30 AMP BBS02?

So a question had been bugging me for a while. Why did my original BBS02 controller draw 30 amps. And why has my bike felt like a bit of a dog ever since I got my replacement controller that draws 25 amps. I managed to go about 1500 miles on the original controller. I frequently rode at max amps for 10 miles straight easily going 32 mph (Now its hard to get up to 30). I finally think I found the answer:

" -Paul EM3EV
The early bbs02 6 fet controllers (roughly early to mid 2014, but don’t quote me) could only be programmed to 20a max, but they would add some solder to the shunt, to up the current to typically about 28a.
If you measure the current with a CA or wattmeter, i think it will confirm this.
the 36v controllers don’t seem so easy to pop a fet as the 48v models.
"
So if anyone else has found themselves wondering the same thing, I think this is the answer.

Sadly this has made me a little less excited about my bbshd on the way, apparently I already know what to expect.

Wow. I had one of the original 20A controller's on my BBS-02 and "upgraded" to the 25A lunacycle controller and did actually wonder if it was slower. I too was having a hard time reaching 31 mph on my 29er.

I thought I was crazy

LyonNightroad said:

but they would add some solder to the shunt, to up the current to typically about 28a.

Click to expand...

so would this not be the simple solution for the new controller as well?

tommie said:

LyonNightroad said:

but they would add some solder to the shunt, to up the current to typically about 28a.

Click to expand...

so would this not be the simple solution for the new controller as well?

Click to expand...

Sounds like it would be. I would like to know how to add solder to the shunt.

Just because soldering the shunt can allow the controller to (mistakenly) add more amps, that doesn't mean that you have added more magnet width or copper mass to the stator. Any amps that you send to the motor over its saturation point will be very inefficient, meaning that a few of the "extra amps" will be added to the motor power, and most of the added amps will be converted to waste heat.

First gen 750W unit used six generic FETs, very inefficient, should be limited to 20A
Second gen added 3, so used 9 generic FETs. Could flow the full 25A, but inefficient FETs create a lot of heat in the controller.
Third gen switched to 9 genuine name-brand 3077 FETs due to Pauls input. More of the 25A reached the wheel, less of the amps was converted to waste heat.

Solder the shunt to flow 30A? yeah, it can be done, and the BBS02 is a couple hundred dollars cheaper than the BBSHD. The BBS02 controller will not get too hot at 30A, but the motor will, along with the generic hall sensors.

Plus, any amps you use above the motors saturation point will be very inefficient, meaning you will only get a few miles for a lot of amps.

The outer shell of the BBSHD may only be a little wider than the BBS02, but inside, the stator is almost twice as wide, with twice the swept magnet area, and twice the amp-swallowing copper-mass capacity (controller using 12 of the 3077 FETs). It has been run with an external controller up to 50A before getting hot. I'd limit it to 40A using a 48V pack (because a 48V pack would be smaller and cheaper than a 52V pack). 52V with 50A will break chains and sprockets, if you try to pop wheelies.

Because of heat, I'd recommend the

BBS02 at 52V X 25A = 1300W (stock controller)

BBSHD at 52V X 30A =1560W (stock controller)

BBSHD at 48V X 40A = 1920W (external controller)

Just my opinion, do as you please. Personally, I enjoy breaking things, and I don't blame the manufacturer when I exceed the limits of the device I'm testing. If you are committed to using the stock controller of the BBSHD, use the 52V battery at its max 30A for (52 X 30 = 1560W), thats only 260W over my max power recommendation for the BBS02, but at least it will run much cooler than a very warm BBS02 at 52V X 25A = 1300W

Thanks for the info Spinningmagnets.

I really didn't have any problems with 30 amps on my bbs02 and abused the heck out of it. The main thing was that I always waited to shift to the next gear after the amps began to fall on the current gear, this way I knew I was in a happy range for the motor.

I'm just curious. Where is the shunt located where you put the extra solder?

I don't know if I was clear earlier, I didn't add solder, I got a very early controller that was already soldered by Bafang. You could theoretically try hunting one down.

If ever a thread needed a pic then its this one!

c`mon, anyone with an early controller showing the shunt please?!!

LyonNightroad said:

Sadly this has made me a little less excited about my bbshd on the way, apparently I already know what to expect.

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Why would that be? The motor is quite different, down to the stator/copper. The old BBSxx had troubles at 750W continuous and this BBSHD (from all accounts so far) seems to be quite capable of taking 1500W continuous.

There is no way I would try to put 30 amps through a BBS02. It really can't handle 18 amps. The nylon gear is the problem. Recently I added a temperature sensor to my BBS02 and was shocked on how fast it reached 145 degrees when climbing a steep hill. Then the nylon gear melted. I replaced the nylon gear and decided to limit the current to 18 amps to keep from melting another nylon gear. This morning I tested the 18 amp bike on the same steep hill and got it up to 135 degrees fairly quickly before I stopped to let it cool down. BTW: This is the third nylon gear that I have melted. (I melted two with the older mosfets without harming the controller) Buy a BBSHD. My BBSHD doesn't even get warm on the same climb.

sather said:

There is no way I would try to put 30 amps through a BBS02. It really can't handle 18 amps. The nylon gear is the problem. Recently I added a temperature sensor to my BBS02 and was shocked on how fast it reached 145 degrees when climbing a steep hill. Then the nylon gear melted. I replaced the nylon gear and decided to limit the current to 18 amps to keep from melting another nylon gear. This morning I tested the 18 amp bike on the same steep hill and got it up to 135 degrees fairly quickly before I stopped to let it cool down. BTW: This is the third nylon gear that I have melted. (I melted two with the older mosfets without harming the controller) Buy a BBSHD. My BBSHD doesn't even get warm on the same climb.

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What kind of gearing are you in on these climbs? Would you include the Chainring and sprocket tooth counts? The motor can take 30 amps if it is spinning, but against a wall, it will eventually burn out at even 1A. So, it would depend on if you were actually proceeding up the hill and at what cadence

Good info,
I bought one of the first 6fet BBS02 from China and my Whatts Amp that usally works well showed 35A max.
I thought the Whatts Amp is broken back in 2014, but it was not.
This BBS was like a rocket. My new 9fet one is not nearly that fast in asseleration...

cal3thousand said:

LyonNightroad said:

Sadly this has made me a little less excited about my bbshd on the way, apparently I already know what to expect.

Click to expand...

Why would that be? The motor is quite different, down to the stator/copper. The old BBSxx had troubles at 750W continuous and this BBSHD (from all accounts so far) seems to be quite capable of taking 1500W continuous.

Click to expand...

The power difference has been trivial. My BBSHD is only about .5-1mph faster on the exact same setup as my 30 amp BBS02. The only part I had a problem with was when the controller finally died on my original 30amp BBS02 (when I was abusing it I might add, if I hadn't abused it, then it might still be going). I would have gladly bought another replacement 28-30 amp controller. You could buy 3-4 for the price difference between the bbs02 and bbshd. That BBS02 ran 1500 watts continuously no problem, you just had to be in the right gear, all the time.

Are you using a throttle at all? I can't imagine that the BBSHD is less than 1 mph faster on full throttle. With PAS, I could see it being limited to the same-ish speeds.

cal3thousand said:

Are you using a throttle at all? I can't imagine that the BBSHD is less than 1 mph faster on full throttle. With PAS, I could see it being limited to the same-ish speeds.

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Yes full throttle nonstop for many miles in the gear that puts the motor just barely at max amps. I don't know whats so unbelievable about it. 30 amps is 30 amps, the efficiency difference isn't going to be that big (when you are in the correct gear, just barely at max amps). When I compare my now neutered 25amp bbs02 to the bbshd, it's about a 3.5 to 4 mph difference.

I am throughly convinced that the bbs02 can handle 30 amps in the hands of a rider who is diligent with gear selection and isn't afraid to bang through all the gears. I wish I could get my hands on some more of those original controllers. I'm sure they are all a little different but probably in the 25-30 amp range. I might have just got lucky and got one on the upper end of what would pass QC.

Wait, what did I ever do with that old controller? Please tell me I didn't toss it out. It IS worth replacing the FETs on it. I already know the motor can handle the power, and with some better FETs, awesomesauce!

LyonNightroad said:

cal3thousand said:

Are you using a throttle at all? I can't imagine that the BBSHD is less than 1 mph faster on full throttle. With PAS, I could see it being limited to the same-ish speeds.

Click to expand...

Yes full throttle nonstop for many miles in the gear that puts the motor just barely at max amps. I don't know whats so unbelievable about it. 30 amps is 30 amps, the efficiency difference isn't going to be that big (when you are in the correct gear, just barely at max amps). When I compare my now neutered 25amp bbs02 to the bbshd, it's about a 3.5 to 4 mph difference.

I am throughly convinced that the bbs02 can handle 30 amps in the hands of a rider who is diligent with gear selection and isn't afraid to bang through all the gears. I wish I could get my hands on some more of those original controllers. I'm sure they are all a little different but probably in the 25-30 amp range. I might have just got lucky and got one on the upper end of what would pass QC.

Wait, what did I ever do with that old controller? Please tell me I didn't toss it out. It IS worth replacing the FETs on it. I already know the motor can handle the power, and with some better FETs, awesomesauce!

Click to expand...

Thanks for the insight on the difference between the BBSHD and BBS02. I love my BBS02. It's smaller... lighter... but like you said, a little slower with the newer controllers set to 25 amps. I've never had a problem with the nylon gear, though I do have a temperature gauge installed and am very diligent about being in the proper gear at all times.

I started this thread a little while back in the hopes that someone would demonstrate how to solder the shunt and where it is located, but no luck.

https://endless-sphere.com/forums/viewtopic.php?f=28&t=80050&p=1188321#p1188321