wiring a generator and battery on my bike

Hey, its been a while, but I am here again with a wierd problem.

What I am trying to figure out, is how I can wire a generator and a lead acid battery pack on my bike.


The reason its complicated, is because I want to have the 12v from the generator charging the batterys ( which are 2 6V batterys that have to be charged seperately ). Then, when the voltage from the generator drops below 11v, ( I can check this with a 12v relay and a resistor I think).

I would like to power my devices ( in this case, a GPS, radio, and AA Battery Charger ) off the generator when charging, and off the batterys when at a stand still.

What I came up with so far, is to use the relays to switch the batterys from running in series to running in paralelle ( they need to be in par. for charging, series for providing 12v ). But thats it.

My brain has gone dead on this, normally I would be able to figure something out really quick, and have it working first shot, but in this instance, I can't get my head around the batterys going from series to paralelle for charging, and switching them in and out of the circuit as the power source.

Thanks for the help,
- Allan.

Your bike has a 6V electrical system?

Try this-


Not sure why you need to charge the batteries in parallel as 6V when you say the generator is putting out 12V- unless you meant to say it puts out only 6V, which would be the only reason you'd need to do this.

Lets see if I get this.

The GPS , Radio, and AA Batery Charger are 12 volts and the Bike is 6v. You want a 12v generator to charge both batteries and use the 12v components and still have 6v available to run the bike.

Why do you need a relay?

This will charge the batteries and power all of the components while running the bike or when the bike is off, No relay needed. Just don't use the 6v generator on the bike at all.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

I posted a reply, but it got lost I think.

I have to 6v batterys, that have chargers that take 6v input only. So I though I could wire the chargers in series off my 12v bike generator.

What I want to do, is to have 12v power to my devices at all times, if the bike is rolling ( and the generator is charging ) or the bike is at a standstill ( and they would need to be running off the batterys ).

Don't know if I mentioned this before, but the mike is a Mountain Bike, not a motorcycle.

HotWaterWizard, would connecting the generator right to the battery lead charge it?

DualSport, What software do you use for the diagram? Its nice.

Thanks in advance,
Allan.

Yes it will, just make sure the polarity is correct.

I use MS Paint for all of my Diagrams.

New Diagram

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

hotwaterwizard wrote:

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Yes it will, just make sure the polarity is correct.

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Wow, that makes it alot easyer then what I had envissioned. I pictured about 4 relays, some to control battery in series or par, then a relay to switch the output's input source..

Thanks, this makes it a million times easyer.

Just thinking, should I put a diode in between the generator and the batterys? Im not sure on the quality of the generator, and would hate to see my batterys drained because they are returning current to ground through the generator, or am I just being paranoid.

- Allan.

You may consider a Solar Charger.

https://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_770399+6228

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Something else to consider.

How much current do all of these devices Draw?

How many amp hours are the batteries?

How many amps does this generator put out?

Most of the small generators put out 12v AC not DC and they have barely enough power to light a headlamp.

You may need to use a bridge rectifier and a capacitor to convert it to DC and then it may not have enough juice to power anything but a headlamp.

Some pictures would help here.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

:) When I saw bike I assumed it was a motorcycle for some reason. Thought you maybe had some older dirt bike with a 6V system-

If your generator can put out enough voltage to charge a 12V battery, which is what you effectively have with the two 6V batteries in series, then you don't need the parallel connection, just do it like hotwaterwizard showed.
If you have a DMM, you can just make a current measurement to see if your generator has any built in diodes; if there's any drain on the battery, then you'll want to add the diode yourself. That'll drop your effective charging voltage a bit though, so you don't want to add it unless you really need it.

After you see how much drag the generator creates when charging, you might want to use a relay to switch it to charge mode only on downhills- it's usually pretty surprising how much work goes into generating a relatively tiny amount of power. Makes you appreciate batteries a bit more.

Hello,

A solar panel would be great to add on later, but I do alot of bike riding at night.

The generator I have found is the same as the one here:
[url]https://www.bikeworldusa.com/product_info.php/products_id/394[/url]

Its 12v at 6watts, or 1/2 amp. The chargers I have for lead acid batterys take in a 6v at 1/2 amp, ( 3 watts ) so I figured I could charge both the batterys off of this.

The batterys I am using I beleive are 2.5ah batterys.

The GPS runs on its own batterys, but accepts a 250mah charger ( but can use the AA batterys in the AA charger ).

And the AA Battery Charger I have takes 1/2 amp at 6v to charge.

I guess I dident add all that up before. Maybe i'll just use the generator to top of the batterys, since I planned on having them plugged in to charge at home/work/gfs house.

I never thought of the drag on the tire from the generator, I will through a switch in there, I'll take draining the batterys over draining my legs after a long day of cycling. ( if I run a light that is ).

Im not sure if it is AC or DC, I always forget to check that, I make the stupid assumption that everything under 24v is DC, been wrong a couple times.

If/when ( depends on how hard it is to pedal with generator ) I add a solar panel, can I wire that in par. with the generator to reduce the load in the sun?

Oh, and last things last, me and a friend are doing a Techy kinda VidCast, and I am doing an episode on my bike stuff, so I'll give you guys all a shoutout, Cause Y'all are ausome.

Thanks guys,
Allan.