A while back I ended up buying a clip plus to use along with my old X5L, but after a while the daughterboard in the X5L had some problems and I ended up having a clip plus as my main player. Of course, there were a few reasons I liked the ol cowon better. Storage was one, but that is easily fixed. The amplification circuit is another, but there isn't much I could do about that. The final thing, was battery life.
As it so happens, the clip (like most DAPs) uses a normal "3.7v" li-ion battery. Unfortunately, it only has a measly 290mah of capacity. So I set about finding some new batteries for it. I ended up buying a pair of "18650" cells, which are exactly the size of what an "A" size battery would be, if there was such a thing. They are also the same size as cells used in laptop batteries. The ones I got were rated for 3600mah each, which I reckoned would be enough. I popped open the clipp with a very small screwdriver and a razor blade and disconnected the OEM battery from it's protection circuit and soldered some wires onto said circuit. I then attempted to run the wires out of the microphone hole, then widened the hole a bit, and then successfully ran the wires though said enlarged hole. A few globs of hot glue, dabs of super glue, and wires later I was all done.
Unfortunately based on my tests comparing run time to the original battery, it came out to something like 1000mah between both cells. I probably should have realized when I saw the typo on the battery label... anywho I ordered some different batteries (this time 2200mah each), broke everything down and replaced the batteries. I ended up with this.
Those are installed the same way the first set was. I used a small amount of super glue to secure wire connections and hot glue for everything else. Hot glue melts at a relatively low temperature (If you've got the right glue gun it doesn't even burn skin!) so it's safe to use on the batteries. I opted to keep the plastic casing around the batteries in order to wedge the wires between the plastic and the connections. Although it's certainly not pretty, aside from my hip-like-pelvis purple buttons, it's actually surprisingly durable. I'd say it's probably just as durable as the original clipp, unless the wires were to get caught on something or it take a fall big enough to directly damage the batteries.
Ah, but the important part; battery life. My bare minimum it to at least have 150 hours, which is the highest claimed of any mass produced DAC (the mobiblu DAH 1900 from the mid 2000s). As for how long it actually lasts, I'm not quite sure yet. I'm doing a full discharge on it right now, and the current run time is around 92 hours. The battery voltage is 3.77 or so, but it has really leveled out since it got to 3.775 or so. In fact, it's been hanging around 3.775 for 4 hours now. There are going to have to be more upgrades if I don't clear 150 hours. It's also worth noting that I believe these batteries are under spec as well, but I'm not sure as to the extent.
Well that about sums it up for now. I'll post the full batterybench when it's finally done running, hopefully in a few days.