Shunt mod to BL36 controller... I think I went too far

[Christobel931]

Just in case anyone has, or is thinking of trying to get more amps out of a BL36 (or Aotema) controller... here's what NOT to do!

I found what I believe are they shunts, there are two in parallel, I don't have a "before" pic, but they were soldered together heavily on one end.
The controller would top out at right around 23 amps with my 36v lifepo. I saw a max of just under 900W with this setup.

So this morning I added a little solder, and I should add, I have no idea WTF I'm doing... now it looks like this:

After doing this I went for a test ride...

Amps peak: 40.86A
Watts peak: 1462 W

I didn't see any smoke on my 4 mile trip, the difference was a noticeable snap in acceleration and a little better hill climbing, but not that much.
I added solder to the ends at the low side (as seen in pic) and a little along the bars. Any coments/suggestions from the experts are welcome. (to a point :wink: )

 

[fechter]

It looks fine like that. Sounds like you have it about right. Just keep an eye on controller temp to make sure it doesn't overheat on long hills etc.

 

[Christobel931]

It looks fine like that. Sounds like you have it about right. Just keep an eye on controller temp to make sure it doesn't overheat on long hills etc.

Oh yeah? That's good to hear... I did clean it up a some and will retest it tomorrow, my test ride is mostly all uphill ~4+% for a couple of miles and the controller felt only very mildly warm on the heat sink side. The motor wasn't warm hardly at all...

Thanks, Chris

 

[Russell]

Dogman posted a picture of the Aotema controller here;

http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=8361&start=0#p126418

that shows it has 12 FETs yet the controller appears to limited to about 20A as it is delivered. However there are resellers of the same kit claiming it's a 50A controller. This begs the question; is the controller really capable of 50A but restricted to 20A?

-R

 

[Christobel931]

Its above my head at this point, however, that is the same controller it appears, and yes, it has 12 FETs.

As posted earlier, I maxed out at a little over 23 amps routinely before. There are two shunt wires, and before I messed with it, it had a glob of solder in between the two wires on one end only. I did the same on the other end and almost doubled the amperage.

It is advertised at Bernson EV as 50amp but who knows about that? The caps are 63V FWIW.

The wiring coming out of the unit wouldn't indicate anything like 50amps....

 

[dogman dan]

WE marketing guys were the ones saying 50 amps. They also like to say 20 miles at 20 mph on 12 ah slas. :lol: :lol: :lol: Don't believe WE's hype is the first thing I learned about ebikes.

 

[Russell]

WE marketing guys were the ones saying 50 amps. They also like to say 20 miles at 20 mph on 12 ah slas. :lol: :lol: :lol: Don't believe WE's hype is the first thing I learned about ebikes.

It DOES seem like with 4 FETs per phase that the controller should be capable of delivering more than the 20-23A people see out of the stock controller. The competition uses 9 FETs for their 20-25A controllers so I wonder why WE uses 12. Don't get me wrong if they want to provide a robust controller then de-rate it so the failure rate is low that's fine by me but it's funny they would go the extra mile on the controller but they won't pop for a couple extra bucks for a double-wall rim!

-R

 

[Christobel931]

Don't get me wrong if they want to provide a robust controller then de-rate it so the failure rate is low that's fine by me but it's funny they would go the extra mile on the controller but they won't pop for a couple extra bucks for a double-wall rim!

-R

I know... :x The rim is a POS. The controller actually looks like a pretty decent unit in my limited experience, maybe they got a "deal" on a bulk purchase.

FWIW, I removed most of my "mod" and it's pretty much back to what it was, now 25amps max. I will be leaving it as is, and looking at a higher voltage/ new controller option, or a geared motor at 48V. I am putting in some serious miles now, with 20-30 mile round trips at least 2-3 times a week, with over 1000ft of elevation change on most.

I'm finding that as it warms up, I can no longer get where I'm going "sweat free" with my current setup, on this hilly terrain.

 

[dnmun]

if you squeeze the 2 shunt wires close together, then you can fill the space between them with solder. it reduces the resistance so the current limit goes up and you don't end up with that pool of solder from just melting it into a pool on the pcb. there are some high side drivers just above the shunt so you should not allow it to run all over the board.

there are 2 types of 36V shenzen controllers i have seen so far. one has the NEC 3435 FETs which are good for 40V and then the other 36V controller is identical except for the p75n75 FETs good for 75A at 75V. that controller can actually be modified to run on 72V lifepo4 too.

solder up the shunt to get to 40-45A. you need to change the caps to 100V1000uF, and adjust the input power resistor to 600 ohms, and you may have to adjust the LVC if you don't have a BMS.

 

[Christobel931]

dnum,

The pic you see with all of the solder, most of that was as delivered. So if I was to redo my "mod', I would need to upgrade the caps too.... :?

I have a BMS and plan to have a CA at some point so LVC isn't a problem i dont think,, as a matter of fact, I haven't gone below 35 volts at all yet.

You mention the Shenzen controllers, these are ecrazyman controllers you are speaking off? My inclination at this point is to call ebikes.ca and order up a 30A, 24-72 pedal first controller with CA plug in, and get a Ping 24V 15ah, to put it series with my 36V... using the CA to limit things if necessary, it might be ok?
After that it's like X5 time, and I am trying to keep weight down.

 

[dogman dan]

I go up 1000 feet, and back down 200 on my 15 mile ride home so I know what you mean. One section is pretty impossible without some sweat. One nice feature of my ride is the last 5 miles is nearly flat, so I get to dry off by the time I get home. Still, I find the 36v setup pretty adequate, riding 30 miles a day. The hill was a lot harder 3000 miles ago last year.

 

[Christobel931]

I go up 1000 feet, and back down 200 on my 15 mile ride home so I know what you mean. One section is pretty impossible without some sweat. One nice feature of my ride is the last 5 miles is nearly flat, so I get to dry off by the time I get home. Still, I find the 36v setup pretty adequate, riding 30 miles a day. The hill was a lot harder 3000 miles ago last year.

That is nice to have a rest like that before you get home, mine is uphill till the last 1/4mi. so even if I try to take it easy, I'm still all overheated when I arrive... no time to "aircool"...

I tried to range test my battery today... I've never had it cut out on me, till today, and it has over 15 cycles on it. I was at around 11ah used and I was near home so I decided to detour down this steep access road to a small reservoir near the house, never been down it before.. we're talking over 12% grade, anyway, tried to climb out while pedaling assisted down to below 10mph, and it cut out at 35v. Reset it and baby'd it the last couple miles back home, luckily this was the less steep approach to my house. It cut out 2 more times before I got back.
I don't know what my ah draw was as I lost the data on the WU meter but it wasn't any 15ah... I don't think it helped I mounted the meter on the handlebars and added about 5 feet to the power line. I plan to put the meter back by the battery and range test it again, with short wires and without the extreme hill at the end.

Anyhoo, today was errand day before my little detour, did 22+ miles round trip with 1423ft of decent, and the same back up... all rolling hills, I'm not sure there are even any flat spots at all around here. :lol: