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As far as I was ever told, doing the negative last means any spike will go directly to ground and nothing valuable. Even though a fuse should protect the circuit.
I do pos then neg, only because I am a bit of a butter fingers. Some how I always hit a piece of metal or I drop my wrench. Do what works for you, or make your life easier by doing the same way, as the other guy when he is around.
Take your pick.
Seems like it’s one of those things where it’s half dozen one way, six the other. The shop was split in two over this and all of us ended up in a debate. It was actually pretty cool. We even let the hourly guys chime in.
For some reason I always have a habit on grounding things before I do anything electrical. I try to keep the same processes for everything, even when I don’t need to. Almost a muscle memory in a way. Perfect practice makes almost perfect kind of thing.
because of the way they make the complex electronics it is setup to absorb small spikes from the power side. attaching negatiive first supposedly can cause more of a spike because you have a very good ground and the voltage wants to go to ground bad. Where the positive first then the negative the ground is going to be poor and slowly get better so its not as much of a shock to the system. Also electricity actual travels from negative to positive if you get into the scientific crap.
That is all theory and yeah sure i get why they say it but, honestly i do it whichever way is easier for me. I have yet to short out anything and i have done it after charging all the batteries separately and arcing stuff 3 inches away (12 big rig batteries one truck makes for lots of amperage) So if you ask me just do it whichever way you want to.
In my Dad’s shop as a kid I was taught to remove the ground cable first when disconnecting the battery and connect it last when reconnecting the battery. The reasoning is that you then will not cause an arc if the wrench hits something while on the positive terminal. This has served me well for over fifty years even on modern cars with all the electronics.
[quote=”Pitt” post=166807]Seems like it’s one of those things where it’s half dozen one way, six the other. The shop was split in two over this and all of us ended up in a debate. It was actually pretty cool. We even let the hourly guys chime in.
For some reason I always have a habit on grounding things before I do anything electrical. I try to keep the same processes for everything, even when I don’t need to. Almost a muscle memory in a way. Perfect practice makes almost perfect kind of thing.[/quote]
There is a lot to be said for having a standard procedure as a habit and always doing it that way. I think this makes you more efficient and less prone to mistakes.
You always want the policy for the negative cable to be the first off and the last connected. Like DaFirnz said, it’s better for the system as a whole. Also, what do you know about ark welding? You’ll do some by accident if the negative terminal is attached and something touches the positive. I don’t know where you found either way being correct. Just look at the instructions on any set of jumper cables.
Also, I often do the battery swap with the vehicle running when possible making sure to cover the terminals completely when taken off (have a boot like thing for this) or I put a memory saver to the OBDII port (not the lighter type, they work on few modern vehicles). It will be a time saver and problem preventer.
I do swaps with the car running also, I find an hourly guy to hold the terminals since they shadow us a lot. When we are slow or a battery looks like utter crap I recommend a battery service. I also do those with the vehicle running.
MBDiagman and Jasonw1178 thanks for the input. What you said makes perfect sense. The terminals are off for literally 15 seconds as you guys well know. Thinking about grounding and the possibility of a wrench touching really comes into play.
I’m thinking forward like electrical diag work. I am starting to dip my toes into it. Your input makes a lot of sense thinking about future work.
I really appreciate it.
[quote=”MBDiagMan” post=166909]… remove the ground cable first when disconnecting the battery and connect it last when reconnecting the battery. The reasoning is that you then will not cause an arc if the wrench hits something while on the positive terminal…[/quote]
This is what I do and why, but I also think nobody here is wrong.
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