Is this a battery separate from the passthru or one of those passthru inline batteries? If it's the inline kind, then if you ware
vaping constantly it might not charge well.
If you are using LR (low resistance) cartomizers or attys on a slim 510 battery you can damage it and one symptom may be not holding a charge as long. In addition, an LR carto or atty will run your battery down very quickly. They are only meant to be used on 450mah+ batteries like Riva and Ego.
And re those inline batteries - I've read some people have problems with them.
If it's a separate battery consider a Joye mega xl manual battery (uses the same charger, 60% more battery life)
I've found a charged battery just sitting on a charger or off a charger can sometimes lose charge over hours of not being used.
And as others have said, you need to make sure your battery ends and charger end are clean and dry before charging. Else the battery could be shorting out between the pole and the thread or have a film on it preventing good charging.
And you could consider a Riva 510 battery and Riva 510 charger (and you need to not charge the 510 on the Riva charger). I use my Riva briefly during the day just when I want some bigger hits, with standard resistance Boge carto I move to the Riva from my 510. That 750mah battery lasts me all week using it like that. And there are ones with more mah too. Figure 100mah is about an hour of moderate vaping.
BTW - what brand is your 510? Joye brand is good (original manufacturer). I would bet Boge brand is good. Not so sure about the other 510 clone makers.
