Wednesday, 13 July 2011

Drill Battery Charger

A few months before I moved to sunny Scotland my dad passed on his nice bosch drill set, which kicked around for a while and now that I want to use it, I discover the charger's dead!

AL 60 DV 1411 charger From drill charger

To the workshop, Batman!

Disclaimer: this one's got mains in it, don't try it unless you know what you're doing. and even then it's not my fault if things go tits-up


After a spot of continuity testing I found the primary winding to be open circuit. Very odd...
I mentioned this to a former partner in crime who suggested it was probably a thermal fuse, so i pulled some of the tape off the primary and found it.
I then bypassed it with a bit of wire, creating what is known in the trade as "a bloody deathtrap" and gave it a quick test.

Old fuse and bypass wire From drill charger

Everything worked fine so i ordered a replacement fuse and a small fan to keep things cool in future.
*Fast-forward 2-3 working days*

I can has sponsorships naow? From drill charger

From drill charger

note: soldering thermal fuses is an interesting game. the fuse dies at 120°C and the soldering iron is 350-400°C. heat-sinks are required.

fuse fitted:

From drill charger

Now for the fan!
I ordered a 12v fan, in retrospect a 24v one would have made life easier, but then again easy is boring!
the easiest place to get power from was the nice chunky rectifier diodes (~22v) so i chucked on a 78L05 (all i had to hand) and a capacitor for the hell of it

From drill charger

I modified the case (read: attacked with sidecutters and pliers) to make the fan's life a little easier

From drill charger

Once the glue's dry i'll take a pic of the finished product :)


From drill charger


  1. sorry, but a 7805 with a 12v fan?

  2. yup, it run's nice and quietly and still moves enough air

  3. each to his own, whatever works.

  4. "note: soldering thermal fuses is an interesting game. the fuse dies at 120°C and the soldering iron is 350-400°C. heat-sinks are required."

    That's why you're supposed to crimp-connect them. Even if you use heatsinks the fuse's integrity may be compromised.

    In fact the datasheets for thermal fuses suggest they should be X-Ray inspected for damage if they were installed using solder rather than crimped.

  5. Wow, bitch moan complain pick apart. Good job man, if it weren't for people like you, nobody would get anything done.

  6. Not sure who you're talking to but if it's me let me just clarify something:

    I'm not trying to pull it apart, I think the repair is good (And yes, I should have said that in my original post, sorry about that)

    But my point about soldering thermal fuses still stands - and if it's the MANUFACTURER who recommends crimping, then you should probably listen to them, since they're the ones who made the damn fuse and probably know a lot more about it than you or I do.

  7. The original fuse was soldered at the ends of the legs (about 20mm away from the body) but I wanted to minimise the amount of uninsulated wire involved. The primary also lost about half a turn in the process, but nothing suffered as a result.

    *adds x-ray machine to the "if I win the lottery" list* :P

  8. Hi,
    do you still have this charger? Mine broke down and two components went up as smoke, unable to identify them.

    1. Yeah, send me some pics and I'll have a look

  9. Hi there

    I have a similar problem with 2 black and decker chargers. I bought a second hand to replace the first one but the second one stopped charging too. I narrowed it down to a faulty battery. So I got rid of the battery and I'd love to fix the chargers now. Any advice on how to do this? I have already opened one and I don't see any sign of over heating, what should I be looking for?


  10. Hi I need to know what the IC is in the charger as it does not charge. The green light comes on and no power on charge terminals. The IC no. is defaced. Any help would be appreciated

  11. Have a 120V Bosch BC130 as well. Stop working about a week ago and it was R3 which is in between two 200V/150uF capacitor.
    Replace i put in is 180k Ohm 2 watt. and the charger is working for now :)

  12. No. The fuse goes open circuit at 120C or whatever its value is, but can be soldered. I've done it too many times to count with no special procedures, just working reasonably fast.