Yes, as Rich points out and provide a highly rated
link, the generally accepted figure is 12.65V for
a 12V lead acid battery, but not all sources use
that number and certainly most people can't
measure that accurately.
A new 1.5 alkaline dry cell usually reads 1.60V or
slightly. The NiMH and Nicads are considered to
be 1.2V cells, but a fully charged NiMH gets to
about 1.35V, and the common 7.4V Li-ion battery
reads 8.25V or so at full charge. OTOH, a NiMH
that reads 1.2V or a Li-ion battery that read 7.4V
is essentially depleted.
Using different kinds of batteries can be a bit of
a mess. Stuff made for alkaline cells, sometimes
just won't run on nicads or NiMH cells because the
appliance won't work when the voltage is below
1.25-1.3V. For example my GPS made for alkaline
indicates that freshly charged NiMH cells are half
The risk of explosion is low, but not for that reason, It doesn't
take a large amount of current to cause a hydrogen explosion, and if
there is a 10 amp fuse, 9 amps is a plenty large current if it isn't
in the wire.
If the current is in the wire, a far larger current is not sufficient
to cause an explosion. Consider the hundreds of amps used by the
starter motor when the car is started.
Any tiny spark can cause a hydrogen explosion, far less than one amp.
Why you don't see many is that hydrogen is only generated when the
battery is charging, not when it is being drained** and in this case
the guy using the drill probably won't need to run the engine to run
the drill. And a hydrogen molecule is the lightest of all molecules,
and they float away as soon as they escape from the battery. Since
they are generated under the battery caps, and I think, not sure,
that maybe only escape rather slowly, that they tend to build up
under the battery caps, and if a spark, from a loosely connected
drill, for example, ignites the small amount of hydrogen outside the
battery, the burning can spread to the larger amount inside, and that
is the explosion.
**Although since one would drive the car to where the drill was going
to be used, it would have been charging recently.
The draining, the discharging of the battery, requires hydrogen, but
it takes it out of the sulfuric acid in the battery, because the acid
is the electrolyte,, and I don't think will normally take it from the
gas above the acid.
Remove NOPSAM to email me. Please let
me know if you have posted also.
Thanks for all replies.
I agree on the fuse. I know the lighter socket is fused, but if I use
that gel-cell I will need a fuse. Does anyone have any idea of the
amperage draw on these drills?
Yes, I know Skil is crap. But I got the thing so I may as well use it
till its dead. Having a drill in the car is sort of handy actually.
One never knows when they might get a toothache while travelling.
---- Drill out tooth, fill with Bondo ---- <LOL>
On Sat, 07 Jan 2006 14:57:37 -0600, email@example.com wrote:
I have an old 12v drill I got from a construction site dumpster.
(batteries cost as much as a new drill)
I put a lighter plug on it with a 20' cord and I use it on my boat for
repairing Nav markers and such..
Sure, many people have done it. Biggest problem is getting the car close
enough to the work, especially if you are putting up curtain rods in the
Skil tools are low end. They meet a price point for the infrequent user and
as in all battery drills, the battery is the first thing to go and can be
very expensive. On more expensive tools with better batteries, they can be
rebuilt and be more cost effective. Any of the "pro" models will cost from
$150 to $300. The Ridgid line is supposed to be good on the lower end.
Ryobi is cheap and batteries are about $25. If you want the best, look at
Panasonic, Bosch, Festool.
you can also use a hgh current AC adapter, 120 V in 13V out in whatever
current rating you want.advantage of this is having a handy 12 volt
source for other uses, even a car battery charger should do. if its
current capacity isnt enough the worst that can happen is a drill with
have a friend who tears apart battery packs and replaces just the
cells, which he has found are always regular rechargeable batteries.
cheaper alternative if your handy and dont mind slodering wires.
Its sad so much is disposable today, battery pack could easily be made
to accept new rechargeable batteries
I think what all this amounts to is that unless one has a lot to spend
on tools, it's better to invest in extension cords. They have many
Once I wanted to drill a hole in the top cap of a chain link fence, in
the woods. I thought Cool, I'll use my converter. But the little
converter wasn't big enough to run the drill. I hadn't noticed how
much current drills use. The same reason it takes money to make a
cordless drill. (I ended up taking off the top cap and taking it home
to drill it. Still haven't used the converter for anything.)
Remove NOPSAM to email me. Please let
me know if you have posted also.
The replys you are getting are nuts. Sure you can
use a 12 volt battery, will work perfect as long
as you use the right wire. That drill can draw a
lot of amperage so you need to connect directly to
the battery. You should not be using wire smaller
than #6. Battery cables may be big enough but you
still need to keep the length fairly short.
There is a reason the lugs on the drill batteries
are heavy and that the batteries are attached to
directly to the drill.
Try it with not less than battery cables and feel
the cables for a temperature rise.
I really don't see that a wire that heavy is not needed They don't draw
that much current. Nuber 10 should be more than adequate. Even a 20 foot
long wire (total of 40 feet) would have a resistance of 0.025 ohms. So it
would take almost 50 amps to get one volt of drop. I am using about a 14
gauge which works fine.
However, stalling is a problem with DC motors. When stalled the back emf
drops and it is possible to burn them out.
to determine the amperage draw run the 12 volts in series thru an
ammeter while you drill a 3/8" hole in a 2"x4" piece of wood to load
its motor. size the fuse accordingly to be in series with the cigar
lighter male plug which is already protected to 10 to 30 amps by your
vehicle. there is probably a cigar male plug with fuse at radio shack
or pep boys. or read the technical information on the label. or simply
shop for less expensive replacement batteries but do the homework on
the battery type to match the charger type. we prefer the 12 volt
makita cordless drills and found a replacement battery with a built-in
led light on it that illuminates the drilling area. watch the weights
as the drill voltages go up you may find some 18 volt construction duty
cordless drills are excessive weight for minor occasional household
uses or at the top of an extension ladder playing with the gutters. use
a regular 110 v drill for major wood drilling jobs reduces wear and
tear on your battery drills.
I've got an old 12 volt Sears drill for just that reason. And then got a
couple Drill Master from Harbor Freight for about $15 each.
Should work just fine. I'm not sure what's the smallest gage of wire that
would work (don't know what the amp load is). I'd suggest 16 ga or larger
wire. Which would be smaller number. I think it's a really great idea.
Of course, for $25 or so you could get a 110 volt plug in drill. I like
saving old equipment like that, too. Some time this winter I've got a
couple rechargable shavers that I'm going to externalize a battery for them.
Christopher A. Young
You can\'t shout down a troll.
Lots of good posts....this will work but forget the fuse theory...
You need a circuit breaker! that will limit a cranking style of battery
(automotive) from frying the drill on stall....On top of that you probably
want to use proper connectors as opposed to battery clips that might get
pulled off and fry your vehicle's electical system..someone here said 30
amps...that might work...not sure what your model of skil drill is but I am
guessing it is about 1.5 amp/hour...so that should do it....good
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