Bafang Bpm @ 66.6v nominal 18s lipo

[Scottyf]

Maybe its because I feed the current in then with the throttle rather than full whack.
If I just opened the throttle to full from standstill it will just wheelie rather than making any decent progress.

A plug and play system would be nice. But I like only having 5 kilo of batteries and controller + connections on me rather than a bulky Lifepo4 cylinder cells which are alot heavier.

I've tired to keep weight down as much as possible while making it still portable.
Any more batteries and it will start becoming cumbersome on me and I'd have to think about mounting it on the bike which I'd rather not do. This has penalties though.
Charging methods are more of a pain breaking the packs down etc...
I now use a bulk lead acid charger to slow charge @ 2amp 72v when I can't be bothered to balance and breakdown the packs.

Mainly becasue I use my bike to go to the shops and its easier to take the batteries with me. Leaving just the bike with a hub motor on it. More discreet and less of a cost should it be stolen.

 

[wurly]

I have my BPM hub up and running now. The judder i experience is when the motor reaches the speed of the wheel rpm and the clutch engages, not sure if it's the same judder JBond is describing, it's more like a 'thud' that i can feel through the bike. When engaged, it seems like the current/power drops off and a slight twist of the throttle necessary to bring the power in once more.
I am only on 36V at the moment, i wonder what it'll be like at 48V??
I am going to choose the controller very carefully i think. It is interesting to hear about the throttle sensitivity Scotty. Most seem like they are on/off without much inbetween. I have considered scrapping the idea of using hall sensored throttles and going for cable operated mechanism pulling a 5K pot. I think Maguera(?) throttles operate this way.

 

[Scottyf]

I can make a video of how smooth it is if you like. The throttle becomes more sensitive the more volts and amps you chuck at it. This makes sense really.
Im just using a wuxing half throttle.

I sometimes get that thud as the clutch engages. It tends to be the known weak point of the first series bpm. The 2nd generation ones are meant to be much better.

It is the weak point. As well as the seals being a bit ****.

 

[wurly]

There are other problems, did you get my PM?
Nice offer of the video but i without the feel of riding the bike it probably isn't worth the effort.
I'm going to try it at 48V first and make alterations as i go. I think i new throttle and controller is on the shopping list. 48V 15Ah Ping battery i bought is here and i'll collect it tomorrow :0)
Hows the charging system working out? i wouldn't leave it unattended....

 

[Scottyf]

Use gt power a6 10amp charger at home to balance the packs every night.
Which I can just leave and let it charge the packs from empty to full in about 3 hours.

Then I have a bulk 60v lead acid charger on 72v hot which puts about 75% capacity back in the batteries without balance charging. More of an emergency charger or top up charger without breaking up the pack. 2.5 amp charge. So both chargers are slow compared to what the lipo can take. But I never need them charged quick than a couple of hours.

If I had more than 6 lipos I'd look at bulk charging 400w or 600w charger.