Bafang Ultra Owners - Does Your Battery Remaining Percentage Jump Around Under Load?

[mail_e36]

Hi friends,

For those of us with the Bafang Ultra Mid Drive Motor, does your battery remaining percentage jump around at all, like when the motor is under load?

Before I got my ebike, I test rode a different Bafang Ultra powered bike, and the percentage jumped around wildly under load. My previous Bafang Hub Drive ebike also jumped around, but my current ebike does not at all, rock solid and seemingly accurate, albeit I haven't drained it entirely even once yet.

I know many folks choose to display the voltage instead of the percentage, I am assuming it is to overcome this very issue?

Any thoughts are welcomed.

(For those curious, the bike I'm referring to goes by several names, including Bikonit Warthog (MD750 / HD750 / MD1000), Juggernaut Ultra Beast 2, Etek Hunter, Steamoon Spectre-X and other unbranded look-alikes from the Asia-based 'Leili' supplier.)

 

[JES2020]

Hi friends,

For those of us with the Bafang Ultra Mid Drive Motor, does your battery remaining percentage jump around at all, like when the motor is under load?

Before I got my ebike, I test rode a different Bafang Ultra powered bike, and the percentage jumped around wildly under load. My previous Bafang Hub Drive ebike also jumped around, but my current ebike does not at all, rock solid and seemingly accurate, albeit I haven't drained it entirely even once yet.

I know many folks choose to display the voltage instead of the percentage, I am assuming it is to overcome this very issue?

Any thoughts are welcomed.

(For those curious, the bike I'm referring to goes by several names, including Bikonit Warthog (MD750 / HD750 / MD1000), Juggernaut Ultra Beast 2, Etek Hunter, Steamoon Spectre-X and other unbranded look-alikes from the Asia-based 'Leili' supplier.)

This is a natural phenomenon of batteries. It has a name and the name is battery sag.

 

[mail_e36]

This is a natural phenomenon of batteries. It has a name and the name is battery sag.

Thanks.

Am I not experiencing it because my BMS is next-generation or advanced? Just curious

 

[JES2020]

Thanks.

Am I not experiencing it because my BMS is next-generation or advanced? Just curious

It will be more pronounced in relation to lower battery voltage .

 

[mail_e36]

It will be more pronounced in relation to lower battery voltage .

Good point! I hadn’t considered that, since my bike has two integrated 15A batteries totaling 30A together.

 

[LimboJim]

This is a natural phenomenon of batteries. It has a name and the name is battery sag.

Glad to know the official name, I always called it "resting" versus "load" voltage/percentage. It's definitely more pronounced at low charge levels.

Yamaha Bosch Shimano etc systems don't seem to do this, though...

 

[JES2020]

Glad to know the official name, I always called it "resting" versus "load" voltage/percentage. It's definitely more pronounced at low charge levels.

Yamaha Bosch Shimano etc systems don't seem to do this, though...

There will be sag with load, but if your motor is small and/or your voltage is on the higher end, the sag will be less noticeable.
Also the sensitivity of your display/ voltage sensor, will have an effect.

 

[kevinmccune]

This is a natural phenomenon of batteries. It has a name and the name is battery sag.

You said it friend.

 

[antboy]

Glad to know the official name, I always called it "resting" versus "load" voltage/percentage. It's definitely more pronounced at low charge levels.

Yamaha Bosch Shimano etc systems don't seem to do this, though...

I think the difference is largely in the BMS, and how it delivers power to the motor.

I don't know about the Bafang Ultra, but for the Bafang hub bikes I've ridden, they're a lot more punchy when fully charged compared to 50% drained, whereas a Shimano or Bosch motor "feels" the same whether it's 100% or 50%.

Pretty sure Shimano/Bosch are using a regulated BMS, as in governing the voltage available to the motor, for a more predictable behaviour at any state-of-charge.

What DOES change on Shimano or Bosch motors is the estimated range based on current level of assist, which is also looking at the performance over the past few kilometers, and giving you updated estimates. I can see my "Eco mode" range go up and down, based on whether I was recently in Trail or Boost for a long stretch of climb, or if I was riding with no assist for a few KM of downhill, or easy paved riding and wanted more exercise.

I'm also not sure how the Bafang controller performs compared to the 3rd party Archon controller, especially if the Archon is programmed to top off at 750W.

To be honest, I've always been curious whether the Ultra has that extra punch at 100%, or if it's the same through state-of-charge.

 

[ElevenAD]

I only get sag if i running a smaller Battery pack and the battery charge level is also low.

 

[Flannel Guy]

My ultra with archon x1 doesn't jump around too much after it gets down to about 87%. But I would use the first 10% in the first mile if it wasn't mostly downhill - after initial blowoff seems more accurate depending on my use. 50% feels like the same juice as 99/100%. My 500 watt bafang hub bike is totally the opposite - stays on 100% for quite a while and the first 15% is like half of a 30mile ride and it's what I call fun juice. After about 65% seems to drop one pas setting down and % goes down quickly - at 35% lucky to make it up a 6% grade.

 

[antboy]

My ultra with archon x1 doesn't jump around too much after it gets down to about 87%. But I would use the first 10% in the first mile if it wasn't mostly downhill - after initial blowoff seems more accurate depending on my use. 50% feels like the same juice as 99/100%. My 500 watt bafang hub bike is totally the opposite - stays on 100% for quite a while and the first 15% is like half of a 30mile ride and it's what I call fun juice. After about 65% seems to drop one pas setting down and % goes down quickly - at 35% lucky to make it up a 6% grade.

Haha!
We've been calling the first 15 "go-go juice". It's REALLY a world of difference from 100 to 50. So below 35% should be called "no-fun" juice.

 

[JRA]

Using a 52v 21700 cell battery is the most consistent method I have found over the stock Bafang 48v 18650 cell one. A little less wh's at 780 but has more range potential and more consistent output at lower voltage. Hot off the charger is for sure the best though.

 

[AHicks]

I only get sag if i running a smaller Battery pack and the battery charge level is also low.

Yup, me too. I have a 19.1ah battery and if I let that voltage drop below 45-46v on a longer run, I'll get enough sag at WOT to shut the bike right down. Thankfully, recovery is immediate if I release the throttle completely for just a second, then resume at a lower setting. That's never happened using PAS, just the throttle - as in when crossing a busy road. Good enough reason for me to be charging when we get down into the 46's. -Al

 

[kevinmccune]

Using a 52v 21700 cell battery is the most consistent method I have found over the stock Bafang 48v 18650 cell one. A little less wh's at 780 but has more range potential and more consistent output at lower voltage. Hot off the charger is for sure the best though.

Would imagine less connections equals more reliability.