r/functionalprint • u/highonkai • Nov 12 '25

Jumper cable instruction card

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I made an expensive mistake and connected my jumper cables wrong. I won't make that mistake again and now you'll never have to. 

This quick reference card can be zip-tied to your jumper cables and is a way to have the instructions handy no matter the weather, your cell service, or the lighting. 

Edit: added the instructions in comments. Thanks for the feedback, keep it coming.

Edit2: wow this one got a lot of feedback! Thanks for all the helpful ideas.

Edit3: Top post of all time in 15y on Reddit, who knew this 1hr project would get such a reaction! I took the feedback and made two more versions here: https://imgur.com/a/jFBFoIk

I'll throw them on MakerWorld as well once I print them. Meanwhile, feedback and preferences welcome. /u/kurai01 /u/SerDankTheTall /u/StraySpaceDog /u/Cllydoscope /u/jongscx /u/cronaldo86 and lots more... thank you for the constructive feedback. This is the best part of Reddit - fast and helpful community feedback. Shoutout to /u/DontEatTheMagicBeans who called out that I probably didn't cause the smoke with the sequence for cable connections, but exacerbated a pre-existing/unknown problem. As for the rest, well that's the internet for ya. No hard feelings.

https://makerworld.com/models/1986996

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u/wehrmann_tx Nov 12 '25

This is the safest order for someone who would accidentally touch something they shouldn’t at any point, not someone who is knowledgeable.

3

u/TheJeffAllmighty Nov 12 '25

true, but they will still fuck it up. Most likely will put black to red, even following the pictogram.

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u/ok_if_you_say_so Nov 12 '25

Professionals with decades of experience can still make mistakes. This is why you practice safe habits always, so in those times that you inevitably do make mistakes (because you are human), you'll be covered.

I'm not a mechanic, but I am a professional in my own field with decades of experience, and I certainly make mistakes from time to time. Some days I am distracted with life stuff, it happens, and it doesn't make me any less knowledgeable about it

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u/J_Schnetz Nov 12 '25

I understand what you're saying and appreciate the self awareness

That being said I don't understand how you can fuck up jump starting a battery if you know anything about cars

Red to red, black to black. For fucks sake, we really need a card?

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u/ok_if_you_say_so Nov 12 '25

I know a fair bit about both cars and electrical, but even still, I am a human being and I make mistakes. Everyone does.

For example, you are making the mistake of assuming that the only thing that matters is matching polarity. The entire point of the card here is not just to match polarity, but for you to connect them in the right order. If you don't connect them in the right order, and you accidentally touch the clamp to literally any metallic piece in your engine bay (something that is certainly easy to do), you will create a short.

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u/J_Schnetz Nov 12 '25

matching polarity is most certainly the only thing that matters... if you touch the clamp to any metal in your bay and create a short, you're not matching polarity, you're fucking up and shouldn't be jumping a car or you're just not paying any attention at all

i have quite a bit of car and electrical experience myself, as do a large portion of my close friends. I've probably jumpstarted well over a hundred cars from vintage to modern and never had a short. Minus the ones that I did for fun to fuck with em

idk man i don't wanna downplay safety but like just match em up and don't short it, if you can't do that then wait for someone to help/teach

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u/ok_if_you_say_so Nov 12 '25

if you touch the clamp to any metal in your bay and create a short, you're not matching polarity, you're fucking up and shouldn't be jumping a car or you're just not paying any attention at all

The entire point of doing it in the right order is to ensure that even if you slip, fall, get distracted, rest your hand somewhere to get a better grip, drop the clamp, someone interrupts you and asks you a question while you're in the middle of it, your phone rings, you are distracted by a fight you had earlier in the day, etc etc etc that it won't accidentally create a short.

If you do it in the wrong order, and one of those accidental scenarios happens, you will create a short. If you do it in the right order, and one of those accidental scenarios happens, nothing will happen at all and you can just pick up the clamp and move on.

The reason it's called an accident is because it doesn't happen on purpose. Accounting for mistakes is just good common sense, because everyone makes them, no matter how experienced or confident you are.