Random Loss of power when pedaling? Bafang Ultra

[Gee_Whiz]

Has anyone experienced a loss of power intermittently on their Bafang Ultra (Frey ht1000 in this case)? As in, you can be pedaling and going at what speed you deem as cruising, but then suddenly the bike feels like it's stuck in mud and there's no power from the motor? The display is still on, you can still hear the motor but it's just not giving it "oomph". If you're in PAS 5 it feels like its in PAS 1.

 

[AHicks]

What if you're in PAS 4 and you shift to PAS 5 when this happens? Or whatever PAS and you shift to an available higher PAS?

 

[Bubba zanetti]

Once. Fairly warm day and a long hill. I was experimenting using throttle and was in PAS5. It bogged as you describe. I also was at about 70% of my usual cadence, so ‘lugging’ the motor. My conclusion was heat. It was a busy road with fast traffic So I didn’t get to touch the Motor to feel for heat for several minutes. When I did it felt slightly warm but not hot. Lowered PAS, stayed off throttle and upped my cadence in a lower gear. Returned to normal.

 

[Gee_Whiz]

Once. Fairly warm day and a long hill. I was experimenting using throttle and was in PAS5. It bogged as you describe. I also was at about 70% of my usual cadence, so ‘lugging’ the motor. My conclusion was heat. It was a busy road with fast traffic So I didn’t get to touch the Motor to feel for heat for several minutes. When I did it felt slightly warm but not hot. Lowered PAS, stayed off throttle and upped my cadence in a lower gear. Returned to normal.

This is the same scenario that I was referencing too.. it's usually on a fairly large hill.. doesn't always happen though.. sometimes it zips right up.. sometimes it conks out lol.

Thanks for the insights!

 

[Bubba zanetti]

Get your cadence “spin” up fairly high. I go for 90 rpm on hills. These motors don’t like to be lugged at high wattage inputs. We had an extremely warm summer, keeping up my spin, I’ve never had this problem again. I also never do full throttle and pedaling on hills at the same time.

 

[Gee_Whiz]

Get your cadence “spin” up fairly high. I go for 90 rpm on hills. These motors don’t like to be lugged at high wattage inputs. We had an extremely warm summer, keeping up my spin, I’ve never had this problem again. I also never do full throttle and pedaling on hills at the same time.

Again, TY! I almost always do throttle+pedal on hills.. Can you elaborate on what "lugged" means?

 

[AHicks]

Again, TY! I almost always do throttle+pedal on hills.. Can you elaborate on what "lugged" means?

Keep an eye on the watt meter to get a feel for the load you're putting on the motor. A high reading is fine for a minute or 2, but left there for long, it's going to get hot....

 

[Bubba zanetti]

Again, TY! I almost always do throttle+pedal on hills.. Can you elaborate on what "lugged" means?

Lugging is spinning your pedals slowly essentially. It means the motor is doing a lot of work at a low rpm. This builds heat. A faster pedalling reduces heat. Using your full throttle with high assist and pedalling slowly will overheat the motor quite quickly.

 

[Gee_Whiz]

Interesting.. had no idea but makes sense

 

[theemartymac]

Any energy your controller is trying to send to the motor that isn't converted to rotation, is converted to heat. So full throttle at low speed (hub) or cadence (mid-drive) will generate a lot of heat. The motor will de-rate to protect itself when the heat builds too high. External motor case temperature (I.e. hot to the touch) is also not a good indicator as the motor can get waay too hot long before the case gets uncomfortably warm. The case isn't meant to be a primary heat sink.

Use the throttle sparingly to boost when required, or watch your display and avoid pinning the watt meter to the top of the scale for extended periods of time. I can run both my geared hub or my Ultra mid-drive very fast and hard for the full range of the battery without issue if I adhere to those 2 points. If I'm sloppy and lazy about it, I can (and did) fault out the hub completely, or de-rate the ultra inadvertently.

 

[tmo1620]

Interesting.. had no idea but makes sense

No different than in a internal combustion engine in an automobile, if you don’t have enough rpm for a certain load, the engine stalls. Like shifting into 6th gear while doing 30mph, just not gonna work out well for you

 

[AHicks]

No different than in a internal combustion engine in an automobile, if you don’t have enough rpm for a certain load, the engine stalls. Like shifting into 6th gear while doing 30mph, just not gonna work out well for you

Actually, it's WAY different. Electric motors have huge torque right from the get go. An IC engine never has, and never will have, that feature. Sure, an electric can be stalled, and reducing the load with a change of gear ratio is effective way to cure/prevent a stalled condition, but rpm doesn't have as much to do with it as when speaking of IC engines.

 

[tmo1620]

Actually, it's WAY different. Electric motors have huge torque right from the get go. An IC engine never has, and never will have, that feature. Sure, an electric can be stalled, and reducing the load with a change of gear ratio is effective way to cure/prevent a stalled condition, but rpm doesn't have as much to do with it as when speaking of IC engines.

Well of course it’s different but same logic, a big Diesel engine produces an even higher torque ratio than electric when coupled to a proper sized torque converter and tranny( and not the type half of you all voted to give unlimited rights) and it will do the same thing and almost never stall out either but it still will under the right condition same as the op’s bike motor. You can drone a diesel right down to below idle at nearly highway speed if you have a tall enough highway gear. I can cruise my diesel 1 ton truck under 600rpm at 60mph, will it have snap and acceleration when I want it? No, so change the gear and away you go.It don’t matter the source of power in which you use to drive the motor,they all work on the same principle and all have their place where they are needed