- #1
Victor.wong
- 5
- 0
Car Battery Problem!
Hi all,
I have to tell my story before actully asking the question. So, please be a bit patient!
I went overseas for a holiday for 3 weeks. Before I went, I washed my car. Unfortunately, I forgot to turn off my cabin light. Of course, I couldn't start up my car when I came back. I could not even turn on the dash borad. I guess since the cabin light blub consumes very small power, so it eventally drain all of the energy in the battery.
I have ask another guy to jumper start (or cable start) my car. unfortunately, we reversed the polarity for about 20 sec.
For the ease of explanation:
The car with battery - Car A
My dead car - car B
The way we did is car A positive to car b negative, and Car A negative to Car B positive.
Car A engine was on at all time.
Of couse, car B would not start, and I saw the cable start smoking. and very hot. i quickly disconnected.
after 1 min, we tried again with the right polarity. And my car finially started and everything was fine. i drive like normal now.
I have a few questions out from this story. I hope any experience Physicists or Engineers may be able to answer..(by the way, i am an Mechatronic engineering grad)
1) have i actually damaged any of my battery or electronics? - like ECU or generator etc. or car A.
2)while it was in wrong polarity, can anyone explain what is happening in car B battery.
-like reversing current in the battery, or any current is going to the Car B electronics.
I have asked a mechanic in a garage. he said:
- since Car B's electronics were still connected to Car B battery while the reverse polarity connection, it will not do any harm to Car B electronics
- since Car B's negative terminal was connecting to Car B chassis. The car B's battery would not be harmed.
- the only harm is to the cable and Car A generator, since the short circuit is drawing to much voltage.
he didnt really said why, and i don't really understand why(the 1st two points he said).
One other guy said it didnt harm my car was becasue my car battery was totally flat. if my dashboard was on while the reverse polarity connection. My car would be damaged.
Can any of you explain the 2 questions in a more sciencitific or engineering way.
thanks
Hi all,
I have to tell my story before actully asking the question. So, please be a bit patient!
I went overseas for a holiday for 3 weeks. Before I went, I washed my car. Unfortunately, I forgot to turn off my cabin light. Of course, I couldn't start up my car when I came back. I could not even turn on the dash borad. I guess since the cabin light blub consumes very small power, so it eventally drain all of the energy in the battery.
I have ask another guy to jumper start (or cable start) my car. unfortunately, we reversed the polarity for about 20 sec.
For the ease of explanation:
The car with battery - Car A
My dead car - car B
The way we did is car A positive to car b negative, and Car A negative to Car B positive.
Car A engine was on at all time.
Of couse, car B would not start, and I saw the cable start smoking. and very hot. i quickly disconnected.
after 1 min, we tried again with the right polarity. And my car finially started and everything was fine. i drive like normal now.
I have a few questions out from this story. I hope any experience Physicists or Engineers may be able to answer..(by the way, i am an Mechatronic engineering grad)
1) have i actually damaged any of my battery or electronics? - like ECU or generator etc. or car A.
2)while it was in wrong polarity, can anyone explain what is happening in car B battery.
-like reversing current in the battery, or any current is going to the Car B electronics.
I have asked a mechanic in a garage. he said:
- since Car B's electronics were still connected to Car B battery while the reverse polarity connection, it will not do any harm to Car B electronics
- since Car B's negative terminal was connecting to Car B chassis. The car B's battery would not be harmed.
- the only harm is to the cable and Car A generator, since the short circuit is drawing to much voltage.
he didnt really said why, and i don't really understand why(the 1st two points he said).
One other guy said it didnt harm my car was becasue my car battery was totally flat. if my dashboard was on while the reverse polarity connection. My car would be damaged.
Can any of you explain the 2 questions in a more sciencitific or engineering way.
thanks