If I increase the speed limit on the Bafang 850c display, will this wear out the controller/motor quicker?

MontyPAS

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In the title really
If I increase the speed limit on the Bafang 850c display, will this wear out the controller/motor quicker?
You will go faster....... Possibly?
;)
 
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Woosh

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May 19, 2012
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the BBS01B is the most reliable among Bafang BBS kits.
The risk of damaging the motor is small but you should still not do it.
 
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MontyPAS

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If it is capable of being increased why not do it. I've got BBS02's and a HD. All pretty much programmed to run at max without too many issues. Had a few failed displays but nothing mechanical..... Yet
 
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vfr400

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Jun 12, 2011
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You have to understand how a crank-motor works. When you give it max throttle or max PAS, the current through it depends on the crank speed. Highest current is at lowest crank speed. Therefore, if you're in top gear at 15 mph and you release the speed limit, the crank speed will go up and the current will go down, so there will be less stress on the motor.

If you have say two more gears at 15 mph, when you hook up the next gear, the crank speed goes down, which increases the current and the stress on everything in the motor goes up.

If you have a high top gear, the motor probably won't have enough power to get up to its efficient speed, which is bad for it and your range.

In other words, as long as you always use the gears to pedal at the same speed in the range 60 to 90 rpm, it'll make very little difference to the motor, but will make a difference to your range from the battery.
 
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JanksDnB

Finding my (electric) wheels
Feb 21, 2021
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You have to understand how a crank-motor works. When you give it max throttle or max PAS, the current through it depends on the crank speed. Highest current is at lowest crank speed. Therefore, if you're in top gear at 15 mph and you release the speed limit, the crank speed will go up and the current will go down, so there will be less stress on the motor.

If you have say two more gears at 15 mph, when you hook up the next gear, the crank speed goes down, which increases the current and the stress on everything in the motor goes up.

If you have a high top gear, the motor probably won't have enough power to get up to its efficient speed, which is bad for it and your range.

In other words, as long as you always use the gears to pedal at the same speed in the range 60 to 90 rpm, it'll make very little difference to the motor, but will make a difference to your range from the battery.
I kind of thought this was the case. I'm always pedaling fast, I don't have a cadence sensor yet, but it is one of my next purchases. I haven't installed the throttle either as I think it's unnecessary and heard it is pretty bad for the kit.

The display shows a power reading in watts, I've noticed if I am not using my legs as much, or haven't dropped to a low enough gear, I see this number going above 250W, will constantly running it at 250W and above wear out the kit? Is this a good indicator of stress?

Is it wise to give the bike a once over every couple hundred miles to check for loose screws/locknuts etc? I've read that the motor can need to be greased after a while, any ideas after how many miles this might be?

I'm really happy with the kit overall and the range I'm getting. I did 40 miles my first night out (Food delivery courier) in an incredibly hilly city, and the battery (18.6mah) still had 50% left. Plus I was able to work the next night, which was the main reason for converting in the first place.
 

vfr400

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The higher the power you see on the meter, the faster you're wearing out the motor. In fact it's probably an exponential relationship.

The controller doesn't wear out, but if you hold too much current for too long by letting the crank speed drop, it overheats and something pops.

250W is nothing. Continuous 400W+ is the danger zone.
 
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MontyPAS

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May 16, 2020
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I haven't installed the throttle either as I think it's unnecessary and heard it is pretty bad for the kit
One of my Bafang's has done close to 2000 miles, with heavy use of the throttle and high PAS. I live in Cornwall and my locale is very hilly.
Use the gears, spin the cranks and you will be fine.

Stop worrying about "what if"..... just enjoy the motor :rolleyes:
 
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JanksDnB

Finding my (electric) wheels
Feb 21, 2021
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The higher the power you see on the meter, the faster you're wearing out the motor. In fact it's probably an exponential relationship.

The controller doesn't wear out, but if you hold too much current for too long by letting the crank speed drop, it overheats and something pops.

250W is nothing. Continuous 400W+ is the danger zone.
Thanks for your advice, this clears up a lot for me.
One of my Bafang's has done close to 2000 miles, with heavy use of the throttle and high PAS. I live in Cornwall and my locale is very hilly.
Use the gears, spin the cranks and you will be fine.

Stop worrying about "what if"..... just enjoy the motor :rolleyes:
Sounds like they really are reliable. I am very impressed with how easy they are to fit, and how powerful they are, even the 250W seems powerful, the 1K must be an absolute monster.

Thanks for the advice.
 
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vfr400

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Jun 12, 2011
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Thanks for your advice, this clears up a lot for me.


Sounds like they really are reliable. I am very impressed with how easy they are to fit, and how powerful they are, even the 250W seems powerful, the 1K must be an absolute monster.

Thanks for the advice.
The HD running at 48v and 25 amps is roughly double (2.168) the power of yours. and the 52v takes it up to 2.33 times your power.
 

MontyPAS

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May 16, 2020
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The HD running at 48v and 25 amps is roughly double (2.168) the power of yours. and the 52v takes it up to 2.33 times your power.
But what fun can be had with BBSHD at 52v / 1000w! ;) :eek:
 
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JanksDnB

Finding my (electric) wheels
Feb 21, 2021
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The HD running at 48v and 25 amps is roughly double (2.168) the power of yours. and the 52v takes it up to 2.33 times your power.
Sounds like a machine. Would you suggest sealing the bottom of the motor where the cable entry is with either silicone or grease? I will avoid using it in bad weather as much as possible, but it probably won't be completely avoidable
 

MontyPAS

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May 16, 2020
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Sounds like a machine. Would you suggest sealing the bottom of the motor where the cable entry is with either silicone or grease? I will avoid using it in bad weather as much as possible, but it probably won't be completely avoidable
I rode one of my BBS02 500w through wet Cornish winter without any issues of water ingress into the controller.
I fit and recommend these https://www.brightonebikes.co.uk/store/p120/Lekkie_Final_drive_cover_BBS01/02(B).html , it makes loobing the internals a breeze without a strip down.

The biggest issue for water ingress is with the displays, meant to be IP rated?
Must be to the chinky standards.
They need a plastic bag over them (secured with a rubber band) in pouring rain. Ive blown two!
 
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JanksDnB

Finding my (electric) wheels
Feb 21, 2021
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I rode one of my BBS02 500w through wet Cornish winter with any issues of water ingress into the controller.
I fit and recommend these https://www.brightonebikes.co.uk/store/p120/Lekkie_Final_drive_cover_BBS01/02(B).html , it makes loobing the internals a breeze without a strip down.

The biggest issue for water ingress is with the displays, meant to be IP rated?
Must be to the chinky standards.
They need a plastic bag over them (secured with a rubber band) in pouring rain. Ive blown two!
Looks great, will definitely look into this more in the next few weeks, seems like it saves a lot of hassle when greasing. I thought the display might get damaged, I'll carry something to cover it with me from now on
 

MontyPAS

Esteemed Pedelecer
May 16, 2020
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