I want pics!

I want pics!

Ok, I will get you some when I have time, and when I can find the camera usb cable...

still waiting.

Oh right! I better do that today! Sry guys:oops:

Here are 4 pics I just shot. Battery mounting is TEMPORARY (along with some wiring), was doing work on it and just threw it back on for the pic. Tires are temporary as well, going to purchase some fat sticky rubber tires soon to really grip hard on our bad roads here. I know I loose about 4kph top speed (and thus Wh/mile) vs. road tires, but the safety and handling is well worth it.

I was pondering the idea about putting the battery in a standard size ammo box and using a rear cargo mount, as they can hold 40+lbs apparently.

Cheers :smile:

aaaah! Finally some pics.... I feel better now thank you :lol:

Very nice even with what you call temporary stuff on it. It looks like a nice, good, solid set up. I read from some people that a big battery in the rear on a rack makes for some funky handling. Many have the opinion that the battery belongs in the frame's triangle, just like what you did for a lower CG and better handling.

I went with a 9C direct drive BL hub motor and 40 A controller from Grin Technologies in Canada (ebikes.ca). Their customer service has been great and the cycle analyst is very useful (low voltage limit, speed limit, Wh/km etc.).
Picture of the completed bike:
https://twitter.com/webetho/status/2.../photo/1/large

Attached is a picture of my torque arm, which is waterjet cut from 6 mm stainless steel, the slot milled to fit the axle and then mounted to the bike frame with an M4 screw. I have one on each side.

I was testing 18s lipo yesterday and reached 63 km/h with max power of 2.5 kW. My drive battery of made of 6s 5 Ah lipo packs. I'm using a seperate 2s A123 battery to power to bike's lights. To avoid sparks when connecting the battery, I split up the positive to an additional connector with a 250 Ohm precharge resistor.

Is it normal that the motor vibrates enough to make a loud noise and I can feel it on the saddle?

Super nice and clean Thomas. Looks very inconspicuous, but it goes over 60 :diablo: I love it.

I bought my kit at Grin as well Thomas. :smile: Their customer service is 2nd to none.

That motor looks like a new design! I am using the "FAST" kit, basically the lower wind core that was meant for a smaller 24" wheel... on 16s A123 I hit 55kph unassisted, but lacks any kind of torque, at least for me.

Following an idea I saw on ES, I bought 14 of these.

http://www.ebay.com/itm/310338999262...ht_4212wt_1188

And I'm going to try to make a charger that is basically 14 little chargers in one to charge my 14S scooter battery. Instead of using a hobby charger that charges at up to 20 amps and then goes into balance mode trying to balance the cells at 0.3 amp for 15 hours, charging each cell individually should be a bit faster even though it only charges at 1 amp and all the cells should still be balanced at the end.

Once I get the chargers and open them up to have the exact dimension of the boards, I should be able to find a project box to house all of them together in one neat charger. Positioning the LEDs so they are visible through hole in the project box. They turn red when charging and when they all turn green, I'm good to go.

Whadaya think?

Any luck with the charger?

I received the single cell chargers and it would be fairly easy to make a box to house all of them in a neat package with the LEDs showing through small holes in the box. I thought that some 40+ pin connector from a computer could do the trick to connect a 20S battery. But I tried four of them to recharge 4 18650 cells. When all the LEDs were green, checking with my Fluke, I got 4 different voltages from the cells ranging from 4.27 up to 4.35V :gasp: So I am disappointed that these little chargers lack the precision that I was looking for. So for now, unless there's an easy way to change something in them to make them cut off at the exact 4.2V mark, I'm stuck with 20 single cell chargers :whip:

bummer man.

Open them up and see what ICs the circuit uses. A datasheet lookup should tell you where/how the voltages are calibrated and then you can make some small mods to the circuit to get the exact voltage you want.

Lucky?
 

If your lucky there might be some kind of a miniature "pot" switch that you can make minute voltage adjustments with. Then you can just calibrate each charger to the same voltage. I was kind of thinking that you might run into this problem, but we never know until someone tries it out. You are the guinee pig here. Thank you. Anyway hopefully you can find a loop-hole with this setup and get it to work right for your application. Good luck.

Here's a few pics of the inside. I don't see a pot and Brian, what is a IC? :oh:

http://i177.photobucket.com/albums/w...p_charger8.jpg

http://i177.photobucket.com/albums/w...p_charger9.jpg

http://i177.photobucket.com/albums/w...p_charger7.jpg

http://i177.photobucket.com/albums/w...p_charger6.jpg

http://i177.photobucket.com/albums/w...p_charger5.jpg

http://i177.photobucket.com/albums/w..._charger10.jpg

Starting from the cord side, I see what looks to be a bridge rectifier, cap filter, an opto-isolated simple switching power supply, and the IC (labeled U2) is presumably the actual charger IC, but the top has been sanded to prevent identification.

However, I do notice the resistors used are 5% tolerance (gold 4th band). No big deal if they aren't used to "program" cell cutoff voltage or whatever, but if they are being used in the charging part of the circuit, I would have expected to see 1% or 2% tolerance precision resistors (5 bands).

Do you think changing those resistors would make these chargers more precise? If they are part of the charging like you said. It would be easy enough to change those resistors and then charge a few 18650 cells to find out what the end voltage is. I just need to know which resistors to get. Thanks Brian.

I'm not sure. If the part number of the IC wasn't ground off, you could look up the datasheet for it and see what purpose/effect any support components would have.

I can't quite make out the color code to know what the exact resistor value should be, and you shouldn't measure it while in the circuit because other components could affect the reading. But once you figure out the default resistor value (looks to be under 1k), you can replace it with a pot and adjust it until it matches the exact value as found on the color code on the resistor. But again, if it's not part of the charging circuit, it will have little or no effect on the output. It's all a shot in the dark at this point.

I was hoping for something more encouraging but I guess it is what it is. Thanks.

This EV thing is turning into a hobby that is worst than RC! I went 72V 30Ah just two weeks ago and I am having so much fun with it that I already want to go 100V 40Ah.

Do it man. Just be careful with 100V DC and your fingers.

Tell me about it, this 72V battery I made bit me a couple times during the construction. My fault, I was in a hurry trying to get it done and I really shouldn't work like that. 100V 40Ah would be with genuine A123 prismatic cells from A123RC. So I need the money before I worry about the fingers. Maybe next year.