Good point,....I wonder if the negative contact were designed to disconnect first within these types of terminals maybe??
- Thread starter earthman
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Good point,....I wonder if the negative contact were designed to disconnect first within these types of terminals maybe??
As far as I am aware they auto disconnect the battery on shutdown.
Seadog
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Well like when removing the leads from a 12V battery, I'm assuming that you wouldn't see a spark when disconnecting the negative first.
mtt.tr
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You see a spark either side both are carrying current
With a name like earthman you better be extra careful handling the +ve lead
I'm 'earthman' because I married an alien (woman).
doubleboost
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On a hybrid once the 12 volt battery is disconnected the main relays in the battery pack drop open
Then there is a isolation plug (like a big fuse)
They had us wearing thick rubber gloves to remove it
Then wait for the caps to die down
Class 4 meter to test for dead then re test meter
The safety procedure was very thorough
To the point of a locked box for the keys and isolation plug
Then there is a isolation plug (like a big fuse)
They had us wearing thick rubber gloves to remove it
Then wait for the caps to die down
Class 4 meter to test for dead then re test meter
The safety procedure was very thorough
To the point of a locked box for the keys and isolation plug
Well what about the correct sequence on connecting jumper leads to a battery then? Personally I've never seen sparks when disconnecting the negative first.
brightspark
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if the batteries are on fire or shorting nothing much can be done because you cant disconnect any cells you will have yourself a good leccy ark welder ive had one that shorted and exploded 12 volt yes ,125 amp dc frightening
I used to have a Toyota Hybrid and I remember something was in the manual about in the event of a crash, there is an inbuilt impact detector that immediately open circuits the battery.
Many years ago when I was an electrical engineering student, a superb lecturer called Jack Priestly, who had lots of experience of working on dc traction drives, would keep telling us the dangers of working on both ac and dc. His tales of past unfortunate work mates left us in do doubt that once current starts flowing through muscles, it can be impossible to let go and told us if we saw someone in this condition and couldn't quickly see how to isolate the power supply, never risk touching them (even with the usual precautionary left-hand-in-pocket), instead find an insulator, such as a dry length of timber and be prepared to swing it with plenty of force. Don't worry about breaking bones as that is much better than electrocution. Wonder what is taught nowadays ?
Many years ago when I was an electrical engineering student, a superb lecturer called Jack Priestly, who had lots of experience of working on dc traction drives, would keep telling us the dangers of working on both ac and dc. His tales of past unfortunate work mates left us in do doubt that once current starts flowing through muscles, it can be impossible to let go and told us if we saw someone in this condition and couldn't quickly see how to isolate the power supply, never risk touching them (even with the usual precautionary left-hand-in-pocket), instead find an insulator, such as a dry length of timber and be prepared to swing it with plenty of force. Don't worry about breaking bones as that is much better than electrocution. Wonder what is taught nowadays ?
doubleboost
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We were told if a person is attached to a DC current
You would need a wooden fence post to get him off
The battery packs have fusible links built in to them
As well as over temperature sensors
Pete.
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Disconnecting earth lead first/reconnecting last has got nothing to do with arcing under load, it's about avoiding the possibility of shorting the spanner to an adjacent metal part as you tighten the battery clamp, or if you're clumsy with the jump lead.
Pete.
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Yes you would, that's why a wooden stick used to be part of an underground train driver's safety gear.
500e
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High voltage DC is nasty stuff had a lucky escape as an apprentice still got a bit of finger missing
The town we were working in had both AC & DC.
Was working on a sack hoist moter & someone decided to refit fuses. My boss beat the living. Out of him I Was still shaking
The town we were working in had both AC & DC.
Was working on a sack hoist moter & someone decided to refit fuses. My boss beat the living. Out of him I Was still shaking
ajlelectronics
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Why? It's the Volts that jolts but the mills that kills. HT leads are high Voltage but the current is insufficient to harm a healthy body.
mtt.tr
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Well what about the correct sequence on connecting jumper leads to a battery then? Personally I've never seen sparks when disconnecting the negative first.
That's only to stop have a live lead loose that can easily arc on any other part of the vehicle
As neutral is at same potential to the chassis no spark
Pigeon_Droppings2
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I googled which is more dangerous....turns out AC is a lot more dangerous than DC....I can't remember if I knew that!
