I have a old duo that I'm thinking about putting a insert in. The problem is that it has the belt pack that takes C batteries. I just can't see using this for caving. Is there any replacement battery packs that I could hook up to the the duo. If not I may sell it on ebay and go another way but would like to try.
I just saw an older model duo go for $30 on ebay. I have also seen ones with "bad conncetions" in different spots which means you can buy older ones for parts to canibalize easily. I see used ones come up every few months. Just a matter of time to find the right one at the right proce. I got my spare one for $40 used for my gf last year.
I was thinking of using a a holder for 18650s. I think I could wire it up in an old zoom battery box or something. My question is will this give me more battery or would I just be as well off with eneloops in a normal duo.
I don't understand much about it, but most people recommend that you just stick with rechargeable AA batteries. Some people modify it with 18650's, but I think there is a risk of overheating and melting the plastic (correct me if I'm wrong). 18650 batteries would have better life, but I think you would have to heavily modify the duo to make them work.
The best lithium ion's have 3100mAh and Eneloops are 1900.I think? 4 x 3100 = 12400 or 4 x 1900 = 7600
With the holder you linked to you don't need to buy protected batts. That will save some money, but you have to be carefull when they are used somewhere else.
They make Eneloop XX that are 2500 mah and the normal ones are 2000 mah. I would love to see the completed mod and a report on it once it is done. I wanted to do it myself, but I have 0 experience with it.
Voltage-wise, a lot depends on the insert that is planned for inside the Duo.
Some may be very much designed for 4.8-6V and not happy with lower voltages
Others may be happy over a range of voltages including the output of single (or parallel single) lithium-ion cells, and may even be more efficient running off 3.6V-4V power than 4.8V or 6V.
I think the latter is the case for at least some (possibly most) of the CustomDuo inserts, as well as for one of the inserts I make.