Connecting Jumper Cables Backwards? Here's What Could Go Wrong!

Ever wondered what would happen if you connected jumper cables backwards, or connected your car's battery backwards? Don't. Len explains why connecting jumper cables could overheat the cables and start a fire, and how reversing the battery could possibly ruin your vehicle's electronics, if the safety fuse doesn't do its job!

Check out more tips from Len and the other 1A Auto mechanics in this playlist:

⚠ DISCLAIMER:
While 1A Auto strives to make the information provided in this video as accurate as possible, it makes no claims, promises, or guarantees about the accuracy, completeness or applicability of the content. No information contained in this video shall create any expressed or implied warranty or guarantee of any particular result. All do-it-yourself projects entail some risk. It is the sole responsibility of the viewer to assume this risk. 1A Auto is not responsible or liable for any loss damage (including, but not limited to, actual, consequential, or punitive), liability, claim, or any other injury or cause related to or resulting from any information posted in this video.

[AAuto]

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[fernandobriseno]

I've jumped several times over the years but one time for whatever reason I switched the cables. I was using my pickup to jump my jeep and was letting it charge for a few minutes as I leaned on my truck when I smelled burnt plastic. I looked at the cables and the side nearest the jeep were melting the insulation off. Luckily no visible damage was done. That was the first and last time I did that. No more distractions after that time.

[cousinjohncarstuff]

Best advice, buy a jump pack which will not turn on if the cables are not connected correctly. They are small enough to fit in the glove box. And, no having to wait for someone to give you a jump!

[KentuckyRanger]

I'll never forget, the one and only time, I hooked jumper cables up backwards.
It was late at night, I was on my way home, from a week stay at the hospital.
I drive a 2015 Subaru Outback, that if left sitting for too long, drains the battery.
Thank God, someone had jumper cables!
They were really old, and the red clamp was so dark, it was hard to tell which one was which.
When I connected the last cable, it sparked, but not really bad.
I figured it was because my battery was so dead, but quickly realized what happened, and disconnected it.
Thank God I didn't try to start the car, because I'm sure that would've killed it.
It's been about 4 months, and so far, everything seems to be working fine.
I did replace the battery, because I think it was damaged when I jumped it backward.
Ever since I did this, I've felt like an idiot, because I was an electrician, as well as electronics tech.
It just goes to show, it can happen to the best of us...

[debiconner]

The cable connected to the starter is positive. The negative is a ground wire usually connected to the body or outside of engine. This is usually easier to see the connection.

[samg]

Jumper cables are never backwards until you attach them to another car at the wrong polarity. Only then are they backwards. That would have been a better demo. Also, the negative clamp needs to go to the block on the dead car in case the battery is shorted out. That prevents shorting out the good battery.

[Lassitude]

I'm still torn on whether I love or hate the bad acting/skits. They're funny, but also embarrasing at the same time. Keep it up, either way!

[TheTechCguy]

I actually did see a few times when people, in the shopping center parking lot, would actually connect the cables with the working car running! No!! Don't do that. You make sure both cars are dead BEFORE hooking up the cables! That way it prevents arcing, a possible fire, injury, and even death! Always take safety into account whenever jumping a dead car!

[Isaac]

Hey how can I share this with myself 3 weeks ago?

[JamieHitt]

I’m so glad that we now live in a world where incompetency is considered the norm.

[DocMackGarage]

I knew there was going to be a scream or two coming up . Quite nice and entertaining.

[MrFiddee]

I scrwed up like this a few weeks ago, I was stressed and it was raining so I didn't check proporly, and I didn't know what damage I may ahve caused doing so. This really helped me understand what happend, the damage I may have caused, and to take this info and experaince with me. Thanks man. ^^b

[zzzzzz...]

I accidently did this the other day as I was in a rush to get it to a shop for a noise. My car had no codes before this. I did this and then after 30 seconds I realized I crossed them and quickly removed them and connected it correctly. Jumped started the car and it started. However, when I tried to press on the gas pedal, nothing happened. Hook up my scan tool and it lit up like a christmas tree, had probably like 10 codes. Checked the fuse box and found 1 fuse half way through that was blown. Replaced it and gas pedal worked again and made the car speed up like it should. Cleared out the codes and all of the codes cleared except for 1 code in the bcm. However, I just wanted to get it over there and I will look into this after. Did look up what the code was as the description on the scan tool was a little unclear and it looks like its about the seat belt system, so not a big deal. I will finish going through the fuses and check the relays once I get it back from the shop to fix that bcm code. So this is my partial experience so far.

[joebarcenas]

5:02 that made me jump out of my seat!!!😂😂

[donlleyo]

I was in a rush and reversed them. I left it on for less than a minute. Started to smoke and I immediately unhooked it. The car lights still turned )I had issues with the alarm system not letting me turn on that car). I don’t think there was any damage. How long does it take to do damage while hooked? I got to it just as it started to sizzle a bit. 😬

[christopherrosas]

My brother did this one time when I was giving him a yeah, he got a yelling and it was his truck that he hooked up wrong.... during day time, so it's not like he couldn't see which was positive and which was negative

[SlowlyFallingUpwards]

Does Reving your engine help speed up charging the dead battery?

[mikelarochemusic]

Bro you're scream at the beginning made my day. Funny as s*** I've seen in a bit

[nikhil]

I understand that these things can happen if polarity is reversed but still if if someone does this mistake, will the car start ?

[jaxondakota]

I ain’t gonna lie, that BOOM surprised tf outta me 😂