Connected wrong terminals on Car batteries
Discussion
LONG STORY, Please try and stay awake.
My father's car died this morning and he asked me to jump it since he was getting late for work. In that hurry, I forgot to wear my glasses and thought I would be fine, after all, I am just jumping the battery. However, turns out this was the stupidest thing I've done this year. It was very early in the morning and kind of dark so I could not see the "+/-" marking on my battery. I only have 1 clamp cover on my battery which is black and has a red "+" sign on it. The cover was not clicked on the clamp properly and was hanging upside down. Since I was rushing, I thought it is black in color, which means it must be negative. I hooked up the negative side of the cable to the positive on my battery, positive on the negative side, and connected properly on my father's car. There was a spark and a little smoke. Thought it might be due to very old cables. Got in my father's car, and it was COMPLETELY dead. Realized there was smoke coming from the cables, immediately disconnected the cables, which were really hot. The wrong connection was there for about 30-40 seconds in total. Went back inside home, got new cables (and my glasses), and did the jumping process properly. The car started up fine. My car was fine for the whole time. Both cars seem to be working fine for now after a few hours.
So my question is, am I screwed or saved? Doing rough visual inspection, both cars seem to be alright except the jumping cables are burnt. Will I see any effects (or affects IDK) in the long term? I am really concerned since I am 90% unlucky in life.
My Car: 2013 Lexus GS350 (V6)
My Father's Car: 2012 Ford Escape (V6)
My father's car died this morning and he asked me to jump it since he was getting late for work. In that hurry, I forgot to wear my glasses and thought I would be fine, after all, I am just jumping the battery. However, turns out this was the stupidest thing I've done this year. It was very early in the morning and kind of dark so I could not see the "+/-" marking on my battery. I only have 1 clamp cover on my battery which is black and has a red "+" sign on it. The cover was not clicked on the clamp properly and was hanging upside down. Since I was rushing, I thought it is black in color, which means it must be negative. I hooked up the negative side of the cable to the positive on my battery, positive on the negative side, and connected properly on my father's car. There was a spark and a little smoke. Thought it might be due to very old cables. Got in my father's car, and it was COMPLETELY dead. Realized there was smoke coming from the cables, immediately disconnected the cables, which were really hot. The wrong connection was there for about 30-40 seconds in total. Went back inside home, got new cables (and my glasses), and did the jumping process properly. The car started up fine. My car was fine for the whole time. Both cars seem to be working fine for now after a few hours.
So my question is, am I screwed or saved? Doing rough visual inspection, both cars seem to be alright except the jumping cables are burnt. Will I see any effects (or affects IDK) in the long term? I am really concerned since I am 90% unlucky in life.
My Car: 2013 Lexus GS350 (V6)
My Father's Car: 2012 Ford Escape (V6)
It would be interesting to get an electronics engineers view on this that works in the automotive industry or something similar, but I would have thought most circuits on modern cars have over voltage protection by means of clamping diodes or something similar.
The other thing with electronics is that it normally fails almost instantaneously (with the exception of cables failing due to heat) when due to over voltage. So if both cars are running fine I would assume no permanent damage has been done.
The other thing with electronics is that it normally fails almost instantaneously (with the exception of cables failing due to heat) when due to over voltage. So if both cars are running fine I would assume no permanent damage has been done.
Agreed, looks like you've dodged a bullet there. This can go very wrong very quickly.
Annoyingly, my project MX5 has 2 black wires leading to the battery and, until very recently, one clamp that could fit either post and the other end had a broken connector that was jubilee clipped to the other battery post. First jump start in the dark was an exercise in caution!
Annoyingly, my project MX5 has 2 black wires leading to the battery and, until very recently, one clamp that could fit either post and the other end had a broken connector that was jubilee clipped to the other battery post. First jump start in the dark was an exercise in caution!
Worst case scenario you might have f
ked both batteries. You have effectively put a very low resistance across both batteries hence the sparking and heat. You are luck something didn't go badly wrong!
The chances of it damaging the cars are pretty low. The voltage would have beenreduced by the shorting, and that's all the cars electrical system will have experienced.
ked both batteries. You have effectively put a very low resistance across both batteries hence the sparking and heat. You are luck something didn't go badly wrong! The chances of it damaging the cars are pretty low. The voltage would have beenreduced by the shorting, and that's all the cars electrical system will have experienced.
98elise said:
The chances of it damaging the cars are pretty low. The voltage would have been reduced by the shorting, and that's all the cars electrical system will have experienced.
It isn't necessarily the voltage which would have caused the damage - it's the huge current which would have been drawn.That said, fuses and / or diodes should provide protection against reverse polarity connection.
At the minimum
Alternator main supply fuse should be blown
If the alternator main fuse hasn't blown there is every chance that the alternator diodes have burnt out
If the alternator diodes haven't burnt out there is a good chance that the alternator main supply cable has overheated
This is before delving deeper, looking at a diagram for what else could be damaged
Take it that the ignition wasn't turned on while connecting and connected incorrectly.........Now that was fortunate
Alternator main supply fuse should be blown
If the alternator main fuse hasn't blown there is every chance that the alternator diodes have burnt out
If the alternator diodes haven't burnt out there is a good chance that the alternator main supply cable has overheated
This is before delving deeper, looking at a diagram for what else could be damaged
Take it that the ignition wasn't turned on while connecting and connected incorrectly.........Now that was fortunate
Basically when you made the first link, you made an open circuit 24v battery (series connection, + to - ). Neither car would "see" any of this so far.
Then, when you connected the second wire, you created a two bar (wire )heater. Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ). Whilst this was all happening both battery voltages measured across their terminals would have plunged , hence it seems no harm done. All the energy was being directed across the jump leads.
Very different outcome if you'd connected direct to the other cars battery clamps disconnected from the battery. Then you'd have shoved reverse polarity through the cars electrical system.
Both batteries may well have significantly reduced life spans now as you may well have warped the plates in them.
Then, when you connected the second wire, you created a two bar (wire )heater. Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ). Whilst this was all happening both battery voltages measured across their terminals would have plunged , hence it seems no harm done. All the energy was being directed across the jump leads.
Very different outcome if you'd connected direct to the other cars battery clamps disconnected from the battery. Then you'd have shoved reverse polarity through the cars electrical system.
Both batteries may well have significantly reduced life spans now as you may well have warped the plates in them.
SS2. said:
98elise said:
The chances of it damaging the cars are pretty low. The voltage would have been reduced by the shorting, and that's all the cars electrical system will have experienced.
It isn't necessarily the voltage which would have caused the damage - it's the huge current which would have been drawn.That said, fuses and / or diodes should provide protection against reverse polarity connection.
Draw it out. It's a simple parallel circuit, and ohm's law determines the current.
Also under a large load the battery voltage will drop significantly.
RogerDodger said:
Basically when you made the first link, you made an open circuit 24v battery (series connection, + to - ). Neither car would "see" any of this so far.
Then, when you connected the second wire, you created a two bar (wire )heater. Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ). Whilst this was all happening both battery voltages measured across their terminals would have plunged , hence it seems no harm done. All the energy was being directed across the jump leads.
Very different outcome if you'd connected direct to the other cars battery clamps disconnected from the battery. Then you'd have shoved reverse polarity through the cars electrical system.
Both batteries may well have significantly reduced life spans now as you may well have warped the plates in them.
Correct. The only damage will be to the batteries which have been subjected to huge loads (and possibly the insulation on the jump leads).Then, when you connected the second wire, you created a two bar (wire )heater. Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ). Whilst this was all happening both battery voltages measured across their terminals would have plunged , hence it seems no harm done. All the energy was being directed across the jump leads.
Very different outcome if you'd connected direct to the other cars battery clamps disconnected from the battery. Then you'd have shoved reverse polarity through the cars electrical system.
Both batteries may well have significantly reduced life spans now as you may well have warped the plates in them.
RogerDodger said:
Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ).
If they were connected in parallel yes, but they're in series so the current is identical and the higher resistance will heat up the most.Pistonheads - being a pedantic arse matters
98elise said:
SS2. said:
98elise said:
The chances of it damaging the cars are pretty low. The voltage would have been reduced by the shorting, and that's all the cars electrical system will have experienced.
It isn't necessarily the voltage which would have caused the damage - it's the huge current which would have been drawn.That said, fuses and / or diodes should provide protection against reverse polarity connection.
Draw it out. It's a simple parallel circuit, and ohm's law determines the current.
Also under a large load the battery voltage will drop significantly.
The batteries were actually connected in series, not parallel. This creates a nominal 24V circuit through the jump leads only. Each car’s circuit is still seeing 12V (or less due to the voltage drop caused by the high current in the jump leads).
The internal current in the batteries would be high but would drop away as the circuit resistance increases due to temperature rise of the conductors in the battery and jump leads.
The exercise is essentially a very fast discharge of both batteries, one of which was already flat. The batteries may or may not have suffered permanent damage. The car’s circuits would have only seen a voltage drop so they are probably fine.
Connecting the batteries in parallel is the correct way to jump start.
What some posters seem to be overlooking is that the Lexus battery was very likely close to fully charged
The Ford Escape battery was low or faulty
If the Ford Escape doesn't have reverse polarity protection (I doubt very much that it has)
The Lexus battery was the dominant one and there was a reverse polarity applied to the Ford Escape alternator, the voltage of the reverse polarity is an unknown one as that is governed by the condition and voltage of the Ford Escape battery
The hand of God has played its part here if both vehicles got away with such a big mistake
Obviously the above is going on the OP explanation being correct and not that the jump leads were shorted together through Earths
The Ford Escape battery was low or faulty
If the Ford Escape doesn't have reverse polarity protection (I doubt very much that it has)
The Lexus battery was the dominant one and there was a reverse polarity applied to the Ford Escape alternator, the voltage of the reverse polarity is an unknown one as that is governed by the condition and voltage of the Ford Escape battery
The hand of God has played its part here if both vehicles got away with such a big mistake
Obviously the above is going on the OP explanation being correct and not that the jump leads were shorted together through Earths
wrong jump lead connection -
yes its like a 24v battery being short circuited, but the reality is that it can often open up a can of worms and all depends on the condition of the electrical system. If the duff battery is due to a loose battery post then connection of the boost battery to the duff electric system will introduce a polarity reversal on the duff system with the resultant effects that will cause.
The above diagram gives an idea, the first jump lead is connected, the second one about to be and that is across the 2nd set of terminals. You can see that the equipment in the car is connected and will be fed with wrong polarity 12v or lower depending on the strength of the duff battery. if the duff battery is strong and the donor car has a weak battery you may find the donor car being affected.
Its complicated as nothing is ever easy lol, connecting in that 2nd jump lead you will have a 24v short circuit, and by nature the jump leads are pretty low in resistance. so you can be drawing a lot of amps and that can do serious damage to your battery, these are designed to give a significant amount of cranking amps, but they really don't like short circuits and can suffer internally from that, every part inside a battery will be carrying that large current and the effects can be to warp the plates destroy the plates and generally wreck havoc.
If you pulled the leads off, and both cars are working okay you got away with it by the skin of your teeth. however new batteries may be required soon.
SS2. said:
It isn't necessarily the voltage which would have caused the damage - it's the huge current which would have been drawn.
That said, fuses and / or diodes should provide protection against reverse polarity connection.
Pop along and tell the alternator diodes this, the alternator main fuse protects the cable, the alternator diodes often burn out before the fuse blowsThat said, fuses and / or diodes should provide protection against reverse polarity connection.
archie456 said:
RogerDodger said:
Of the two jump leads, the one with the least resistance would have heated up the most, with the other not very far behind (as they'd be nearly identical resistance ).
If they were connected in parallel yes, but they're in series so the current is identical and the higher resistance will heat up the most.Pistonheads - being a pedantic arse matters
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