What do you do when your car battery dies and you don’t have a jump pack on hand? You could call AAA, or reach out to a fellow motorist to help. But, if you’re like me, and you hate talking to other people, you might prefer to solve the problem on your own. Here’s how a power drill can get you out of trouble.
Rewind back to 2016. I’d just moved to a new state to take on a an engineering role with a major automaker. I was out shopping for my new home, and when I returned to my car, I realized I’d made a mistake. I turned the key and got nothing. I’d left the lights on, and the battery was dead.
I had jumper cables, but no friends in town, and my fellow shoppers looked unfriendly and mean. I also had no road service, so I was on my own. Rustling around in the back of my Daihatsu netted me a solution, though. I found my trusty Ryobi power drill. Surely, this thing could get me going again, right?
See, here’s the thing about modern cordless drills. The vast majority of them use a small lithium-ion battery pack. Inside the drill battery, the lithium cells inside are often the same 18650 cells that you find in laptops and even some EVs like the Tesla Model S. In the case of my Ryobi drill, it had a string of five cells in series, adding up to a nominal voltage around 18 volts or so. That’s higher than a car battery, but we’ll get back to that in a minute.
I’ve always been tinkering with electronics, and I was well aware these cells could happily deliver 20 amps or more without really breaking a sweat. I suspected they could theoretically hold up to maybe ten times that in a short-duration burst, such as cranking over a small engine. All I had to do is find a way to hook it up to the car with my jumper leads.
But wait! At this point, you’re probably hearing alarm bells. We’re told that most cars use 12-volt electrical systems, and here I am talking about jump-starting with an 18 volt battery. That’s six more volts, right? Surely that’s too many!
Here’s the thing, though. Cars do run on 12-volt electrical systems, but that’s a nominal rating. We call it 12 volts, but reality is more complex. A car battery actually sits closer to 12.8 volts when it’s fully charged. Meanwhile, an alternator outputs anywhere from 13.8 to 14.4 volts in normal operation. It’s the same for my Ryobi drill battery. It’s nominally 18 volts, but it ranges up as high as 21 volts when fully charged.
The Ryobi battery did sit at a higher voltage than my little Daihatsu Feroza was built for, it’s true. But there was really only a few volts in it. I figured it was close enough that I was unlikely to damage the simple automotive-grade electronics in my early 1990s car. I also knew that when I hooked it up to the dead car battery, the Ryobi battery’s voltage would sag significantly. This is because the dead car battery was trying to charge itself back up off the Ryobi pack, and that was a significant load on the small drill battery.
The hardest part was actually hooking everything up. My jumper cables were short, so I had to carefully place the Ryobi pack on the front bumper. I then hooked up the the red jumper lead to the positive terminal of the car battery, and then wriggled its jaws on to the positive contact on the Ryobi battery. This was hard to do, as the drill battery contacts were recessed and not easy to access. I then repeated the same with the black jumper lead.
This was an incredibly delicate operation with minimal room for error. The jumper cables were just millimeters apart, and the slightest slip would have seen a nasty short circuit potentially ending in a small fire. I tried to set it up so that if the Ryobi battery fell off the bumper, the jumper cables would slide off the car battery side and hopefully fall clear.
With the batteries hooked up, I gently climbed into the cabin. I noticed the Daihatsu’s volt meter was right in the healthy range, sitting nicely above 12 volts. Even though my knowledge told me this was an okay thing to do, I was nervous.
The moment of truth had come. I feared smoke or flames, but as I turned the key to the ON position, there was none—just the usual friendly lights on the dash. I cranked the starter, and the car burst into life with precisely zero drama. Success! I quickly disconnected the drill battery to stop the alternator back-charging it at the wrong voltage, and drove on home.
I was psyched, because I was now able to drive home and I hadn’t needed to talk to any randoms for help. It might sound stupid, as I’m pretty extroverted, but people in mall carparks are generally pretty uncomfortable about random people approaching them. Plus, I’d pulled off a nifty hack and hadn’t blown up my car to do it. It’s easy to sound confident about this after the fact, but I had been sweating right up until it worked. Even better—I hadn’t killed the drill battery! I plugged it back into my drill and it ran just fine.
It’s worth noting that this worked for a very obvious reason—the difference between my drill battery and an off-the-shelf jump pack was minimal. Both pack a bunch of lithium-ion cells into a small plastic case. The only difference was mine was less convenient to hook up to a car battery, and the voltage was a touch higher. As my success proved, that wasn’t a big deal in my specific case. Indeed, four years later, I’d do the same hack with a DeWalt battery and my 1992 Mazda Miata, and it worked just as well then as it did here.
I would warn you, though, not to try this at home unless you really know what you’re doing. While my early 1990s cars were perfectly able to handle a little extra voltage, your car might not be so robust. I’d be particularly reluctant to try this on more modern vehicles with more complicated and fussier electronics. I’d steer well clear of doing it on a modern BMW, for example. In contrast, though, you could absolutely do this to a Tesla Cybertruck, as it has an advanced low-voltage electrical system designed for jumping from 12-volt, 16-volt, and 48-volt power.
In any case, I found this to be a useful technique for getting myself out of trouble. There are just a few key points to note when doing this. It’s important to take extreme care when hooking up your batteries. Drill batteries often have very small, recessed contacts that are incredibly difficult to connect with automotive jumper leads. You want to avoid short-circuiting your positive and negative leads at all costs, lest you cause a fire with the drill battery or your car battery—or both. At times, I’ve used creative solutions to hook up to a drill battery, by using bits of metal to create larger, more accessible contacts, for example.
You should also accept that you risk wrecking your drill battery in doing this. The excess current draw might over-drain your batteries to the point of failure, particularly if you have a large engine with a big starter motor. Using the largest drill battery you have will also help—bigger batteries can deliver more current. There is also another way to avoid this—you can simply hook up your drill battery to your car battery, and leave it sitting for half an hour or so without cranking the engine over. The idea is that you’re using the drill battery to effectively recharge your car battery. You then disconnect the drill battery before you try turning the engine over.
Hopefully, your car battery is always full, and you never have need to do this. However, if you’re ever stuck far from help, and you absolutely need to get some juice into your vehicle, this might just save your butt one day. It’s a good idea to keep in the back of your mind, if nothing more.
Image credits: Lewin Day
If anyone watches Vice Grip Garage on YouTube, he will use Milwaukee 12V batteries to run fuel pumps, connected to a gas can, that is strapped to the front of his car or just sitting on the passenger seat floor. It’s fantastic entertainment.
Clever……Reminds me of the most unconventional thing I ever did with a drill. At work (electrical controls manufacturer) We had a production line that wired up big power panels for medical applications. The panels were laid on their backs on a special cart with the doors facing up. The ladies wiring them complained that having to open the heavy doors were an ergonomic issue so I was tasked with coming up with a way to lift the door and keep it open without relying on the operator to do it. I ended up buying cheap trailer jacks, lopping off the handles and welding sockets to them so I could connect a cordless drill they already had at their stations it to extend/retract it. I mounted them on the carts with a special end to support the doors and voila! No more safety issue!
That sounds inventive, and I’m glad it wasn’t what I feared it might be after reading Torch’s “Hot Start” earlier today.
I thought I was going to read about you using a socket on a crank bolt and was wondering how you were going to avoid loosing your arm.
Cool, but will this work on a ’79 St. Regis that’s been sitting overnight in below-zero cold?
Recently saw part of a video in which the guy posits a dead truck battery and showed how to use a chainsaw to spin the alternator plus a Milwaukee battery to excite it. He brought a flat battery up surprisingly quickly.
The channel is profane, purposefully offensive & polarizing and so on, so I won’t post the name.
-common plastic connector s & old-style tires will get you there if curious. NSF for sure
-definitely not an endorsement, but I thought it inventive
Well, that would certainly be an upgrade for Torch when it comes to truck batteries and chainsaws
Haven’t done this, but I have F1 started my pressure washer with a drill directly on the flywheel after the pull-cord broke. The replacement unit cost more than half the value of the pressure washer.
I have a RAM pickup with the eTorque 48V hybrid system. It uses the 48V battery to start/stop the engine, but uses a traditional starter with the 12V battery to initially start the car. When my 12V battery went bad and was too weak to start the car, I remember thinking how nice it would be if the car had been programmed to use the 48V battery to start the car if the 12V battery was too low to do it (or if the starter failed) and then give you a check engine light and message after. or to at least give you an option to start it with the hybrid system buried someplace in the infotainment screens. But nope.
Interesting. In a Prius the traction battery is used to start the engine. The 12V is basically just there to power up the contacts for the big one and to provide accessory power when the car is off. The down side to that is you don’t find out your 12V battery is going bad until it’s too weak to close the contacts because there’s no slow crank to warn you ahead of time.
Same on our Kona Electric. 12V can be near death and the car will function normally until on time the 12V can’t power the safety systems and close the contactor in the traction battery. Uh-oh. Not been a problem.for us.
I’m surprised it even has a 12V starter. Basically every other hybrid out there just uses the motor/generator as the starter and the 12V only runs electronics etc.
Usually the traction battery can’t start things without the 12V because of safety – the 12V’s needed to run the contactor that connects the higher-voltage battery. Maybe less of a problem for a 48V system than a 400V one, though.
It’s actually a bit of a different problem for hybrids and especially PHEVs. Usually you can tell the 12V is dying because it cranks longer and slower, but if it’s only powering the computers and contactor it can be in much worse shape before there are any symptoms. Which means the first thing you see is a bunch of glitches/errors/codes on startup because it doesn’t have enough volts to get a good reading from sensors.
I once jump-started my car with a stack of hearing aid batteries.
JK
I’m pretty sure your Daihatsu is a manual, did you try push starting it?
I’ve push started a 2CV by myself, but to do it on your own with an actual car requires some convenient geography.
I too am no stranger to push-starting a small french car on my own – a Renault 4 in this case. One time I had to do it in reverse because that’s where gravity allowed me to go more easily. Recently the battery has been acting up again due to the cold weather in the morning, and I’ve had to roll it down the street a couple of times in the last couple of weeks after depleting what little charge the battery had left trying to start the car normally – the carb has some leaks and the cold morning air doesn’t help, so it takes quite a bit of cranking+choke+gas+praying that it won’t flood to start the engine.
I often push-started my Spitfire in high school. Sometimes were more miserable than others, like on rainy days. I was no athlete but I had the finesse to do it where most linebackers would’ve failed.
Same with the Spitfire. Got good at it…
I have idly wanted to try jacking up a drive wheel, wrapping a rope around the tread, and trying to pull-start a manual car.
‘Idly’ = never got up the gumption to actually do it
That video would go viral. You need to do it. Even if you fail, the video would be great.
I’ve push started a Mazda 121 by myself in a deserted area and that was incredibly difficult to do without tripping over it or sending it rolling slowly into a wall
No chance I was going to try that in a loaded carpark with a vehicle that weighs 1.5 times as much
I went to the Nurburgring in an old BMW 535i, and that had to get push started a few times. It was hugely stressful because even with a team of helpful passers-by doing the actual pushing the car park was rammed full of shiny expensive cars.
A new battery would have cost about a sixth of what the car was worth, so I just started it with my jump pack, which went flat after all the starts during the 500 mile trip to the track. Old cars are character building.
My old ’76 Dasher had no starter. Hill at home, hill at work, hill at the girlfriend’s house. Everyplace else I just left it running.
wonder why they don’t make adaptors to do this at least I haven’t seen any
They do – https://www.ryobitools.com/products/details/33287215379
Yikes I thought I would save money using my own battery
Yeah, you can buy a nice dedicated jump pack for that. I guess the upside of the Ryobi version is being able to just swap out the battery once a year instead of having pull it out to charge and then risk forgetting to put it back in. Which will, of course, be the occasion when your battery dies and you need it.
Makes sense! Most 18650 cells (which is what most power tool batteries are comprised of) are rated for pretty high discharge and you’d expect the ones in a 6Ah battery to be even more so
That’s a good time to check the water levels too (if applicable). Charging a severely depleted battery low on water is a good way to kill it. Given you were out shopping for your new home would expect that would have been the perfect time to pick up some distilled water if it was needed.
You can check and fill water on most “maintenance free” batteries still. Use distilled.
Not really maintenance free then is it?
I refuse to speculate, I recall that term as marketing as a kid. I pop the caps off and still check occasionally. I believe AGM are truly sealed – have to go out to my SUV and check.
Even if it’s not sealed, there’s no fluid in an AGM to refill. It’s all absorbed in the glass mat (per the name).
My drill batteries are expensive. I’d call for a jump start.
A portable jump battery costs less than a hundred bucks, and comes with an air pump, work light and USB jacks to keep your phone topped up. It sure is nice to be back on the road in less than about three minutes. I have helped out a few strangers this way.
They’re like $50-70 for all but the largest diesels.
And every time you rescue someone with one of them, it’s the greatest advertising ever. I’ve bought so many not because they’re a terrible product, but because the person (usually a friend but sometimes a random) often wants to buy mine.
I have a jump pack. Love it.
I used to have the big plastic ones that were always dead when I needed them. These new ones are small and light and hold their charge in storage. This reminds me I need to buy another.
Without road service, calling for help would have probably cost me more than the $100 cost of a new Ryobi battery. If your batteries are significantly more expensive, though, I get it
I’ve recently switch to Milwaukee, so depending on the battery size it’s probably more. Hard to tell right now with all the tools / batteries bundled for the holidays.
This story did inspire me to finally order a few more portable jump start boxes so I can have them in every car.
I do this with my 36V mower (3x12V lead acid) and a 40V snow blower battery.
May not be that bad for a battery, since Ryobi now sells kit to jump cars using the same battery…
https://www.ryobitools.com/products/details/33287215379
Since I have a bunch of Ryobi 18V batteries from buying tools when they were free with a two-pack and charger, I considered getting one, but they’re priced about twice what a discounted jump pack would be, even with a tire inflator (which I did buy from Ryobi to make use of the battery stash.) They do make good consumer-grade tools.
I find their tools to be just fine for my weekend warrior stuff. The real reason they get my loyalty is because they have the good sense to not change battery shape rendering all my tools semi-useless or relegated to off brand batteries from ebay. Eye-daggers to you, Craftsman.
Now I want my Rocky back.
I miss my Feroza every day
if only the head gasket didn’t pop less than 30 miles after I had had it done…yeah, it was a pretty great little rig, but obviously a massive design flaw
I’ve jumped my car from it’s own battery using a screwdriver. I don’t advise that, I advise cleaning battery terminals before a screwdriver is needed.
I shortened a screwdriver by a few inches doing that. Bad solenoid. A few hundred amps is no joke.
Its easier if you are jumping from a lightly cleaned terminal to the cable still attached to it. Lightly cleaned meaning the screwdriver scraped to fresh lead then a tip jammed between the terminal and cable.
I was jumping a broken solonoid. I kind of expected to damage the screwdriver, just not vaporize it.
A lot of tractors had sheet metal screws driven between the terminal and cable end as a fix for your situation.
Now you need to come up with a 3D printed adapter to make the jumper cables fit better!
You can buy adapters that take most common power tool batteries to pig tails. We have some around at work that we use to power our GPS system if someone (Blake) forgets to charge the external battery.
If you’re buying stuff, there are jumpstart packs with electronics and all that take tool batteries.
That seems substantially less sketchy than jamming the bare wires into your battery connections. That alone makes me much less likely to buy it.
Also I got a jump pack a few years ago from work. It’s come in useful a couple of times, definitely a product I’d recommend people have.
Dammit, Blake!
Also, those pigtails have awfully small wires compared to a jumper cable.
And here I though we were going to see you hook up the drill bit to the starter motor or accessory drive…..
I’ve never noticed those packs actually label the positive/negative terminals. I wonder if they are anticipating situations like this because normally why would it be necessary since you should in theory just be plugging into a tool that only plugs one way?
Also reader beware, this might not work with all brands. Some of the more expensive brands have sort of a “handshake” protocol between the pack and the tool/charger to prevent people trying to use off-brand third party packs to save money. So in those cases, unless the battery recognizes a connection with a compatible tool/charger, the terminals won’t get any juice
Those are some crazy looking jumper cables. What decade are they from?
Lewin, you’re probably too young to remember the original MacGyver TV series, but Richard Dean Anderson would be very proud of you. Nice hack!
I am willing to bet that show steered a LOT of us GenX kids into STEM careers. We didn’t have the Space Race. I know it influenced me, as well as dad’s Golden Age Sci Fi. MacGyver was the thinking man’s A-Team.
I’ve seen it a few times!
These 18v & 20v batteries can spice up your kids Powerwheels toy too allowing plastic tire donuts and a big smile on your kiddo’s face.
I used mine to speed up my electric scooter! Good fun until the smoke comes out.
Holy shit, a rocky! My mom had a teal and gray one when I was a kid. Took the top off of it all of 1 time but it was still cool! Nobody in the family was mechanically inclined and parts were unobtainable pre-internet days, so it ended up being a pain. Ate oil and eventually ran dry on a road trip. I’m sure it’s either scrapped now or sitting in some field.
Also, drill batteries are great for checking window regulators and door locks at junkyards before paying for them.
Yeah, those Daihatsu engines don’t seem to last forever. Mine eventually succumbed to oil starvation to the head for some unknown reason.
Yea my mom’s ate oil and she relied on my dad to check it. That was a mistake.
Drill baby, drill!
I’ve done this exact sketchy dance with my old motorcycle and a 4S battery pack from a RC car.