Best mid drive for extended, legal power limit, reliability

[AF7JA]

Having finished my commuter e-bike, pictured below, with a 36V geared hub motor; I am preparing for another project.

The next plan starts with my trike:

I am planing to go mid drive. Stage 1 is to get the trike working. I hope to do that this year.

I mention stage 1 because there is a stage 2. Stage 2 is to build a solar trailer for extreme distance touring (hey, why be a teacher if not to do epic stuff during my summers). Stage 2 is relevant to stage 1 in that it seems to be limiting my voltage choices. I am looking at solar controllers, like this one:

http://genasun.com/all-products/solar-charge-controllers/for-lithium/gvb-8a-li-lithium-solar-boost-controller/

I am seeing that most of them are 48V. This limits my trike to a 48V pack. I am looking at mid drive because I feel I am going to get the best performance out of them with a continual 100W-200W output (eventually I will be limited by my solar panels).

Even with the expectation of 100W-200W continual output on tour, I expect that in-town I will be sometimes running at up to the legal limit; but most operation will be about 500W. Reliability is job 1; I do not want an 'unrepairable on the side of the road' problem on Hwy 50 through Nevada in the summer.

I am now at the point where I am ready to order a motor. My priorities are:
1. Reliability at low power levels
2. 48 V (for panels)
3. Relative ease of repairs

I have looked at these:
GNG 2016

http://www.gngebike.com/gng-belt-kit-2016

+ cost
+ two chain-rings
+ seems to use good, and serviceable, parts
+ I like the way it looks

- reputation, I keep reading "stay away, far away"
- older model had poor reliability
- no support

Cyclone 3000W

http://lunacycle.com/mid-drive-kits/

+ overbuilt motor
+ cost

- needs a lot of tinkering to get working
- weight
- the thread on this one leaves me wondering about its reliability
- internal gears, making it hard to service

Bafang

http://lunacycle.com/motors/mid-drive-kits/bafang-mid-drive-and-parts/bafang-bbs02-750w-mid-drive-with-upgraded-3077-controller/

+ fewer external parts
+ replaceable chain-rings

- all parts internal making it hard to service
- internal controller (more fears of being stranded, a long trip would necessitate a spare contriller)

Lightning Rods Small Block
http://www.lightningrodev.com/kits/index.html

+ reliability
+ high level of support

- cost


My brain says Lightning Rods, this is due to both that I like the way it looks, and the level of support. Frankly, it will cost about twice as much as the other packages; but in a year I may have forgotten the cost and be enjoying the reliability.

The next is the Ba Fang, I am just concerned with how hard to service it looks. would really like to like the new GNG. It looks great on paper. I am just worried about the stories regarding the earlier models. If I could get past the fears regarding the earlier models, it would jump to first place.

As I said, i wan to order this monty or next, any suggestions?

 

[bobc]

Re: voltage limits, if you have a maximum power point controller on the solar, you just have to make this a boost converter & you can have absolutely any battery voltage you want. Sorry I can't suggest anything commercially available, just know I made a MPPT for charging 24V of SLA from 17V cells There might be something out there....

 

[Warren]

It sounds like you are hoping to get most of your energy from PV in real time. IMO the only one that makes sense at 100-200 watt power levels is the 500 watt, 18 amp Bafang BBs02. The no load draw of anything bigger will be over half of what you will be running it at most of the time. At those power levels it should last years with no maintenance. In fact, since that solar controller is available in a 36 volt version, I would suggest the 350 watt, 18 amp Bafang BBS01.

http://em3ev.com/store/index.php?route=product/product&path=50_36&product_id=217

It will do over 600 watts max, and with the smaller motor probably has the smallest no-load losses of any aftermarket mid-drive. It also has the advantage of a better cadence match to full time pedaling.

They use different nomenclature on their site, but you can deduce that they correspond to:

BBS01 110 mm dia. 3.8 kg wt. bb width 159 mm

BBS02 111 mm dia. 4.3 kg wt. bb width 159 mm

BBS03 123 mm dia. 4.8 kg wt. bb width 175 mm

http://www.szbaf.com/en/components/motor.html

 

[Marin]

There's a good looking L/R small block in the for sale used section.

 

[rurbano]

Hi all,

I’m looking for something similar but with a bit more power for a 20 km daily commuting.
My comfortable riding cadence is 60-70 rpm, and I don’t want to go much higher than that. The commute trip has some hills always less than 15%.
My options are:
• 48V BBS02 750W
o +weight
o +power, over 1 KW
o +power/weight ratio
o +simple
o – Efficient cadence about 90rpm ??? ?(too much for me), efficiency about 80% at this rpm??? What happens to battery consumption if I ride at 60 rpm cadence?
o –likely to have some heating problems if pushed too hard
o – difficult to have two chain rings working properly
o +- reliability

• 36V BBS02 500W
o +weight
o +power, over 800 W (enough for me)
o +power/weight ratio
o +simple,
o + price, cheaper 36V batteries
o + Efficient cadence about 67 rpm ??? (close to my personal cadence)
o + reliability
o –likely to have some heating problems if pushed too hard (25Amps)
o – difficult to have two chain rings working properly

• 48V 1 KW BBSHD
o +- weight
o +power, over 1200 W ( a bit too much for me)
o +power/weight ratio
o +simple
o – Efficient cadence about 112 rpm ???
o + no heating problems
o + Bigger motor = more efficiency ???
o – difficult/impossible to have two chain rings working properly
o - price

• Cyclone 3000W
o – weight (9 kg the complete set…)
o +power, over 2000 W (too much for me)
o +power/weight ratio
o –not simple at all to build
o – not stealthy at all
o + Efficient cadence depends on battery voltage and second reduction on the chain ring so I suppose it varies
o + bigger motor = more efficiency ???
o + no heating problems
o + have two chain rings working properly
o + price, cheap considering the power

Any ideas? Is there any other kit that would be better for me?

Bike: scott aspect 500,
chain rings: 42,32,22
Cassete: 11-32
weight: 14 Kg

My weight:90 kg

This will be my first build!!!

Thank you all.

Rui

 

[Lurkin]

Depends - do you want to tinker with it or just ride it? Further, how much power do you want?

You probably need to ride a few first - that will give you the best indication of what power you require. Its a trade off - more power, more battery capacity required, higher speed and vice versa.

Measure the bottom of your BB width and post it up as well.

 

[rurbano]

I wouldn't mind tinkering. I have access to professional tools if needed.
600w-700W efective mechanical power
I just want a good combination of power vs efficiency at a 60-70 rpm cadence.
Weight might not be a problem if efficiency is good.
For example bbshd it's a bit heavier than bbs02 but doesn't heat up so much and it seems to have a good torque at low rpm but this means that it's efficiency is good at those rpm?
Usually, if a motor not heating means that it is converting all the charge into mechanical power or that it just dissipates heat more efficiently (I'm thinking of bbshd an cyclone)?
Don't want to use the battery energy to produce unecessary heat instead of power.
My bb size is 68mm.

Thank you.

Rui