I know most of you wouldn’t hesitate to change a lawn tractor battery, but I have an unexplained and unnatural fear of working with electricity. I was told to remove the red wire first being careful not to touch anything metal in the process. And, also attach the red wire first when installing the new battery. Is this correct… (i.e., do not reverse the removal procedure)?
Also, I should ask about working with metal tools: Again, you all probably take this for granted. Many of my wrenches and ratcheting tools do not have a plastic or rubber grip. As long as I do not accidentally touch the tool to metal, I should be fine…even if needing to work with two wrenches to loosen the nut (while holding another nut still)? Is that correct? I know there’s a saying about a good electrician works with one hand (to avoid creating a circuit across the heart). I wager as long as I only touch one terminal at a time and nothing else, the two hands are at the same potential? And, it is only 12.6V…so, can 12.6V hurt you? …or, is it the amps, not the volts?
Thanks for your patience, I just need to know what to expect (from all aspects of the job) before I do this.
It’s near impossible to be harmed by a 12 volt battery, even if touching both terminals simultaneously (with your hands - don’t do that with a metal tool!). I wouldn’t do that on purpose, but I wouldn’t worry about it either.
It’s best to remove the ground cable first and replace it last, to minimize the chance of an accidental short circuit. Be careful to avoid letting a metal tool touch a battery terminal (specifically the non-ground one) AND the metal chassis/frame of the vehicle at the same time.
The ground cable connects to the metal chassis/frame. It’s virtually always connected to the battery’s negative terminal. The standard coloration is red for positive and black for negative, so you probably want black to be first off/last back on, but check to verify which cable goes to ground.
you won’t get a dangerous shock from touching both terminals of a 12-volt battery with your hands, but a metal-to-metal short-circuit can generate a lot of sparks. You should wear eye protection when working on a car/motorcycle/boat/tractor battery.
the “+” terminal is generally well-protected against inadvertent contact, as seen in this photo. Since the ground terminal of the battery is generally connected to the vehicle’s chassis, having the “+” terminal exposed would create a risk of accidental short-circuits from tools, loose wires, etc. However, this is true only as long as the ground terminal of the battery is connected…so the first thing you should do is disconnect the ground terminal. There’s no danger whatsoever if your wrench bangs against the vehicle frame or anything else while doing this, since there’s already an electrical connection between the ground terminal and the chassis. Once you’ve disconnected the ground terminal and moved the cable away from the battery (so it can’t sneak back into position and touch the ground terminal), it’s safe to uncover the “+” terminal and remove that connection. With the ground connection already removed, there’s no risk of a short if your wrench bumps the vehicle frame while disconnecting the “+” terminal.
Same thing in reverse: position the new battery, connect/cover the “+” terminal, then connect the ground terminal. Done.
A 12 V car battery can’t hurt you if you touch the terminals, but you touch a wrench across them and kapowzer. Quite impressive, as the wrench welds itself across the terminals.
Remove ground first, then hot. Because if you do it other other way, and drop a wrench so it lands on the + and the car chassis, you get welded wrench.
Second to all of the above. 12 volts won’t hurt you, but arcing a big battery like that will make your heart skip a beat. I’ve never used insulated tools to disconnect a battery, so don’t worry about that. If you are truly terrified by the possibility of creating an arc, throw something like a rubber floor mat or scrap of carpeting across the other side of the battery and the chassis as you work on a terminal. 12 volts won’t overcome even very flimsy electrical resistance.
The closest I ever came to being hurt by a battery was when the carry-strap on a boat battery failed. Batteries weigh a ton and it almost landed on my foot.
Almost certainly inapplicable in this particular case, but: some very old equipment may be positive-ground. This didn’t become standardized until, I think, around 1960. (I have two mid-to-late 1950’s tractors which are positive ground.)
The battery will be marked. If the equipment’s old, take a good hard look at the battery before removal, and see which side is positive. And make very very sure to put the replacement battery back in the same way around; getting it wrong can fry the electrical system.
Come to think of it, be sure to put the replacement battery in the same way around, even presuming that the system’s negative ground.
One other reason to wear eye protection when working with lead-acid batteries:
Depleted or mostly-depleted batteries may have free hydrogen around them, as well as inside the casing. If there’s enough present, a spark can ignite it. A bang around the outside of the battery is scary, but an explosion inside the battery will launch bits of plastic and battery chemicals at you.
Here’s a safety demo. Also, here’s an oops. in the latter video, the guy is deliberately shorting the terminals with a thin piece of wire, looking for sparks to confirm the battery has a charge. This particular battery has hydrogen around it, and it blows up in his face.
Echoing the advice in the above replies. In similar fashion, when jumping a battery, attach the positive first; when the other car starts, remove the negative first. “Positive on, negative off.” Thanks to my father for that advice – he’s the one that learned the hard way.
I have similar issues due to pine exploding battery in the early 80s and one that caught fire in the 90s. I have an AAA membership. They will come out and install a new battery for no labor charge. I’ve compared the cost to other places plus the convenience of not having to find a friend to cart mine to the battery store AND the fact that I’m guaranteed to wreck at least one nail. Worth it.
I accidentally touched the terminals once. The arc of electricity vaporized a pea sized chunk of one of the terminals.
the most dangerous post is the positive post because all the metal around it is grounded. this is why you remove the negative cable first and install it last. By doing that you remove the ground to the rest of the metal.
Practice makes perfect. I’ve been pulling batteries out my motorcycle every winter for many years without fear.
Like kayaker said, pull the black terminal first.
