anyone know anything about charging batteries?

[Mr.GhettoRig]

So ive been running one of those dynamo/generator light setups on my weedeater bike for a couple months now and im getting tired of the fact that they dim and turn off at slow speeds and stopping. both lights are supposed to run off 6v. So I was thinking, I've got a 6v battery laying around that I could put on the bike and run the lights off that, and then set up the generator to charge the battery. The problem I see is that the generators voltage is relative to speed, at full speed its gotta be pushing 12v or more, and at lower speeds its probably just at 6v or less. I have no experience in charging systems so I don't really know where to start on that one. I figure there's gotta be more to it than plug it all in and go. :shrug:

 

[Neck]

The lighting coil puts out AC current, so for it to charge a battery you would have to put a rectifier in the circuit.

 

[Havasu Dave]

The lighting coil puts out AC current, so for it to charge a battery you would have to put a rectifier in the circuit.

In addition to the rectifier, does the voltage need to be regulated?

 

[Neck]

Without actually measuring the current output I cant say for sure. But probably not.

 

[paulhew]

I'm kinda thinking he has a friction Dynamo/generator like we all had on are pedal bikes like the ones that run off the wheels. Those put out aprox. 6v DC current, not sure if it would be enough to keep his 6v battery charged ( u need at least 7v to keep it charged), In that case I would give it a shot, even to try it without a voltage regulator. But he would have to measure the output of the dynamo first before trying.... hey but I could be way off base of what he actually has :shrug:

 

[Neck]

I honestly don't know how those Dynamos are wound. Hooking one up to a battery may let the smoke out!:shrug:

 

[KustomKartKid]

The lighting coil puts out AC current, so for it to charge a battery you would have to put a rectifier in the circuit.

Yes ...preferrably a "Full-Wave" rectifier for optimum charging capacity...

(I don't know what that means but I read it somewhere and it makes me sound just a little smarter than Neck....:biggrin

 

[delray]

couple problems i see. the unit puts out AC(how much?) and the rectifier will change it over to dc,but what would be the dc volts? and your generator only might be putting out a 1 amp or so, just enough to run the lights. even if the rectifier made the dc correct? i don't think you would still have any amp's to change the battery.............:shrug:

 

[Neck]

Now, after reading about Dynamos (online of course) essentially they are electric motors, and driving them off your wheel makes AC current, but, if you hook them up to a battery, they will turn like a motor.

 

[paulhew]

Now, after reading about Dynamos (online of course) essentially they are electric motors, and driving them off your wheel makes AC current, but, if you hook them up to a battery, they will turn like a motor.

Was "shocked' to find out... They are AC !! Ok im way way off base here, Interesting stuff! :thumbsup:

 

[Boostinjdm]

You need a diode in line. This will do two things. It will block half of the AC cycle to give you DC. It will also prevent the dynamo from draining your battery when it is putting out less than 6v. I'm not sure what to do about regulating the voltage. I would think that a full 12v would cook the battery, but you still need more than 6v to do any charging.

 

[b52bombardier1]

My six volt CT90 and ST90 Honda minibikes like a regulated DC recharge at around 7.5 volts DC to prevent the boiling of the lead acid battery electrolyte. And most of us start thinking about changing the rectifier when we see more than a half a volt AC measured at the battery at half throttle or more.

We use Radio Shack rectifier pn 276-1185 at about $4.50. It is good up to 50 volts peak inverse and I think 25 amps of current which we never see with a 62 watt maximum even when brand new stator. This device has four tabs - one ground, one to the battery and two AC input tabs. The Honda CT70 rectifier has one AC input but you will need to build this from Radio Shack diodes - not hard to do and might be more suitable here.

There is no need for a regulator if you can more or less balance loads / consumption with whatever that dynamo puts out. A six volt flooded lead acid battery in a six amp-hour size or larger is a pretty good regulator all by itself.

Rick

Two Honda ST90 and Two CT90 Bikes
2006 Honda Foreman 500 (Resto In Progress)

 

[bikesandcars]

Look up rectifier diode / bridge diode... that takes the AC and turns it into DC pulses.

That doesn't however regulate charging voltage / amperage and you could fry the battery.

To regulate charging amperage you can drop a 25uF capacitor in line similar to a bootleg (and dangerous) battery charger or get a voltage regulator circuit from an old alternator.

 

[Mr.GhettoRig]

sorry i haven't replied sooner guys.. getting two seconds of free time is tough lately. :hammer:

I thought the generator might spin over like an electric motor too but I thought if as long as the generator was making more power than the battery it wouldn't be a problem would it? use some kind of regulator to only allow current to flow from the generator to the battery if its at a certain amount (7v+?).. as for how much voltage or amperage is actually making I'm not really sure. I had to upgrade from the original 6v bulbs to 7.5v because they kept blowing out, and the 7.5v's actually shine a little brighter than the 6v's did.

I dunno, as it sits right now it would be a pain to try and hook a multimeter to it because its hooked up to my engine tensioner which means the bike has to be moving for the lights to be on. But I gotta order a new generator anyway because mine fell apart the other day after 300 miles of use. I'll see what the new generator is actually producing and get back to you guys. then see what my options are.

 

[delray]

has anybody figure out that he won't have enough amp's to recharge his battery,because his lights will be using up what little amp's it maybe putting out..........:shrug: or am i looking at this wrong.....:shrug:

 

[b52bombardier1]

I am beginning to think the same thing. Until we get hard numbers on the output of his generator, its tough to give good advice.

Rick

Two Honda ST90 and Two CT90 Bikes
2006 Honda Foreman 500 (Resto In Progress)

 

[bikesandcars]

I'm confused if it's a generator or an alternator...

:shrug:

Need to understand wattage of lights

Bottom line... yes a battery will help the situation as the lights will always get the same voltage. It sounds like a rechargable 6V battery would do the trick. The battery will also buffer voltage spikes.

If the battery isn't charged quick enough you will need to manually charge it. If your lights are always on I doubt you would over-charge the battery much.

Why isn't this 12V?

 

[Neck]

Seriously, how much night riding do you do?

 

[delray]

lets do the math or i should say try too........:laugh:

12watt/12volts=1amp

6watt/6volts=1amp

most 6volt bicycle generators put out only 3watts. that just enough power to run the lights. i played around with a new bicycle generator couple years ago and with nothing hook up to it and just free spinning my 6volt unit max out with 8volts. but under a load(lights) the volts stayed way down. just enough to run the light bulbs. i converted my lights over to leds and notes right away that the lights come on little better when the generator is spinning. i think it just lets everything power up quicker because the leds don't draw anything or very little.

video of my lights working on page 3
http://www.oldminibikes.com/forum/project-logs/1171-minibike-finish-3.html

also thought i would ad this too (page 4) how i built my generator so it would hold up for a long time......
http://www.oldminibikes.com/forum/project-logs/2993-great-minibiker-build-off-delray-entry-4.html

 

[Mr.GhettoRig]

I ride the bike at night just about every day, it's my main transportation to work and it's always dark when I get off. it's not a huge deal if the wattage isn't high enough to charge the battery, for the most part I'm on the bike cruising at about 20mph which lights the bulbs plenty for me to see in front of me and other drivers to see me as well. the lights shutting off when I stop is more one of those "well I'll fix it if I can" sorta things.

I've been told plenty of times to just get the bell led lights and solve that problem but I'm stubborn and like the look of the lights that came with this particular kit. :hammer: