Battery Operated Drills - Power Loss??

[Beltzington]

My 37618 Bosch 18v drill I have used for several years has gotten weak. it has started stalling when drilling soft metal and I can even stop the motor by gripping the chuck with my hand. Batteries are fully charged and one of them is only a few months old. Today I pulled the brushes and they have no cracks and other than some wear look good, no strange smells or excessive dust. Seems to work fine in the high-torque mode but not high-speed. Hate to throw it away and buy another if I can fix it but hate blindly buying and swapping parts. Ideas?

 

[KYKub]

I've replaced brushes on a couple of Dewalt cordless tools lately. I was experiencing the same symptoms you describe and replacing the brushes fixed the problems. It's a simple and cheap fix so even if it doesn't work you're not out much time or money. I'd be surprised if it doesn't take care of it. I ordered brushes through Amazon. Good luck! Jeff

 

[drizler]

You can get most common parts at a fair price from ereplacementparts.com. I have gotten more than a few parts from them and they always were fine. Their schematics help in taking things apart and putting them together again.

 

[Beltzington]

Thanks folks, I'm going to order the brushes, I guess a $15 gamble is a good bet if it saves a $160 drill. It is good to hear it fixed others problems, although mine look in perfect shape with plenty of carbon and spring pressure left.
Yep, ereplacementparts is a great resource and where I started.

 

[k0ua]

Any way you can measure the voltage of the battery pack under load? You might have to open the drill up to get to the connections, or bring out some small wires so you can measure while placing the same kind of load on the drill motor as when you have the failure, I but you have a serious voltage drop. My first thought would be battery, but any connection could be the problem.. I would measure at the motor. You should have some drop, but I bet you have a severe drop. I could be wrong. I have been before..BUT, I am often right too.! A quick voltage check under load will tell the tale.

 

[Beltzington]

Thanks for the sanity check K0ua, batteries where my first choice but I convinced myself two batteries would not exhibit the exact same issue, maybe they are older than I remember. Checked the voltage at the brushes and 18vdc no load but could drag it down to 5vdc with my super human grip. Looks like a new battery is needed. Attached is a picture of the left brush, they look exactly the same, picture makes it look a bit worn on the ends but they are both razor smooth.

 

[/pine]

Could it possibly be the charger that is faulty?...not charging or not reporting the status correctly??

 

[k0ua]

Thanks for the sanity check K0ua, batteries where my first choice but I convinced myself two batteries would not exhibit the exact same issue, maybe they are older than I remember. Checked the voltage at the brushes and 18vdc no load but could drag it down to 5vdc with my super human grip. Looks like a new battery is needed. Attached is a picture of the left brush, they look exactly the same, picture makes it look a bit worn on the ends but they are both razor smooth.

As long as it is not another high resistance connection problem in the battery to drill contacts or problem in the switch. I would try to go further back towards the battery if you haven't already done so, to make sure the voltage is dropping excessively ( and I would consider a 13 volt drop pretty darn excessive) coming out of the battery pack.. You may have already done that. I hope you get it going soon.

 

[Beltzington]

Could it possibly be the charger that is faulty?...not charging or not reporting the status correctly??

Good thought slash but I have two chargers one a docking station and another the Bosh Shop Radio. I have always been suspicious of the radio as it always drains the battery when left off for a few days so additionally I just looked up when I ordered my "new" battery and found it is over three years old. Looks like my brain isn't running on a full charge either.

 

[k0ua]

Good thought slash but I have two chargers one a docking station and another the Bosh Shop Radio. I have always been suspicious of the radio as it always drains the battery when left off for a few days so additionally I just looked up when I ordered my "new" battery and found it is over three years old. Looks like my brain isn't running on a full charge either.

Time flies when you are having fun.