ebike and rc stuff

[kramdra]

Ordered some bits for an ebike conversion.

4x 5000mAh, 6S Turningy lipo's, Imax B8 charger, etc.. Plan to connect as two 12S packs, switched rather than parallel. That way I'll have a fresh pack for return journeys.

Not sure on motor and ESC. Ill be going long distances so a small, high speed RC motor would probably do quite nicely as direct drive to tyre, looking for 250-500w constant plus pedalling. Not sure about rim brakes, 700x 37c tyre, and rest of bike. If direct drive, everything could be contained in a small topbox.

However a small RC motor is not what I have - a spare 120mm CBR6 generator. Its quite a heavy lump, 2.3Kg. I believe these have higher temperature Samarium-cobalt magnets and should take quite a bit of abuse. Its pretty much the same diameter, depth and weight as hobbykings biggest, most expensive 10kw outrunners

With a lathe could be lightened by 500g or so and also needs a shaft/bearings/case. I intend to test it, and need a cheap, beefy ESC to test with. Suggestions?

I couldnt find any examples of a motorbike gen used as a motor on youtube/ rcgroups.. bit disappoint. Suspect it'll need rewind.

[The Artist]

I am using 8x 5000mAh 6S Turnigy's as well. Imax B8 will suck balls. 50W charger IIRC which will take hours and hours to charge. Turnigy sell a 4x6S charger on HK which is what I use.

I don't see a benefit of switching rather than just going parallel other than that you are more likely to damage a cell by undervoltage by using less.

You can get hub motor kits which are decent that will come with a controller and be much more suited to the job than an RC motor usually. Not sure about an ESC for your needs but there are quite a few cheap options on aliexpress.

[kramdra]

I want to keep the rear wheel and gearset for pedalling, and direct drive hub motors dont seem very efficient. Plus they cost quite a bit

Parcelforce fucked up, should have been delivered Tuesday (express 24). Now they took it to a tiny post office rather than main depot, which has utter shit opening hours (9 till 3)

Charger - the B8 is 150w so 3.5 hours to charge 4 packs. slow probably being safer? I suspect any of these brands might crap them self after 5 minutes. It would be useful to have a second charger at work, but would be nice if someone made a 12S version. Btw hobbyking have 6s packs and some other stuff slightly cheaper right now. I made my order from UK warehouse as china wants 40 quid for postage, works out the cheaper from UK

https://i1133.photobucket.com/albums/m593/Kramdra/IMG_20150209_233721_zpsaxfpwpqt.jpg

That is my motor



Is it safe to parallel a lot of packs together with balance leads, or do they still need to be seperated occasionaly to be checked/charged?

[The Artist]

I am not that knowledgeable on balancing of LiPo's but have a read through the electric bike thread in the cycling section and visit endless-sphere for loads more advice on motors and batteries etc.

My rear wheel with hub motor still has a 6 gear cassette on it.

[kramdra]

Whats the weight difference between your original wheel and this hub motor wheel? from the ones Ive looked at, it seems 6-8kg difference

Impressed with the charger, bloody good for 20 quid. Im now abusing it to recover a dead bike Pb battery

Hate bannana plugs and the short balance leads

Where can I buy extensions? and the oled cell voltage monitors you showed in other thread look nice. Where from?


Deciding whether to use 65mm square drain pipe, or square alu tube for hard battery case. Alu is reasonably fireproof and I can weld them together/waterproof, but going to be heavier - cant find any thin wall stuff

[The Artist]

[kramdra]

Too much weight for me, just hub motor is more than everything I plan to add I might often use without electrics connected.

Lipos are 50x50mm x 150mm length. Case should be a little longer for wires.
https://www.ebay.co.uk/itm/360941104777
2.5" x 3mm wall, 7.5mm spare, 3.75mm padding. Need 700mm+, asking seller.

https://www.ebay.co.uk/itm/141459469874
60mm x 2mm wall. 6mm spare width gives 3mm each side for padding.

Go to read up what grades are suitable with 5356 wire.

OR 2.5 meters of plastic drainpipe for 6 quid It'd look shit and not be fireproof....

[G]

There's a few options for 12s chargers, but none of them cheap.
Much cheaper would be to use two 6s chargers to each charge half at a time.

Be interesting to see how it turns out.

You could have a look at https://alienpowersystem.com/ for ESC - if you end up going down the 'RC' motor route, they also do kits with the motor and so on.

Are you going to have a freewheel, if so, how are you going to do it?
For another project I worked out some plans using thrust bearings to adapt a disc mount to also taker a sprocket between the disc (which would be moved out a bit) and the spokes. However, going for FWD on that project using a Disc BMX rear wheel - will then mount a big sprocket on the bmx freewheel.

I did consider direct drive as the motor I have would work from that and there's some really simple elegant solutions for that (ie just spring mounted with the rotation of the motor engaging it), but does have some down sides too.

[kramdra]

Done lot of reading, looks like ebike controllers are best, not decided which to buy.

Freewheel shouldnt be difficult, sprag clutch bearings are cheap enough.


Cut the centre out of rotor. Quite challenge to do without proper tools, as its made of a decent grade of steel and reasonably thick. Cobalt Making a spindle might not be as easy.
https://i1133.photobucket.com/albums/m593/Kramdra/ebike/IMG_20150220_231323_zpskyaduaxc.jpg

Lipo tube, perfect fit, space for some padding.
https://i1133.photobucket.com/albums/m593/Kramdra/ebike/IMG_20150220_214930_zpsderhbxxt.jpg
https://i1133.photobucket.com/albums/m593/Kramdra/ebike/IMG_20150220_211849_zpsq3xumotm.jpg

Lipos 3100g
Tube 1600g
Motor 2000g, so saved 300g.

6700g so far. If I dont enclose motor (which might include some light oil for cooling if I need moar powar) I think under 8kg is possible.

[G]

Including the lock, I've probably added 8kg to my push bike without electric .

Where are you thinking of mounting the sprag bearing? I spent a while looking at options, researching it to a fair degree and found that in reality the options weren't that great - one of the best ones actually seemed to be to get a second hand motorbike starter one; though they were often wider than I wanted.

Ended up going for FWD and using a BMW rear on the front, as it'll save a load of fabrication and my bike's usually a bit rear-heavy anyway.

[kramdra]

Tempted to use the largest and least useful (for pedalling) rear sprocket for motor drive, motor sprocket would be on a sprag.


Motorbike ones are a bit large. I got one with the rotor, but its missing the inner race. Id look for a bicycle hub type or one of these:
https://www.ebay.co.uk/itm/121552416085

[G]

Ah, I was looking for a way to not have the chain turning when pedaling; but mine is only for occasional use is the idea.

[kramdra]

[G]

Have you looked to see if you can get one in the right size that can handle the power you're going to put through it?

[kramdra]

[G]

My local bike shop will build a wheel for a pretty reasonable price (they've recently refurbished and I think changed ownership at the same time, as they were pretty expensive.)

It cost me £24 to get an entire set of spokes on one side of a decent mtb rear wheel replaced; parts and labour.

[kramdra]

Started welding up the alu cases, small bit was a test (and it came out better )

https://i1133.photobucket.com/albums/m593/Kramdra/IMG_20150308_195432_zpsnavnhkt1.jpg