Electric Drill Charger Question

[TallPaul]

I have a Bosch B2110 cordless drill that I bought for $15 at a garage sale a few years back. One battery won't charge past 1 volt, so probably is dead, but the other battery charges to about 6 volts only. The batteries are rated 9.6 volts. I plugged in the charger and it was putting out about 6 volts. So I am suspecting the charger is bad (and one battery is bad). The good battery won't charge past 6 volts because the charger is only putting out 6 volts, right? Is is not true that a charger must put out as many volts as the batter is to be charged to?

Anyway, guess this drill goes out to the trash. Time to buy a new one. Any suggestions? I don't want to spend a lot, yet would like something decent that comes with two batteries. I don't need superheavy duty, just general purpose as I have a couple of plug in drills for the big and/or tough jobs.

 

[tom slick]

I think you need to toss it.
It's tough to beat Ryobi stuff from Home Depot for basic homeowner use.

 

[oilyriser]

Maybe a diode blew in the charger as it was trying to fill the shorted cells. Diodes are cheap, if you have time for surgery.

 

[Bob Woods]

It depends on the circuit design, you could be reading average dc voltage and that would be less than the peak voltage. Before you condemn the charger you need to have load on the output, if you can get some jumper wires and measure the voltage with the battery hooked to the charger. When you convert ac to dc you have a series of pulses that repeat at the rate of 60 times a second or 120 if its a full wave circuit. The average dc voltage of 6 would tell that the peak is somewhere around 9 or 10 volts and could be enough to charge your battery.

 

[1sttruck]

For lighter duty I use an 'egg beater' drill that I bought at an antique store for $5 years back. It handles bits up to about 1/4in, and works fine on everything but steel. Cordless tools seem fine if you use them a lot, but otherwise I see friends looking for charged batteries, buying extra batteries, and eventually moving up from 9V to 12V etc.

But, most seem to prefer cordless tools.

 

[dwendt44]

Watch for sales, make sure the unit has two batteries and don't look back.
Been there done that.

 

[TallPaul]

Originally Posted By: Bob Woods
It depends on the circuit design, you could be reading average dc voltage and that would be less than the peak voltage. Before you condemn the charger you need to have load on the output, if you can get some jumper wires and measure the voltage with the battery hooked to the charger. When you convert ac to dc you have a series of pulses that repeat at the rate of 60 times a second or 120 if its a full wave circuit. The average dc voltage of 6 would tell that the peak is somewhere around 9 or 10 volts and could be enough to charge your battery.
Now that's the kind of info I was looking for. I have drained the one battery that seems to have any life in it and am recharging it to see if it will come back to full vigor. If I have one working battery, I'll live with it. Usually don't use it long enough to drain one battery.

If I go to a new unit, will definitely check out the Ryobi's at HD and make sure have two batteries.

"Been there done that." Hmmmm, new acronym. Bet it's not in the list.

When it comes down to a serious drilling job I get out my old metal cased Sears 1150 rpm Craftsman 3/8 industrial rated drill, which is 120 volt and 2.3 amp. That baby torqued my elbow once and I had to have the doctor remove an ounce of clear green fluid from the joint. This drill was my father's and probably dates back to the 1960s.

 

[alreadygone]

If you ever buy on EBay be sure to check there first. Have no idea where sellers get product, but most (even buy it now) seem considerably cheaper than big box outlets.

Bob

 

[TallPaul]

Ebay, yeah, that's an idea.

Well, I got the batteries mixed up, but one is at zero volts and won't take a charge. The other one was down to about 1.9 volts and charged up to around 8.5 last night. Left in on until morning, still 8.5. Looks like it improved quite a bit, so I'll drain it out again and charge again, hoping to reach 9+.

 

[oilyriser]

If it won't reach full voltage it means one cell is shorted internally, and discharging will only make things worse. Is is a NiCd pack? Maybe you can take apart the totally dead pack and find the one good cell, then use that to replace the shorted cell on the pack that still works.

 

[TallPaul]

Originally Posted By: oilyriser
If it won't reach full voltage it means one cell is shorted internally, and discharging will only make things worse. Is is a NiCd pack? Maybe you can take apart the totally dead pack and find the one good cell, then use that to replace the shorted cell on the pack that still works.
Ohhh yes, of course. Basic battery 101. A 9.6 volt battery will be made up of 6 individual cells. I recall dismantling one of those transistor radio 9v batteries, the one with the terminals both on top so you could stick it to your tongue for fun as a kid, and volia, 6 tiny cells, maybe size AAAA.

So 8.5 says that 5 cells are in great shape.

Oh yeah, the D, C, AA, and AAA are nor really batteries, but are cells. Only a battery when more than one together.

Maybe try the take apart. First with the dead battery. If one cell good, will proceed to the good battery. That way, I learn the procedure on the bad one and don't wreck the good one.

 

[The_Jeff]

Does the charger have a seperate wall wart? With no load you should have around 13-15 volts measurable at the mini-jack.

Could be the wall wart portion is bad, and you could find a comparable wall wart in your junk box.

 

[TallPaul]

No, just one big charger plugged direct into the wall. I drained it by running the drill for an hour or so. It went to 1 volt. Charged back up to 9.5 in very short time, maybe an hour or two. Another 4 hours, it's up to 9.72 volts. Looks like this battery is fine, just needed to fully discharge and recharge a couple times. I have read that NiCad batteries need to be "cycled" about every 6 months to keep them working right. So I have one good battery. That'll do for now.

Thanks all.