I haven't had a good watch since I bought a Bulova auto at a pawnshop in the early 80's. I just got a Casio G-Spot 5610-1 thing. The problem. It was only on M charge level so I had to fix it.
The answer. Sky Ray King flashlight on Low. (Click for larger image)
It's 3 XML LED bulbs driven by 4 18650 batteries. I think it cost me $28 and I had it laying around. Seriously, on low I need to put some toothpicks across the front of the flashlight to give it some clearance or it will cook my watch. It starts getting warm after 20 minutes or so. When raised up a bit on low it's ok. On High it would cook my watch in 10 minutes or less. Maybe way less. Anyways. After one short session my watch went to H. But then back down to M soon after. After one more session it stayed on H all day today while on my wrist under long sleeve black shirt.
I love the watch. I'm in Mid Michigan USA and it took me 3 tries to manual sync it during the day when I first got it. But that night it synced up on the East side of an aluminum siding house while in my wrist. (Last night). I hope that keeps up. So far I'm pleased.