correct way to handle car battery, Never been sure about it |
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correct way to handle car battery, Never been sure about it |
machina |
Nov 23 2004, 05:21 PM
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#1
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Advanced Member Group: Benefactors Posts: 2,030 Joined: 21-June 03 From: Miami Beach, FL Member No.: 848 |
When connecting and disconnecting the battery, does it matter if ground or + goes first.
Everytime I DC the battery to work on the car, I unhook the + lead. Always feel wierd about touching that big cable though. Let a wrench touch the + lead on the starter the other day and it damn near welded to the post, and I almost wet my pants. (IMG:style_emoticons/default/unsure.gif) |
SLITS |
Nov 23 2004, 05:28 PM
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#2
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
Neg (-) first - no ground no spark
Hooking it back up - Pos (+) first...................... |
Curvie Roadlover |
Nov 23 2004, 05:34 PM
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#3
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Two trunks are better than one! Group: Members Posts: 2,025 Joined: 29-December 02 From: Southeast Michigan Member No.: 42 |
I could be wrong but I'm pretty sure you should always unhook the (-) first and here's why: If you unhook the (+) first, touching just about any part of the car with the (+) will cause a spark because the entire car is still all ground while the (-) is still connected. If you unhook the (-) first, the entire car is no longer grounded and a spark will only happen if (+) touches (-) on the battery itself.
True?? + (IMG:style_emoticons/default/unsure.gif) - |
machina |
Nov 23 2004, 05:50 PM
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#4
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Advanced Member Group: Benefactors Posts: 2,030 Joined: 21-June 03 From: Miami Beach, FL Member No.: 848 |
QUOTE(Curvie Roadlover @ Nov 23 2004, 06:34 PM) If you unhook the (-) first, the entire car is no longer grounded and a spark will only happen if (+) touches (-) on the battery itself. Well now that makes sense. So its better to unhook both leads from the battery when working on the car? I have just been doing the + |
McMark |
Nov 23 2004, 07:27 PM
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#5
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
(IMG:style_emoticons/default/agree.gif) Unhook the negative first. Only unhook the positive if you're positive you're taking it out of the car. Catchy? (IMG:style_emoticons/default/idea.gif)
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Series9 |
Nov 23 2004, 07:58 PM
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#6
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Lesbians taste like chicken. Group: Members Posts: 5,444 Joined: 22-August 04 From: DeLand, FL Member No.: 2,602 Region Association: South East States |
Negative should be first off and last on. Make sense?
In a negative-ground car, having the negative disconnected 'safes' the battery. |
machina |
Nov 23 2004, 10:21 PM
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#7
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Advanced Member Group: Benefactors Posts: 2,030 Joined: 21-June 03 From: Miami Beach, FL Member No.: 848 |
OK, got it, but bear with me.
So instead of unhooking the + I should be unhooking the - ? (when working on the car) Or do I remove both to be safe? If I leave the + connected, then isn't the big wire that runs back to the starter still hot? |
Aaron Cox |
Nov 23 2004, 10:24 PM
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#8
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
think this way.... if you unplug the + terminal when working, and you drop a tool that touvhes the positive terminal and ANYWHERE on the body...you have a tool arc welded to the body.....
if you unplug the - and you drop a tool and it touches the body, nothing happens,..... unless you touch the pos and neg side of the bat, (IMG:style_emoticons/default/ohmy.gif) |
hargray2 |
Nov 23 2004, 10:52 PM
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#9
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fuh-q Group: Members Posts: 302 Joined: 12-December 03 From: hardeeville,sc Member No.: 1,432 |
(IMG:style_emoticons/default/agree.gif) QUOTE If I leave the + connected, then isn't the big wire that runs back to the starter still hot? QUOTE
No, the pos cable to the starter is no longer an issue if the NEG side is disc. from the battery. When NEG. is connected, the entire car becomes the negative post of the battery and that's why it's easy to short something while working. Disconnect NEG. while working. In this way, it is only possible to have a short if you short the two posts at the battery. This isolates the uninsulated car body and engine/ transmission from wrench happy "mechanics" |
SirAndy |
Nov 23 2004, 10:56 PM
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#10
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Resident German Group: Admin Posts: 41,676 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(SLITS @ Nov 23 2004, 03:28 PM) Neg (-) first - no ground no spark Hooking it back up - Pos (+) first...................... (IMG:style_emoticons/default/agree.gif) off - first on + first |
DJsRepS |
Nov 24 2004, 04:53 AM
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#11
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Member Group: Members Posts: 431 Joined: 4-November 04 From: Sarasota Florida Member No.: 3,060 |
I strongly agree with neg first. I whitnessed an accident with gas leaking and horn stuck on. I argued with the fireman cutting the pos cable with bolt cutters to stop and cut the neg instead. I backed away as the idiot ignored me cutting the pos having a little trouble twisted it to cut through and sparked it to ground. The driver was out already and the car did not explode but I yelled at the guy with the bolt cutters and called his station to talk to fire marshal. I guess cause Im not a trained fireman like him I dont know crap about electricity, I did know enough to get away from that guy when he was cutting and sparking on that Pos battery wire.
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machina |
Nov 24 2004, 06:31 AM
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#12
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Advanced Member Group: Benefactors Posts: 2,030 Joined: 21-June 03 From: Miami Beach, FL Member No.: 848 |
thanks guys, I usually need things explained to me 3 or 4 times. (IMG:style_emoticons/default/blink.gif)
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Joe Ricard |
Nov 24 2004, 06:45 AM
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#13
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Yea now I'm more confused. I take the negative off 1st and then the positive.
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Carl |
Nov 24 2004, 10:47 AM
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#14
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Ummm ... what? Group: Members Posts: 781 Joined: 17-January 03 From: San Jose, CA Member No.: 163 Region Association: Northern California |
QUOTE(914RS @ Nov 23 2004, 05:58 PM) Negative should be first off and last on. Make sense? In a negative-ground car, having the negative disconnected 'safes' the battery. Negative comes off first and on last in a negative ground car. Positive ground cars (early 50's Fords, for example) would be just the opposite. The idea is to eliminate the body of the car as a return path for the current. |
SLITS |
Nov 24 2004, 10:56 AM
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#15
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"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
QUOTE(DJsRepS @ Nov 24 2004, 03:53 AM) I strongly agree with neg first. I whitnessed an accident with gas leaking and horn stuck on. I argued with the fireman cutting the pos cable with bolt cutters to stop and cut the neg instead. I backed away as the idiot ignored me cutting the pos having a little trouble twisted it to cut through and sparked it to ground. The driver was out already and the car did not explode but I yelled at the guy with the bolt cutters and called his station to talk to fire marshal. I guess cause Im not a trained fireman like him I dont know crap about electricity, I did know enough to get away from that guy when he was cutting and sparking on that Pos battery wire. firemen are good guys, but their brain capacity is washed away by their training. I used to be in Hazmat and some of their ideas were farther out than I am. (IMG:style_emoticons/default/wacko.gif) PS - Especially the ones that wear the starched white shirts, with medals and waxed down hair. The wax must cause brain rot. |
iiibdsiil |
Nov 24 2004, 01:15 PM
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#16
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Needs Door Locks Group: Members Posts: 605 Joined: 19-November 03 From: Tampa / Boca Raton, FL Member No.: 1,362 |
I guess on a 914 this might be a problem, I wouldn't know because my battery is in my rear trunk. Everyone argues over this, or gets confused. If you disconnect the + then make sure you don't touch the + battery terminal to any metal on the car, which shouldn't be hard to do, since metal usually bounces when dropped. There are also arguments on the sparks igniting the hydrogen or whatever that the battery is emitting, same thing as smoking around batterys. When you reconnect + is has a bigger spark than -. Never seen a battery explode, never even met someone that has seen a battery explode.
The technician that I work under/with at the dealership since I am a student always has me disconnect +. I dunno if that is a Ford only thing, or what, but that is what he wants me to do, so I do it. Personally, it doesn't matter to me, as long as one side is disconnected. |
Carl |
Nov 24 2004, 01:41 PM
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#17
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Ummm ... what? Group: Members Posts: 781 Joined: 17-January 03 From: San Jose, CA Member No.: 163 Region Association: Northern California |
QUOTE Personally, it doesn't matter to me, as long as one side is disconnected. It DOES matter, maybe not to you, but it should. Metal (a wrench, let's say) will bounce when dropped unless it's busy welding itself to a metal part of the car because the battery wasn't properly disconnected. Disconnecting the ground strap FIRST ( - on most cars) will then allow you to then remove the positive cable and, if your wrench happens to strike a part of the body while doing so, you won't be greeted with a shower of sparks and feel like an idiot, or worse. Obviously, if the ground strap is not disconnected, and if you're trying to remove the other battery cable in a tight space, any body metal the wrench touches will remind you of the 4th of July. Your technician should have told you this. |
iiibdsiil |
Nov 24 2004, 04:40 PM
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#18
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Needs Door Locks Group: Members Posts: 605 Joined: 19-November 03 From: Tampa / Boca Raton, FL Member No.: 1,362 |
If either side of the battery is disconnected, there is no way to spark it. Unless you manage to drop a wrench on the positive terminal and it grounds out.
I have forgot to diconnect a battery a couple times before when changing starters, and I have yet to see a wrench get welded to anything. It gets hot, real hot. I have seen a couple people when changing oil filters tap the positive on the starter bolt too, once again, it sparks and gets hot, no welding. I am sure, under some circumstances it will happen though. I am just saying of all the times I have seen and heard, I have never had that happen. QUOTE Obviously, if the ground strap is not disconnected, and if you're trying to remove the other battery cable in a tight space, any body metal the wrench touches will remind you of the 4th of July. Obviously how? If the positive is disconnected from the battery, and the ground is not, there is no current flow, therefore there will be no spark. You have to have a complete path from positive to negative to have current flow. So, if the positive is disconnected, you have an open in the circuit, no current flow. If I tap the positive wire on the starter to ground, and the battery is disconnected at +, then there will be no spark. Unless I am missing something here... |
Carl |
Nov 24 2004, 04:53 PM
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#19
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Ummm ... what? Group: Members Posts: 781 Joined: 17-January 03 From: San Jose, CA Member No.: 163 Region Association: Northern California |
QUOTE If either side of the battery is disconnected ... If the positive is disconnected from the battery ... So, if the positive is disconnected ... Back up a step, this is all about how to disconnect the battery in the first place. |
Rhodes71/914 |
Nov 24 2004, 04:53 PM
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#20
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Glacier Group: Members Posts: 1,374 Joined: 8-August 04 From: End of the Road, Alaska Member No.: 2,482 |
QUOTE Disconnecting the ground strap FIRST ( - on most cars) will then allow you to then remove the positive cable and, if your wrench happens to strike a part of the body while doing so, you won't be greeted with a shower of sparks and feel like an idiot, or worse. iiibdsiil I think this is the main reason to disconnect the (-) first. Can you honestly say that you have been removing the Pos (+) side before the neg (-) and have never touched the wrench to the body an sparks went flying. If so you are lucky. |
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