I have a 18 volt nI cad Bosch charger .can I get it repaired and by who

MMBT2222A a general purpose NPN transistor. data sheet link is below
http://www.s-manuals.com/pdf/datasheet/m/m/mmbt2222a_compact.pdf

Yes you can. On tools, 18 volts is 18 volts. Tools don't 'know' how the power is being created, either by Ni-Cad or Li-Ion means. Chargers are totally different. Most Li-Ion chargers can charge older Ni-Cad and some Ni-MH batteries but older Ni-Cad chargers will charge Li-Ion battery untill they overheat and sometimes start on fire because older chargers can't detect when the Li-Ion batteries are full.

A lot of ni-cad packs have one or two bad cells. to find the bad one(s); unscrew the cover on the battery pack and use a voltmeter set on dc volt 2v full scale and test the cells one at a time. they should each have at least 1.25 volts. The bad cells can be removed and replaced with good cells from other discarded packs. If they're not too old many ni-cad cells will still work. You can also revive some cells by unplugging the vent hole in the top of the cell so it can breathe (seriously). Also, I have zapped single cells by momentarily connecting them one by one (even in the pack) to a car battery. plus to plus,minus to minus. But only for about a half second. Also, heating ni-cads will kill them.

Lithium Ion batteries don't charge the same way ni-cads or ni-mh do. You need a lithium ion specific charger to charge them. (Some chargers do multiple types.)

Check my previous response to this. I do hope and think it will work as it is exactly my past situations an I've solved them.

If the battery has been used a lot or has not been kept charged up it likely is shot. A battery that is not used a lot should be kept charged. I keep my battery operated drill on the charger almost all the time. I have two and change them once every two weeks. Several years old and they both work good.

The AR AW721 headphones require 3 AAA NiMH batteries, not Ni-Cad. The original batteries are 1.2 volt, 550 mAh. I replaced mine with Energizer 850 mAh AAA batteries, which work well and actually last longer per charge than the originals.

Makita makes two 12V Ni-Cad pod batteries: Battery 1222/2.0Ah (PN: 192598-2) and Battery 1220/1.3Ah (PN: 192681-5). Makita's universal charger (PN: DC1804) will charge any Ni-MH or Ni-Cad pod or stick battery from 7.2V to 18V.

Join the battery collectors club. I have 25 batteries, 12 guns, I quit buying the batteries, I found it cheaper to buy the gun with new batteries and charger once a year. Cause they don't even last that long. I have tried different brands too all the same. Got batteries?? Sure do.

As long as the charger voltage and the battery voltage match (7 volts) there should be no problem. A fast charger just runs more current thru the battery (per unit time) than a not-so-fast charger. If you notice the battery getting really hot when it's charging (like too hot to touch), stop using it.