Guest Bike Conversion

[Benjahmin]

Thanks Alan, I'll try him now.

 

[Benjahmin]

I've had an answer from Jimmy, I'll put it up here because what he says may interest others:

Hi Ben,

Thank you for your email regarding your battery requirement. You have chosen a good time to contact me as I have just acquired the best battery welder in the universe. The welder is the 250i2 EV from Sunstone Engineering and is a pulse arc welder that can weld copper interconnects. Usually nickel is the chosen interconnect material which is 4 times less conductive than copper.

Copper is only second best conductor of electrical current to silver (100%copper, 105%silver, 22%nickel), the due to being a difficult metal to weld, nickel is most common. The ultimate battery would be one that has copper interconnects which would have the best power, lowest overall resistance (creates heat), longest life cycle, just to mention a few of its benefits.

The choice would be either Panasonic NCR18650B 3350mAh, or NCR18650PF 2900mAh. Using the B cells the capacity would be 17Ah or 14.5Ah with the PF cells (5P10S configuration). Cycle life is 500.

I would strongly recommend the Boston Power Swing cells (USA) which would be over 15Ah with a cycle life of 2000-3000. These are excellent cells that NASA use in their robots as well as Volvo in the ev.

I normally use 25A continuous current discharge high quality BMS with my builds which means cooler running and higher reliability. The price of the build would be £325-£350 depending on which cells you choose. Needless to say, I'd be using copper interconnects for obvious reasons.

Best regards,
Jimmy

Anyone heard of the 'Boston Power Swing cells'? Sounds like some sort of 60's elite wife swapping group

 

[trex]

I would stick with the tried and tested Samsung or Panasonic or Sony cells - welded with 100% nickel tabs.
BTW, Boston Power cells are made in Shenzhen and Taiwan.
http://www.bloomberg.com/research/stocks/private/snapshot.asp?privcapId=30029539

 

[Benjahmin]

Thanks Trex,
I was thinking of asking him for a 4P10S made from Panasonic B cells as this would work out at 13.4Ah, which I think would do.
As for the copper straps, what he says about conductivity makes sense. Is the concern for a bi-metal junction at the battery?

 

[trex]

yes, that's what bothers me about copper tabs. The choice is down to the metal used to make the cell cans. Most 18650 cans are made of stainless steel coated with nickel, so we know nickel tabs work well.

 

[Deleted member 4366]

a motor that doesn't come in the CST flavour sadly.

Are you talking about the Q100? Here's the CST version:

https://bmsbattery.com/ebike-kit/618-q100c-cst-36v350w-rear-driving-ebike-hub-motor-ebike-kit.html?search_query=q100c&results=7

Also, the Q100s don't run very well sensorless, so stick with a sensor controller, like S06S or KU65.

 

[Nealh]

Are you talking about the Q100? Here's the CST version:

https://bmsbattery.com/ebike-kit/618-q100c-cst-36v350w-rear-driving-ebike-hub-motor-ebike-kit.html?search_query=q100c&results=7

Also, the Q100s don't run very well sensorless, so stick with a sensor controller, like S06S or KU65.

I didn't put it very well, I meant that the CST doesn't come in a 260 version, though you could run a 201@ 48v.

 

[Benjahmin]

Decided to go for this one:
https://bmsbattery.com/ebike-kit/632-q100h-36v350w-front-e-bike-motor-wheel-ebike-kit.html
Only thing that bothers me about it is the radial spoke pattern, think it'll be a problem?

 

[Deleted member 4366]

You only get the radial pattern with a 16" wheel.

 

[Benjahmin]

Gotcha, so a 700c will be standard pattern, thought it looked a bit odd.
Thanks

 

[eBike Battery Team]

I've had an answer from Jimmy, I'll put it up here because what he says may interest others:

Hi Ben,

Thank you for your email regarding your battery requirement. You have chosen a good time to contact me as I have just acquired the best battery welder in the universe. The welder is the 250i2 EV from Sunstone Engineering and is a pulse arc welder that can weld copper interconnects. Usually nickel is the chosen interconnect material which is 4 times less conductive than copper.

Copper is only second best conductor of electrical current to silver (100%copper, 105%silver, 22%nickel), the due to being a difficult metal to weld, nickel is most common. The ultimate battery would be one that has copper interconnects which would have the best power, lowest overall resistance (creates heat), longest life cycle, just to mention a few of its benefits.

The choice would be either Panasonic NCR18650B 3350mAh, or NCR18650PF 2900mAh. Using the B cells the capacity would be 17Ah or 14.5Ah with the PF cells (5P10S configuration). Cycle life is 500.

I would strongly recommend the Boston Power Swing cells (USA) which would be over 15Ah with a cycle life of 2000-3000. These are excellent cells that NASA use in their robots as well as Volvo in the ev.

I normally use 25A continuous current discharge high quality BMS with my builds which means cooler running and higher reliability. The price of the build would be £325-£350 depending on which cells you choose. Needless to say, I'd be using copper interconnects for obvious reasons.

Best regards,
Jimmy

Anyone heard of the 'Boston Power Swing cells'? Sounds like some sort of 60's elite wife swapping group

Re the Boston Power Swing cells, here's a link which you may find helpful: http://www.boston-power.com/products

 

[Benjahmin]

Bike bits ordered, all from Rose.
Front Magura HS11. An Ergotec 300mm quill stem and the Shimano 21 speed shifters.
I'll be ordering the kit when the debit cards cooled down a bit.
Yet to make a final decision on the battery.

 

[Benjahmin]

Just tried to order the wheel, controller etc, from BMS. It came to £124.35 BUT it said shipping would be £100.87 !
Is that usual?

 

[Deleted member 4366]

Sounds about right. Where else can you get that stuff from for £225?

 

[Benjahmin]

Well I had started to look at the Panda bikes front wheel kit for £250, at least it's only being delivered from Nottingham. But is it any good?

 

[Deleted member 4366]

The Panda kit is very good. You get a guarantee too (sort of). I prefer the Q100H motor, but there's not a lot in it.

 

[Benjahmin]

Thanks d8veh.
The Panda motor says it's 187rpm for a 700c wheel, whereas the BMS one would be 260rpm. I guess this would mean more torque, lower speed from the Panda?
Also I'm putting a Magura HS11 on the front, the Panda spec says that the kit is unsuitable for hydraulic brakes. I'm guessing that this is just because of the supplied cut off levers, not that the twin wall rim isn't suitable.
I'm veering towards the 'Eco' kit for £220. As far as I can see the only difference is a LED display instead of an LCD. For a guest bike I think that would do. I guess that would loose the de-restrict function, oh well.

 

[Deleted member 4366]

Yup, you've figured it all out pretty well except that you don't need to worry about derestriction with a 187 rpm motor. You don't necessarily get much more torque, but you get better efficiency at low speed, which means that you can climb steep hills for longer before the motor heats up and you use less battery. the torque depends on whether they change the speed by the motor winding or the internal gearing - most likely the motor winding, which doesn't give more torque.

 

[Benjahmin]

Well for west Wales, that sounds just the ticket, lots of slow speed hill climbs around here.

 

[Benjahmin]

Magura brake, gear changers and quill stem arrived from Rose today. Just ordered eco kit from Panda. The bullet has been bit and the fun begins.