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Author Topic:   Shorted Battery

krisst posted 04-29-2013 02:04 PM ET (US)
Hello. At the risk of sounding like a genius, I managed to touch both my positive and negative terminals on one of my two batteries when installing them this weekend. It is a two battery set up with a Perko switch. Everything still seems to work so it looks OK, any other thoughts?
I do realize I am lucky to be OK since when this happened, there was a decent fireworks show.
Thank you,
AK
jfortson posted 04-29-2013 03:13 PM ET (US)
If all you did was to short or make contact with the + and - terminals at the same time, the only harm I would expect is to your pride. I have done that many time on cars, boats, etc. and never anything bad except for adrenalin/surprise factor when the sparks fly.
swist posted 04-29-2013 04:26 PM ET (US)
The amount of current a storage battery can produce when shorted is unbelievable. Many years ago, I accidentally put a screwdriver, and not one all that small, between the terminals of an auto battery - the end with the blade on it turned into something like a blob, and I had to throw it away. Demonstates that power (watts) = volts * amps. Even if volts is small (and 12 volts is too small to feel), hundreds of amps gives you thousands of watts.
jimh posted 04-30-2013 10:15 AM ET (US)
As mentioned above, the battery contains a great deal of stored energy, and if its terminals are short-circuited together, a large amount of energy will be released in a short time.
The concern in any short-circuit situation is the path the current took, that is, what conductors it traveled through. If the short-circuit current only traveled through a very short and contained path, such as just through a single wire connecting the two battery terminals, then the damage from the current surge will be confined to a limited path, just that conductor and the terminals themselves. If the path for the short-circuit current was longer and more complicated, a very high current might have tried to flow on conductors that were not sized for that type of current. If that happens, the conductors can become so hot that they act like fuses, the copper of the conductor melting and creating an open circuit.
logjam posted 05-01-2013 02:18 AM ET (US)
Unless I'm traveling without my wife, I usually don't wear a wedding ring.
The brand on my ring finger is sufficient to remind me that I'm married.
weekendwarrior posted 05-02-2013 06:37 AM ET (US)
If you survived the original short then you're probably fine. If you've ever seen a flooded lead acid battery explode, it's enough to give you the willies every time you touch a battery. My buddies battery exploded in his truck, and there were battery bits and acid everywhere, thankfully the hood was down at the time and no one was hurt. If someone had been standing there, they surely would have been covered with acid in the least. I had the pleasure of helping to clean that up..
A byproduct of flooded lead acid battery charging is hydrogen gas. If the electrolyte level (acid) gets low, there can be an air gap between the plates. If the battery comes under significant load (short, starting the motor, etc..) then a spark can jump between the plates igniting the hydrogen.

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Author	Topic: Shorted Battery
krisst	posted 04-29-2013 02:04 PM ET (US) Hello. At the risk of sounding like a genius, I managed to touch both my positive and negative terminals on one of my two batteries when installing them this weekend. It is a two battery set up with a Perko switch. Everything still seems to work so it looks OK, any other thoughts? I do realize I am lucky to be OK since when this happened, there was a decent fireworks show. Thank you, AK
jfortson	posted 04-29-2013 03:13 PM ET (US) If all you did was to short or make contact with the + and - terminals at the same time, the only harm I would expect is to your pride. I have done that many time on cars, boats, etc. and never anything bad except for adrenalin/surprise factor when the sparks fly.
swist	posted 04-29-2013 04:26 PM ET (US) The amount of current a storage battery can produce when shorted is unbelievable. Many years ago, I accidentally put a screwdriver, and not one all that small, between the terminals of an auto battery - the end with the blade on it turned into something like a blob, and I had to throw it away. Demonstates that power (watts) = volts * amps. Even if volts is small (and 12 volts is too small to feel), hundreds of amps gives you thousands of watts.
jimh	posted 04-30-2013 10:15 AM ET (US) As mentioned above, the battery contains a great deal of stored energy, and if its terminals are short-circuited together, a large amount of energy will be released in a short time. The concern in any short-circuit situation is the path the current took, that is, what conductors it traveled through. If the short-circuit current only traveled through a very short and contained path, such as just through a single wire connecting the two battery terminals, then the damage from the current surge will be confined to a limited path, just that conductor and the terminals themselves. If the path for the short-circuit current was longer and more complicated, a very high current might have tried to flow on conductors that were not sized for that type of current. If that happens, the conductors can become so hot that they act like fuses, the copper of the conductor melting and creating an open circuit.
logjam	posted 05-01-2013 02:18 AM ET (US) Unless I'm traveling without my wife, I usually don't wear a wedding ring. The brand on my ring finger is sufficient to remind me that I'm married.
weekendwarrior	posted 05-02-2013 06:37 AM ET (US) If you survived the original short then you're probably fine. If you've ever seen a flooded lead acid battery explode, it's enough to give you the willies every time you touch a battery. My buddies battery exploded in his truck, and there were battery bits and acid everywhere, thankfully the hood was down at the time and no one was hurt. If someone had been standing there, they surely would have been covered with acid in the least. I had the pleasure of helping to clean that up.. A byproduct of flooded lead acid battery charging is hydrogen gas. If the electrolyte level (acid) gets low, there can be an air gap between the plates. If the battery comes under significant load (short, starting the motor, etc..) then a spark can jump between the plates igniting the hydrogen.