Dewalt 18v nicd battery not holding any charge! what can i do

If the charger is not working the input lines must be check for continuity on the both the lines, preferable one wire might be damaged hence it is not giving supply to transformer.....

Any dewalt similar type will be fine. A 18v NicD type dewalt one with this male socket is perfect.

What I do know is that some NiCd 12V Black decker batteries that look similar to the dewalt ones they are charged by the dewalt charger.
But there are 12V Nicd black and decker batteries that they can not be charged due to an extra plastic edge that does not allow to be charged by the dewalt charger.
Now if you do have the dewalt lithium 36V charger and if the black and decker battery is a 36V lithium one and can not be charged due to a plastic edge then I would recommend to risk to destroy the plastic edge in order the black and decker battery to be charged.

May read instructions and see if charger is compatible of charging the two types of batteries you are charging ,,,,I have 32 dewalt 18v dc9096 batteries and 1d dewalt 18v dc9099 battery

No, the P110, 18V NiCad battery charger, will not charge a 18V lithium ion battery. You need one of the dual-chemistry chargers. If you have the Ryobi ONE+ batteries, you can get the P117 charger ($30) or a charger with an extra battery (P126) from a store like Home Depot. A 6 battery charger and a 12V in-car charger are also available.

I wish that I had better news for you.

Cindy Wells
(who has the Ryobi 12V drill and charger, a few of the 4V tools, and a number of the ONE+ 18V devices and chargers. The single chemistry battery charger is not used much any more.)

As long as the voltage of the battery is the same as the tool, the tool won't mind if the power is coming from a NiCd or lithium battery. You do have to have a charger that works with lithium batteries to charge them up. Chargers that can charge lithium batteries can also charge NiCd and NMH batteies. NiCd chargers are not always programmed to detect when lithium batteries are full and may continue to charge them to the point of melting or starting on fire.

If both batteries won't hold a charge the problem may be the charger (not providing a full charge). If one battery is OK and one not holding a charge, the problem is probably a defect with the battery. I know there expensive, (I recently had to replace one for DeWalt).

Use
AC / DC Power Adapter Replaces Ryobi One+ Batteryhttp://lcdpayless.com/ryobi_one_power_adapter.php

Are batteries for the dewalt cordless drill interchangeable? Will an 18 volt battery fit in a 12 volt drill?

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