If you have issues with longevity you should focus on getting a new charger. Many chargeres over charge the batteries and completely ruins them. Do it once and they are ruined forever and they wont hold charge anymore. Take a look at lygte-info.dk (don’t worry the site is in English) where he reviews chargers. I can recommend many of the xtar chargeres.
Direct link for comparison of chargeres. https://lygte-info.dk/info/roundCellChargerIndex UK.html
Those are rookie numbers…