Much simpler is to get a couple additional spare batteries, they are not that expensive any more. And a car charger if you are camping.

And may be slow down on drilling, 100 a day?

You can also try taking the old battery, remove the guts of the pack and wire it the terminals inside the pack, seal it up and then you do not have to cut into the case, no worries about people plugging it in, ( as it is the battery itself), no worries about opening up the drill, no added weight since the old battery case is now empty, no need for pigtails, etc. Essentially, remove the guts and use new guts with an extended lead in. I found an old battery at batteries plus and they gave it to me for free.

Thank you for sharing your work "foxtrotuniform". This feedback is not intended as a slight or criticism. It's your first try and you were winging it. I hope that others will improve upon your modifications. Enjoy DIY and building projects. It's so much more rewarding than buying something off the shelf. Look forward to seeing your third generation prototype project.

As someone who has converted a couple dozen Bosch Bulldogs (model #11213 and 11213R) since 1988 to use remote battery packs, and has modified several Bosch Annihilators (#11225VSR and 11225VSRH), I see several improvements to be made.

The best improvement would be to put the motorcycle batteries where they belong (in motorcycles). Having two containers of wet, spillable, sulfuric acid strapped to your body while on approaches or climbing is not a good idea :idea: Forget about "deep cycle" and "maintenance free" batteries.

And "thetroutscout"s idea of Optima batteries is interesting. I love Optima batteries. In fact, I won't use anything else in my Jeeps and 4x4 van. They are sealed, "unspillable" sulfuric acid, and can be run upside down if you wanted to. Yeah, I've winched myself back right-side-up :oops: Unfortunately, each battery weighs 33 to 39 lbs. So two 12volt batteries = 66 to 78 lbs. Perfect for those times when you can drive a pickup truck to the base of the route and belay from the tailgate (like never?).

Do some research on "Sealed Lead Acid" (SLA) batteries, commonly called "gel cells". These are smaller, available in various sizes, and relatively inexpensive at $12 - $25 each. Two powerful 12v batteries in a fanny pack will weigh in at 6 to 12 lbs. Get the type with "Fast-on" (spade) connectors. Usually 3.0Ah (amp-hour) to 7.0Ah in size is right for most climbers. The Annihilator standard battery, Bosch #019 (which may be out of production now) is 1.7Ah @ 24v. Your larger #021 is 3.0Ah @24v. So, two 12v, 3.0Ah SLA's = the power of the large Bosch battery. Two 12v, 6.0Ah SLA's = 2 large Bosch batteries. That's a lot of "firepower".

Since I ditched NiCad batteries 17 years ago, I have not regretted it even once. NiCads have many limitations. The worst is that the expensive factory NiCads go bad after a just a few years. I still use SLA batteries that are 15 years old!

A small SLA battery may be more expensive than a larger size. Look for commonly used sizes (for computer backup power, alarm systems, etc.) as they are more inexpensive.

SLA batteries should be charged slowly, using a 500 to 1000 milliamp (0.5 to 1.0 amp) "smart" automatic-shutoff charger. Gruber makes one for under $20.

Here are a few other tips:
There is better electrical cord available. Look for round rubber covered cord, sold by the foot. Get 3 wire (and only use two of the wires). Use a larger size (numerically lower gauge) for less voltage drop, particularly if you will use an extension cord. I have used 50' extension cords for drilling on lead, though 35' is my usual.

The hot male plug from your battery pack is exposed to possible short circuiting. If any metal comes across the male plug, you will be in for fireworks and a nasty meltdown in your pack, car, garage, or home. Better to switch the male plug to the drill and the female plug to the battery pack.

This is aesthetic only, but I cringe when I see the shredded rotohammer housing. Try a coarse round file, or a rotary file, or borrow a body grinder. Please, anything but that saw.

Soldering the connections inside the rotohammer housing would be an improvement over the butt connectors. To prevent the cord from pulling out, there is little room for the easy overhand knot trick inside the housing. Just below your yellow butt connectors, wrap the wires tightly with a few wraps of electrical or duct tape. Pull a bit more cord into the housing, as much as will easily fit. Then wrap with two wire ties, and cinch tightly. When reassembled, these wire ties will prevent the wires from ripping out. In my case, it's important because the cord extends 5' from the housing to the battery pack (or extension cord), and the cord doubles as a leash in case the rotohammer is dropped. One can add a shock absorbing bungee to this leash.

Hope this helps. Feel free to PM me if you have any specific questions, want links, parts sources, or photos of battery pack modifications.

or... one of the accessories that is available for the hilti

http://www.netspy.net/...gear/hilti/te-2a.jpg

is the "Belt Adapter",

http://www.netspy.net/...lti/belt-adapter.jpg

just wire an extra battery on ?

So this is embarrassing...I bought an Annihilator used online with no battery. Had someone modify it with a new hand made battery/fanny pack combo and it's good to go.

I go to put a bit into it....annnnd can't figure that part out. It seems like there are no teeth inside the chuck. What am I missing?