• Increase font size
  • Default font size
  • Decrease font size
Home News Tech-Talk Pimp my Hilti

Pimp my Hilti

In 1998 I happened to walk into a climbing store in Grand Junction, Colorado. I found an issue of Climbing laying around somewhere and flipping through the pages I came across a report about some guy who tuned his battery powered hammer drill, making it more suitable for bolting routes.

I loved the idea of customizing a 700 € tool so it fits your needs even better. In my case, the age of my original batteries made some improvement necessary anyway.

I got my drill, a Hilti TE 5A in 1996 directly from an engineer who worked for Hilti in Lichtenstein. Even today the mechanics of the machine work great, but the Ni-Cd-batteries never really met to my expecations. Over the years the batteries eventually depleted to a state I could no longer tolerate. An this is when I decided it was time for an upgrade.

[Taking a small lunch break during the bolting of Easyrider, 8a+/8b, Zigeunerloch, Austria in 1996]


The idea was to not only achieve higher battery-capacity but at the same time make the whole machine lighter. I decided the best thing to achive less weight was to not only use cells with higher energy density but to get the weight off the drill and onto your harness. This way, bolting overhanging routes should be less exhausting.

[Step 1: Opening one of the old battery packs and taking out the depleted cells]

[Step 2: Connecting the pins to some wires]

The pic above shows the opened battery pack Hilti BP40. There are 5 pins that will either connect to the drill or the charger. It turned aout that 4 were used for a parallel array of 2 x 12V and the 5th one was connected to a ptc, which just controls the temperature of the batteries while in the charger. So, in my case it was no longer necessary. In the beginning I wasn't really sure what the drill would do "inside istself" with the current coming from the two 12V batteries, so I decided to check on it before designing the new battery-pack.

[My friendly collegues at the Graz University of Technology were also curious about my bolt gun]

[The TE 5A being prepped for the lab test]

[Current at nominal voltage as the Hilti TE 5A was idling]

My measurements showed that my assumption was right and 2 parallel sources of 12V were sufficient. But since I was aiming for newer cells using Li-Po technology with a voltage of 3,7 V/cell I had to make sure that the drill would run fine with either 11,1V of 14,8V. But since the noise at around 13V got unbearable I considere 2 x 11,1V that is 2 x Li-Po 3s (three cells in series) to be fine. Apart from that I expected the voltage drop of the new cells during load to be less than of the old batteries. Furthermore, when fully charged the 3s reaches levels around 12,4V.

[Batteries and charger are here!]

I ordered the parts at hobby king, deciding to go for the fairly cheap turnigy batteries for my first experiment. They offer 5000 mAh at weight of 480g for around 30 € each. I also got a processor controlled charger that would allow to fast charge, discharge and monitor 4 batteries at once. It runs on 12V so I can use it in my van when I am traveling or when I need to quickly recharge during a longer bolting-session.

Next, some assembly had to be done:

[Finishing the "dummy-battery", which will be plugged into the drill while the actual

energy storage can be clipped to the harness to get the weight off your hands]

[There you go! The emptied battery housing with the new connection cord]

[Done! The final setup chargin' up for the first use]

So, the whole project looked promising and during my first test, the drill easily ran more than an hour before my low voltage alarm kicked in. Still, how would the system work out there on the rocks? I took it out on a field test to Peggau where I bolted 2 new easy routes in the sector "G-spot". After 24 holes (10mm diameter, 90 to 100mm deep) I was tired but the battery nowhere near empty. Seems like 40 holes should be realistic with one charge. That's nice, since the weight was reduced by 50% and the capacity increased by at least 200%!

[Taking the "new" TE 5A out for a fiels test]


If you have any questions concerning the electric stuff or how to tune a drill in general, please do not hesitate to drop me an email!











Umfrage: your vision!