure how much the headlight takes but that could be measured. I think 5A for grips should be OK, but no guarantee. If it did blow up, here is a similar unit for about $20usd. Rated for 72v m...
by fechter
Dec 13 2018 10:44am
Forum: Large EV General Discussion
Topic: Toro Workman MDE conversion
Replies: 21
Views: 757

Re: Toro Workman MDE conversion

The batteries do seem pretty expensive. A DIY pack made from EV car batteries would be a great option if they were available. Seems like the supply of those is pretty limited in your area. Bummer. Personally, I would never go back to lead-acid. In the long run, the lithium batteries should be more c...
by fechter
Dec 13 2018 10:38am
Forum: Battery Technology
Topic: Replace Cells?
Replies: 33
Views: 539

Re: Replace Cells?

I could see the pictures OK. Removing and replacing the nickel strips doesn't look too bad, but there is no way to remove cells without cutting away part of the cell holders or completely un-welding the entire pack. To replace a cell group, I would pull the nickel strips off both sides of the bad ce...
by fechter
Dec 13 2018 10:23am
Forum: Stand-up E-scooters and E-skateboards
Topic: Stand-up scooter "VOSTOK 1"
Replies: 15
Views: 267

Re: Stand-up scooter "VOSTOK 1"

CNC porn. :bigthumb:

I like the huge pile of swarf on the floor. That's going to be one really nice looking scooter.
by fechter
Dec 13 2018 10:17am
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2764
Views: 160740

Re: Sur-Ron - New Mid drive Bike

A Domino throttle should work fine but will need a couple of resistors to make the output in the same range as a hall. The microswitch is not really needed. Over a long time, these had a track record of wearing out. There may be some decent quality hall effect twist throttles out there that would be...
by fechter
Dec 13 2018 12:17am
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 2764
Views: 160740

Re: Sur-Ron - New Mid drive Bike

Would anyone happen to know what that silver device I circled in the picture is? It has 3 wires going to it, Black/Green/Red wire. Is that the DC/DC converter? If it is, does anyone know how many amps it is rated for? Yes, that's the dc-dc converter. I couldn't find any marking on mine, but didn't ...
by fechter
Dec 12 2018 2:18pm
Forum: Stand-up E-scooters and E-skateboards
Topic: Stand-up scooter "VOSTOK 1"
Replies: 15
Views: 267

Re: Stand-up scooter "VOSTOK 1"

The suspension looks like it's really doing its job. Also looks like you really need it around there. I thought the roads here were bad...
by fechter
Dec 12 2018 11:06am
Forum: Battery Technology
Topic: Generic-Chinese-Bluetooth-BMS-communication-protocol
Replies: 21
Views: 1442

Re: Generic-Chinese-Bluetooth-BMS-communication-protocol

That's great work. Thanks for posting.

If they use TI chips, would the datasheet for the chip tell us about the available commands?
by fechter
Dec 12 2018 10:57am
Forum: Stand-up E-scooters and E-skateboards
Topic: Stand-up scooter "VOSTOK 1"
Replies: 15
Views: 267

Re: Stand-up scooter "VOSTOK 1"

Looks great so far...

What motor are you going to use? You may want to use two motors to get that much power.
by fechter
Dec 12 2018 10:51am
Forum: Battery Technology
Topic: Help with BMS
Replies: 6
Views: 109

Re: Help with BMS

It's possible the charger discharged the pack when not plugged in.
by fechter
Dec 12 2018 10:49am
Forum: Items for Sale - New
Topic: JP spot welder
Replies: 1130
Views: 141030

Re: JP spot welder

hello friend. Could I replace the battery with a modified microwave transformer? The welder circuit won't work with AC. If you had a rectifier on the output of the transformer, it could possibly work but the rectifier would need to handle over 1000 amps. I don't think a transformer would be able to...
by fechter
Dec 12 2018 10:45am
Forum: Battery Technology
Topic: Replace Cells?
Replies: 33
Views: 539

Re: Replace Cells?

Post a picture of your pack. Replacing a cell group may be challenging to impossible depending on pack construction and your skill level. I have a couple packs with bad cell groups but the welding and gluing was very strong and hard to take apart without destroying the good parts. Never fixed them. ...
by fechter
Dec 12 2018 10:30am
Forum: Motor Technology
Topic: Sensorless at standstill, development updates and status
Replies: 53
Views: 2607

Re: Sensorless at standstill, development updates and status

Great news on the design. I know what you're talking about with commerciallizing an invention. The business aspect is not something most engineers are good at. It's even worse in the medical device business to get things implemented and turned into an actual product that people can buy. At this stag...
by fechter
Dec 11 2018 9:07pm
Forum: Battery Technology
Topic: Pneumatic spot welder sticks to cells
Replies: 16
Views: 375

Re: Pneumatic spot welder sticks to cells

My electrodes are made from copper rods about 5mm in diameter. At the tip I round them slightly so the contact spot is around 1mm. Not super pointy.
by fechter
Dec 11 2018 9:36am
Forum: Battery Technology
Topic: 17ah Samsung 35E at 30A
Replies: 39
Views: 965

Re: 17ah Samsung 35E at 30A

How far is the commute? The other thing is you will likely run less than 30A at cruising speed. The bike simulator can give you a good idea of power consumption for a given speed.

On one of my bikes I replaced the velcro straps with some gigantic zip ties. They make some really hefty ones.
by fechter
Dec 11 2018 9:27am
Forum: Battery Technology
Topic: pswpower battery dimensions
Replies: 1
Views: 47

Re: pswpower battery dimensions

It looks like a CAD drawing so you could just measure off the drawing. The angles, for example look pretty close to 40deg.

Print a copy on paper and measure one of the given dimensions. Then use a calculator to come up with a scale factor.
by fechter
Dec 11 2018 9:17am
Forum: Battery Technology
Topic: How does a BMS balance cells ?
Replies: 7
Views: 163

Re: How does a BMS balance cells ?

Interesting. Does that mean those bms would not balance half charged packs at all ? Correct. The typical cheap BMS can only balance when the cells reach around 4.2v. If you charge the pack to a lower voltage, it will never balance. New cells in good condition will tend to stay balanced for a long t...
by fechter
Dec 11 2018 9:04am
Forum: E-Bike General Discussion
Topic: Stromer STX1 -> Hack
Replies: 9
Views: 241

Re: Stromer STX1 -> Hack

That looks very similar to my A2B motor. It certainly was a pain to remove all the spokes and pry the motor halves apart but now that I have the right tools it wouldn't be that bad. I cut off the stock controller and went with an externally mounted one with much more power. Totally worth it but a lo...