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Bosch Drill Rewiring


This info is for a 24 volt Bosch Drill, but the method will work on 36 volt drills (Hilti) by adding a battery to the chain.

For more than you ever wanted to know about batteries, try one of the links below.

Solarmike battery chemistry page



www.sourceguides.com for lead acid batteries

www.sourceguides.com for lead calcium batteries

Bosch Drill
Two 12 Volt Lead Acid or Lead Calcium Batteries
Battery Charger (trickle type)
Push on connectors to fit your battery type (4)
Red Wire (fat as you can get into your connectors)
Black Wire (fat as you can get into your connectors)
Polarized household extention cord 8ft or so. Cut so you have a 6 ft male and 2 ft female.
Electrical tape
Duct Tape
Webbing / Runner
Soldering Iron
Volt meter....unless you are sure of yourself.....better go get one.
50ft extention cord. (nice fat one)

How to do it:

The Drill:
First off, ditch all that crap on your drill like the handle, depth gauge, and battery attachment clip thingy. With the now naked drill open, find the + and - wires inside the handle that went to the battery connectors. Snip them off and bare the ends for 1/2". See where you can drill a small hole in the handle to let the new wiring out from inside the drill. Drill the hole. Now feed the male cord into this hole and tie a knot on the inside of the drill handle. Be sure to leave enough wire inside the drill to solder to the wires that were going to the original battery. Solder the wires so that the big plug is the positive or red wire. Tape the bond. Stuff all the wires inside and reclose the drill. Now you should have a drill, with no fluff on it, and a 6 ft wire with a male plug hanging out of the ass end. Got it? Good.

The Battery:
Now the hard part. How many holes and how much weight do you want to carry? The bigger the batteries the more holes and weight. I went for a compromise and my battery pack weighs about 15 lbs. Call an electronics house for batteries. they should cost about $18.00 to $30.00 depending on how many Amp hours they can store. Powersonic is one brand and is even available on the web at www.powersonic.com. Buying in a hobbie store or Radio Shack can be pricey...shop around. Now, get your two batteries and look at the contacts. Hopefully where you bought it from set you up with the right connectors to go on your terminals. You are going to hook up the positive (red) terminal of one battery to the negative (black) of the other battery. You can do this with a short piece of your wire, either color. Now the other two exposed terminals should be a negative (black) on one battery and a positive (red) on the other battery. Now solder the other two connectors to the female plug and wire. Keep it so the big hole is poitive, as to match with the big male plug. (ooohhh my!) Tape the connection. Now if you plug the two connectors to your battery and check the voltage inside the female plug it should read around 24 volts. Put the red test lead into the big hole and the black lead into the small hole. If it reads nothing or bounces the other way, check your connections to see that you are using the positive in the big hole. Got 24 volts? Good. Now you can tape your batteries together with the duct tape and be sure to insert the runner around the batteries for a handle. I also snuck the female cord inside the duct tape wrappings so it sould not pull on the terminals. Plug in the drill, the correct or polarized way, and pull the trigger breifly...the drill should fire up and go clockwise. If it goes counter-clockwise your terminals are crossed. Fix it quick and try it again. That is about it. Charging the batteries is done as per the directions that the charger came with. Overcharging can happen with some chargers (automotive) and ruin your batteries. Be careful and read all directions.

Using the set up:
What I do: I have the battery pack and the extention cord in an Atom Smasher. The extention cord and female plug are knotted and clipped into one of the inside daisy chains. This way they can not unplug....ever! The drill is equiped with a long daisy chain attached to the handle and the male cord is snaked throught the daisy loops. This gets clipped to my harness. A biner clipped right at the handle stows the drill on my waist while I'm climbing. (yep, I'm talking ground up...ever heard of it?) With this I have enough reach for overhead drilling without ever taking the drill attachment off my waist. The extention cord is knotted to the male plug cord and clipped to the same point. This way they cannot come unplugged. I lead and then drill a bolt. No big mystery. Now I can pull up the Atom on a zip line and attach it to the bolt with a hook for later retreival. Repeat the process. I have found you get about 25% less holes and power using the 50 ft cord. For rap drilling, I take the extention cord out of the system and just use the attached plugs. This gives me about 30 holes in granite.

Re: External battery pack for Bosch -- help!  
Author: trango
Email:   trango@xxxxxxxxxxxx
Date: 1995/08/04
Forums: rec.climbing

In article <3vqpnl$595@newsbf02.news.aol.com>, miklan@xxxxxxxxxxx (Miklan) wrote:
>If you've got any experience with installing external batteries to
>Bosches, I need your help to figure out what to do. So far, I've
>installed two 12-volt, 3.5 Ah sealed gel cells, wired in series, using 16
>gauge wire. I use 3/8" x 4" bolts. On a full charge, I am only getting
>about 3 1/2 holes drilled--not what I expected at all. Granted, I'm
>drilling on some exceptionally hard stone, but this is still much less
>juice than I though I'd get.

Get a 10AH battery or something better. Screw the tiny ones.
(I'm not a driller but I used to experiment w/ these batteries and made IC
controlled chargers for 'em)

>Could it have something to do with my charger? Output is 13.5V and 1.8A.
>I charge each battery individually, and after about three hours, the
>battery gets incredibly hot--hotter than I feel comfortable with. Friends
>tell me that my charger's output of 1.8A is way to high and will cook the
>batteries. The guys at my local electronics shop says that the charger
>can put out as much as it wants, that the batteries will only absorb
>energy at the appropriate rate to gain a full charge and not to worry.
>The advice I get is conflicting and I wonder how so many people can be so
>positive about such different opinions.

Gel cells can be bulk charged (high amperage) in the beginning of the charger
cycle, but then amperage must decrease or it really fux up your battery. Your
battery isn't smart enough to understand that it can't charge fast or it will
get messed.

>If anybody has similar experience with this setup, please post or e-mail
>Michael Lane

If you want I can dredge up a dearth of knowledge about gel cells and their
charging. But not right now.
Robert "woo hoo! I'll walk in.......4 weeks!" Ternes

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