Hybrid velomobile - a formula for success?

What happens when one combines a fast and sporty velomobile like a Waw with the advanced electrical assist/generator like a BionX? Do they reinforce eachothers advantages or their disadvantages? Find out my and others experiences here. If you do not know what a velomobile or an electric assist is, check out the links first. (An electrical assist that helps up to only 25km/h and with power limited to 250W, remains a bicycle by EU law)

Monday, March 20, 2006

Winter riding (not) and some problem with the BionX (now solved!)

I has been a while since the last post. I haven't been riding a lot for many reasons. Nr.1 is that I had my first immobilising velomobile mishap/accident in ten years of riding. Bit tired, in the dark, unfamiliar road, some snow cover and blinded by car lights, I rode the Waw straight onto a 10cm high curb at approx. 30-35km/h. From the tracks in the snow, one could see I had been "flying" about 3m. I was quite shaken but uninjured and feared the worst for the wheels and suspension of the Waw. My worst fear was that the blow would have torn out the suspension mounts in the body. It turned out the wheels and mounts were undamaged, and that the blow was taken by some uncritical bending of the front suspension. Pfew. Soon after I was abroad for 6 weeks and after coming back I was sick a few weeks. And after that, we had the worst snow since a long time…

I have ridden now and then, shorter distances. With a studded MTB rear tire, traction is sufficient to make riding possible in snow and ice, although within limits. The assist is a welcome help to plough through the parts where the roads have not been ploughed from fresh snow. Much depends on the quality of the snow, some snow gives hardly any (rolling) resistance, other types are so mucky that only a few centimetres is enough to seriously hinder progress.


On my latest two rides, I have noticed that sometimes the assist (not generator) tends to switch on and off every few pedal strokes. On, off, on, off. Sometimes it occurs, sometimes it doesn’t. I haven’t had time to look into it in more detail, but I intend to investigate and write about it. I suspect it occurs less when the system is warmed up and that it is a glitch in the control, not the power circuitry. Perhaps the power measurement (which is most sensitive) is a bit off in cold weather? As said I need to investigate more...

***********UPDATE*********

The answer to the BionX hick-ups problem is given in the comment section. My interplenation: in cold weather the voltage of the cold battery is lower. So when the assist switches on, the voltage drops even more and the control cuts the power since it thinks the battery is empty. After that voltage raises again and the assist switches on again, only to repeat the cycle. Or something like that.

Solution: one should not leave the battery outside in freezing temperatures, which I do (to see how far one can go? -5C here). It is very easy to take the battery out from the Waw and take it inside, so that is what I will from now on during winter...

2 Comments:

At 21/3/06 16:41, Anonymous Alexandre said...

Hello Frederick

What you need to know it's with low temperature NiMH battery have less energy. Than it's important to keep the battery inside before the ride and always use assistance (25% or more) when it's very cold. Than the battery will keep warm and you should always have assistance. BionX had put a intelligent system to protect the battery and when the battery go lower that 18V the assistance cut. With that low temperature the voltage was probably droping faster and than the assistance was cutting. It's giving the same filling when the battery is completely empty.

If you got any other interrogation you could send an e-mail to the customer service at BionX. The best person to write to is probably Carole. c.richard@bionx.ca
I hope that will help you.

 
At 23/11/06 08:49, Anonymous Anonymous said...

Interesting and thank you all for posting this. I have had a similar experience viz my bionX kit NiMH did not activate the motor at all when the battery was cold: there was no regeneration or assistance actuation, and no speed readings, although the controller read about 90% batt charge and all other controller functions appeared normal (no speed/distance readings either though). The diff from above postings is that my motor showed no activation at all i.e. there was no on-off intermittency. Charging at room temp for 30 mins solved this (presumably ambient temp plus heating cells via charging warmed the batt), but I have to say the battery was not particularly cold (i.e. not "frozen" when this happened - I would guess around 2-5degreesC. I wonder what the freezing temp of the NiMH cells is anyway. Subsequently during the immediate ride after this charging the batt charge level indicator on the controller vanished for about 10mins for some reason, and then reappeared. Strange, inconvenient, but not critical.

 

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