smorgasbord
Well-Known Member
- Region
- USA
While most of the discussion of Bafang Ultra motor's settings revolves around the somewhat cryptic Torque Tab, the Basic Tab, on which you set up your PAS level behavior, is the simplest yet most important tab to setup. I think every Ultra rider should setup the Basic Tab, as no OEM does it well. For instance, the Bafang default starts at a high boost even at PAS level 1 and the higher PAS levels don't have much power distinction between them. Even Mike/Frey makes the percentage number versus power applied mistake. But, let's go back to the top and look at what's on the page, EggRider style:
As everyone says, do not mess with the first value, Low Battery Protect, as it's set by the OEM according to whatever battery has been installed.
Similarly, the Limited Current (A) value is hard-limited via the controller firmware and you can't increase it (that would burn out the motor), but you can, if you really want, decrease it to effectively reduce the motor power under all circumstances. Perhaps if you needed to have your bike officially inspected to not go over some legal power limit you could use this to pass that test.
Now onto the real meat of the tab - specifying current percentages for each of the PAS levels (more on how many and which of these PAS levels you actually can specify as a rider later). When you ride your bike, you choose a PAS level and the corresponding values in this Tab tell the controller how much to scale the power output generated by how you're riding using parameters from the 3 other Tabs. That's done by multiplying the motor Current value generated by the Percentage value you specify here. In effect, this scales the power of the motor between 0% and 100%.
The Limit Current value you specify per PAS level is a percentage. If you specify 30 in the PAS level, then no matter what you do in that PAS level, the motor's output will never be more than 30% of its possible maximum (so if your Ultra is rated 1000 watts it would only produce 300 watts in this PAS level no matter what). This isn't a hard cut-off limit despite the name, though, it's actually a scaling factor. So if your motor would otherwise want to be generating, say, 700 watts of power, then a PAS Limit Current of 30 would mean it would actually be producing 210 watts.
In use, the PAS levels are physically intuitive - you're on-the-fly selecting the motor power you want in the current circumstances. But, this is different than the Bosch/Brose/Yamaha motor controllers, which have different real Modes that control power output not based on simple scaling but on applying different parameters for determining power in those different Modes. They are much more elegant systems, and take better advantage of all their motors can provide, which is how they provide great riding experiences with only 250 watts (or whatever, they're much less powerful than the Ultra). If Bafang would give us a few real Modes - even just the ability to select from a few different settings for the Pedal Assist and Torque Tabs, then we'd really have a great experience on our Ultra-powered bikes, too, but that doesn't appear to ever be in the cards. So, we work with what we have, and can only dream of the day when we would have a "Hill Climbing" Torque Tab and a "Road Racing" Torque Tab, etc. Sigh.
Lots of people have set up PAS levels without giving it too much thought, with the result that some say one doesn't need 9 levels, that 5 or even 3 levels of choice are fine. I believe that's the result of conflating an increase in current percentage with an increase in actual applied power. Going from 10% of 1000 watts to 20% of 1000 watts is a 100 watt increase, which is a double of the previous power level. Going from 70% of 1000 watts to 80% of 1000 watts is also a 100 watt increase, but that 100 watts is only 14.2% more power than the previous power level. And that's the Bafang default for level 7 to level 8! No wonder so many people feel like they have too many PAS levels - the upper ones are so close to each other!
Don't make that mistake - what I advocate here really makes a HUGE difference in your day to day riding, at least if like me you have quite varied terrain
EDIT: Talking about this off-board with another eBiker, who came up with the analogy: "It's like number of teeth on my sprockets. At the low end the difference is only 1 tooth (10 to 11 to 12), but at the high end the differences are greater (31, 36, 42, 50), yet the perceived difference in effort remains uniform." I add it here in case it helps people understand the nature of power increments.
Here's my 3 Step Process:
1) Establish what Limited Current Percentage makes your eBike feel like a good acoustic bike. Our eBikes, especially Ultra powered eBikes, are heavier than equivalent non-powered analog bikes. Heck, the Ultra motor itself is about 12 lbs, plus you've probably got another 8-10lbs of battery. The goal is to find the lowest scaling factor that you would ever want. Remember, you will always have PAS 0 to provide no assistance should you want the workout. My idea is that making my eBike feel like a good acoustic bike is the best choice for the lowest power setting.
I can't give you a percentage - this is going to vary based on whether your eBike has a carbon fiber or aluminum or steel frame, plus whether your wheels are heavier plus whether you have fat tires because it's an eBike and for acoustic you'd go narrower or even whether your Ultra is an unmodified 1000 watt version or something more souped up (52V vs 48V, modified controller hardware/firmware, etc.). For me, 7 was a good number - so far I've not felt the need to have less assistance than that. Note that Bafang and most OEMs start with 30! On my souped-up ludicrous Ultra and carbon-fiber frame, that's an insane amount of power for the lowest level. And with the throttle, I might as well be riding an electric motorcycle. That's not my scene.
2) With your lowest assistance percentage established, you know the highest assistance percentage is going to be 100. OK, maybe the Ultra is too powerful for you, but in that case, I'd still choose 100 for Assist9 and simply cut back on the value for the top Limited Current(A) field, which limits overall power.
3) Now the idea is to scale from your lowest Percentage up to 100 over 7 steps (those levels between Assist1 and Assist9). The tendency here - and I suffered with this for too long - is to have the difference in percentage between each be the same. In other words, a linear increase percentage values. To give credit where it's due, It turns out the EveryAmp's web article on the subject is spot-on in this regard (but wrong in many other places).
What you want to do here is pick a scaling factor that is same between each assist level, and that when applied starting with your lowest value in Assist1, ends up with close to 100 in Assist9. I did this in Excel with the formula where A2=A1*1.4 and dragged that down the column with "7" in A1. That ended up with Assist9 having a 103.4 value, which I deemed close enough. If your starting number is higher than 7 you'll choose something smaller than 1.4, if you starting number is lower than 7 you'll choose something higher than 1.4.
That's it - round the values and enter them in the Basic Tab for Limit Current(%). Now you've got power steps where each is a linear percentage of power more than the previous. For me, each step provides 40% more power than the prior step. That feels SO much better when riding.
OK, the rest is as everyone says:
• Probably set Assist0 to 1 or 2 for Limit Current(%). That way you get essentially no assist when pedaling, but the throttle will still work (make sure the Throttle Tab is setup correctly, more on that in another thread). If you don't want throttle in the 0 level, choose 0 and 0 for the values. EDIT: Apparently you shouldn't set Assist0 to 0 for current, as the controller overrides that with some default value of some assist. I also found that I also had to set 100 for Limit Spd(%) as well - with Limit Spd set to 1 I was getting more assist on PAS 0 than PAS 1! And finally, I have Assist0 set to 2 for Limit Current, not 1, as that actually produced less power. I don't know quite what's going on here, but my suspicion is that the controller defaults to some pre-determined value if the value you set is too low. This may be because my controller is a Luna Cycles "Ludicrious" version.
• Set the Limit Spd(%) for Assist1 through Assit9 to 100 since you certainly do not want to limit power based on motor RPM, and even if this is bike MPH speed, you probably don't want to limit it there, either. BTW, if you play around with other values and determine for sure whether it's motor RPM or bike speed or something else, please come back and tell us!
• Set your Wheel Diameter(Inch) to the closest value for the nominal wheel size. I have 27.5" wheels and I run 2.8" wide tires so I choose 28". I'm not sure what this affects, as your Display probably has another, independent, wheel size setting and that's used with the wheel rpm information to determine what speed is says you're traveling at.
• All Ultras use External Wheel Meters - the little magnet on the rear wheel that goes by a sensor. And you probably have only 1 of these, so choose 1 for SpdMeter Signal. You'll notice that in the screen grab I have this set to 2 - that's a special thing where I tell the controller there are 2 magnets and then set the wheel circumference to twice the actual wheel circumference. You'll read more about this on the Torque Tab thread. Note that I think only EggRider users can do this since most displays limit the circumference value you can set.
• Your bike's display might be setup to display only 3 or 5 PAS levels, plus a "0" level. If you delve into the display's settings you can probably find a place to change that. I personally like the 9 settings with the 40% step up in power for each. If your display is set to 5 levels, then you only get to access every other of the 10 levels - and whether that's the odd-numbered ones or the even-numbered ones depends on the Mode you've chosen (if your display lets you choose, which some do): Eco or Sport (aka Road or Off-Road).
That's it. If you try this constant percentage power increase process, report back and let us know how you like it.
As everyone says, do not mess with the first value, Low Battery Protect, as it's set by the OEM according to whatever battery has been installed.
Similarly, the Limited Current (A) value is hard-limited via the controller firmware and you can't increase it (that would burn out the motor), but you can, if you really want, decrease it to effectively reduce the motor power under all circumstances. Perhaps if you needed to have your bike officially inspected to not go over some legal power limit you could use this to pass that test.
Now onto the real meat of the tab - specifying current percentages for each of the PAS levels (more on how many and which of these PAS levels you actually can specify as a rider later). When you ride your bike, you choose a PAS level and the corresponding values in this Tab tell the controller how much to scale the power output generated by how you're riding using parameters from the 3 other Tabs. That's done by multiplying the motor Current value generated by the Percentage value you specify here. In effect, this scales the power of the motor between 0% and 100%.
The Limit Current value you specify per PAS level is a percentage. If you specify 30 in the PAS level, then no matter what you do in that PAS level, the motor's output will never be more than 30% of its possible maximum (so if your Ultra is rated 1000 watts it would only produce 300 watts in this PAS level no matter what). This isn't a hard cut-off limit despite the name, though, it's actually a scaling factor. So if your motor would otherwise want to be generating, say, 700 watts of power, then a PAS Limit Current of 30 would mean it would actually be producing 210 watts.
In use, the PAS levels are physically intuitive - you're on-the-fly selecting the motor power you want in the current circumstances. But, this is different than the Bosch/Brose/Yamaha motor controllers, which have different real Modes that control power output not based on simple scaling but on applying different parameters for determining power in those different Modes. They are much more elegant systems, and take better advantage of all their motors can provide, which is how they provide great riding experiences with only 250 watts (or whatever, they're much less powerful than the Ultra). If Bafang would give us a few real Modes - even just the ability to select from a few different settings for the Pedal Assist and Torque Tabs, then we'd really have a great experience on our Ultra-powered bikes, too, but that doesn't appear to ever be in the cards. So, we work with what we have, and can only dream of the day when we would have a "Hill Climbing" Torque Tab and a "Road Racing" Torque Tab, etc. Sigh.
Lots of people have set up PAS levels without giving it too much thought, with the result that some say one doesn't need 9 levels, that 5 or even 3 levels of choice are fine. I believe that's the result of conflating an increase in current percentage with an increase in actual applied power. Going from 10% of 1000 watts to 20% of 1000 watts is a 100 watt increase, which is a double of the previous power level. Going from 70% of 1000 watts to 80% of 1000 watts is also a 100 watt increase, but that 100 watts is only 14.2% more power than the previous power level. And that's the Bafang default for level 7 to level 8! No wonder so many people feel like they have too many PAS levels - the upper ones are so close to each other!
Don't make that mistake - what I advocate here really makes a HUGE difference in your day to day riding, at least if like me you have quite varied terrain
EDIT: Talking about this off-board with another eBiker, who came up with the analogy: "It's like number of teeth on my sprockets. At the low end the difference is only 1 tooth (10 to 11 to 12), but at the high end the differences are greater (31, 36, 42, 50), yet the perceived difference in effort remains uniform." I add it here in case it helps people understand the nature of power increments.
Here's my 3 Step Process:
1) Establish what Limited Current Percentage makes your eBike feel like a good acoustic bike. Our eBikes, especially Ultra powered eBikes, are heavier than equivalent non-powered analog bikes. Heck, the Ultra motor itself is about 12 lbs, plus you've probably got another 8-10lbs of battery. The goal is to find the lowest scaling factor that you would ever want. Remember, you will always have PAS 0 to provide no assistance should you want the workout. My idea is that making my eBike feel like a good acoustic bike is the best choice for the lowest power setting.
I can't give you a percentage - this is going to vary based on whether your eBike has a carbon fiber or aluminum or steel frame, plus whether your wheels are heavier plus whether you have fat tires because it's an eBike and for acoustic you'd go narrower or even whether your Ultra is an unmodified 1000 watt version or something more souped up (52V vs 48V, modified controller hardware/firmware, etc.). For me, 7 was a good number - so far I've not felt the need to have less assistance than that. Note that Bafang and most OEMs start with 30! On my souped-up ludicrous Ultra and carbon-fiber frame, that's an insane amount of power for the lowest level. And with the throttle, I might as well be riding an electric motorcycle. That's not my scene.
2) With your lowest assistance percentage established, you know the highest assistance percentage is going to be 100. OK, maybe the Ultra is too powerful for you, but in that case, I'd still choose 100 for Assist9 and simply cut back on the value for the top Limited Current(A) field, which limits overall power.
3) Now the idea is to scale from your lowest Percentage up to 100 over 7 steps (those levels between Assist1 and Assist9). The tendency here - and I suffered with this for too long - is to have the difference in percentage between each be the same. In other words, a linear increase percentage values. To give credit where it's due, It turns out the EveryAmp's web article on the subject is spot-on in this regard (but wrong in many other places).
What you want to do here is pick a scaling factor that is same between each assist level, and that when applied starting with your lowest value in Assist1, ends up with close to 100 in Assist9. I did this in Excel with the formula where A2=A1*1.4 and dragged that down the column with "7" in A1. That ended up with Assist9 having a 103.4 value, which I deemed close enough. If your starting number is higher than 7 you'll choose something smaller than 1.4, if you starting number is lower than 7 you'll choose something higher than 1.4.
That's it - round the values and enter them in the Basic Tab for Limit Current(%). Now you've got power steps where each is a linear percentage of power more than the previous. For me, each step provides 40% more power than the prior step. That feels SO much better when riding.
OK, the rest is as everyone says:
• Probably set Assist0 to 1 or 2 for Limit Current(%). That way you get essentially no assist when pedaling, but the throttle will still work (make sure the Throttle Tab is setup correctly, more on that in another thread). If you don't want throttle in the 0 level, choose 0 and 0 for the values. EDIT: Apparently you shouldn't set Assist0 to 0 for current, as the controller overrides that with some default value of some assist. I also found that I also had to set 100 for Limit Spd(%) as well - with Limit Spd set to 1 I was getting more assist on PAS 0 than PAS 1! And finally, I have Assist0 set to 2 for Limit Current, not 1, as that actually produced less power. I don't know quite what's going on here, but my suspicion is that the controller defaults to some pre-determined value if the value you set is too low. This may be because my controller is a Luna Cycles "Ludicrious" version.
• Set the Limit Spd(%) for Assist1 through Assit9 to 100 since you certainly do not want to limit power based on motor RPM, and even if this is bike MPH speed, you probably don't want to limit it there, either. BTW, if you play around with other values and determine for sure whether it's motor RPM or bike speed or something else, please come back and tell us!
• Set your Wheel Diameter(Inch) to the closest value for the nominal wheel size. I have 27.5" wheels and I run 2.8" wide tires so I choose 28". I'm not sure what this affects, as your Display probably has another, independent, wheel size setting and that's used with the wheel rpm information to determine what speed is says you're traveling at.
• All Ultras use External Wheel Meters - the little magnet on the rear wheel that goes by a sensor. And you probably have only 1 of these, so choose 1 for SpdMeter Signal. You'll notice that in the screen grab I have this set to 2 - that's a special thing where I tell the controller there are 2 magnets and then set the wheel circumference to twice the actual wheel circumference. You'll read more about this on the Torque Tab thread. Note that I think only EggRider users can do this since most displays limit the circumference value you can set.
• Your bike's display might be setup to display only 3 or 5 PAS levels, plus a "0" level. If you delve into the display's settings you can probably find a place to change that. I personally like the 9 settings with the 40% step up in power for each. If your display is set to 5 levels, then you only get to access every other of the 10 levels - and whether that's the odd-numbered ones or the even-numbered ones depends on the Mode you've chosen (if your display lets you choose, which some do): Eco or Sport (aka Road or Off-Road).
That's it. If you try this constant percentage power increase process, report back and let us know how you like it.
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