"Big Cat" Bafang 8fun 26" Fatbike "kit" Troubleshooting

Get all your technical information about electric bikes here.
Post Reply
User avatar
amberwolf   100 GW

100 GW
Posts: 28676
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group

"Big Cat" Bafang 8fun 26" Fatbike "kit" Troubleshooting

Post by amberwolf » Nov 07 2019 2:08am

So I found an almost complete hubmotor wheel / controller setup at Goodwill today.
--26" fatbike wheel
--Bafang 8fun geared hubmotor BFSWX02 48v500w(13)
with gear cluster and 180mm disc rotor
--controller LM1605-066-J, 48v 18A / 9A, 500w
--961 LCD (antiscratch plastic still on it)
--halfgrip throttle with half-bar grip and full grip for other side (both appear unused)
--PAS 12-magnet ring
--torque-arm kit (unopened)
--wiring harness with partly JSTs and partly Higos.
--No ebrakes, no PAS sensor, no battery or battery holder.
1106192327-00.jpg (57.92 KiB) Viewed 286 times
1106192328-00.jpg (41.42 KiB) Viewed 286 times
1106192328-01.jpg (50.23 KiB) Viewed 286 times
1106192330-00.jpg (47.86 KiB) Viewed 286 times

Had to improvise a test setup, as I have nothing at hand with wide enough dropouts in the rear for a fatbike motor, so I used some short (pitbike?) crappy forks in a heavy steel cruiser frame (to counter the wheel weight) as a test stand. I think the bent Luna fatbike fork might also work but these were on top of the "junk" pile so they got used.
1106192329-00.jpg (63.45 KiB) Viewed 286 times

Powered it on with an old 13s Luna battery kept around for testing stuff like this, and it does operate off-ground, until it reaches 9.5mph, then it shuts down, and stays shutdown for a while, before it will respond to PAS or throttle again. (Used a PAS sensor from the old Fusin kit). If I keep throttle down below that speed, it'll keep running as long as I care to do it, AFAICT.

Found the C961 LCD manual in a few places, and verified the settings all appear to be correct; speed limit is maxed at 40km/h (which should be around 25mph, not 9.5).

The only setting I can't verify is one called (IIRC) "hl 4", whcih will go up to I think 60; this comes up before the timeout setting but isn't in any of the manuals for the 961 I can find.

The speed sensor is working or I wouldn't see the MPH on the display. ;) (some systems stop if they don't get a speed signal).

There are no error codes coming up on the display. I can force an error by disconnecting the hall cable, so I can see how they would come up if there were any happening.

Current draw is normal.

There are five unused connectors, all 2-pin JSTs. One pair are black and white wires, the other pair are black and gray, and then there's a single black and red. Comparing this to another controller I've had pics of from a Rad fatbike, the gray wires probably connect to the ebrake levers. Don't know about the white or red ones; they're not in the pics of the Rad controller, or on the Fusin.

Probably have to open it up to check where those wires go.

Any ideas on why it is shutting down after reaching 9.5mph?

I verified the motor itself works (offground) by using an old LiShui controller and Kingmeter SW-LCD display. Took a bit of wire swapping of the cntroller's hall connector to match the 8fun's hall output, but once that was done it ran fine, at anythng up to the 25mph or so max speed that controller allows.

Second question: I know there are Kingmeter SW-LCD manuals around here somewhere, but I can't find them. I can only find the SW900 series, and that doesnt' match the old SW-LCD that I have. It looks similar, and most of it is the same, but if I hold down all the buttons I get a screen with "Prog 1310" (IIRC) on it, and haven't found a secret combination of button presses to get past that into anything else, and then ti times out after some seconds and goes bakc to the main display.

Anybody know what that display might mean, or if there are deeper menus for this SW-LCD like there are for the SW900 LCD?

Voltron   10 MW

10 MW
Posts: 2172
Joined: May 02 2013 4:53pm
Location: Santa Barbara CA

Re: "Big Cat" Bafang 8fun 26" Fatbike "kit" Troubleshooting

Post by Voltron » Nov 07 2019 1:00pm

Total guessing, but if it's doing it at that exact speed, some controllers switch from sensored to sensorless after getting rolling, so maybe something going on there?

User avatar
amberwolf   100 GW

100 GW
Posts: 28676
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group

Re: "Big Cat" Bafang 8fun 26" Fatbike "kit" Troubleshooting

Post by amberwolf » Nov 07 2019 9:23pm

I thought about that, but it works fine on this other controller. (which is a different brand, so might have different needs and behavior, so may not be relevant).

I haven't gone thru and tested the hall sensors, for instance, but there's no error code on either controller as long as the hall connector is plugged in.

It is strange, but it does happen at that speed. I can gun the throttle, or use the PAS, and it will spin up very quickly to something faster than that speed, but it also cuts out "instantly", and just coasts down to zero.

Another thought that occurred to me is that the controller has a very low ERPM capability, and that speed is at it's max. *Or* that it's got the wrong settings for the number of poles / gearing ratio / etc., if it has such a setting (like maybe it's setup for a DD hubmotor, not a geared, if that's possible). I just don't know how to get into any settigns it might have for that stuff.

I can't test it riding on a bike, as I have no tire that will fit this rim yet (might be able to borrow an old one from Cvin if she's got any),

I'm gonna open up the controller that came with it and see if there's anything visually wrong (blown caps, etc), if I'm lucky. ;)

Post Reply