Using an 18V power tool battery to jump your dead car (truck?) battery... (1 Viewer)

[e9999]

I just got dragged by Youtube algorithms into a bunch of vids showing that it is possible to jump your car battery with an 18V power tool battery. I did not yet see if it possible to jump a bigger engine like in our trucks, though. Be that as it may, it is rather impressive. I saw one interesting vid where the guy was measuring all the currents and voltages. Surprisingly, he got something like 130A out of a 12Ah (IIRC) Milwaukee 18V. It was less with smaller capacity batteries, I think. But enough to start the engine.
Now, there are issues. I guess the main one for me is that the car battery when jumped can get up above 15V which is concerning as far as ECUs etc. It is also entirely possible that this would cook smaller 18V batteries, I imagine.

TBH, I don't think this would have crossed my mind without seeing it. But in retrospect there are all these powerbank jumpers, so I guess it is not entirely farfetched, I just don't know what voltage those powerbanks are.

But, and concerns not withstanding, if I am stuck in the desert with a dead battery and running out of water, I'm trying that...! (I'll probably now take more than one battery with me too, there go my hard-won weight savings...)

 

[e9999]

well, I guess I got some answers about the questions I had above. Seeing more of those vids in my YT feed. This one is closer to home (damn Big Brother...) :
This guy managed to get his Cruiser started with a 6Ah Makita 18V battery AND 2 FORKS! Leave it to our Aussie good friends to come up with this kind of genius hack...




And only used 1 bar!



Of course, this could all be completely fake. Guess what I'm gonna try this weekend...

 

[Josie'sLandCruiser]

Seems easy enough to just carry a quality lithium jumper pack. I like the "GooLoo" brand, costs less than $100, doesn't take up much room, and from my experience will hold a charge for many months.

 

[ducktapeguy]

It'll most likely work if it's a lithium battery, that's pretty much what those small jumpstarter packs are made of. I wouldn't be too concerned about the electronics as long as the starter battery is still connected, it'll act like a voltage sink to keep the voltage around 12V. However, I'd be more concerned about damaging the battery. High amperage drain like that will shorten the lifespan of the battery, especially if they're not designed for that type of load. It'd be cheaper to just buy a cheap jumpstarter than risk expensive tool batteries.

 

[e9999]

If I remember correctly, when the guy measured the voltage of the main battery the 18V was connected to, it was climbing well over 15V. You would think the bigger battery would not increase that much in voltage but it did.
Now, it seems that there would be two ways to do this: connect the 18V and immediately start the engine and that worked for the bigger 18V pack, presumably because if can handle a 100+A (the cells must have been capable of 30 or 40A in each row - 3P), or connect the 18V for a while and let it bring the voltage of the truck battery up enough, which is what the guy in the vid above did, IIRC, and the current would be less then.

Obviously, a dedicated jump starter made specifically for 12V jumping would be better, but the point is that if you are ever in an emergency and need to get the engine going, this may get you out of a pickle. Well, as long as you have metal forks or some wire with you... And one should not assume that everybody can afford to drop a $100 on a jump starter pack on the remote chance they will need it, whereas we probably all have some sort of 18V battery floating around, so good info to know IMO. And interesting technically speaking, I'm surprised it works.

 

[80t0ylc]

It seems like one of the things we learned in basic electronics was if you hook up batteries in parallel, the result would be the average of the batteries involved. IIRC from the video, the run down main bat in the truck was measured at 6.5 volts. So considering the tool bat is 18 volts, the average of that is 12.25 volts which should be sufficient, without going through all the other math. I'm surprised they showed the rig bat at 10 volts in their math. Where'd that come from? Anyway, in an emergency, you'd probably try it and deal with any consequences later - such as a fried tool bat or ignition system damage.

I'm constantly amazed at what my 18 V Milwaukee tools can do! With my impact driver, I can bust loose the lug nuts on my 80 and my Ford Ranger. Haven't tried it on my F350 yet, but it's lug nut torque rating is 140 ft lbs, so it might not work.

 

[e9999]

^ it would be (something like - it's not a linear process) the average, if the 2 batteries have the same capacity, otherwise not. You could empty a small battery with a consequent big drop in voltage into a big one which would go up in voltage only a little bit.

 

[Mark W]

And one should not assume that everybody can afford to drop a $100 on a jump starter pack on the remote chance they will need it, whereas we probably all have some sort of 18V battery floating around, so good info to know IMO.

Nope. Personally I WILL confidently assume that anyone who can afford to own a Cruiser and afford the assortment of other gear that they damn well better have to take it places where they will not have outside infrastructure to support them... can afford 100 of today's dollars to ensure that they get their passengers home without walking. I mean, what is $100 anymore? About a dozen phucking happy meals? Have you ever seen all the crap that our intrepid "overlanders" pack into their rigs?

There are not a lot of high school and college kids driving POS '40s around town as their daily drivers any more. The POS '40s have all faded away, and we all grew up, got old, learned from our lessons... and have more than $1.27 to spend on our rigs every month.

Of course $1.27 used to buy a lot more than it does now... but still...

It is a cool trick to know. And, sure I happily would use it and giggle giddily if I had to and had no other choice. But justifying carrying your Dewalt tool batteries as a backup instead of having a set of jumper cables around town... or buddies or a jump box (or $30 used battery tossed in the back as a spare) when you out "not in town"... nope.


Mark...

 

[Mark W]

^ it would be (something like - it's not a linear process) the average, if the 2 batteries have the same capacity, otherwise not. You could empty a small battery with a consequent big drop in voltage into a big one which would go up in voltage only a little bit.

Have you seen the capacitor style jump boxes? Now those do get my attention. You charge them up when you are ready to use them. Unless you battery has been physically damaged or has been connected to a load for long term, draining it down to the last few ergs... there is virtually always gonna be a few amps at very low voltage lurking in there. The capacitor box will pull that out... a few amps at tiny voltage and store it until it has enough to convert it to 12(ish) volts and sufficient amperage to spin the motor as well as your original starting battery would.

Pretty amazing the first time you see it happen.

What really caught my attention is that a lithium jump box will SUCK when you pull it out of the rig at -10F and try to start a rig that turned out to have a marginal battery. It will laugh at you and tell you that the "battery is too cold". Often even at much warmer temps.

If you are at home, you go inside and set it on the heater vent and wait. Did you need to be somewhere on time? tough luck.

I guess if you were out in the field climbing out of your tent, you *could* stick that brick of cold inside your coat and chop wood to stay warm until the jump box was happy. Have fun there. ;(

Actually, I expect that the tool batteries would also have the same problem. They just would not have the electronic override telling you not to even bother.

Anyway, while I have not tried it yet, I expect that the capacitor box could pull power even from a cold lithium until it was ready to kick your engine over nice and hard. And they will definitely pull whatever energy is left out of a car battery, regardless of the temp.

I would not ignore a tool battery if that was all I had. But for my money, a lithium jump box in the back alongside a capacitor jump box... if my dual batteries under the hood ever let me down... I got it handled. Anywhere, any time, any conditions.

For under $250 invested.


Mark...

 

[jgranthevagrant]

FWIW, my tool batteries definitely struggle below zero (celsius) and will only charge above zero. I bring them inside to charge. I have Makita tool batteries and Ryobi snow blower batteries. I have not tried jumping with either, but interesting to know.

 

[80t0ylc]

What really caught my attention is that a lithium jump box will SUCK when you pull it out of the rig at -10F and try to start a rig that turned out to have a marginal battery. It will laugh at you and tell you that the "battery is too cold". Often even at much warmer temps.

If you are at home, you go inside and set it on the heater vent and wait. Did you need to be somewhere on time? tough luck.

I guess if you were out in the field climbing out of your tent, you *could* stick that brick of cold inside your coat and chop wood to stay warm until the jump box was happy. Have fun there. ;(

Actually, I expect that the tool batteries would also have the same problem. They just would not have the electronic override telling you not to even bother.

FWIW, my tool batteries definitely struggle below zero (celsius) and will only charge above zero. I bring them inside to charge. I have Makita tool batteries and Ryobi snow blower batteries. I have not tried jumping with either, but interesting to know.

Yes, it is a known negative symptom, maybe the only one of lithium bats. Well, except the extremely high price. EV's suffer from this, too. It would seem to be not a great decision in colder climes, to have to rely on a system, with out a battery heater of some sort, that it's main source is lithium battery(s). Otherwise, their performance is head and shoulders above other types.

 

[PAToyota]

AFAIK, Ryobi is the only OEM to make a jump starter that uses their tool batteries: 18V ONE+ JUMP STARTER KIT - RYOBI Tools - https://www.ryobitools.com/products/details/33287215379#

I have seen "aftermarket" versions for other tool batteries - here are Milwaukee, DeWalt, and Makita version: Search: 3 results found for "jump* starter*" - https://bearhollowsupply.com/search?type=article%2Cpage%2Cproduct&q=jump*+starter*

And, as noted, there are DIY setups across YouTube and such.

Nope. Personally I WILL confidently assume that anyone who can afford to own a Cruiser and afford the assortment of other gear that they damn well better have to take it places where they will not have outside infrastructure to support them...

Despite having the money to buy other gear, my issue is having a bunch of different "platforms" that I have to remember to keep maintained and charged. Personally, I ended up with DeWalt cordless tools and have bought a number of things in the DeWalt lineup for more money than other options just because it is all compatible with the same batteries - particularly for things that I'm not going to use as frequently. When I do need to use it, I know there will be a DeWalt battery ready to go for it instead of that being the one thing that uses that battery and the battery is dead - or toast from lack of use.

 

[e9999]

I did not know that these 18V battery jumpers were available, interesting. I looked up the Ryobi but oddly could not find it without the battery and charger. With them it was at $200 which is more than a good quality lithium jumper I think, so that would not do it for me since I don't have any interest in starting yet another battery platform. Plus I don't know if what the tool does (probably lowering the voltage I guess) is worth the big $. Now, having one that fits my existing batteries would be interesting but the ones above (thanks!) seem to be generic chinese, still $140, and oddly have a 60A breaker. Of course, the breaker would not trip instantly but that is still odd. So, not a compelling buy for me. Especially since it would not blow people's minds like the forks trick! Also, I would think you need to be careful to use a big enough battery that it can deliver enough amps.

Thanks for mentioning that, I'll look some more into it.

Am I the only one who finds it astonishing that a little tiny battery like that can spin a big engine...?

 

[PAToyota]

Yeah, I scratched my head at the 60A breaker as well...

I was more just showing that they're out there than saying I was going to put my money down to buy one.

The Ryobi can be bought as a bare tool (LINK), but it is only $20 cheaper than the "kit" with the charger and a 2Ah battery. I somewhat trust the Ryobi more than I trust the cobbled together aftermarket setups. And like you, I really don't want to get into another battery lineup.

I'm a bit surprised that other tool OEMs haven't done similar, but maybe that says something? You'd think DeWalt and Milwaukee would be jumping on it if it were viable. Having said that, I just went and searched and turned up this DeWalt "Battery Booster" (LINK). They basically say that after several minutes of "boosting" you'll be able to start your car rather than "jumping" it. Curiously, I haven't been able to find anything about that item on the DeWalt website.

We had a guy come through the shop with a little lithium battery in his dune buggy. It was maybe a third to a quarter of the size of a regular automotive battery. I forget the brand. The lithium configuration makes for a smaller battery, but realize that the tool battery jump starter is just going to start it a couple times. This battery in the dune buggy was still smaller than a normal battery, but quite a bit larger than your average tool battery for regular starting use.

 

[e9999]

That booster is probably just a buck converter. But the boosting part does not seem utterly compelling to me, although that seems to be what the guy in the vid above did (IIRC). If you think 5Ah in 18V, it is something like 7.5Ah in a 12V battery, so at best it would increase the state of charge of the 12V main truck battery by 7.5% if it's a 100Ah battery. That's not a lot. And maybe not enough if it's completely flat. But, yes, maybe enough in a marginal charge situation. So I'm thinking the jumping approach may be better if you have a big enough 18V battery.

 

[ducktapeguy]

Have you seen the capacitor style jump boxes? Now those do get my attention. You charge them up when you are ready to use them. Unless you battery has been physically damaged or has been connected to a load for long term, draining it down to the last few ergs... there is virtually always gonna be a few amps at very low voltage lurking in there. The capacitor box will pull that out... a few amps at tiny voltage and store it until it has enough to convert it to 12(ish) volts and sufficient amperage to spin the motor as well as your original starting battery would.

I've switched over to from the Lithium jump packs to using the capacitor style jump starters. The Li-ion work great when new, but they have some weaknesses. First, with regular use they have limited lifespan, the high drain on the batteries really kill the batteries. I got maybe a few years use of out them regardless of brand. Two, lithium batteries don't like to be stored with a at high temperatures or at full charge for long periods, which isn't useful for something like a jumpstarter which are stored fully charged in a hot car all the time.

The capacitor style ones are very useful, and act like bluetooth jumper cables. If there's another car around, you can charge it on their battery then move it to the dead battery, without needing to move the cars next to each other. They will work on low batteries, but there is a minimum voltage needed to get them to work and if the battery is borderline it takes a while for them to charge. If you have dual batteries it's not an issue, you can always charge from the auxiliary battery. I have dual batteries and solar, so I stopped carrying any type of jump pack because the chances of me needing it were almost zero. They're also rated for something like 10's or 100's of thousands of cycles, a lifetime of jumpstarts for most people. I have killed one before because I didn't realize there is a duty cycle on them, but I don't think that's a problem most people would have.

Obviously, a dedicated jump starter made specifically for 12V jumping would be better, but the point is that if you are ever in an emergency and need to get the engine going, this may get you out of a pickle. Well, as long as you have metal forks or some wire with you... And one should not assume that everybody can afford to drop a $100 on a jump starter pack on the remote chance they will need it, whereas we probably all have some sort of 18V battery floating around, so good info to know IMO. And interesting technically speaking, I'm surprised it works.

To me this seems more like a parlor trick, kinda like sealing a hole in your cooling system with pepper or an egg. Yeah, I'd do it in an emergency but it'd be a last resort and only if I ran out of all other options. Might be useful for a contractor who always has batteries ready to go, but I wouldn't assume people leave expensive power tools in the car all the time either. The probability of me having a fully charged, $200+ high capacity battery and a couple of metal forks in my car while I'm in a remote area needing a jumpstart is pretty low, and I wouldn't want to risk using it when I could just get a $50 jump pack dedicated for that purpose.

 

[e9999]

I have since seen a video where the guy did jump/recharged his car with a few AAs. 9, I guess, so about 13V, but that would only be something like 2Ah, so even more marginal. Seemed legit but who knows. Cute, but unlikely I would ever have that many AAs with me in the desert... Still, I would not mind being the one who saved the day with AAs, stuff of legend...!