PSA, just in case

[canuguzzi]

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.

[Tom H]

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

[Muzz]

Wise words indeed N.P.

I have been asked "why?" before. Not a stupid question if you just don't know or understand why.

[thepittsburghguzzi]

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! 

[cruzziguzzi]

Is the negative one, the one with the hose clamp?

Todd.

[JeffOlson]

Of course, just to confuse matters, on my Norge, positive is red, and negative is black. 

[MGPilot]

Reconnecting - Why positive first?

[Sasquatch Jim]

 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.

[Muzz]

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?

[nc43bsa]

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.

[oldbike54]

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  Seriously , seems like I read somewhere that it allowed for some savings in copper .

 Dusty

[Muzz]

 
 seems like I read somewhere that it allowed for some savings in copper .

 Dusty

That sounds about right dusty!

[kirby1923]

 

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.

[oldbike54]

That sounds about right dusty!

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

 Dusty