My DEWALT DE9503 18v 2.6Ah NiMH BATTERY wont fully charge

Question edited for a lot more clarity. All questions need full 'make model (what it is)' please.
Question moved from Garden to make model category.

It is this one with wildly differing prices!

https://www.google.com/search?q=Dewalt+DC9096+charger

..

This torch has a Proprietary rechargeable nickel-metal hydride batteries (2,200 mAh), that is its made for this torch and nothing else. NiMH like to be kept fully charged and if you discharge the battery too much or leave it discharged it wont charge up fully or at all.
All I can sugest is to trickle charge for 12 hours then discharge fully and recharge for 12 hours again, repeat cycle till it lasts longer or replace the battery.
A replacement battery will be expensive.

I use LED torches with cree led and 18650 Li cells, last much longer than NiMH, easy to replace and cheap.

Yes normally means faulty battery pack try another one

On some chargers, when the light blinks rapidly, it means that the battery is bad. Try looking up charger information on-line.

Check the battery with a meter to see if it's fully charged.

A fully working 18v Dewalt Battery will only take 90 minutes to just over an hour to fully charge from going flat. This fully charged battery should last about 4 hours of use (depending on the load). So the answer is 1 hour.

Depending on how old or more to the point how many times you have already charged the battery, it may be worn out. All rechargeable batteries do reach a point where they won't charge up anymore. If you have fully discharged the battery and tried to fully charge it up again and it won't take a charge or only lasts a few minutes on a charge it may be time to recycle it and buy a new one.

on the charger there is a red LED that blinks while it is charging when it is fully charged it will not blink usually about 1 hour to charge a DeWalt 18v battery

NiMH is a universal replacement battery. It will work in place of nicad and other types of rechargeable batteries, and will work with virtually any charger

the newer type of battery had an electronic inside only. older style battery had sensor only.