YW Sin Posted March 22, 2003 Share Posted March 22, 2003 I know that when disconnecting battery, I have to disconnect the negative (black) lead first. But I have no idea why. Any body could educate me in this issue? A ll standard, Classic 1.7 X-flow Link to comment Share on other sites More sharing options...
Buda Posted March 22, 2003 Share Posted March 22, 2003 I'm not sure, I got it wrong a while back and managed to blow the ecu fuse, I've taken to taking this out when connecting and disconnecting the battery now, just to avoid irritation more than anything. Link to comment Share on other sites More sharing options...
Lawrence_Z Posted March 22, 2003 Share Posted March 22, 2003 Disconnect the black (chassis earth) first to avoid the tool being used from short circuiting the battery accidentally. Then, when the red is disconnected any contact with any metal surfaces will have no adverse effect. HTH Lawrence Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted March 22, 2003 Area Representative Share Posted March 22, 2003 As the negative terminal is already connected to the chassis so any contact with the spanner to the chassis, engine etc. when disconnecting the lead has no effect at all on the battery. As Lawrence then says disconnecting the live teminal and touching any chassis, engine point is safe because the battery is effectively out of the loop (or should than read, circuit) HTH Nick Yellow HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
YW Sin Posted March 22, 2003 Author Share Posted March 22, 2003 But.... The loop can also be out when you first disconnect the positive as well... *confused* Sorry, electronic has always been my mystery subject . A ll standard, Classic 1.7 X-flow Link to comment Share on other sites More sharing options...
Area Representative Nick Chan Posted March 22, 2003 Area Representative Share Posted March 22, 2003 YW Sin, Sure the loop is out when you disconnect the red/positive as well, but as you might have found if you undo the positive first and touch the chassis, sparks fly! as the negative is still connected. Disconnecting the earth/black first means that inadvertent contact with the chassis/engine does not cause any problems because the negative terminal is ALREADY connected to the chassis via the earth strap and so any additional contact between the negative terminal and the chassis is not a problem HTH Nick Yellow HPC - A 2.0 VX - 😬 Link to comment Share on other sites More sharing options...
YW Sin Posted March 22, 2003 Author Share Posted March 22, 2003 Give me two days and I will try to understand it 😬 Thanks! Now, time to turn on the news again... A ll standard, Classic 1.7 X-flow Link to comment Share on other sites More sharing options...
Chris W Posted March 22, 2003 Share Posted March 22, 2003 If you leave the earth cable connected and disconnect the red positive lead first and your spanner happens to touch the chassis while its other end is around the bolt on the positive, your spanner will become a permanent part of your chassis as 300 amps flow through it and weld it to the car. Your hand will also rise to about 500 deg C if you are still holding it at the time. Look at the words "Chrome Vanadium" on your spanner in a mirror. This is what you risk having tattoed on your hand for the rest of your life if you don't disconnect the earth cable first (and reconnect it last). Chris 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Tony C Posted March 22, 2003 Share Posted March 22, 2003 Electrons flow out of the negative terminal of the battery, through the chassis/components in circuit and back into the positive terminal. Removing the negative lead stops electricity from leaving the battery. Chris is right - don't try for the tatoo BRG SV kit. 😬 Only six days away Link to comment Share on other sites More sharing options...
YW Sin Posted March 23, 2003 Author Share Posted March 23, 2003 Guys, Points well taken. I am NOT under any circumstances, going to carry any free advertisements (though in inverse) on my skin 😬 ❗ I will disconnect the black one first. Edited by - yw sin on 23 Mar 2003 09:01:31 Link to comment Share on other sites More sharing options...
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