48V BBS02 at 36V?

[BCBeaver]

I have a 48V BBS02. I also have 2 700WH 39V batteries (11s5p). I don't have a programming cable. Before I build or buy a programming cable can my controller even be programmed to run on 36V (or 39V)?

The batteries were from a BH Atom something, they're new but will not work in the bike they're designed for so I've ripped one open and removed the BMS but not disassembled the pack, I'm thinking the easiest thing to do would be put in a new BMS and run my BBS02 off them.

 

[tomjasz]

Sorry we missed this, but no! 48V charges to 52.4V 11S is 46.2V and to close to the LVC (low voltage cutoff) to be practical.

 

[BCBeaver]

Can the controller be programmed to run at 36v?

 

[harryS]

THis website say you can lower the LVC with the programming cable. I have no cable, so I never tried. I can say though that if you attach a 36V (10S) pack, you get an immediate low voltage warning.

A Hacker’s Guide To Programming The BBS02 & BBSHD

One way that the BBS02 middrive unit shines over other competition like the Bosch is the ability to program the controller yourself. Although the process of programming the controller will void any…

electricbike-blog.com

 

[Gionnirocket]

I haven't tried to set an LVC that low on my 48v setup so I don't know if there is a hardware restriction and/or if the controller will accept a setting that low... but you are given the option in the software.
That said the Programing Cable is the best accessory I have purchased for my BBS02B. Being able to tweak the controller to how I ride has made it so much more enjoyable.

 

[tomjasz]

The problem will be the controller. Bafang often used FET’s that were in the range of the labeled power. Perhaps with firmware settings they could be changed to allow higher voltage with reduced amperage. Not clear to me and to geeky for me to even mess with it. If I were to recycle a 48v pack I’d reduce the pack to 10S and use a 10s BMS with the rated output of the motors amp specification. Remember early on the FET limit was an issue with BBS02A and I think early “B” versions. Both I believe were updated to higher power 3077 FET’s.

my understanding may be muddled some by my lack of electronics training.

However, EM3EV writes,

• “We emphasise that the 36V kits can only be used on a 36V battery. The 36V kit absolutely cannot be used with a 48V battery (31V LVC). It also cannot be used with an 11S (39.6V nominal) battery pack.”

I think this is better asked on endless_sphere.com Much smarter folks there than me. And most of all fellas that like to be inventive. Me? I stay with the model specifications and don't try to use higher voltage batteries on lower voltage systems. To many potential gremlins IME.

Now a GD MAC motor EM3ev voltage/Amperage programmable controllers and some motors and controllers of ebikes.ca are designed to run across voltage ranges.

Unfortunately, the controllers are potted and reading component ID is a major chore. Also important is whether it's an A or B model. Also in the mix are BBS01 motors at 36V. BTW "A" versions are out of luck finding a new controller and other parts!

 

[tomjasz]

The problem will be the controller. Bafang often used FET’s that were in the range of the labeled power. Perhaps with firmware settings they could be changed to allow higher voltage with reduced amperage. Not clear to me and to geeky for me to even mess with it. If I were to recycle a 48v pack I’d reduce the pack to 10S and use a 10s BMS with the rated output of the motors amp specification. Remember early on the FET limit was an issue with BBS02A and I think early “B” versions. Both I believe were updated to higher power 3077 FET’s.

my understanding may be muddled some by my lack of electronics training.

However, EM3EV writes,

• “We emphasize that the 36V kits can only be used on a 36V battery. The 36V kit absolutely cannot be used with a 48V battery (31V LVC). It also cannot be used with an 11S (39.6V nominal) battery pack.”

 

[Gionnirocket]

The problem will be the controller. Bafang often used FET’s that were in the range of the labeled power. Perhaps with firmware settings they could be changed to allow higher voltage with reduced amperage. Not clear to me and to geeky for me to even mess with it. If I were to recycle a 48v pack I’d reduce the pack to 10S and use a 10s BMS with the rated output of the motors amp specification. Remember early on the FET limit was an issue with BBS02A and I think early “B” versions. Both I believe were updated to higher power 3077 FET’s.

Thomas... I believe that BCBeaver is trying to go in the other direction... Higher Voltage motor and lower Voltage battery. Typically electronics rated at a higher voltage can be used at lower voltages though if it's way out of range you might sacrifice efficiency. That said using a lower voltage battery will increase current draw and that could potentially be a problem with the FET'S

Me? I stay with the model specifications and don't try to use higher voltage batteries on lower voltage systems. To many potential gremlins IME.

Now using things as designed is always sound advice ;-)

Since this would be a hack and getting any specifics on Chinese hardware is near impossible... I'd either use the 36V batteries to build a 48v or just sell them and use the $ to buy a proper battery. Sometimes dyi just ain't worth the hassle.

 

[harryS]

I really don't see an issue running the 48V BBS02 at a lower voltage if the firmware allows it.

He probably got the BH packs for not much money. Wonder why he felt the need to pull out the BMS. HE cpuld add 10 more cells to make it 13S-5, but I'd just stack a 2S pack in series. As long as the transistors in the 2S BMS can hold off 60V, it should work OK.

 

[Gionnirocket]

Nominally speaking he's going to draw approximately 25% more amps using a 36v battery vs a 48v... so depending on how he intends to ride it is something to consider.

 

[tomjasz]

A 36v demand depending on the controller can be as low as 13A. Or as high as 25A. I'm in the school of buying matching gear and not overthinking and trying to make mismatched adaptations. I just road home on my new BBS01B 36V 250W folder. It hit 18MPH.42T X1 1T. I'm a 250lb white whale. Saying a 36V will draw more amps isn't a universal number. It's not simply about easy math. At least that's my experience. I find 36v apporpriately sized batteries matched to a controller to be every bit as efficient.

 

[Gionnirocket]

A 36v demand depending on the controller can be as low as 13A. Or as high as 25A. I'm in the school of buying matching gear and not overthinking and trying to make mismatched adaptations. I just road home on my new BBS01B 36V 250W folder. It hit 18MPH.42T X1 1T. I'm a 250lb white whale. Saying a 36V will draw more amps isn't a universal number. It's not simply about easy math. At least that's my experience. I find 36v apporpriately sized batteries matched to a controller to be every bit as efficient.

Yes Thomas.. I totally agree.

I was speaking specifically about the 48v motor that BCBeaver currently has.
Generally speaking it will draw 25% more amperage if run with a 36v battery as compared to a 48v battery.
As I mentioned before, when components are not used as designed, efficiency suffers

 

[harryS]

I was speaking specifically about the 48v motor that BCBeaver currently has.
Generally speaking it will draw 25% more amperage if run with a 36v battery as compared to a 48v battery.
As I mentioned before, when components are not used as designed, efficiency suffers

THe above would be true of some gear (amplifiers) when you can force the output to the same power level, but as these are motors, the rpm's will drop at lower voltage and the currents is less at lower voltage..

 

[Gionnirocket]

THe above would be true of some gear (amplifiers) when you can force the output to the same power level, but as these are motors, the rpm's will drop at lower voltage and the currents is less at lower voltage..

Good point... But then I'd assume that your speed and torque would drop as well. So in order to have the a similar experience you will have to push it harder.

 

[harryS]

You can push it harder on lower voltage , but it can't run any faster than what physics allows. Rough rule of thumb is 20% slower on 36V as opposed to 48V.

 

[Gionnirocket]

So if 36v is roughly 20% slower
then you'll have to push it 20% harder to do an equivalent 10mph
= roughly 20% more current to do the same 10mph

 

[tomjasz]

Argh! Please stop the fuzzy math! I can get 20mph with a 350w BBS01 36V. My 48v isn’t any faster or less efficient if I run at 13-15A.

 

[Gionnirocket]

Thomas I think that you may be confusing the discussion.
We are talking about running a 48v motor at 36v
Not comparing 36v motors to 48v motors

 

[tomjasz]

Thomas I think that you may be confusing the discussion.
We are talking about running a 48v motor at 36v
Not comparing 36v motors to 48v motors

Regardless it’s a silly thread. Want 48v buy a 48v motor. Want 36v? Buy a 36v motor. Any other twist will be fraught with problems .

 

[Gionnirocket]

Regardless it’s a silly thread. Want 48v buy a 48v motor. Want 36v? Buy a 36v motor. Any other twist will be fraught with problems .

I agree it's not worth pursuing that setup... But the person who asked the question ended up with those components unplanned and was curious if it could work. We're just bouncing thoughts to try and help him make a decision on whether or not to try.

I'm sorry it doesn't meet your standard of an acceptable thread.
But considering that the person was looking for help, this forum has very little participation and that no one was harmed in the discussion, not to mention that you were the first to reply... You might want to refrain from passing judgment.