Gas Electric Hybrid, Hypothetically

[duivendyk]

No not necesarily,the problem is really to find a generator which will put out the right voltage&current (power) to charge this battery with,in the 4-6 k rpm range preferably.Car alternators are an overkill, they can supply the 36V (with suitable modifications) and can run at these speeds, but can put out about 30/50 Amps easy their main drawback is that they are bulky&heavy look at one on your car,but they may be the only game in town.The other possiblity is to use a dc electric bike motor (not a hub motor of course).They can be used as a dc generator but the only way you can control the output voltage is by speed control of the IC engine which likes to be in the 4-6k rpm range (output is proportional to engine speed).Of course you can resort to pulleys&belts to match speeds,that gets mechanically messy,but we may have to.Locating one behind the other with a belt drive in between on the back rack is the best place.Fuel efficiency is not really a major consideration,engines are usually most efficient&durable at 3/4 load,running them at full power continuouslyis not a good idea generally, esp the low quality Chinese ones which I would definitely NOT mess with unless you want to tinker away forever.The best bets would be the Subaru Robin engines.Go to www.staton-inc.com look under engines, the Subaru EH 025 or EH035 are well engineered and easy to start.Honda's are OK too.You did not answer me question about battery life,do you commute,or use your bike just for riding around?

 

[Flapdoodle]

There are car alternators that are the size of my fist, but a little hard to find. Honda N360 sedan comes to mind. Another source is motorcycle alternators. eBay is a good place to look for a used one. Some have built in regulators.

Years ago I saw a Honda portable generator that was surprisingly quiet and about the size of a toaster.

 

[stoppit]

Mainly I'll be using this bike for recreation, daily commuting (about 2 - 3 miles), and if this hybrid idea works out, possibly road trips to visit anybody and anything within a 50 mile radius of an Amtrak station. I'm still having to jerry-rig a few things before the electric stuff is even running (can't very well start that until finals are over and done with).

I saw a couple 900 watt generators similar to what you mentioned, flapdoodle. They were online and weren't too expensive ($300 - 700), plus all had dc and ac outputs (a big plus if I were to go hobo camping with this thing).

Any thoughts on modifying an old army ammo box to house the guts of the generator (so it's detachable)?

 

[duivendyk]

You don't want some clunky heavy monster at your back,that makes the bike harder to handle and takes the fun out of riding.If we could come up with some generator you could mate to that 25 cc Subaru engine,200-300 Watts,36V/6 Amps or so, we'd have it made.The trouble with motorcycle generators is that they are 15 V or so and frequently amalgamated into the engine,you need to have a bolt-on type. With some electronics tricks up my sleeve I can get around the voltage limitation and charge a 36V battery.I remember that little Honda motorgenerator, I think it was in this power range.
This project,if it ever comes to fruition,will of necessity involve a fair amount of crafting things by hand,do you have basic metal working tools, are mechanically oriented and have access to some kind of work shop?.

 

[stoppit]

As a student at the uni, I've got full access to a machine shop. Experience wise, I took shop in h.s., have done wiring in houses, p/a's, guitars/amps, never really worked extensively with metal (more woodworking). I can handle the likes of a drill press, filing, grinders, benders, with some efficacy, but haven't really futzed around with metal on a lathe or anything that complicated. I am at least a quick learner and know some people who do art with metal, as well as a few folks who are gear heads in the motorcycle/hot rod sense.

 

[duivendyk]

OK you're in excellent shape as far as the mechanical stuff is concerned,tell me more about this "battery management system",is the charger part of it or do you hook the charger up to it,also how big (heavy)is the charger itself.It's possible in principle to generate 120V ac from a motor driven gen. and go through the charger to charge the batt.This gives you more gen. options.These LI batteries need to be handled with some care (I'm not all that familiar with them),for instance you must not fully discharge them,or they'll croak.They are also quite expensive,so circumspection is prudent.Going thru the batt. management would be safer.

 

[Flapdoodle]

Any thoughts on modifying an old army ammo box to house the guts of the generator (so it's detachable)?

I would be afraid the ammo boxes would not allow sufficient cooling, and they are a bit heavy. Had two 30 cal boxes on my Yamaha Enduro as lockable saddle bags.

Decades ago my dad and I made a portable gen using a B&S lawn edger engine, a car alternator, and separate regulator. The frame was pop riveted aluminum angle from the hardware store. Some panels were diamond pattern aluminum mash, and a rudimentary control panel with meter. My brother has it now and still uses it.

 

[stoppit]

...tell me more about this "battery management system",is the charger part of it or do you hook the charger up to it,also how big (heavy)is the charger itself....They are also quite expensive,so circumspection is prudent.Going thru the batt. management would be safer.

Well, here's some of the info on the battery management whatsit:

BMS(Battery Management System):
Over-Charge Protection: 3.85V per cell - 46.2v ( 12 cells )
Over-Discharge Protection : 2.3V per cell - 27.6 (12 cells )
Max Discharge Current: 25A
Max Charge Current: 5A
Short Circuit Protection: Yes
Balancing: Yes
Battery Pack:
Dimensions: 14" x 2 3/4" x 6"
Weight: 10 Lbs
Voltage: 36 V
Capacity: 10 AH
Cycle Life: 1500+
Charger:
2 Amp charger

from the website I bought the battery: "The intelligent charger ... is engineered to regulate charging once the battery is fully charged. It will shut itself off when your battery pack reaches a full charge, but it is always a good idea NOT to leave your battery pack plugged in all the time. Just unplug the charger when the charger light is green." here's the Battery Website

 

[duivendyk]

That looks pretty good.Good news (maybe),I surfed around and the thought struck me that the electric lawn mowers might have motors(generators) that operate in the 4-5k rpm range and might be in our power range.I found a potential candidate !.It's the motor from a CUB battery powered electric lawn mower.It runs of 48V which means that it can run as a generator at 36V+ (the gen output V is about 80% of motor V,they did not give the rpm but others (24V types ran at about 4.5k rpm),as do most types gas powered mowers .The EH 025 has enough torque to drive it and should be able to easily supply the charge current and may be more.In theory you ought to be able to charge through that batt. management gizmo plus supply the excess directly to the motor,but there might be some tricky aspects to this.In any case the thing is now to extract that motor from someplace (or at least info) without being held for ransom.CUB used to be IH (Int Harvestor and is supposed to make good stuff (according to CUB at least, which is heartening).I latched onto 'Partstree'.com they deal in repl.parts for outdoor eqt,had nothing on CUB CC-500BAT (NOT EL!) that is a corded 120 V ac. affair,they wanted a mere $250 or so for what looked like a 0.5 hp 3500? rpm induction motor for that EL
thing.Which is at least $100 too high.So I figure they'll want an arm&leg for the 48V dc motor.The only thing I don't know is what speed this thing runs at, but there is plenty of voltage reserve (12V).I found a CUB dealer in this area Farmservice (you can find them on the CUB site).Take a look around on the web or take a real life sneak peak.

 

[gppeej]

Cool thread guys. I have wondered for a while if a small RC airplane motor could turn a small dc motor backwards to create usable charging. I like to imagine a tiny little set-up that could even be slaved to the throttle to make noise - less at idle and more at WOT. They make RC motors from 5cc up to 50cc, and even 110cc boxer style motors. Most are very light.

Something like this:

http://cgi.ebay.com/New-26cc-Gas-En...0|66:2|65:12|39:1|240:1318|301:0|293:1|294:50

Notice the RPM from 1400 to 9000 and a weight of 1215g! that's only 2.7 pounds. But, I wouldn't know what alt/gen/motor would be best for these apps. Good luck.

Peej