Two batteries, one charger

[Rogwi Nehar]

I'm trying to build a saber using a 3w and a 5w. I'd like to use a separate battery for each LED with its own buckpuck, but can't figure out how it might be wired to use one battery charger for the two batteries. The batteries will probably be Li-ion 3.4v, 850-1100mah.
If anybody has any ideas, I'm open for suggestions. If I have to I'll use two recharge ports, but I'd really like to only use one.

Thanks, Rogwi Nehar

[Hasid Lafre]

A luxV needs 7.2V

[DarthFender]

There will be no practical way to wire those battery packs to one recharge port as they run a different volts. You'll need two recharge ports.

[xwingband]

Well, why do they have to be seperate? Are they independant of each other?

If not you could put them in series and power both on one puck.

[Er Dan Gill]

Well, why do they have to be seperate? Are they independant of each other?

If not you could put them in series and power both on one puck.

How would you get away with doing that. Wouldn't it overpower the three watt?

[xwingband]

As I've stated a million times... forget the wattage BS. Wattage depends on how you drive it.

In series a set of LEDs acts like one LED with the sum of the forward voltages. So you could do that and the forward voltage you'd need would be about 3.9V + 6.8V = 10.7V

OR

You could have one larger pack and two pucks. Then just throw a second switch to put either in the loop (or a 3PDT slide). Your battery drain would be high (too high if you want to stick with a 14500 pack).

[xwingband]

Or yet again... if for some reason the only way to do what the OP wants is two different packs and circuits you could use a switch at the charger.

You could have it setup to charge one or the other on a slide. Not ideal as it would be one at a time and take longer. You also couldn't hot swap, you'd need to unplug, switch and then replug the charger in.

You could also have the upper part of a slide to keep them seperate... then when in the lower position the packs would be in parallel or series for charging.

[Rogwi Nehar]

If I used two 3w's with two 750MA buck pucks on one switch and use a single 7.4 Li-ion battery, would it work if everything is wired in series. There is a thread that talks about using two in parallel and getting a forward voltage of 1050mA, but I haven't found anything that talks about wiring them in series.

[xwingband]

That was talking about wiring the pucks in parallel. Tim got a different reading (correct one of 1400mA) so the idea was confirmed.

What you are thinking of is okay if you understand the switch situation you'd need, but you wouldn't need to put anything in series.

Since you seem to be missing the point a bit I'll clarify. I'm not talking about doing anything with the pucks... I was talking about putting the LED's in series. If you look at the datasheets for the pucks it will show you what this looks like.