Bicycle range extrender.

[Teh Stork]

I see range extenders being discussed loosly in different threads here on ES.

I'm thinking about experimenting with a small two stroke motor, witch should be able to produce 2-3 kW. Parts would be sourced from the moped crowd. A cylinder, case, crank, exhaust and injection system with a rc motor attatched for power generation should come in at under 4kg. Similarly, we could certainly make it even smaller and have it churn out 1kW - be it at a higher price.

My e-bike is allready illegal, so adding a ICE to mine wouldn't really make much of a difference.

I've yet to see such a hybrid tho. Go discussion, what would you like?

 

[dogman dan]

It will produce less than you think. Way back about 3-4 years ago there was a long discussion about how to hack a smaller, lighter generator than a honda 1000w unit. The idea was to use a very small honda motor, from a weedwhacker I think. Aiming for a lighter unit, I think the aim was for less wattage than the honda 1000w generator. A 3kw generator takes a pretty big gas motor and generator unit. Mine weighs about 100 pounds, perhaps more. I can just pick it up, but not carry it far.

Soon after, much better batteries became easier and easier to get your hands on in the USA, and the general conclusion was that it got easier to just carry more battery. Two ping batteries for example, will take many riders much farther than thier ass can tolerate.

But the generator on the bike idea won't die, particularly if the place you are going has no plug to recharge. My feeling is that like solar charging your bike, it works, but it's a bit heavy and awkward compared to an oversize battery.

 

[Teh Stork]

Well, the weight assosiated with 4-strokes and commercial generators are clearly too high.

My moped developed a peak effect of 13 kW on a 80cc cylinder, this was measured at the wheel. But the fuel efficiency was craptastic - using 1,2L per 10km. Double that of normal cars :?

Making a unit to only run at one rpm, it should be doable to tune the exhaust and mixture very nicely - giving better efficiency. Like huge diesel trucks having electrified drivetrain.

Solar will hugely depend on weather and it's also expencive and non-robust, not qualities needed on a ebike.

 

[Kingfish]

More Batteries. Until the extra weight becomes a factor and negates the benefits.

Was that to simple? KF

 

[dogman dan]

Hey, go for it. You reach those specs for weight and power in a generator, and you'll be on your way to millions.

Definitely the ideas tossed around in the past would be much lighter than the current honda 1000w. It's built to run 24 hours nonstop and not melt down. You are just going to find out that much more than 500w of continuos power will get a bit heavy. It can't be something that overheats in 30 min. I'd rather carry some more pouch cells than more copper windings myself.

But if you could buy a 400w honda generator including a charge controller that weighed less than 10 pounds, It would be a game changer. 400w gets you about 20 mph, which means your 800wh battery would go twice as far or more with you running a 600-800w draw, and charge itself a bit if you stopped for a pee or a bite to eat. That 10 pounds includes the fuel for 4 hrs operation btw. You'd be completely free of plugs, needing only a tiny bit of gas. If you could have that device, it would be really nice. Especially if it ran on veggie oil, and you could smell only french fries all the way.

 

[Hillhater]

Most cyclists already have the most efficient, lightweight, compact, integrated, range extender ever invented......
.... a pair of legs ! :wink: :lol:

 

[nechaus]

My legs do enough for range extending.

I often start my rides with a goal b4 i come lazy and just rely on the motor.

If its a normal pleasure ride, I try to get my body atleast 15 mins of hard cycling at the beginning of the ride.
I try to keep my heart rate up and burn calories.

I have a 1.4kwh in my back pack so i have about a 40 km range if i flog it

 

[csm]

I've yet to see such a hybrid tho. Go discussion, what would you like?

I have been considering picking up one of these Honda EU1000 generators, and either carrying it in a trailer or strapping it to the back of the bike. Although, i am concerned about the potentially safety issues and transporting it around in city. It probably would be great for cold and/or rural locations.. it produces 1000 watts and is fairly quiet. I think there is a generator that is even smaller than this one that produces about 500 watts. Anyone know of any that are smaller?

[youtube]UYOLmBnVx5w[/youtube]

This looks intriging. the description says it can produce anywhere from 75-250 watts.
[youtube]VOayHpHfqfI[/youtube]

 

[dogman dan]

That's looking real close to the design talked about a few years back for a very light generator. It would be nice to have it all into a package as druable and easy to use as the honda 1000w.

Fwiw, I did do a test using my honda 800w generator in a schwinn trike. A much older model honda,it's very heavy for 800w. So in the end, it's power was not worth lugging more than 50 pounds of weight for. But at 800w, it would have run my bike infinitely when combined with a 800w charger, which would weigh another 10 pounds or more. At that point it becomes stupid. put a chain on the gas motor and ride. Leave the damn weight of the generator and charger at home.

We have seen that done by somebody in a past thread I seem to recall. Gas motor driving the rear wheel, plus a front hubmotor. That would be the best way to go about it really.


I have seen some small two stroke generators in harbor freight, but they are still pretty dang heavy. 39 pounds shipping weight.
http://www.harborfreight.com/engines-generators/gas-engine-generators/800-rated-watts-900-max-watts-portable-generator-66619.html

So what would be your range if you carried 39 pounds of lipo? Hundred miles at least. But a similar thing that weighed only 10 pounds for 400w, that could be real interesting. Perfect to run a 350w meanwell.

I have a feeling they don't try to make a generator very light. Likely if they did, it would tend to walk around all over the place when it was running like the old time electric football game. Heavy, they stay put when running instead of spinning around in circles.

 

[csm]

I would like to get some feedback on this circuit I am working on.. that in addition to providing what think could be range extender, it could also be used as a kind of turbo or booster power supply. One of the concerns I have about this circuit is what would happen if the main battery(LiMgCo) becomes nearly depleted and the person activated the booster battery circuit with the fully charged battery(SLA). I am supposing the BMS on the Lithium battery would still activate a cut off of power to the lithium battery if any of the cells it was monitoring dipped beneath thier set threshhold, as before.
Masters of ES, please take a look and comment on this circuit and it's application.
http://endless-sphere.com/forums/viewtopic.php?f=1&t=39824

 

[dogman dan]

Repeating from the other thread, extend range by paralelling batteries of the same voltage, at the start of the ride. Or unplug one battery, and continue with another.

 

[csm]

Repeating from the other thread, extend range by paralelling batteries of the same voltage, at the start of the ride. Or unplug one battery, and continue with another.

My battery hack is for when a person has a battery pack (for example 36v 16ah lithium with BMS), and has a few 12v SLA batteries to use. If a second matching battery is not practical or possible, would adding a 12v SLA in series (within the circuit I refered to above) work for adding some additional range without causing damage. The added benefit, as this controller would allow it, an add 12 volts in series would bring the total voltage to 48v, and give added power/speed when engaging the booster circuit?

 

[dogman dan]

I know you dig your switch idea, but you don't need the switch, you need the higher voltage for the whole ride.

Just add voltage in series at the start of the ride to add more watthours to the total capacity of the pack. Idealy, you'd add the same capacity of battery, so they all run to 80% dod at about the same time.

Say you have 36v and 300 wh. You add a similar capacity 12v battery that has 100wh. With the original battery you rode at 25 wh/mi. So that's 12 miles of range. If you add the 100wh, and ride the same 25 wh/mi, you add 4 miles.

If you only use a boost switch for a tiny part of the ride, you'd only see a tiny bit more range. Most of the time, you'd be pulling all your amps from the original 36v pack, so it would continue to be discharged at the same rate, and get drained at the same mile mark on the ride. So you ride 90% of the ride at 36v, at 25 wh/mi. That's getting you about 10.8 miles. Then you ride 10% at 48v, but having more power you ride that 10% at 35 wh/mi. That 10% gets you up the hill, but in the end, you still pulled 25 wh/mi out of the original 36v pack for the whole ride. So you still run out at 12 miles.

Doing the math, it's easy to see that you also extend range if you add the 100wh by adding three 12v batteries of 33wh each, paralelling the battery so you have a 400wh 36v pack.

Basicly, it's pretty simple. You have to have the extra wh avaliable for the whole ride, to make range longer. Or you have to use one battery, then unplug and use a second battery.

 

[Sancho's Horse]

You are in good company.

http://www.dodsbir.net/sitis/archives_display_topic.asp?Bookmark=29267

The department of defense is working on small <250 w stirling engines. They are looking to use propane. I had the same idea, but I wanted to also use a fresnel lens over top, and convert a mylar doritos bag into a parabola for underneath to capture some sun energy. Of course I also wanted to be able to cook with the propane, and create an enclosed cooling pipe loop to insert in someones beer cooler (increasing the efficiency of the engine). Throw in some bratwursts and we have a fully charged battery.