How far can I push this controller/motor?

[Baron]

I have this 48V 1000W kit from ebay: http://www.ebay.com/itm/48V1000W-26...-Conversion-/371289491857?hash=item5672940991

I want to see how far I can push it.

Opened up the controller, it has 12 fets labeled 80nf70 and the big caps are 63v 470uf.

photos of the controller innards can be found here (not my pics but same exact controller) https://endless-sphere.com/forums/viewtopic.php?f=2&t=68634

looks like the fets are rated 68v and 98a? http://www.st.com/web/en/resource/technical/document/datasheet/CD00276203.pdf

Let's say I wanted to run 16S lipo and modify the controller to increase the max amps to around 35-40. Could it be done? that's around 2200-2500W peak.

solder on the shunt for more amps? i can monitor amps with a wattmeter wired up to my bike

Beef up the phase/power wires in the controller and going into the motor? I doubt I could fit anything thicker than 12 or 14 awg through the axle, but I haven't checked it yet. I have some 10awg wire to use everywhere else.

how do I adjust the LVC/undervoltage protection if I want to go to 16s?

i think i will have to do some cooling mods on the motor. holes in the motor shell and insulating varnish sprayed on the inside? beefed up phase wires?

I realize I could just get a new controller but I'm kind of interested to see how far I can push this controller/motor in the name of SCIENCE.

 

[Baron]

possible spec sheet for the controller:

http://www.szktdz.com/en/news_show.php?article_id=352

1. Rated voltage：DC24-72V;
2. Rated current：12-20A;
3. Maximum current：25-40A;
4. Rated power：350-1200W;
5. Maximum power：700-2400W;
7. Under-voltage protection：it can be set according to customer requirements;

and some helpful info i found browsing e-s regarding the fets: "The datasheet says that you can run 98A through the FET if you can hold the junction temperature at 25C and 68A if you can hold the junction temperature around 100C; as far as I know those ratings are most likely severely inflated, and if you stick to 25-30A continuous and 40-50A peak with good heatsinking you stand a decent chance of being OK"

 

[wesnewell]

if you want to go to 16s lipo (67.2V), you should also replace the 63V caps with 75V or higher caps. IIRC that controller comes with a 26A max. So it shouldn't be a problem taking it to 40A max with a shunt mod. The other problem is will the LCD display work with voltages over 60V. And then you have to figure out how to raise LVC, which without doing may affect regen. I'm pretty sure everything will work ok with 14s, and maybe 15s, but I'm pretty sure it will take major mods for 16s voltages to work right. The motors no problem though. I've been running the earlier version on 24s with a 72V 1500W 40A controller for over 3 years now, but not long at top speed.

 

[dogman dan]

15s is about the max that controller will take, un modified.

The motor itself can take a lot more than that controller will dish out, so why not just get a 72v controller? 72v 40 amps is about the most you should try to run through that motor, assuming you ride hard all the time. 20s for the battery.

Bear in mind though, that some cheap bikes are not safe at 40 mph.

 

[MadRhino]

Good to have a spare on the shelf before pushing a controller, for you might have to push the whole bike.

 

[Baron]

I do have a 72V controller, but testing with my ammeter shows it peaks around 45-50 amps. On 20s lipo this is way too much for the motor, except in short bursts. I suppose I could use that controller and just go easier on the throttle, but I would always be worried about overheating the motor.

 

[wesnewell]

I run mine on 24s with 40A 72V controller, and have for over 3 years without a problem. But I've never run wot more than a couple of miles. So you can either control yourself or cut one or more shunts in the controller to lower the max amps to force yourself to.

 

[dogman dan]

Well, the spec sheet is a piece of paper, that may or may not be fact.

But if you see a 63v cap in the controller, I would call that a fact, and 63v would be your max voltage fully charged. Of course, some have pushed a 63v cap higher, and got away with it. But I would think you'd be at risk of blowing the caps at anything over 15s, or 16s for lifepo4.

Different controller, hell yeah the motor can stand 72v, but I found above 20s hard riding heated it up significantly faster. So while 24s is certainly proven to work, ride time at max speeds, or hard hill climbing, hard cornering with lots of wot after, will overheat faster on 24s vs 20s.

So the way Wes rides, 24s is fine. The way I'd ride, 20s a better maximum for that motor. On 20s I can ride hard as I want, for about 10 miles street, or 6 miles dirt before the motor gets really hot.