Max Battery voltage for Ultra motors

[greeno]

I know the Bafang motors are rated for 48v and 52v as seen on the outer housing sticker.
I also know that they will operate on either a 48v ( 54.6v max charged ), or 52v ( 58.8v max charged ) battery's.
I was also led to believe that the max these motors ( Ultra ) liked was 60v.
Would that be for the 48 or 52v series?
Would the max voltage be determined by whatever controller is installed? I would guess that the display's available are voltage specific.

Just thinking out loud.

 

[JRA]

There is so much copper in an M620 that it is hard to believe that it won't take over volting beyond what you say. However it will be limited by the controller and not sure what controller if any will allow for taking it up a notch or two. My question would be why? I find that 52v batteries are a bit of a wake up call over 48v but the point of diminishing returns is if you desire more power or more range.

 

[AHicks]

I think of controllers not so much as limiting voltage, but way more about limiting/controlling amperage.

As far as applying more power in general, I think this is going to be about where your priorities lay. Personally for instance, my bike rarely sees anything over about 15mph while under power. We both know the M620 isn't even breathing hard at that kind of speed, but it's not using a lot of power either....

Clearly, when you start applying more power, especially for any length of time, there's going to be a point where your reliability is going to go to hell. These big geared hubs are not real great at dissipating heat. It takes them a while to get hot, but at that point, if there is no cool down period, things could turn ugly quickly.

 

[loamoaf]

Here you can see a 63V marking on the stock M620 controller (blue) and an 80V on the solid state capacitor on the Innotrace controller (green) - I cannot make out the voltage on the electrolytic caps on the Innotrace (the big ones with black wrapper)

 

[JRA]

Maybe you can but my eyesight is not that good but I'll take your word for it. So with the Innotrace you could run 72v but stock caps at 52v with full cap of 58.8v.

 

[loamoaf]

A 72V (20s) pack is 84V at full charge - so I would not go over that 80V cap rating. If the bigger caps have a lower rating, I'd use that to inform my decision. I'm not sure if there'd every be voltage spikes from the pack either - I would assume not because 63V with a 58.8V fully charged pack doesn't seem like a lot of headroom.

I've got a programmable DC electronic load on the way so I can properly calibrate BMS voltage and current offsets for whatever shunt in the BMS... for whatever reason mine did not come with the proper base calibration and it's not reading charge or discharge (though it does charge the cells slowly, albeit while telling the charger to give it ~15V and 15A instead of pack voltage and 5A). I think I've fully committed to this now and have to start offering a battery building service to scrape a little bit of the setup money back. DIY is definitely not cheaper until you're 3 or 4 batteries deep, heh - but at least now I can be 100% sure of accuracy and also do a real capacity test as opposed to using numbers from the datasheet - if I want to go through the trouble. 72V is upgrade Sur Ron pack territory (which would recquire an aftermarket controller like KT or ASI)

 

[rtp]

A 72V (20s) pack is 84V at full charge - so I would not go over that 80V cap rating. If the bigger caps have a lower rating, I'd use that to inform my decision. I'm not sure if there'd every be voltage spikes from the pack either - I would assume not because 63V with a 58.8V fully charged pack doesn't seem like a lot of headroom.

I've got a programmable DC electronic load on the way so I can properly calibrate BMS voltage and current offsets for whatever shunt in the BMS... for whatever reason mine did not come with the proper base calibration and it's not reading charge or discharge (though it does charge the cells slowly, albeit while telling the charger to give it ~15V and 15A instead of pack voltage and 5A). I think I've fully committed to this now and have to start offering a battery building service to scrape a little bit of the setup money back. DIY is definitely not cheaper until you're 3 or 4 batteries deep, heh - but at least now I can be 100% sure of accuracy and also do a real capacity test as opposed to using numbers from the datasheet - if I want to go through the trouble. 72V is upgrade Sur Ron pack territory (which would recquire an aftermarket controller like KT or ASI)

The pic and post should be the answer but not completely - the caps along with probably the mosfets also have max ratings. Check some of the deep dive threads on e.g differences between M500/510 and M600 controllers - not for the Ultra but the parts differences are telling and relevant for any controller…

 

[greeno]

I was told a long time ago by EH at Luna that the Ultra will take 60v all day long and not blow.
Probably why the 52v pack (58.8v fully charged ) is so popular.
Read a bit on EP about this motor and they did reference the 63v rating on the stock capacitor.
Going to a higher voltage gives you what?
More snap? Like that's needed.

Hell I went for a ride today and had this little tough section at the top of the canyon so I went with a level 4 on the climb and I'm running a 38t in the front and was using my 40t cog in the rear and never missed a beat until I forgot to drop my assist level back down to 2 and went around a tight little corner, put a little umph into my pedal stroke and whiskey'ed off the trail into some bushes.

Been running this motor for almost 2 years and it's been flawless compared to the BBSHD's I had on other bikes and always had to replace the controller every 6 months.

As far as voltage goes I have my 7 x 14 pack (24ahr) and my larger 10 x 14 pack (34ahr) and have made a few smaller 48v battery's for friends and the extra cell in each group makes a difference for me. Im all about range and bigger is better sometimes.

If your riding on the road it probably wouldn't be noticeable but off road you can tell when you have to put the hammer down.

Thanks for the feedback.

 

[loamoaf]

I haven't ridden a 48V ebike but will say for packs a higher voltage also means lower current draw from the pack so there's a few ways it's better on the pack (longer cycle life, more energy available from the pack at a lower current draw) - but I would think going from a 4p to a 5p would make a bigger difference in that respect, as it's a 25% increase in current capacity vs a <10% increase in voltage. But I'm unsure if pack voltage correlates to phase/drive voltage or not - if it does then the motor has a higher top speed and maybe more torque? I'm not an EE though, I'm just a guy on the internet who is kind of nervous around electricity