A FRESH START

[brianw]

After bad experience with two bafang BBSO2 motor kits, controllers and LCD's,I've decided to start again from scratch.
I'm looking for advice from forum members to decide which mid drive kit to buy.
I'm looking primarily looking for reliability for use on road and mild off road use, not down hill wild stuff.
My bike is a Marin Wolf Ridge full suspension which has a good frame shape for mid drive motor mounting.
I have a 32 teeth chain wheel and prefer high cadence. I believe this should protect the controller.
What voltage and power will be sufficient my requirements? Is it correct that higher values of these used at low end power will give less trouble?
Which make of kit are available? Bafang are cheap but, as they say, you get what you pay for.
Which type of battery will give reasonably long life and ease of use? I'm getting tired of constantly trying to balance LiPo battery cells.
If after satisfying all these and I do get a problem, where can I get an expert repair company?

 

[Woosh]

tried and tested combo: external KT controller + external pedal sensor + GSM motor.

 

[Nealh]

This is the next mid drive I will use with 17a dual voltage KT controller and a home welded GA or VTC6 13s 48v battery main battery.

 

[anotherkiwi]

tried and tested combo: external KT controller + external pedal sensor + GSM motor.

I am a tried and tested user!

A 17 A 36/48v KT controller, KT 12 magnet PAS and a 44.4v 12S battery is probably mid drive happiness.

What LiPo are you having problems balancing? Hobby King Graphene costs, Graphene rocks!

 

[brianw]

I am a tried and tested user!

A 17 A 36/48v KT controller, KT 12 magnet PAS and a 44.4v 12S battery is probably mid drive happiness.

What LiPo are you having problems balancing? Hobby King Graphene costs, Graphene rocks!

My batteries are Turnigy 5000mAh 6 cell 20-30C discharge 22.2v
I have used two in series and another two in parallel but lately just one series pack
The parallel arrangement often gives preferential use of one series set and as they get older one cell discharges down to less than 3.8v on one pack using either setup, and my balance charger will not cope with that low cell

Which motor do you use on your mid drive?

 

[brianw]

tried and tested combo: external KT controller + external pedal sensor + GSM motor.

tried and tested combo: external KT controller + external pedal sensor + GSM motor.

Do you sell the kit you describe?

 

[brianw]

This is the next mid drive I will use with 17a dual voltage KT controller and a home welded GA or VTC6 13s 48v battery main battery.

Will that be using a Bafang BBSO2 motor?

 

[Nealh]

Will that be using a Bafang BBSO2 motor?

No, I already have BBS01 now on it's second controller.
GSM with out internal controller as sold by Woosh Bikes.

 

[brianw]

No, I already have BBS01 now on it's second controller.
GSM with out internal controller as sold by Woosh Bikes.

Cheers

 

[Nealh]

I am a tried and tested user!

A 17 A 36/48v KT controller, KT 12 magnet PAS and a 44.4v 12S battery is probably mid drive happiness.

What LiPo are you having problems balancing? Hobby King Graphene costs, Graphene rocks!

Aren't they damn heavy and I only have the 8ah ones which I use in 10s config. I am slowly dumping my lipo once I have fully discharged them.
Haven't decide what to do with the G's at the mo but may wire up a permanent 10s bms for more manageable charging.

 

[anotherkiwi]

My batteries are Turnigy 5000mAh 6 cell 20-30C discharge 22.2v
I have used two in series and another two in parallel but lately just one series pack
The parallel arrangement often gives preferential use of one series set and as they get older one cell discharges down to less than 3.8v on one pack using either setup, and my balance charger will not cope with that low cell

Which motor do you use on your mid drive?

GSM from woosh. My LiPo is 10 Ah, I had problems with a 4S Multistar brick but once I started paralleling with a 4S Graphene the low cell started balancing! With 20 Ah I am not putting any stress on the packs, sag was down to the 10ths of a volt

 

[anotherkiwi]

Aren't they damn heavy and I only have the 8ah ones which I use in 10s config. I am slowly dumping my lipo once I have fully discharged them.
Haven't decide what to do with the G's at the mo but may wire up a permanent 10s bms for more manageable charging.

They are heavy but the quick charging and huge output more than compensate I feel. I am pretty sure I could almost get 10 Ah from the Graphene without going much below 3.6v per cell.

As I have often said in other threads I will probably get a welder and build a 20700 cell battery. I am back to thinking about balance charging 6S 20700 batteries (so no BMS) which I will series and set the controller LVC to C = 3 (39.5v). That way I can continue to use the two Turnigy Reaktor chargers. The LiPo will be on board as a 8 Ah backup battery.

 

[anotherkiwi]

An update to this thread after +2 months commuting to and from my new flat in a hilly area:

- in order to save weight I have been running with the Graphene bricks in 10S 36v 10000 mAh mode
- I get about 35-40 km from a charge (down to 37-37.5v or so, read below)
- I am charging every 2 days

After saying that Graphenes don't sag on hills I have found some hills where they do! About a volt on my regular routes. I know where there is a >30% gradient in my immediate neighbourhood, haven't tried it on the bike just yet but it is a 1st gear hill in your average diesel car...

I am using the 32 tooth chainwheel which has advantages and inconveniences such as me spinning too fast for the motor and generating back EMF. Not much fun on the hills! I have tried training myself to spin more slowly but it is counter intuitive to me

I am very fit now I typically see battery usage of 5.8 Wh / kilometre and speeds between 32 and 37 km/h. Top speed 47 km/h over about 50 meters (that steep!), average speed 23 km/h and hill climbing lowest speed of 14 km/h (assistance level 5, battery hot off the charger and me pedalling like a maniac).

Yes I have also tried with the big 20 Ah battery and yes, it does make a difference, but... It is very heavy. The Multistars take too long to charge compared to the Graphenes. So most times it stays at home.