1RM

I recently had to charge my flat battery ( not using car very much at the moment) and when I attached the neg lead back to the battery (with pos obviously already connected) I accidently (and clumsily) touched the ratchet used to tighten the nut between the neg and pos terminals of the battery resulting in big spark and me jumping quite high.

The car has been used since then and everything seems normal, but my question is could there have been damage to the electrics and/or the battery?

Many thanks.

AdN

Nothing to worry about, shortest current path was through the ratchet. Touching the ratchet from the pos terminal to the chassis on the other hand has potential for damage though still quite unlikely as you're point of contact would be close to the battery.

ncmx5

electrics have fuses, so they wouldve blown first. battery cells could get damaged but unlikely, only way is to get a tester or if it doesnt hold charge. letting the battery discharge a few times (i.e. run flat) damages the cell... i learnt this the hard way... well... $180 way.

1RM

What could potentially be damaged? Would you know if it was damaged? I have heard of people burning there standard computers doing this.

daevilone

it'd be a bad electrical system if they fried their ECUs. As said, the current goes through the fuse block first and would blow the 100amp main fuse.

if the car runs fine, don't worry about it.

1RM

I was always under the impresssion that you could fry your standard Ecu especially if the ignition was turned on while you shorted

AdN

Shortest current path was through the ratchet, the current would never have passed through any fuses.

Two things can happen at the very extremes i.e. high amperage battery and thin ratchet, you can melt the ratchet from heat caused by the current passing through it. The battery may explode as the quick discharge of the battery will also cause it to heat up.

So if you're not dead then no damage has occured, if you car runs which you have stated it does, then the ecu hasnt been damaged.

Edit* the extreme situation from above is not possible with a standard car battery and a ratchet that would actually work as a tool, incase that wasn't clear.

/thread

1RM

Well you're right, the car is fine and I do appreciate your help.
I am just curious to know how you could actually fry your ECU from doing this? If the shortest path is through the ratchet, doesn't that mean it's not possible to fry the computer?

AdN

pretty much is impossible from the incident you had.

Majority of the sensors that are wired to the ECU would be 5V inputs, if you had shorted your battery (12V) to a sensor then you could blow that sensor input. Depending on the design of the circuitry of the board will determine how much damage can occur.

1RM

How would you know if a sensor was wrecked?