Hybrid EBIKE


New Member
Local time
6:07 AM
Oct 29, 2008
Melbourne, Australia
Hey 1WDer's,

I'm running a LiFePO4 48vdc 1000w system and was getting around 30-40k before needing a charge and that was using a fair bit of pedal assist.

Does anyone know if it's possible to run a little honda petrol genny, drop current down to 48v, somehow convert to d.c and run the elec motor off this? Would I still need my batteries at all? Genny is much lighter than the batteries are!!!

I know this sounds a little backwards but I cant ride a petrol motored bike without registering, and yet there are no laws here about elec bikes as long as they were originally 'human powered design'. The genny, if I can get this to work, would run the elec motor for 5hrs at very little cost. Massive distance!

Any ideas with the electrical side of things in this project would be much appreciated. I'm just a poor fitter/turner and not too good with Mr Spark.

Photos of current setup are posted.



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skyl4rk is the man

skyl4rk's post is pretty cool, love the project!

I was wondering something more along the lines you were thinking. I have a honda generator that I use a few time a year on camping trips. It would be fun to put that thing to use. Throw it on a trailer maybe, plug a converter into the 110 output. Would only need the trailer on extended trips.

Just wonder what components would be necessary to convert 110VAC to 48VDC.

skyl4rk - I didn't see a wiring diagram on your post. That would provide an interesting visual.
The main issue I run into is that any of those generators put out a very ****y amount of continuous amps. I'm not sure what motor you run on your bike but mine need a good 60amp to go at its potential. I played with the idea for a while....you need a 'rectifier' which converts the a.c to d.c, then you also would need to drop current down and smooth out. Can certainly be done but like I said the amps that are put out will not be enough, maybe ok for trickle charging but not really for running.

I have however been playing with another idea. I have been quoted for a 48vdc brushless alternator which provides 70amps at 2800RPM. My elec motor spins at 3600 on high speed. I am going to key another drive sprocket onto the motor spindle and see what kind of amps I get out of this alternator.

The alternator is less weight than a 2nd battery pack and I will of course be able to get some pretty long distances. Should be fun...need to work out the wiring but it is a goer.
watts is watts

watts is watts (I think). my genny can put out 1800watts continuous, 2400watts peak. it should be able to support the 600watt hub motor on my bike no problem.

wish my dad was still alive, he was an electrical engineer and could figure this stuff out in his sleep.
Correct. A genset will put out AC, you want DC and a lower voltage. You would do this with a switchmode powersupply for weight reasons, or a toroidal transformer for simplicity / cheapness.

Erm... Since you are in Australia as well, I would recommend using a pair of the Jaycar electronics 500W toroid 50V+50V (gives you a LOT of headroom) - some 63V caps (4700uf would probably do) and some bridge rectifiers.

You could do it for about $250 AUD. Switchmode is a LOT more expensive, a 600W 48V power supply (eg Powerbox PBB20C-48X) is $810. Erk. These are farnell prices so... YMMV.
Genny is much lighter than the batteries are!!!

WHAT!#!@?!?! You said you had a 48v Lifepo4 setup correct? I know my mates 48v 20ah pack is 10 kilos of weight, what generator can you get that would be large enough to run the motor at the same speed is lighter than 10 kilo? I have a 800watt genie here that wouldnt cut it and thats over 20 kilos in weight ...If you got a petrol generator with in built inverter im guessing closer to 30 kilo, thats 3 packs worth of Lifepo4s in weight which incidently would well over 100 kilometers of range (if they are 20ah packs)
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Yep I do have 48v Lifepo4 but its its 10ah. I bought the 13C (high discharge) battereis for around $1100 as I am running a fairly big motor... compared to the 20ah packs which were over $2200.I know you can get much cheaper 20ah packs but if you do your research you will find your 'mates' 20ah pack has a pretty crappy C rating. :)
If you read my first post I am not interested in a petrol genny. However the alternator IS THE SAME WEIGHT as a battery pack and I would much rather stick an alternator on than 2 extra packs at $1100 each.
Maybe you have a little more money than the rest of us Mr Jester.
I have actually decided to use Konion cells (as per Makita use in their packs) require no balancing and have a 10c discharge with 30 minute charge time. IMHO Lifepo4 are way over priced, if i was to buy Lifepo4s i would opt for the Yesa pack but they are VERY expensive...Alternativeley the Headway 38120S cells 3.2v/10ah look impressive-->


Thats a members pack on ES forum 48v 20ah still waiting for his BMS

i require a pack that can handle 120 amp discharge, most of the lifepo4 packs peak at 60amp and trip the BMS so of little use to me. I can pick up the Konions off the ES forum at a VERY reasonable price when they are available...If i did have the $$$$ to throw at it i would be buying A123s

Best of luck anywayz..

p.s 1100 dollars aint expensive for Lifepo4s yeah u can get the cheap duct tape packs but they are ****...Any quality Lifepo4s cost over a grand. Where did you get your pack from?
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