Rotary Hammer Drill 12Ah Remote Battery Pack for Under $100!

I use a Makita 18v rotary hammer drill which uses 3Ah lithium ion battery packs that sell for about $95 each. There was no way I was willing to pay that kind of money for one pack when it not only added weight to the drill but also had pretty bad battery life. I wanted a remote pack I could either wear in a hip pack or build into a small box and leave at the bottom while I was drilling. Something I could also use to hang sheetrock or do framing with when I didn't have access to power. I also needed a configuration that allowed me to charge in parallel (6v) yet use the batteries in series (18v) and the versatility of swapping in different cords depending on the situation. This was made easy by having two different male trailer connectors and configuring the inside of each with jumper wires for use by either the charger or the drill yet leaving the female the same for either. I came up with a pretty simple and low cost solution so here's the info:

$48 Batteries
$20 Charger
$17 Trailer Plugs
$10 Extension Cords and Misc

$95 Total for a 12Ah sla remote battery pack.

If you run a 24v drill you could use the 4 pin trailer plugs with two 12v batteries and if you use a 36v drill you can do the exact same thing I did with 12v batteries so this will work for any of them. The added benefit is that you can find drills like the Hilti 36v on ebay without a battery or charger for $160 shipped so you have the option to buy a cheap drill cause the batteries are missing or dead. On the drill side I tool the other chunk of extension cord and used it with an old battery to make a slug with a plug (sounded too catchy not to use) for the other end of the cord.

If you have any questions feel free to ask and I can give you more details.

That is similar to what I am using in Thailand at the moment. We have very unstable current on the island so charging batteries with a normal charger wastes them after only a few charges.

Our alternative was to buy two 12v motorcycle batteries and connect them in a a series for our 24v Bosch. We also charge them in a series with an automotive battery charger.

Since we never have to change the cords around, we just soldered everything in place on the batteries. Then we cut an extension cord open, soldered it to the battery terminals, and on the other end, soldered on male parts that fit into the female parts of the drill (where a normal drill battery would go). A bit of duck tape and we have a light drill ('cuz it has no battery) which is good because we drill in roofs a lot in Thailand.

The batteries hang between my legs. I bought a 6 liter plastic water bottle from the 7-11 and cut the top off. The batteries fit into it well, then I set that in a dry bag, seal it up, and write (danger battery acid) on the bag!

Could you explain more about how you are charging your batteries, and how they connect to the drill? Does the white cord in the picture connect directly to an extension for the drill?

Also, you said that you "charge in a series (6v) and use the batteries in parallel (18v)." Am I confused... or is that backwards? If you have the 6v batteries connected in a series, you have a 18v battery pack with the capacity being the same for the pack as it is for each individual battery. This is what you need for your 18v drill right? AND if you have the batteries connected in parallel then you have a 6v battery pack where the capacity is three times the individual battery capacity. Why would you ever need to put them in a parallel set up? Am I missing something?

OK I think I answered my own questions. Looks like you just swapped the words "series" and "parallel" in your description. The diagram is correct. You charge in parallel for 6v cuz you bought a 6v charger. You drill in series for 18v.

So you cut an extension cord in half, attached the half with the male end to the drill, and the half with the female end to a trailer plug that can be plugged into the battery trailer plug.

Still have a few questions though:

How did you connect the cord to the drill? We didn't use any old batteries... just used the points where the battery would connect.

I've never really examined a trailer plug. How did you connect the female extension cord (white one in the pic) to the trailer plug? Is the other side of the trailer plug just two prong +/-?

Again, how did you attach the charger to the trailer plug?

Finally... how many holes are you getting, diameter, depth, type of rock?

Thanks! Maybe this makes my life easier.

Okay Ryan, I swapped it, I often have things correctly in my brain yet mix them up when I try to articulate.

The trailer plugs have brass holes with a screw in the side much like you would find on a car amp, inverter or something else along those lines. So you can put a wire in and tighten the screw down on the side to hold it in place and make contact. With six of them I used a 1.5" chunk of 14g wire to jump the connections and in some cases such as hooking up the charger I doubled up the wire so there is a jumper wire and a wire from the charger both going into the #1 and #6 hole.

You do need to charge batteries (SLA anyway) in parallel to make sure they're all being charged evenly.

As for connecting, I have a dead battery with the other end of the plug coming out of that. That way if I only need 8 feet I can connect them directly, if I want 30, 60, 110 feet I can bring an extension cord and leave the pack on the ground.

I did see John's posts though I didn't want to modify the drill and I didn't want to deal with having to disconnect any wires when switching from using the pack to charging it which I think he has to do if I'm not mistaken. I wanted very simple, very clean, plug and play setup with the option of using my normal battery pack if I'm just tossing in anchors.

John, that's a lot of holes! I had no clue what to expect as I haven't had to drill that many. I was expecting 12-18 but it looks like I may be super low with that estimate.

power drills have ruined what was once a true sport.

Thanks for the help guys. I don't think I'll be making any changes to the system while I'm here. I only have a few dozen bolts left and after three years I've had about enough of living in Asia. I've organized the purchase of a never used Ryobi gas drill next year and Shamick (The rebolting General) already has it. They will use that next year since most of the work is re-bolting from above.

We are moving to Australia next year though and I AM planning on taking the 24volt with me. I rarely sport climb when I'm not in Thailand but I have enjoyed re-bolting and putting up new routes and Aus has a lot of both that need to be done.

John, I love your setup and that is probably the way for me to go. I don't have to modify my drill to set it up like that since the connections are exposed already. I just need to clean it up a bit.

I like the wiring on the batteries also. Makes it easy to charge, then drill.

I was already aware of the danger of using motorcycle batteries and have taken every precaution to keep the batteries sealed well. Remember though, I do live in Thailand, where nothing is done properly. You should see the trad rack we use here!

Allen Hill wrote:power drills have ruined what was once a true sport.

I could say the same thing about guidebooks, which I'm sure you have plenty of. I think you are being very close minded, not to mention unhelpful.

You don't know anything about Me, why I use a power drill, or my ethics in general. The only area I've ever placed a bolt is an area that traditional gear simply does not work (and we often go go ground up anyways). Also, I am living in a third world country where no one can afford to buy gear. I bolt climbs so that they are safe for the locals to climb.

If I ever bring my hammer drill to your "traditional" area, then fire away. Otherwise, leave the issue alone.

Allen Hill wrote:power drills have ruined what was once a true sport.

I've heard it said that "sport climbing is neither". I've heard people say ropes have ruined what was once a true sport as well. I think you guys need to get together and come up with an etiquette book so people have some idea if they're doing something that falls within the lines of "true sport" or not though I suspect reading it would ruin what was once a real sport. Gotta love opinions and I sure do love yours.

Hi, thanks for the pics.

anybody ever done this with a hilt TE 6A? I wired up three 12v batteries in series and am getting 36V on the multimeter. However I am confused as there are four wires inside the drill (see picture). The other issue, is that while I figured out which two wires run to the battery (top left and right in the picture), when I touch the wires of my battery to those terminals to test... I get a nice big arc, some good smoke, and short-term blindness. This is without the trigger pulled.

What am I doing wrong?

Nevermind guys i figured it out

drewp wrote:Nevermind guys i figured it out

What did you end up figuring out? I'm having a similar issue

I can send you the wiring diagram if you want, but (at least in the te6a) there are a whole other set of connectors up in the handle where the trigger mechanism actually is. You have to take the screw out that holds the panel on the handle on. You can figure out which ones are the correct ones by using a multimeter and checking the connection. It should only form a circuit when the trigger is pulled.

if you could send the diagram, that would be awesome!

Awesome! Thanks! Where did you find that???

ClimbBaja wrote: A 110' extension cord will cause signiicant voltage drop. I've used a 50' with my 24v Bosch, though my preferred cord is 35'. 50' is probably pushing it with an 18v system.

try beefier extension cords. Less resistance = less voltage drop.