New 36v 250w BBS01B - seems underpowered?

[Louey]

Hi all, have fitted the above with DM03 display to my wife’s bike, with new 19.2ah 36v battery. Just doesn’t have any poke, barely crawls up a 7% hill pedalling in first gear on full power. Ok on the flat, but nothing special. My points of reference are having ridden a Scott with an entry level Bosch mid drive, c.40nm of torque, and a Giant with their 70nm version of the Yamaha mid drive. Both blew the socks off this Bafang. Expected it to have more under the bonnet, with claimed torque of 80nm. Will try fitting the thumb throttle tomorrow and see if throttle only makes a difference. Brake and gear sensors aren’t causing any issue as I haven’t fitted them. Display is reading 40-odd volts from the battery, wheel size is set etc - not sure if something is set wrong, faulty, or if I was just expecting too much.

[Bonzo Banana]

Is there anyway to calibrate the torque sensor? Is there a parameter for maximum wattage from the battery. Mid-drive motors take a lot of current when climbing hills, Bosch has been reported to be well over 700W when hill climbing. I wonder if the parameters default to a lower setting by default. 250W is only 7A (250W shared by 36V) but mid-drives often use 3x that for hill climbing. You do need to look at the full spec of the battery to judge how much wattage you can take from it safely.

Geared hub motors take a lot less current at peak typically so can be used with lower capacity battery packs with individual cells that have lower peak current output. Hence you get such ebikes sometimes starting with little over 100Wh capacity at the budget end. Basically you need a decent battery with a mid-drive motor. It sounds like you have a very capable battery at 36V 19.2Ah unless its a fake aliexpress battery and only really a third of that capacity or similar.

[rjb]

Try resetting the battery management system. It can clear up many similar issues. I did this by reverse charging my battery. IE charging the battery briefly at the output terminals. Make certain you respect the correct polarity if you do this. Plus to plus, negative to negative.
Search online for more info on this. "Ebike battery reset" returns several links on how to do this.

[Louey]

Bonzo, no way of adjusting much without a programming cable, all I can really change is wheel size and max speed. Battery sourced in UK and built with Samsung cells, specifically avoided AliExpress rubbish.

rjb, thanks - will have a Google:)

[Louey]

rjb - PS: me too on the Raleigh Stowaway and Dawes Discovery tandem

[rjb]

rjb - PS: me too on the Raleigh Stowaway and Dawes Discovery tandem

I have my Tongsheng 250w mid drive motor on the tandem. No more struggling uphill.

[Trikesnbikes]

Before trying anything complicated, just try carefully remaking all the battery to motor connections. I had the same symptoms i.e. gutless performance on one of my first Bafang mid motor conversions and cured the problem by re-doing the wiring. It might not work, but then again it might and you won't have lost anything by trying.

[Bonzo Banana]

Bonzo, no way of adjusting much without a programming cable, all I can really change is wheel size and max speed. Battery sourced in UK and built with Samsung cells, specifically avoided AliExpress rubbish.

rjb, thanks - will have a Google:)

I have no idea what they cost writing this but if the programming cable will give you full control of parameters this might be exactly what you need to get the motor exactly as you want it.

[hemo]

The Bafang is a cadence rotation sensor mid drive, the lack of power will be down to the keep current and other parameters set by the supplier to prevent controller failure and warranty come backs. Most users tend to use the programming tools to boost the power.
Years ago my now defunct BBS01 came via Woosh bikes and KC was set for 20% so 20% of 18a was the power I got, most
programmers & guides reccomend to simply adjust the KC to 100% and a few other parameters.

[yakdiver]

Cold weather = very cold battery = loss of full power

[Cowsham]

Don't mess about with reverse charging lipo's -- there's a battery monitor wire connected to each battery ( or there should be ) if anything was wrong the built in battery monitor would show a fault. Sounds like there's a fault in the system or there's a torque sensor setting wrong.

[Louey]

Thanks all. Programming cable on order, battery had been indoors for a few days prior to test ride so unlikely an issue, remade all battery connections before posting, not mad keen on zapping my new (and expensive) battery backwards until tried other things. But all good suggestions.

[Cowsham]

not mad keen on zapping my new (and expensive) battery backwards until tried other things. But all good suggestions.

Don't ever -- it could go off like a very hot flare burning everything within 3m of it.

[Louey]

Quick update- programming cable arrived, tweaked keep current and current decay, also changed 44T chainring for 40T once adapter finally made it here from China. Was crawling uphill in first, now goes happily uphill in 2nd/3rd. All sorted.

[Cowsham]

Good to hear you got it sorted --- any pictures of the finished ebike?