electonic question tho not music related

[daz]

I'm asking here because you guys would know this and i don't know where else to ask. I have a 10.8v Li-ion battery powered makita impact driver. One of those ones that looks like a drill but takes screwdriver hex bits. anyways, the batteries are dead and won't charge any longer and i don't want to buy new ones since it's a tool i rarely need. But when i do it's indispensible. So i wanted to use a wall wart to power it. But i'm unsure exactly what to get. First, i would naturally just opt for a 12v since thats the closest thing i'd likely find in a wall wart to 10.8. But the odd voltage they use has me wondering if theres a reason. So theres my 1st question....can i use a 12v or is there some reason they are 10.8? If i can use a 12v, the second question is amps. What do you think i'd need? Battery says 1.3 Ah, but thats just how long it'll last right? How can i determine what the minimum amperage i should look for in a wall wart? Thanks..

[The Dude]

Many Li-ion batteries don't charge to "rated" or "full" capacity. That's why most don't last as long in wireless devices. If you check a fully charged 9V Li-ion battery, it will rarely read a full 9V. Varta rechargeables are one exception. The advantage, of course, is not having to buy batteries all of the time. I'd guess that's what's going on here. The batteries are probably "12V" batteries and 10.8 is what they actually charge to. Using 12V to power the thing should be no problem at all. I've no idea what kind of current it draws, but you might be able to look up the battery specs if there's a part number on it.

Also, just in case: Battery for Makita 10 8V 10 8 Volt BL1013 TD090D TD090DW LCT203W 194550 6 Li Ion | eBay

Not a bad price for staying "wire free".

[tedmich]

those are 10.8v 1.3Ah batteries usually so that's 3x Lithium ion cells in series at a crappy 1.3Ah, if you open up the battery case you can likely replace them. Unless the charging or protection circuitry is bad...

To turn it into a corded drill (RETRO!) you just need to feed it 12v or less at a couple amps, I'd probably get a laptop like supply like this
12 VDC 5 AMP POWER SUPPLY | AllElectronics.com

the peak current on Li ion are great so for that snappy torque you'll need good amps...good luck!

[daz]

Thanks ! So u think 5 amps should be sure to deliver all the battery did? Just need to be sure because i only use that driver for one thing, but it's a real tought piece of work that takes everything it's got.

[Enzo]

The funny voltage is for the battery, not the drill. The drill doesn;t care. Give it 12v and it will run a little faster than at the 11v.


Batteries are electrochemical things. They take different substances and put them together, and a natural voltage difference occurs. A lead acid cell makes 2v, That is what is in most cars. That Die Hard has six led acid cells. A mercury cell makes 1.3v, we use them is special applications. A zinc/carbon cell makes 1.5v, and that is the common flashlight cell.

Each chemical type cell makes a specific voltage. SO put several in series to make something close to 12v and you wind up with odd voltage totals.

I have a 9.6v battery drill here. It isn't because the drill is fussy, that is just what the battery pack full of NiCads adds up to.


Batteries store energy, so you can do light drilling a long time or heavy drilling a short time. Batteries can supply high curent but not for a long time. So your wall wart needs to be able to supply enough current that the tool doesnt stall every time it is asked to work hard. I have no idea, but I'd find a 12v high current source, and insert an ammeter, the see what the drill motor draws when working hard.

One good 12v source is a car battery. Car not running.



Oh, and to be official, a single cell is not a battery. We call them flashlight batteries, but we should call them flashlight cells. C-cells and D-cells. It is a battery if it has more than one cell. Your car battery has six cells. If you open up a dead 9v battery you will find a stack of six cells inside. You battery drill has a battery of cells inside it too.


It is like that whole lamp versus bulb thing. At home, mom would ask, "would you please put a new bulb in that lamp?" And I would. But on a stage, the exact same lighting fixture would have the prop master ask "would you please put a new lamp in that light?" I don't really care about the cell/battery thing, but someone probably wants to know.

[km6xz]

And here, they would say "please put lamps in my amplifier" or "put a new jack on my cord" meaning "vacuum tube" and "plug" respectively.

As Enzo suggested, measure the current when running the impact wrench on a car battery to know the peak current required for heavy loads. Or, get a wallwart of 14 volts at .5-1 amp and use it to charge a 12 volt gel cell by connecting a series resistor to limit current from the wall wart but connecting the gel cell directly to the drill. That way any peak currents needed could be supplied by the gel cell and the wall wart would keep the cell topped up. Gel cells are low cost and can deliver a lot of current. You could go by a motorcycle repair shop and probably be given a "bad" gel cell which is still capable of powering the impact wrench but not to start a 4-6 cylinder bike on a cold morning.

[Enzo]

I took a couple years of Russian in college. Didn't do too bad. But that was like 45 years ago. I remember little of it, other than a few dialogs that stuck. But I do remember the cyrillic alphabet, and it is fun for me to sound out Russian words when I see them. I recall when they opened their big new McDonalds in Moscow, it was on the TV news. I was trying to read the wall signs in the background. I was amused to find a picture of a hamburger, and under it it said Beeg Mek.

I have been buying Sovtek stuff for many years, and was pleased with myself to read on the tube box labels "Elektronaya Lampa" or Electronic Lamp.

But my fave was when I got a Big Muff that came in the original wooden box, and on the box I sounded out "deestorshun".


Hey, I am easily amused...


Of course it CAN be useful, like reading a data sheet for some tube, knowing the English letter equivalents helps interpret.


But by golly, if someone needed me to say "Truthfully speaking, I had hoped to take the bus instead of the subway, so I could look out the window", in Russian, I think I could still do it. By request I could also do "close your books" and "here is your change".

[popoahi]

sometimes it won't charge a battery that's really dead, just no residual voltage left in them..so they will just refuse to be charged
haven't tried it but was told you need to trick them... start with a low battery that will charge once you get em going slip them out and put in the dead batteries.
it suppose to start charging? like I said I haven't had real dead batts so don't know if this works? I think this was the procedure?? if I'm wrong hopefully someone knows the correct procedure?

[Leo_Gnardo]

Similarly I've had lots of trouble with failed Black & Decker battery packs. Another B&D item, a pistol-grip Li battery screwdriver, has built-in batteries which charge just fine but wires from batteries to switch have broken several times. The last time I replaced them with bits of thin solder-wick, more flexible than multistrand cable, and no more failures since in over 2 years. Other than the wire breakage the B&D driver has turned out to be an excellent tool in daily use, with a scary amount of torque. Beats the hell out of the weak-sister Skil driver it replaced.

[Tom Phillips]

daz,

Do the test with a car battery that Enzo suggested in post #5. You will probably be surprised at how much current your drill requires. It takes power to do work and there is no way around the laws of physics.

I have one relatively small corded 3/8" drill. The current requirements are listed as 3 Amps on the placard.
I just made the following actual measurements using my metered variable transformer set to 120V
At turn on the current meter spikes and you cant get a good measurement of the turn on surge but it is probably over 5A at line voltage.
Running under no load it draws 1 Amp which is 120 W.
If I squeeze the chuck with my bare hand the current rises to 2 Amps so the drill motor was already consuming 240 Watts before it was under much load. For full performance my drill would be consuming even more power but let's just stop there and do the math. If a drill was doing that relatively light amount of work AND it was running from 12 V it would be drawing 20 Amps. Modern batteries are designed to supply high current. They just can't do it for very long.

Do the car battery test with your cordless drill and let us know what you discover. Use a capable current meter and remember that the drill will draw increasing current as the work load increases.

Cheers,
Tom

[km6xz]

I just tried my Black and Decker 14.2 volt cordless drill by removing the battery back and connecting my current and voltage regulated lab supply and found it puling 1 amp when running at its highest speed without load and that went up to 6 amps when the drill was really loaded and slowing down a bit. I use it with its variable clutch for my main bench screwdriver but is is strong enough to turn a 3 1/2" diameter hole cutter I used for steel and aluminum. I use it everyday and charge it only once every 10 days or so. It charges very fast with the lab supply, about 30 minutes from almost dead to it not pulling any more current from the supply. So based on that, I figure a 6amp/hour gel cell would be a good supply for the impact wrench.

[Tom Phillips]

I just tried my Black and Decker 14.2 volt cordless drill by removing the battery back and connecting my current and voltage regulated lab supply and found it puling 1 amp when running at its highest speed without load and that went up to 6 amps when the drill was really loaded and slowing down a bit...

Interesting data. It appears that the modern DC motors used in the cordless tools are really efficient. All part of what makes cordless tools practical.

[tedmich]

its unlikely the OPs driver draws more than 2-3 amps from its Li ion pack, as its only a 1.3Ah pack and it can probably run 20 min under a heavy load. Pb batteries can substitute well for Li Ion current wise but they are heavy as...LEAD. Either way take apart the batter pack as that's the best way to get a connector for your wired power supply (or alt battery) Once its opened up first test the cells to see if they are bad (usually by their voltage, impedance etc) and look into replacements if they are. These can be had pretty damn cheap. If its the associated charging or protection circuit thats kaput you can cludge a fix as discussed. If its a frayed wire you are home free!

[Chuck H]

Listen to Ted!!! Rebuilding the batteries is the way to go. If the cells are dead the battery is likely rebuild-able.

As a painting contractor I often have need of a cordless drill. When my old one failed and I had to buy a new one I was cajoled by a couple of guys I know in the trades to get the newest, highest voltage li-ion battery system. Lighter, more compact and higher voltages!!! I was skeptical. After doing some research I found that MANY people are having trouble with the li-ion powered hand tools and that the batteries are disproportionately expensive. One problem is that they require such critical charge and discharge parameters to avoid damage that every battery has a circuit board inside. Now combine that with the natures of SMT electronics and power tool abuse! Apparently many manufacturers are still trying to find an effective means of coupling the charger electronics parameters to the battery electronics in a way that doesn't damage the batteries and render the tool at half power or dead in a short time. Three guys I know complained that they left their new li-ion batteries in their truck for a couple of nights below freezing temps and now their tools only work at half power.

Screw all that! Li-ion for hi current demand usage is new tech and the kinks aren't worked out yet. I bought a NiCd powered drill and never looked back. My old drill worked perfectly for twenty years with the original two batteries! More reliable technology, period. I've got a job to do and fussy tools won't do.

[daz]

I really don't want to do the battery thing, as this device will be needed only maybe once every 2-3 years. And with all the posts and opinions i'm still unsure....what amps will a supply require? Is there a value everyone would agree on thats enough? Or can i even get a wall wart that will have what you;d all agree is safely enough?