12v gas generator output to 24v Ebike battery work?

[Living E Caveman]

I got a very little generator, and will be running it thru a (6 amp) charger which I'm plugging in my battery as I go, in order to increase my range legally with gas assistance.
But I was wondering what would happen if I used the direct DC plug on the generator to boost my batteries range, being as it is 12v output, but a 24 volt battery. I will experiment (can't hurt)and post my findings later(2014). Just curious if someone has real knowledge on this to help me in some way I can't even guess yet. :? :? http://endless-sphere.com/forums/posting.php?mode=post&f=14#

 

[amberwolf]

Well, if it's 12V output and your battery is 24V, it wont' work directly. The best you could do is put a switch on there to first charge up 12V of your battery, then the other 12V of it, while you're stopped. (or make something to automatically switch between them for short bursts, alternately, while riding, to keep them charged).

Or, again while stopped, have something that parallels each 12V half of your battery, and hten connects the 12V out of the generator.


And that is all assuming that your battery is *exactly* 24V, and the gen output is exactly 12V--neither one is probably true, but it still might work if yoru battery is two SLA or other lead batteries in series.

Then since the gen output is probably really 13-14V, like on a car, and SLA/lead is the same, then it would still work with any of hte methods above.


If the battery is instead a lithium or other chemistry, it's voltage may not be that of lead types, depending on number of cells/etc., and those ideas may not be applicable at all.


Short version: it's probably way easier to just plug your charger into the ac side of the generator (assuming it's regular wall voltage) and simply leave the charger on the batteries while riding (or stopped), along with the generator running at the same time. Not very efficient, but it would work and is very simple to hook up.

 

[Xrain]

They make 12V -> 24V DC DC step up converters. You will have some efficiency losses (the one posted below is 80% efficient). But it will do what you want it to.

Example:
http://www.digikey.com/product-detail/en/VHK75W-Q24-S24/102-2268-ND/2162745

That definitely isn't the only one made there are hundreds that will perform the same function, that is just the one I found in 5 minutes of searching that can handle the 72W coming out of your generator.


As for if you just plugged the 12V output of your generator straight into your battery, nothing will happen other than possibly damage your generator. 12V is too low to charge the battery even when it is completely depleted. You will have a tough time running the motor off of that generator as well since 72W is pretty small to power the e bike motor it might however still possibly move on the generator alone.

 

[dnmun]

if you look at the windings you may be able to rewire it and place the windings in series if there are two windings so it would make the "24V".

 

[dogman dan]

In most cases, the 12v dc output is intended for use to charge a car battery. So while your generator may put out 7 amps of 120v it will only put out about 2 amps of 12v. So,,, you only have about 24w of 12v dc. vs 800w of 120v ac.

That's how both my gennies are, but yours could be different. Just run the generator through the charger. That gives you about 120w of continuous input to the battery, allowing you to run a slow 200w discharge for twice as long at least. Or, stopping from time to time, catch up a bit too.

You might look into 24v power supplies that can output a wattage much closer to your generators wattage. with 350w for example, you could ride 15-20 mph without discharging the battery at all. With a higher output 24v supply, you might need a bms that would allow a higher wattage input than 5 amps.

 

[jay7264]

How many cc/HP is this generator most generators 12v is unregulated and has a pretty high no load voltage of about 16-18v there is a rectifier in there that will burn out pretty quick if you plan on using the 12v socket. Like dogman said use the charger

 

[Living E Caveman]

Thanks, you all.
Very good advice. I will stick with the 1st idea. I'm testing ideas to remove the reservations some people have about E.V.s. Know that I look up to you like a kid looks up to adults, ya know how ebikes can make you feel. (you may be younger than me, but not in experience) Thanks for the truly priceless help, I hope to be a moderator on this forum in a while. Awesome!

 

[efMX Trials Electric Freeride]

here is an electric motorcycle company doing something similar..
Electric / hybrid dirt bike : http://endless-sphere.com/forums/viewtopic.php?f=10&t=55680&p=829060

"The Tacita range extender for electric motorcycle

To our knowledge, this is world first: a semi-automatic generator (programmed to start at a certain level of charge remaining - configurable) it works with E10 and even if the power available is then limited (50kph max speed) it is useful for emergency cases! The range extender weighs 15kg and is powered by a 10 liter tank."

http://www.technologicvehicles.com/...eicma-tacita-t-race-first-electric-motorcycle

also interesting :
http://74fdc.wordpress.com/2013/10/28/e-venture-a-motorcycle-biophilia-experiment/

Thanks, you all.
Very good advice. I will stick with the 1st idea. I'm testing ideas to remove the [range] reservations some people have about E.V.s. Know that I look up to you like a kid looks up to adults, ya know how ebikes can make you feel. (you may be younger than me, but not in experience) Thanks for the truly priceless help, I hope to be a moderator on this forum in a while. Awesome!

 

[dogman dan]

The bits and pieces are all there to make a good series hybrid bike or motorcycle. It's just a matter of time before they show up on the market.

What would be really nice for a bike, would be a 200w continuous generator that weighed less than 15 pounds. The light motors exist, but most of the smallest generators are still a tad heavy compared to 20 miles worth more battery. It would be cool to have something like that built into a longtail. You could ride at 1000w on the battery, but when it was gone, still get down the road at a 200w rate. Unlimited range, and just parking it long enough would fill the battery back up.

I'm just not willing to carry 50 pounds to do it, like a Honda EU 1000 generator.

Where I have found using a generator to work great, is on road trips to the mountains. In the campsite, no plugs. So having a recharge there at the camp allows multiple trips all day without having to own a ton of spare batteries. My lightest generator is nearly 100 pounds.

 

[Living E Caveman]

Yes, weight is critical, and generators under 20 lbs are absolutely possible but none are mass produced. (I looked) Mine is ~30-the smallest available at $200 which destroys the lighter but $1000 honda genny.
Soon I will make it a project to build a tiny genny, even 20 lbs is not too much, this I know from using SLA batteries. Also, I just realized there are many very simple options for the 5 Amp or higher chargers needed for a small enough (removable) generator to give a boost. Car battery chargers are right around the high amps needed! And easy/cheap to procure. I hope a 10 amp rate will not shorten the life of a lithium battery, I am assuming the 10 amps cannot hurt a battery drinking up just as much juice as it is being fed. (wiring size considered) Also, a youtube video I saw with a genny setup like this was using dead :| sla's and worked ok, so beat that with a long range battery's price!. Something about a field in the battery to optimize the generator's output. Happy Holly days

 

[Living E Caveman]

Oh, I forgot to mention, camping is my goal in this. I want to go on tour a few thousand miles like justin, but basically living off the gear I can carry, like a futuristic backpacker. And it is my favorite thing to do, staying out in the campsites you can't hear or smell cars or industry. Should be early 2014 I go. I already know you wish me luck, this is the most positive forum I've ever seen. God Bless.

 

[efMX Trials Electric Freeride]

consider a small portable wind turbine generator & solar collection tarp..
concept image:

Oh, I forgot to mention, camping is my goal in this. I want to go on tour a few thousand miles like justin, but basically living off the gear I can carry, like a futuristic backpacker. And it is my favorite thing to do, staying out in the campsites you can't hear or smell cars or industry. Should be early 2014 I go. I already know you wish me luck, this is the most positive forum I've ever seen. God Bless.

 

[dogman dan]

I would assume carrying all that, mast and etc, would get difficult on a bike.

I did some thinking about how to best carry solar panels, and that could be a viable option. I was thinking if you were towing a trailer anyway, make it a fairly big flat one, able to mount 100w worth of solar panels on top, including angling them any direction. Good for about 600wh per day average. Enough to extend range by 20-30 miles I'd think. Trouble is, 100w of 48v solar panel is really huge. You might have to get just half of it charging on the fly, and fold out more in camp. Could camp all day, and ride into the twilight.

Camping and charging in town could be a pita. Basicly, you carry enough to go 70-100 miles. Then charge fast someplace mid day. At best, you end up with a 4 hour siesta someplace daily, then can go to the sticks to camp. Even in the west, 70 mile range will get you from plug to plug. Towns tend to be about 60-70 miles apart, because trains needed to stop that often back in the day. But carrying just 100w of solar panel could cut that siesta time at the plugs you find to a much shorter charge time, since you could be traveling on only 150watts from the battery with the solar charging as you go. Carry about 1000wh, instead of 2000wh. And then need only a 1000wh max charge when you find a plug.

The last thing I'd really want to do, is ride across the country listening to a generator as I go. Bad enough firing that thing up in camp. But it could be a decent option to carry a very cheap generator for a portion of the ride, when out west and wanting to ride into the mountains where a plug just won't be there. In the east, there are towns everywhere and you would not need a generator much.

This is the generator you can get in any larger western town. It's about 40 pounds. No telling how long one lasts.
http://www.harborfreight.com/900-Peak800-Running-Watts-2-HP-63cc-Gas-Generator-60338.html?ccdenc=eyJjb2RlIjoiNzE4NTk1OTEiLCJza3UiOiI2MDMzOCIsImlzIjoiOTkuOTkiLCJwcm9kdWN0X2lk%0D%0AIjoiOTA1NyJ9%0D%0A