Plunge Taken - Electric Folder

[homemoz]

Well, after much deliberation I have entered the realms of electric bike owners. The bike is a Dahon Caio conversion from CH White. So far first impressions are favourable. Although not as powerful as some mentioned on this forum - 180 watts, it got me to work and back yesterday, about 6 miles each way by the direct route with a few smallish hills, with no problem and pretty quickly too.

A couple of criticisms concern the weight which at 18kgs without battery make it too heavy to be heaving in and out of the back of the car on a frequent basis. I take Fleccs comments on lithium batteries, but a smaller, lighter battery that could use the standard rack would make all the difference to portabilty.

The twistgrip throttle, although easy to use, is a little small in relation to the handlebar grip and could be tricky if you have a poor grip. Even though I have a decent grip, I may need to modify this. Removal of the front wheel also looks daunting and could do with some way of allowing the motor wiring to be disconnected easily. I suspect that this may be common to a more than a few ebikes.

The Caio may look a little strange but is a joy to ride. More comfortable that my other folder - a Trek F600, which feels very harsh in comparison. The 5 speed hub gears also seem well suited to electric power.

On balance I'm quite pleased - especially with quality of the Dahon. The service from CH White has been very efficient and the fact that they are a well-established firm was the main reason I bought from them instead of one of the cheaper ebay bikes. May have a go a writing a review when I have had more use of the bike.

 

[rooel]

I think you made a wise choice with a Dahon folder. All their models are good high quality mass produced bikes, and if electric traction is to be added to a bike, it makes sense to choose something stylish and reliable.

I use the Sram Sparc system on the Dahon Speed P8 and with 18.5* volt lithium 10 amp cells replacing the Sparc nimh 16.8 volt 8 amp I have an overall weight, including battery, of around 18kgs. This is lighter than just about everything else, not too noticeable when riding, but a huge difference if the bike has to be lifted through doorways, up steps, into trains or cars, yet with 20 inch wheels these folders handle, and travel, much like "full-size" bikes. There is a further advantage in having an overall length of 1500mm against 1800mm so that often enough their folding ability does not have to be used for storage in the house or on vehicles.

*This 10% over-voltage alone makes the cost and long term question marks for lithium well worth the risk. It provides a noticably "zippier" performance, and possibly saves battery power by providing more rapid acceleration up to the 15mph cut-off point.

 

[homemoz]

Thanks Roo. I agree with the comments about the Dahon bikes. Your weight for the speed is pretty low. I seem to recall these are the steel frame folders? Also, interested in your comments about the lithium replacement for your Dahon. Are the lithium and NIMH batteries generally interchangeable provided they have comparable specs? I would probably invest in a lithium longer term, so I can tranport the bike more easily and reduce weight, if it were possible to get one to fit.

I got the impression from CH White, that there are incompatabilities with the controllers if a lithium is substituted for an NIMH. Maybe Flecc would know about this? Also, Wasn't sure how to go about getting one that has the right connecter etc. Are there firms that supply custom batteries to order, or are we talking standard fitting (unlikely, I know)? At this stage of my knowledge it still seems fairly esoteric.

 

[rooel]

Well, perhaps 19kgs is nearer the mark with Sonx front dynohub, lights, flashers, bell, speedometer, and mirrycle added to the basic Speed P8 with mudguards, propstand, lithium battery and Sram Sparc system. The Rooel I purchased from CH White last year with the same additions weighs around 18kgs. These weights are obtained by hanging the bikes from a 25kg spring balance with 100gm divisions, and correspond roughly to the measurements obtained by balancing the bikes on the bathroom scales.

I have not noticed any problems with combining lithium cells with the original Sram Sparc controller/battery meter, and they do not seem to have had any adverse effect on the circuit board inside the hub. Electricity is electricity no matter its source, but there may be questions regarding "impedance" on which I am no expert.

As far as substituting cells is concerned you would have to measure the dimensions of the cells inside the battery container and then obtain a supplier who offers lithium cells of similar or smaller dimensions, or else substitute a new battery box. I found that the 18.5v lithium packs from Rechargeable Battery Pack Li-ion NIMH NICd Li-Po Battery Charger (batteryspace) were of similar dimensions to the Nimh packs sold with the Sram Sparc system, so that I was able to fit them into the box which fits on the rear rack.

 

[alex]

Hi Rooel. That is a useful link (batteryspace), & I am interested in your Sram Sparc upgrade. I will probably try 18.5V battery packs myself when my 16.5V ones are worn out. Does the Ah of the new packs have to be the same as the old ones (8Ah), & if anyone have experience of ordering batteries from the U.S. have they had problems, are they classed as hazardous perhaps? Alex

 

[rooel]

The only problem about ordering from the US is the high courier charge (60 to 70 US dollars) which is added to the total price for purposes of calculating VAT and import duty. With a further fixed charge of around £11 for the clearance fee you can expect the final price to have increased by approximately 23% over what you pay batteryspace.

As for amps they can be as many as you can cram into the space, so the 10 amp pack is probably better value than the 8 amp one as they both fit in the Sram Sparc box.

I am not sure how far the over-voltage could go. Some of us suspect that the "upgrade" of the Sram Sparc system trumpeted a few years ago was achieved simply by the over-volting which occurred when 16.8 volt NiMh was substituted for 12 volt Sealed Lead Acid. When fully charged the NiMh have a no-load voltage of 18.5 and the lithium 21. It would interesting to know what would happen if a 25.6 volt lithium pack were tried - it would fit in the Sram box. I have no doubt the motors could stand it but would be more doubtful about the components on the hub circuit board.

 

[flecc]

Hi Homemoz,

Lithium batteries are interchangeable with NiMh ones and are usually a slightly higher voltage, improving the performance a little. If your system is a 24 volt one, the lithium voltage will normally be about 26/27 volts with the commonly used lithium cells.

My remarks on Li-ion problems in here concern use with high powered motors, so I can't see you having any problems with that 180 watt motor since it's maximum current drain should be within most e-bike battery capabilities.
.