A few tips on fitting a new Bafang BBSxx controller

[Fordulike]

Finally got round to moving my lazy arse and fitted my replacement BBS02 controller.
The original one had given up the ghost, due to the infamous expiry of the crap mosfets Bafang used on the older units.
Luckily, all new controllers come with IRFB3077 mosfets.

It's a pretty straight forward job, but I thought I'd post a few tips on how to make life a little easier when installing a new controller.

• To remove the controller, you need to use a 3mm hex headed tool to unscrew 3 bolts. I used a 3mm screwdriver. The bolts are in really friggin tight, and I recommend using a high quality tool to prevent stripping the heads. I bought one from Wera (link here), which has the benefit of allowing a spanner to help turn the screwdriver. I wouldn't have undone the third bolt without using a spanner for extra leverage.
  
• You don't have to remove the secondary drive plastic cover to remove the controller, just loosen it. I removed the cover, so I could regrease my final drive to save doing it later. If you do totally remove the cover, then make sure you clean mud and crap off the drive unit first. You don't want this crud mixing with the black gear grease.
• Inside the unit there is a black connector, a white connector and three coloured phase wire connectors. The phase wires have bullet plugs and pull straight out. The black one requires a squeeze on the release catch, but pulls out easily. The white connector is covered in white rubbery sealant. Using a Stanley blade, I carefully cut away at the sealant before pulling the connector out. On installing the new controller, it's a good idea to reapply some sealant to this connector.

All in all it took me about 2 hours to complete. You could do it in an hour, but I like to take my time heat shrink tubing the cables and routing them neatly along the frame.

 

[Fordulike]

Went out for a spin today and had forgotten how lackluster the Bafang factory parameters are. So back in for a quick tune up with the programming cable, and it's now back to the performance it had with the old controller.

One thing I noticed, which is a bit odd, is that the Limited Current(A) was set at 24A



Considering this is a 25 amp controller, one amp less;

a) wouldn't make any impact on performance.
and
b) wouldn't serve to prolong controller longevity.

So god only knows why Bafang programmed it like this.

I set the Limited Current(A) to 25A, and the only other parameter which I changed from stock settings is the 'Keep Current'.
Bafang set this at 60%, and I don't see the point of having a 25 amp controller, if you can only use just over half of the available amps.

Changing this to 80% improves performance vastly, and limits the overall available amps to 20, instead of 15. This compliments the max '2C' rating of the battery.
It's a nice compromise between performance and battery longevity.