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Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 12 Dec 2018, 3:22pm
by AJ101
Anyone gone down the route of aftermarket e-bike kits? Got to do a commute in January that would be easily do-able it normal clothes if it wasn't for a couple of huge hills in between. Not wanting to go the dedicated cycle clothing / shower / changing rooms kerfuffle, so I'm looking at affordable e-bike kits as an option.

Its a toss up between the Swytch Bike kit which I can get for £360 on pre-order or trying to put something together from e-bay.

Bit worried about the eBay route in terms of battery reliability so the idea of a UK backed kit is appealing. Especially for the money.

Did anyone get a Swytch when they were on the kickstarter thing? How has it been? Was it easy to fit?

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 12 Dec 2018, 4:28pm
by philg
Ordered my 50mile 700c kit from Swytch for £375 in May with the delivery quoted for September.
Latest update is early February but I'm not holding my breath!
Despite the delay I'm optimistic about it being pretty good, though not convinced that the RRP is realistic.
Watch this space!

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 12 Dec 2018, 5:22pm
by Canuk
If you're buying the kit from eBay, even if it's from China or Hong Kong you'll get it in 3-4 weeks or your money back, via PayPal guarantee. Batteries are now so universally reliant on the Panasonic 18650 cells (lots attached in series) that everyone uses them from Tesla to the humblest Chinese supplier. They are pretty much identical. No worries there.

I am thinking of taking a punt on the ebay kit myself, I just need a gap in the DIY in this house and I'm away!

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 12 Dec 2018, 8:41pm
by thelawnet
There are lots of different 18650 cells and it's literally dangerous to assume they will all be nice ones. Probably safe in this case.

I'm not.keen just because it lacks presumably torque sensor

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 12:52am
by The utility cyclist
thelawnet wrote:There are lots of different 18650 cells and it's literally dangerous to assume they will all be nice ones. Probably safe in this case.

I'm not.keen just because it lacks presumably torque sensor

Loads of old ex laptop 18650s are still coming up on the market from china, one of the biggest scams going and totally unregulated/policed! :x

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 8:13am
by Canuk
The utility cyclist wrote:
thelawnet wrote:There are lots of different 18650 cells and it's literally dangerous to assume they will all be nice ones. Probably safe in this case.

I'm not.keen just because it lacks presumably torque sensor

Loads of old ex laptop 18650s are still coming up on the market from china, one of the biggest scams going and totally unregulated/policed! :x


If you buy Panasonic cells from reputable sellers you won't go far wrong.

Most of which is moot because the brand new 30% more capacity Panasonic 2170 cells are just about to be released (Tesla was first to get their hands on them).

Benefits :

A 3kw 12 cell pack can be charged 100% in 12 minutes

Can be shipped with no charge (0V) on them

30% more energy density for roughly same size

Will still retain 80% of charge capacity after 1500 cycles

Same (or lower) price as 18650's

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 8:27am
by Mick F
How do these things work?
How does the system in the front wheel know you are pedalling and not just freewheeling?
Can you not just sit there and let the motor do the work?

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 9:09am
by Oldjohnw
I don't know the technicalities but on my bike there is a sensor disc on the crank a mm or so from the pedals. If the motor did all the work the battery would barely last 10 mikes.

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 9:22am
by Tinnishill
You will find technical and legal e bike info on here

https://www.atob.org.uk/electric-bicycle-zone/

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 9:26am
by pete75
I bought one of these kits. Came within 10 days weeks and no duty or vat charged if you choose the ships from Germany option. Bought a 17ah samsung cell battery from a German supplier on Ebay complete with charger and bike mounts for a couple of hundred .

https://www.aliexpress.com/item/36v-250 ... bb84e360c4

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 9:51am
by Mick F
Oldjohnw wrote:I don't know the technicalities but on my bike there is a sensor disc on the crank a mm or so from the pedals. If the motor did all the work the battery would barely last 10 mikes.
Thanks.

What happens if you pedal backwards or pedal very slowly? Does the sensor pick up that you are pedalling and therefore give assistance ......... but going forward for no effort from you?

I ask these questions because I was riding along Embankment Road Plymouth the other day on the shared use cycle/pedestrian footpath, and a lady shot past me ringing her bell as she passed. I put a bit of a spurt on and followed her for a few hundred yards - but she was still gaining on me. I noticed easily as it was very evident indeed, that she was hardly pedalling at all, just turning the cranks very slowly. Her speed remained constant and I couldn't keep up with her.

The road is basically level alongside the river, but there was quite a brisk headwind. Looking at my records for the ride, I was doing 14mph. She could have been doing 18 or more.

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 9:53am
by pete75
Mick F wrote:How do these things work?
How does the system in the front wheel know you are pedalling and not just freewheeling?
Can you not just sit there and let the motor do the work?


This senses pedalling. A lot os systems these days are torque sensing and vary the amount of power assistance with the effort being put into pedalling. Well at least that's how I think it works.
Image

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 10:16am
by Canuk
I too have been #surprised when overtaken by a middle aged woman cycling uphill at what must have been 17-20mph. I thought I was doing well at 14...
.
Having tried a few electric bikes it is possible to ride along at 20mph without much effort. But you won't get far on it maybe 5-8km before it goes phutt...

I am looking forward to these new Panasonic 2170 battery packs though (they're selling heavily into the aerospace industry). Promising two to three times the range for a similar or perhaps cheaper price. Its the range option which has put me off assist bikes so far. With 2170's you should be able to get 100-150km out of a charge, such is more realistic for me around these parts.

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 11:14am
by Oldjohnw
I don't know about back pedalling but otherwise, the harder you pedal the more support you get. There are usually several levels of assist - 5 on my bike. The trick is to use gears and assist level to maintain momentum and maintain battery. Power alone would barely get you 10 miles. Freewheel and power switches off, unless you use the override.

Re: Add-on e-bike conversion kit - Swytch or eBay kit?

Posted: 13 Dec 2018, 11:20am
by thelawnet
Canuk wrote:
The utility cyclist wrote:
thelawnet wrote:There are lots of different 18650 cells and it's literally dangerous to assume they will all be nice ones. Probably safe in this case.

I'm not.keen just because it lacks presumably torque sensor

Loads of old ex laptop 18650s are still coming up on the market from china, one of the biggest scams going and totally unregulated/policed! :x


If you buy Panasonic cells from reputable sellers you won't go far wrong.

Most of which is moot because the brand new 30% more capacity Panasonic 2170 cells are just about to be released (Tesla was first to get their hands on them).


They are called 21700 rather than 2170.

And they are available.

Short version is:

21700: 69g for 5Ah http://budgetlightforum.com/node/62761
18650: 49g for 3.5Ah https://electricbike.com/forum/forum/ba ... r18650-35e

This works out at 1.38kg for 100Ah for the 21700s, and 1.4kg for the 18650.

Nothing compelling there.

And shouldn't come as a surprise given that they are the same chemistry.