noob basic light wiring questions

Edit: this information is inaccurate. This is theoretical battery output, but in practice you get about half. See post #7.

Too much or too little depends on the current draw of your lights. If they are anything other than LEDs they will have a large current draw and your light won't run a very long time. As I understand 18650s are Li-ion? If so, 4 of them in series will give you a 14.4V 4Ah battery. That is plenty for an LED lighting system with under 10W draw. If, however, that lamp is a halogen or other high-power type, let's say a 60W, then your battery will only provide power for an hour at most. The calculation is 14.4V*4Ah = 57.6Wh. This means it can provide 57W for an hour, assuming it's full brightness till it dies and without heat loss. But then if you opt for LEDs, let's say headlight and taillight totalling 10W, the number is closer to 4 or 5 hrs of usage before the brightness begins to drop off.

I am personally setting up a dual 12V pack NiMH system, using 20 1.2V 3500mAh cells arranged in two 10-cell 12V batteries which when paralleled will be an effective 7Ah battery. My lights are LED and there will be a switch to change between the two batteries for use and for charging. In my estimation I will get at least a couple hours of light from each before the power starts to drop off. Only the charging must be done separately, so I will have a switch to select between the two batteries - both for use and for charging. I originally planned to use a 12V SLA, but although these are more forgiving to charging and general abusive use, they are much heavier than NiMH. My two NiMH packs totalling 7Ah are 1/3 the weight of a 12V 7Ah SLA.

Thats a pretty smart idea^ along the same lines i was thinking too. Its just so difficult trying to run lights off the circuit we are dealing with, low volt ac with constantly variations in rpm. When you say charging your battery are you doing it from the engine or separately like removing dead battery and hooking it up to a charger?

i have been eyeballing my usb solar charger lately. mount it beside my phone case and just dump the internal charge into my 18650 batteries, phone, etc...

and just let it recharge it's main battery on it's own.

egjsc said:

Thats a pretty smart idea^ along the same lines i was thinking too. Its just so difficult trying to run lights off the circuit we are dealing with, low volt ac with constantly variations in rpm. When you say charging your battery are you doing it from the engine or separately like removing dead battery and hooking it up to a charger?

Click to expand...

It's pointless to set up a complex system like that if you have LED lights. I use a separate wall "fast charger". My first test made after the above post showed that my H3 LED bulb headlight and LED taillight lasted at least 8hrs on a single charge of the 12v 3500mAh AA pack. I may not even construct the second pack. At about 7hrs it seemed like it started getting dimmer.. But I could have been getting tired at 2am. At 8hrs I simply turned it off and hooked it back up to the charger, calling the test a success.

Edit: this headlight bulb was unbelievably dim in the real world. Read on below.

I need to add to this thread. In my recent testing, the reality of batteries vs watt draw is different than as I posted above. Lights of any kind need a certain voltage to operate at. Battery voltage begins to drop off just last halfway through the charge. So, on a single 3500mAh NiMH 12v pack, the regular 55w bulb should theoretically burn for 45mins, but the reality is that it burn for 20min at which point the voltage drops off.

With two 5w LED headlights:
http://m.banggood.com/12V-80V-5W-Mo...or-us-moblie&gclid=COWpzKOs2cgCFREoaQod1F0ApQ

A total of 10w, I got 2.5hrs before they started strobing due to low voltage. When in theory they should have continued for 4.2hrs.

So if I run one of these as my primary and have a second as a hi beam (these are plenty bright for this! Surprisingly so!) and assume that my taillight and gauges also suck up 5w, I can get about 4hrs solid light on two packs. With the high beam on all the time I would get maybe 2.5hrs, when in theory I should have double that.

candlepowerforums will be extremely helpful for this

Along what beginner said, 10W is plenty for a led light Cree example and that produces 1226 lumens. You'll need a reflector to focus the output though. There's options out there that use less wattage as well. You might even find led units with the driver circuits attached all packaged into a nice bulb unit that might fit in that housing. I'm also a biiig fan of 18650s. You can get them from e-cig shops for $9/each and grab a Foxnovo charger (works for all batteries btw, annoying beep though). I don't think you'd need a protected 18650 since the draw won't approach anything near a e-cig so might even be cheaper.