Thanks for all the input.
Spec, I will look into trying to measure the current.
I have a box of old batteries lying around I would love to try to recover. I have read about jiggling the battery in the charger or turning the charger on and off quickly and tried those with no success.
My drill is a dewalt dw988 drill driver hammer drill 18v DC, the only information on the label is performance data 0-450/min/0-1450/min/2-2000/min(RPM) 0-34,000 BPM
Thanks; that is useful information.
The way I see it, is to test your drill and then to have a way of testing your batteries.
As you no doubt know, in broad terms, there are three battery chemistries used in power tool battery packs:
(1) Nickel/Camium (NiCad)
(2) Nickel Metal Hydride (NiMH)
(3) Lithium Ion (LiIon)
LiIon cells have many advantages and are taking over most battery applications, apart from traditional applications where lead acid batteries are still predominant, automobiles for example.
In terms of charging, NiCad anf NiMH are similar, but LiIon is quite different and requires a different charger. Having said that, LiIon batteries are much simpler to charge, but LiIon batteries require relatively accurate charging and discharging voltages or they will be damaged.
With a little experience and the right equipment you should be able to make your own battery packs as has already been described by tcmtech. But one thing you cannot do with success is to mix different cell chemistries in on battery pack.
You can make a very good 3A/H (3000mA/H) 18V LiIon pack from seven new 18650 liIon cells at a total cost of around £28UK but the cells would have to be a specific type from a reliable source and not any of the many rip-off cells on the market.
Many power tool users have been interested in powering their tools from the mains. This is relatively straight forward and very-cost effective compared to buying battery packs.
spec