backyard electrical engineer question

[yamahonkawazuki]

Need assistance, on my knee scooter, im goofing off. currently ive got 6 strands of LED lights. each strand of 10 lights is powered by 2 AA batteries. heres the issue. its cluttered. i wish to power it with 1 battery if possible. using a scooter handlebar switch which patrick sent to me 3 years ago. :"( is it possible to perhaps power it with mAybe a 9v battery, with lamp strings wired in series? (fused of course)
would be great if possible. considering a flasher at a later date. this to be done on one circuit. ivvve got 3 circuits available on switch set currently mounted to handlebar. any advice would be great. ive got a decent BYEE ( BackYard Electrical Engineer)   knowledge. but my experience using LEDs is a bit more limited. thanks again for any help.
Aaron

[qcbaker]

AA batteries are 1.5V each, and each strand is powered by 2 of them. Do you know if the batteries are currently in parallel or series? If they're in series, that's 3 volts per strand. If they're in parallel, its still 1.5V per strand. I would guess they're in parallel since LEDs are pretty low-voltage in general but I dont know for sure.

However: 1.5 * 6 = 9 and 3 * 6 = 18 (which is 9 * 2) so in either case, you should be able to power the lights with 9V batteries if you wanted to. It would just depend on how everything is wired:

Series:

You can power 6 3V lights with 2 9V batteries if you wire them in series. You might be better of wiring 2 sets of 3 strands per 9V instead of putting them all together, but theoretically either way works.

Parallel:

You can power 6 1.5V strands with 1 9V battery. This is probably the ideal scenario for you.

None of what I wrote is taking current draw or heat into account though so be careful.

[mr72]

Heat won't be an issue. Odds are those light strands are powered by the two AAAs in series to make 2.4-3V. In that case you can wire three sets in series and power that with a 9V, and wire the other three strands in series, powered in parallel with the first strand.

If that doesn't make sense, then I can ASCII-art it but it sounds to me like you are on the right track.

There's nothing special about LEDs. They have a dropping resistor somewhere to limit current and as long as you exceed their forward voltage they will light up. My guess is each of those light strands actually has one dropping resistor for all LEDs and the LEDs are wired in parallel with each other. So as long as you supply it with >0.7V (or thereabouts, depending on the LED color) then it will light the LEDs, and as long as you don't exceed the supply voltage designed in by too much, the LEDs won't burn out. More voltage will make them brighter. Too much and they will smoke the LEDs (no longer light, no longer conduct). Even if you get it wrong by a factor of two, too high, it won't do much except make the LEDs brighter, IMHO. Get it wrong by 1/2, the LEDs will just be dim and it'll be obvious you need to rework the series/parallel combo.

You're putting LED Christmas lights on your scooter? Good times!

[qcbaker]

Heat won't be an issue. Odds are those light strands are powered by the two AAAs in series to make 2.4-3V. In that case you can wire three sets in series and power that with a 9V, and wire the other three strands in series, powered in parallel with the first strand.
...

You're probably right about heat not being an issue, I just don't want my advice burning someone if I goof up lol.

And I didnt even think of wiring 2 sets of 3 in series in parallel... That's a much more elegant solution if the batteries are in series.

[yamahonkawazuki]

had a looksee at the wiring. there are 2 wires coming out of the battery box. im assuming  + and -- . these go into the first led then out to the next. same unto the last one. reason im wanting to do this is because ive got 6 battery boxes in 3 locations. errm 2 boxes in 3 locations. 1 it looks sloppy or cluttered. and the combination of boxes  and wires has a vague resemblance  to a redneck bomb  or maybe a jihad scooter lmao. anyways ill post a pic here in a few minutes with them lit. anyways id rather either flip one switch lighting all, OR using the 3 electrical switches on the bar mounted scooter control go 2 each. ive got 2 red, 3 white and 1 blue.
Aaron

[qcbaker]

had a looksee at the wiring. there are 2 wires coming out of the battery box. im assuming  + and -- . these go into the first led then out to the next. same unto the last one. reason im wanting to do this is because ive got 6 battery boxes in 3 locations. errm 2 boxes in 3 locations. 1 it looks sloppy or cluttered. and the combination of boxes  and wires has a vague resemblance  to a redneck bomb  or maybe a jihad scooter lmao. anyways ill post a pic here in a few minutes with them lit. anyways id rather either flip one switch lighting all, OR using the 3 electrical switches on the bar mounted scooter control go 2 each. ive got 2 red, 3 white and 1 blue.
Aaron

Sounds like the lights themselves are wired in parallel, but we'd also need to know how the batteries are wired. Batteries wired in series stack voltage, but not capacity, batteries wired in parallel stack capacity but not voltage. You'd need to know the voltage of the power supply (the battery pack) before you can figure out how best to power the lights themselves.

The switch would be rather easy, just solder all the + wires from each strand's switch to the + end of the switch, and do the same with the - ones. Then you have 1 switch operating all 6 strands.

No matter what you do, you're in for quite a bit of splicing and soldering, but I'm sure you knew that when you started considering a project like this lol.

[yamahonkawazuki]

Aaron

[yamahonkawazuki]

btw there IS a diode or resistor? in the battery boxes. will get a macro of it shortly. yes the install IS ugly. but had to toss it together for a church christmas party. i do wish there was a flasher that would work on these lower voltages. anyhoo will have macro in 10 minutes.
Aaron

[qcbaker]

Definitely looks to me as though the lights themselves are in parallel, presumably to prevent them from all going out if one goes out. Still can't say for certain how the battery is arranged though.

[yamahonkawazuki]

I stand corrected. There is no diode/resistor.

Aaron
P.S.  I didn't show the bottom end of battery box. It was just a metal bridge. No wiring down there

[qcbaker]

Looks to me like mr72's guess was correct and that the batteries are wired in series. So your power supply is 3V per LED strand. So, you can probably do what mr72 originally said and wire 3 strands in series, then wire the other 3 strands in series, then wire those 2 sets of strands in parallel with each other, connected to the 9V.

Not sure what the current draw is so no telling how long they'll stay on running on the 9V. Can't imagine they consume that much power...