I don't think batteries are worth replacing unless their bloated or have severely degraded capacity. With the DS you can just pop off the back and look.
Honestly it's so messed up that companies stopped making batteries replaceable knowing all batteries will all eventually degrade and be unusable. I bought a new PSP battery and it's simple to replace but I have no idea what I'll do about all my other devices. This sucks.
Upgraded my old PSP from 5.00 M33 to 6.61 Ark-4. It's so satisfying to have every decent game sitting on a console (even if I'll never play them).
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