Best Motor/Battery for a Dahon Folder?

[Cyclezee]

I want to fit a motor to a Dahon folding bike and would like some advice and recomendations as to the best motor, battery, controller for this project. I would like to acheive low weight, maximum performance and reasonable cost.

John

 

[Cyclezee]

OK, looks like I am going to opt for a TongXin motor and controller, as used by Frank on his excellent kit bike, haven't fully decided on the other components yet.
This may sound wacky, but I am thinking of carrying a battery, weighing under 4Kg, in a small rucksak / backpack on my back whilst riding, with a telephone cable style connection lead exiting the back pack and connecting to a socket mounted under the saddle. That way the battery is removed from the bike when I get off and doesn't require any sort of permanent fixture or brackets on the bike.
Has anybody tried this?
My other thought was even more wacky and inspired by suicide bombers A battery belt worn around the waist, this could also help speed progress through traffic if worn in full view of motorists. I can envisage one little problem with this one though, the anti terrorist branch and their German friends, mein Herren Heckler und Kock

John

 

[flecc]

The Team Hybrid e-cycle stunt team ride that way John, battery weight detached from the bike and in a rucksack, allowing stunt jumps and the like on their Crystalyte motored BMX bikes.

Works well, and there's a lot to be said for it.
.

 

[tgame]

A battery belt worn around the waist,

A fascinating thought. A belt would give a lower centre of gravity than a rucksack. But carrying heavy stuff oneself rather than letting the bike do it does seem a bit masochistic.

 

[Jeremy]

The rucksack battery sounds like a reasonable plan, especially as it resolves the battery mounting problem neatly.

The best (and probably cheapest) connectors would be a pair of Anderson Powerpoles. These pull apart fairly readily with a good tug, so would be OK if you forgot to unplug and just walked away. They will also comfortably handle 30 amps.

They are readily available from suppliers like RS Components rswww.com | Welcome to rswww.com, but you have to dig around their website to find all the bits you need. I ordered some a while ago, so here are all the part numbers you'd need to make up a red and black pair:

Black housing (pack of ten) - 534-979 £3.12/pack plus VAT
Red housing (pack of ten) - 534-985 £3.12/pack plus VAT
30A contacts (pack of ten) - 534-963 £1.54/pack plus VAT

These housings slide together to make multipole connectors, so you can make a polarised 2 pole connector easily. For a two pole connector pair you will need two red housings, two black housings and four contacts. The mating contacts are all identical.

I have some of these spare, as I ordered ten of each type of housing and 20 contacts, so if you didn't want to buy packs of parts that you wouldn't have a use for in future, I could let you have four housings and contacts for what they cost me, plus postage.

If you type the part numbers above into the search box at the top left of the RS website page you will go straight to the part description, with a picture.

Jeremy

 

[Miles]

A fascinating thought. A belt would give a lower centre of gravity than a rucksack. But carrying heavy stuff oneself rather than letting the bike do it does seem a bit masochistic.

I carry my battery in a backpack designed for carrying laptops. The zip is all around the sides for good access (this also allows the coiled power cable to exit at the bottom). I have a socket attached underneath the saddle and have run the cable down through the saddle post/downtube.

If the weight is on the person the centre of gravity isn't important in the same way. If the weight is higher up and you are leaning forward slightly, 4 kgs is almost unoticeable. Weight on the bike is much worse than weight on the rider.... well, in this context, anyway

 

[Cyclezee]

Brilliant Miles and other respondants, that is all very helpful.
I was thinking about running the cable down the seatpost somehow and I already have a Belkin laptop backpack, but would probaly use a smaller one that I also have with a bit of added reinforcement and padding.
2 more questions Miles, do you have any photos and what battery are you carrying?

John

 

[Miles]

This may sound wacky, but I am thinking of carrying a battery, weighing under 4Kg, in a small rucksak / backpack on my back whilst riding, with a telephone cable style connection lead exiting the back pack and connecting to a socket mounted under the saddle. That way the battery is removed from the bike when I get off and doesn't require any sort of permanent fixture or brackets on the bike.
Has anybody tried this?
John

Sorry John,

I read through the thread too quickly..

Yes, this works fine. If you're lucky you can still find the old coiled electric kettle leads. I used external mains sockets and plugs from Wickes.

It's very convenient being able to get off the bike and easily carry it up steps etc.

The weight is to a certain extent "suspended".

The bike handles much like a normal bike (my motor and drivetrain add about 3.5 kgs).

 

[Cyclezee]

What bike and motor are you using Miles?

John

 

[Miles]

Brilliant Miles and other respondants, that is all very helpful.
I was thinking about running the cable down the seatpost somehow and I already have a Belkin laptop backpack, but would probaly use a smaller one that I also have with a bit of added reinforcement and padding.
2 more questions Miles, do you have any photos and what battery are you carrying?

John

I'll post some photos of the whole set-up in about a week. At the moment it's somewhat disassembled whilst I do a final neat wiring job.

The laptop bag that I have has 2 pockets. The battery goes in the one furthest away from my back, with flameproof padding in the inner one

The battery is just a provisional set-up for testing - 4 Wickes 18V NiCad power tool packs (2s2p).

 

[Miles]

What bike and motor are you using Miles?
John

Moulton TSR 27

The motor is a one off made by Southwest Windpower in the USA

Synchronous belt to the Dual Drive hub gear.

Derailleur use the 4 remaining sprockets.

It has 3 freewheels

 

[fishingpaul]

This is probably silly but i can just imagine you being ordered, to lie down on the ground whilst surrounded by armed police,or knocked off your bike by an upstanding citizen,sorry guv i thought you were a suicide bomber.

 

[Cyclezee]

Moulton TSR 27

The motor is a one off made by Southwest Windpower in the USA

Synchronous belt to the Dual Drive hub gear.

Derailleur use the 4 remaining sprockets.

It has 3 freewheels

Respect Miles,
sounds very exclusive and rather expensive?
Would love to see some pics if possible?

John

 

[Miles]

Respect Miles,
sounds very exclusive and rather expensive?
Would love to see some pics if possible?
John

The only expensive bit was the bike....

I promise I'll post some pics here, before the end of the month.

Miles

 

[Cyclezee]

Look forward to seeing your photos Miles.

Thanks ,

John

 

[mk1]

Moulton TSR 27

The motor is a one off made by Southwest Windpower in the USA

Synchronous belt to the Dual Drive hub gear.

Derailleur use the 4 remaining sprockets.

It has 3 freewheels

Miles, have you had chance to take any photos of the bike yet?, I would be interested in seeing them!

Martin

 

[Miles]

Sorry, Martin, I've been too busy with work to spend the time finishing it off. Hopefully, within the next couple of weeks...

 

[flecc]

It has 3 freewheels

Makes a lovely noise but doesn't actually drive anything?
.

 

[Miles]

Actually it makes more noise when you pedal without any assistance from the motor. The sound of the motor drive is less than the sound of the freewheel isolating it.. Think I'll swap the freewheel for a sprag clutch, in the future...

 

[kraeuterbutter]

battery in a rucksack: thats the way THEY do it here on the pics as well:
http://www.bike-elektro-antrieb.ch/07_aug/Kabel_01_.jpg
http://www.bike-elektro-antrieb.ch/Bilder/Antrieb_47.jpg
http://www.bike-elektro-antrieb.ch/bilder3/dev_3_4.jpg

for 4kg battery-weight:

inthe other Bromton-20"-Folder with Nano-Thread
HERE: http://www.pedelecs.co.uk/forum/electric-bicycles/1673-test.html
he says: up to 9miles range with 36V BOSCH battery 2,6Ah

when you dismantel the BOSCH-Battery-pack and reconfigurate the cells, so they are very FLAT and can huddle against your body, very close to your budy
cell-weight: ~860g

so 1kg should be doable (schrinkrapping or taping the pack and applying some foam plastic between the cells and your back)

i think 1kg flat mounted on your back should realy not be much feelable