Bosch AL2404, 7.2 to 24V drill it rubbish ?

Thread Starter


Joined Jul 31, 2013
I have an old Bosch 18v drill that had two NiCad batteries that are now defunct. I thought I'd revive it now that there are plenty 3rd party batteries on Amazon etc - which had the added advantage of being NiMh and higer capacity (3000MaH instead of 1200Mah ) Having not reseached the charging regime I just posted a question on the Amazon site relating to that particular battery re if the orginal charger would be suitable. I was actually hoping for a reply from the seller but that's not how it works ;-) I quickly gor 6 replies all saying basically it works Ok - so I ordered.
Then, having read the tiny info sheet that came with it I was not so sure... so googled/reseached the matter.
A smart charger is recommended and dire warnings about proper battery care if a good life is expected..
The original Bosch charger is an AL 2404 and I downloaded the user guide. The most salient fact learned was that that charger does not shut off at end of charge.. Hmmn perhaps explains why the niCads didn't last long..
SO.. how smart is the AL2404 charger .Does it just respond to over temperature using the thermistor built into the battery pack I wondered..
I dissembled the charger to find out. Basically it's not smart in any sense of the word. It outputs 27v offload and there's virtually nothing in it except the bridge rectifier. The spec sheet says it charges at 400Ma. I can't see any sign of a constant current element.
Infact the thermistor contacts on the Bat Pack do not even connect to anything in the charger.
The only thing that baffles me is that on the mains side there is a Triac, a transistor and some R's and diodes but no feedback path the the DC side. Ther is a question ! Does anyone know more about these apparently totally dumb chargers that I can't see ? I can post a photo of the internals if wanted..


Joined Nov 6, 2012
Believe it when you see warnings about having a proper Charger.
They are vitally important for Battery-Life-Expectancy,
and some can even start Fires.