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General Category => General Discussion => Topic started by: canuguzzi on February 23, 2016, 04:23:09 PM

Title: PSA, just in case
Post by: canuguzzi on February 23, 2016, 04:23:09 PM
With all the talk about batteries, voltage and what does what, when and how, please remember:

When you are fiddling with the bike's battery, if you want to disconnect it for any reason...

1. Ground (negative - ) cable off FIRST!

When reconnecting:

1. Positive (+) first
2. Ground (negative - ) last

Back to our regularly scheduled voltage regulator and battery "discussion".

Even a motorcycle battery can become a welder.
Title: Re: PSA, just in case
Post by: Tom H on February 23, 2016, 04:56:17 PM
Good advice, something we do often forget!

In the old days it might have welded your wrench to the frame, now I think it can fry an ECU as well.

Tom
Title: Re: PSA, just in case
Post by: Muzz on February 23, 2016, 05:16:57 PM
Wise words indeed N.P.

I have been asked "why?" before. Not a stupid question if you just don't know or understand why.
Title: Re: PSA, just in case
Post by: thepittsburghguzzi on February 23, 2016, 09:18:09 PM

1. Ground (negative - ) cable off FIRST!

It's kind of funny to see "NEGATIVE" in bright red, as opposed to black :P

But for real, solid advice, and always worth reminding people!  :whip2:
Title: Re: PSA, just in case
Post by: cruzziguzzi on February 23, 2016, 09:41:14 PM
Is the negative one, the one with the hose clamp?

Todd.
Title: Re: PSA, just in case
Post by: JeffOlson on February 24, 2016, 12:04:25 PM
Of course, just to confuse matters, on my Norge, positive is red, and negative is black.  :wink:
Title: Re: PSA, just in case
Post by: MGPilot on February 24, 2016, 12:10:39 PM
Reconnecting - Why positive first?
Title: Re: PSA, just in case
Post by: Sasquatch Jim on February 24, 2016, 12:25:21 PM
 Positive first because with the negative disconnected there is no chance of your wrench arcing to the frame or any other short hapening.  Then once it is connected, go ahead and do the ground.  Since the wrench touching the frame is nothing more than an accidental ground and you were grounding anyway, no problem.
 Be careful with some older bikes, especially european.  Some used a positive ground.
Title: Re: PSA, just in case
Post by: Muzz on February 24, 2016, 12:33:00 PM
Positive first because with the negative disconnected there is no chance of your wrench arcing to the frame or any other short happening.   Be careful with some older bikes, especially european.  Some used a positive ground.

The original Mini had positive earth. Could be changed by reflashing the generator. Not sure why BMC did that. Must have been a reason.

Anyone know?
Title: Re: PSA, just in case
Post by: nc43bsa on February 24, 2016, 12:42:51 PM
The original Mini had positive earth. Could be changed by reflashing the generator. Not sure why BMC did that. Must have been a reason.

Anyone know?

I was told it was because the negative ions generated by the charging battery reacted with the positive wires.  It was preferable for the corrosion to be distributed along the chassis (positive) rather than the wiring harness.
Title: Re: PSA, just in case
Post by: oldbike54 on February 24, 2016, 12:45:17 PM

That is probably the best way to do it, any electrical engineers want to comment? Ha!

Austin Healey and many Lucas systems use Pos ground which causes practical problems in the "modern"
era.

 The British car and bike industry , along with Chrysler used pos ground

 
The original Mini had positive earth. Could be changed by reflashing the generator. Not sure why BMC did that. Must have been a reason.

Anyone know?

 So the 'lectricity could run backwards  :rolleyes: Seriously , seems like I read somewhere that it allowed for some savings in copper .

 Dusty
Title: Re: PSA, just in case
Post by: Muzz on February 24, 2016, 12:49:21 PM
 
 seems like I read somewhere that it allowed for some savings in copper .

 Dusty

That sounds about right dusty! :grin:
Title: Re: PSA, just in case
Post by: kirby1923 on February 24, 2016, 12:50:38 PM
 
I was told it was because the negative ions generated by the charging battery reacted with the positive wires.  It was preferable for the corrosion to be distributed along the chassis (positive) rather than the wiring harness.


 :1: Over simplified but on the mark.
Title: Re: PSA, just in case
Post by: oldbike54 on February 24, 2016, 01:02:43 PM
That sounds about right dusty! :grin:

 We are discussing an industry based largely in the English Midlands , ans area famous for being , er , frugal  :evil:

 Dusty