Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have old Bosch PSR12 driver/drill that all NiCA are dead. I've modified it successfully to work as Corded after removing batteries and connecting 12V 1.5A (220v) adapter. The drill works but when I push for full speed it stops, So I guess the adapter is just not enough. The Battery box has a 12V 1.2aH label on it.

What adapter should I get ? Doesnt 1.2aH equiplivent to 1A ?

share|improve this question
I get the theoretical interest, but is is really practical and cost effective to do this instead of getting a new corded drill that does what you want? Or a new cordless one? The price of the adapters and rube-goldberg supplies must rival a new device. – bib Jan 23 '14 at 14:31
up vote 1 down vote accepted

No - aH (More commonly Ah since M. Ampere is a proper name, and hours are just hours) is Amperes*hours and is a quantity of charge. 1.2 Amperes for 1 hour, 2.4 amperes for 30 minutes, 0.6 Amperes for 2 hours - all = 1.2 Ah.

NiCads (when happy) are capable of providing very large currents - so you'll need a 12V adapter with a bit more current capability to be able to run your drill at full speed as a "corded" drill. Cut and try is the best I can suggest - i.e., find a 2.5A or 3A 12V DC supply and see if it will run the drill at full load or not - or else find a large 12VDC battery (such as a car battery) and a DC ammeter and see what the drill actually uses for current when under full load. A car battery charger is often the cheapest high current 12VDC supply available, unless you have an old computer power supply with a high current 12V section. The only trick there is that a 12V (nominal) lead acid battery (as from a car) actually operates at a slightly higher voltage than a 12V NiCad battery pack...

share|improve this answer
Thanks. eBay offers 100-220V to 12v 6A. Its probably what I need ? – Chura Jan 22 '14 at 20:14
It would probably be adequate. – Ecnerwal Jan 22 '14 at 21:33
If going the testing route be sure to actually be drilling something as you test. It will draw more when there is resistance, and usually a LOT more when stalled. – Grant Jan 22 '14 at 23:06
Even old battery powered screwdrivers like at least a 2amp (5v DC) wall wart for conversion to plugin style. – Wayfaring Stranger Jan 23 '14 at 15:06
Ofcourse it will be tested with resistence. I've ordered from eBay a 20A 12v adapter. for this price it worth a shot. – Chura Jan 23 '14 at 20:07

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.