cordless tool 18V to 12V converter

We covered like topic before - buck/boost. Just need to "buck" - reduce voltage from 18V to 12V In your opinions - small fitment going into battery "shoe" of 12V tool adapting to fitting an 18V battery pack and having the "buck" volts-to-amps trade - is viable? They exist and are offered - eg. on Alibaba.

Want an SDS drill small enough to carry in a shoulder-bag through a mine

- but use existing 18V batteries - not expensive option of starting stock of 12V batteries. For drilling holes - 10mm or 14mm for "feathers" - rock-splitting wedges. Into hard granite - so needs a "serious" hammer-action drill.

Maybe have to get 18V drill. Helpful advice this morning - for same voltage - 18V to 18V - has straight-through couplings going eg. DeWalt to Makita. So can choose smallest neatest 18V tool.

Thanks in advance, Rich Smith

---------------------------- Viable - yes, easy - perhaps not. That's the sort of thing I do. An adapter to plug into to the 12V tool could be made from a dead battery pack, though you have to strip the batteries out while keeping the retaining latch, and the contacts may depend on the cells (or waxed dowels) to stay in place. Flexible silicone-insulated wire is very helpful to reduce strain on unintended solder connections. The straight oval Makita packs unlatch to disassemble.

Then you can measure the stall current of the motor and select a converter that can handle it. In my experience the cheap import voltage converters aren't too hard to fry from an overload and their max current rating is only with external fan cooling. Be sure to fuse the wiring.

Unless I carve a connector holder on the milling machine my DIY battery pack connectors are thin strips of copper or brass jammed into the slots, since the packs don't usually reversibly disassemble to allow soldering internally. Nickel strips sold as weld-on tabs for replacement battery cells might survive dampness better. The charger contacts could be wired to bring out power from a plugged-in battery though that might be too awkward and vulnerable down in the mine.

I mark the battery terminals with red (+) and black (-) nail polish to avoid accidents. Asking a female clerk for help finding it can be an adventure.

The simpler approach may be to make a corded portable battery pack from a

If you are converting from old dead NiCads to currently available NiMH packs, the old charger may or may not damage them by overcharging. I bought a cheap compatible Vinida charger for my converted DeWalt.

Good Luck!

Want an SDS drill small enough to carry in a shoulder-bag through a mine

- but use existing 18V batteries - not expensive option of starting stock of 12V batteries. For drilling holes - 10mm or 14mm for "feathers" - rock-splitting wedges. Into hard granite - so needs a "serious" hammer-action drill.

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This is what I have and it's barely fast enough in granite for homeowner use:

Must take my 240V power tool to the mine and at the surface try it on pieces of granite from the mine. Calibrate my judgement of what an impact energy in J(oules) relates to as a drilling ability. Looking to identify suitable battery-powered drill. The holes for the "feathers" need to be 2inch to 3inch deep - not a lot. To have a smaller lighter drill (the machine), could be willing to pilot-drill and full-size drill.

Thanks for comment I read as being that to "buck" in such a small space

- between an 18V battery and a fitting into the 12V "shoe" - is not likely to be a robust device.

Rich S

Just run the 12 volt drill on 18 volts. A friend built an entireZenith 701 airplane using a 7.2 volt cordless drill wired to a

I too have been the recipient of tools the previous owner couldn't fix . Mostly chainsaws and other small engine powered equipment . These hillbillies aren't always big on routine maintenance .

Possible, as Jim Wilkins said, and maybe viable, but likely to be a jury-rigged lashup. Do you already have a 12V SDS drill on hand, that you want to adapt? If so, get a motorcycle-size 12V battery (like Jim Wilkins mentioned) or just use 18V straight (like Clare Snyder suggested). If buying new and have a choice, go with a modern 20 V or higher voltage SDS drill, or if 18V is de rigueur, an 18V unit.

I expect that the lighter the tool, the longer it will take, if it works at all, and in any case, extra batteries will make up much of the weight you need to carry. BTW, how long would an extension cord need to be? A cord might be better use of money. Am I correct in surmising a gas-powered generator is out of the question due to its exhaust, or is the mine's air circulation just peachy?

If you are drilling under a dozen holes, get a sledge and a star drill and manually make the holes.

Thanks for comment I read as being that to "buck" in such a small space

- between an 18V battery and a fitting into the 12V "shoe" - is not likely to be a robust device.

Rich S

------------------------------- I don't have experience with the higher powered buck converters except for this, which may be more money and complexity and less ruggedness than you want:

The ones that failed were >10A buck-boost converters, a different circuit. The smaller 4-5A buck and buck-boost converters have been fine.

A freshly charged NiCad / NiMH can be quite a few volts higher than its nominal voltage. The voltage from my "14.4V" charger reaches 22V just before full charge shutoff, and the battery measures 17-18V. A meter or storage scope shows the small voltage steps down as each cell fully charges and begins generating oxygen instead. They set the amount of anode and cathode material unequal to make it generate oxygen which recombines and raises the temperature before hydrogen which would have to vent. The extra contact is for an internal temperature sensor. AGMs do the same, the reason their charging current should be limited.

I wasn't going to suggest running on the higher voltage because I haven't tried it, my second hand cordless drills aren't beat-up enough to sacrifice for a data point. Drilling thin aluminum isn't like chugging several inches into granite. The hole needs to be about as deep as the length of the wedge.

I too have been the recipient of tools the previous owner couldn't fix . Mostly chainsaws and other small engine powered equipment . These hillbillies aren't always big on routine maintenance . Snag

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My first chainsaw which I used until parts became unavailable was a combination of two basket cases (same peach basket), one that wore out and another a tree had fallen on and cracked the case. The fix wasn't apparent to the owner.

If you are drilling under a dozen holes, get a sledge and a star drill and manually make the holes.

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Have you actually tried drilling granite that way?

Like the "parts saw" I spent a dollar on a few years back. "Damned thing won't run!" the fuel line was pinched between sections of the case.

Like the "parts saw" I spent a dollar on a few years back. "Damned thing won't run!" the fuel line was pinched between sections of the case.

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I've done that with the kill switch wire, which has soft high temperature silicone insulation.

I bought a cheap 'broken' floor jack that needed a 70 cent snap ring to keep a lift arm from popping off. I bought a $300 VW Beetle convertible that was making an alarming noise in the engine area until I tightened the loose bumper bolts.

Around thirty years ago L blew a whole three bucks on "some kind of electric meter" a Fluke 77. Junior made his college instructor jealous when he started taking it to class!

I haven't. I have heard of star drills. I wondered whether for 10mm (3/8") a lump-hammer and a said star-drill would work... But haven't acted on in - even looked it up, whether currently available.

The granite This type of drill

Can't carry a big battery down the mine and up the raises. Ladders.

Any mention of "mains" - some parts of the mine are running with water. Area doing work at moment is dry - solid granite no water penetration. But simply cannot run 240V cable around.

Basically it's

• turn on the compressor and use a big rock-drill
• battery-powered "cordless" drill

Videos "gold mine" showed using cordless SDS drill for bit of prospecting and chipping - in granite. So seems is viable.

Going to try 240V SDS on surface with mine granite seeing reality of what the drilling is like.

No chance of gasoline generator down mine.

Around thirty years ago L blew a whole three bucks on "some kind of electric meter" a Fluke 77. Junior made his college instructor jealous when he started taking it to class!

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Good catch!

I got a pretty good deal on an older Fluke 8020 with a fading LCD display. Fluke was happy to sell me a replacement LCD at a reasonable price. I also picked up a Keithley DVM with the same problem and they laughed at me when I asked about a replacement.

If you have air available... there are smaller Rock Drills. For instance:

I haven't. I have heard of star drills. I wondered whether for 10mm (3/8") a lump-hammer and a said star-drill would work... But haven't acted on in - even looked it up, whether currently available.

The granite This type of drill

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The Makita came with a 4-flute 1-1/4" bit that was useless on granite, but a

Plan B was to move the intact boulder, which got me started with portable DIY gantry hoists and discussions that led to the Makita. When I decided to cover my window trim with white aluminum I made a long enough bending brake for it, and while working on it outside on the tailgate of the truck that neighbor came over, saw it and offered to loan me his commercial 10' Tapco brake. I happened into a neighborhood of very handy people, carpenters, electricians, welders and mechanics. It's not odd that one owns a bucket loader.

Solution come into view - will run an airline up the raise and use out "Holman 303" sinker (jackhammer). Very similar to the CP jackhammer you linked to. So that is simply breaking the rocks with a chisel bit in a jackhammer.

If you already have the equipment... might as well find out if it will work for this job👍