Hi
When looking into the cost of 10+Watt lights I was not real happy with the cost of the NiCad batteries.
Since I had plenty of used notebook computer batteries I pulled them apart and built my own Li-Ion batteries.
If you open up a spent notebook battery you will liley find 9 3.6volt batteries in 3 groups of 3. Because I used the suspend function of the notebook must often and ran on power most of the time, I found that only 3 of the 9 battery cells were dead, leaving 6 rechargeable 3.6 volt batteries.
I cut up one of those aluminium extension poles (like the ones used for paint rollers) into small sections and just soldered two batteries with wires and put them inside, plugging the ends and using cheap connectors on the wire ends.
That gave me three batteries each two battery cells long. And the batteries fit perfectly into the vista light bracket.
I bought the 10+ watt vista light for $65 and the vista bracket to hold the batteries for $10.
I use two battery cells in series to give me 7.2 volts and then two of these in parallel to give me running time.
The slightly high voltage has not blown a single globe and the batteries hardly ever need charging (they get used about 1/2 an hour each night).
Note, using the six battery cells (or more if you have other batteries) in two batteries at the same voltage would give more running time. I'd say that I get about 2+ hours from the 2 by 2 setup I'm using.
As for charging, I use a Li-Ion camcorder charger and the electronics from a spent Li-Ion camcorder battery.
I broke open a Sony Li-Ion battery and it had the same (but much smaller) 3.6v olt Li-Ion batteries as were in the notebook computer. I just remove the dead battery cells and soldered wires into the open shell to connect my batteries to. Then I plug that casing into the charger and it thinks a 3.6v battery is on the other end. This charges the battery correctly and swithes off when finished.
Hope this helps you if you want a very high quality though inexpensive lighting system.
Note . the connectors I used to wire the batteries together I pulled from an old 486 PC, they are the white four wire connectors.