question about recharging batteries

after trying many chargers I bought the most popular charger "Nitecore D4" for my AA and AAA batteries. The batteries i am using are state of art Sanyo eneloop , i charged them to status FULL but when i put them in my GPS or AC control unit they both indicate "batteries low" status ?

There are "standard" alkaline AA / AAA cells that should not be charged at all. There are more expensive rechargeable cells but some require to be `charged by "their" chargers and often fail with other chargers.

I used various combinations of chargers and rechargeable cells and always it worked quite well. Some cells tend to get shorted after 3-6 months of use, others do not deliver the full charge. For occasional use the low-cost alkalines eem to work better. Rechargeable cells are best for a "massive" use of battery-run devices, the cost may be less.

Test your devices for a current they draw from the battery. Use AA cells in place of AAA if the current is > 100-300 mA.
Best of all, use a regulated DC power supply if possible instead of a battery. Or use D cells for a higher current to save money.

You have a good smart charger. It will charge Eneloop Ni-MH cells perfectly, if it is working properly.
Maybe your GPS or AC control unit indicate the 1.5V voltage of ordinary throw away carbon zinc or alkaline battery cells, not the 1.25V of your Ni-MH rechargeable cells.