A short hint: I bought this funny device here:
Graupner BATTERY GUARD für LiPo/LiLo/LiFe/NiMh/NC
http://shop.graupner.de/webuerp/servlet/AI?ARTN=7599It's really cool, showing you all data about your accu, like total voltage, cell voltage for each cell, charging state and gives alarm, if one of the cell voltages drops down too low. Remember, a LiPo will die when its discharged down too low. The discharge curve for LiPo's remains flat until it is empty, then drops down very fast into the danger level. The price of it is about 15% of the price of one accu, it's a good investment, I like it.
Another update: the LiPo's of 14.8 V (4 cells) I bought for my lamp turned out to have a too high voltage. It's a problem of the nominal voltage and the actual one. When charged, the voltage is >16 V. I used two diodes in a row to burn away 2.8 V, but that's a bad solution as its produces an unnecessary amount of heat. Now I bought a pair of 11.1 V LiPo's (3 cells) producing about 12.6V when charged fully. Much better. Expensive learning.
Last point: I build a cable to connect the lamp with the car. Saves accu power and might come handy if TSA does not like accu's in your luggage. Its anyway an interesting discussion if accus should be in the hand luggage or not. Last point was hand luggage because you can react if something happens which TSA likes. On the other hand, if you shortcut LiPo's they most likely will explode. Can't imagine TSA want that in you hand luggage.
Cheers,
Stefan
