HarleyTechTalk

Yesterday I had parked the bike in a public lot while I was working as a volunteer for a local triathlon.  Was away about 4 hours and came back to a dead battery with 0 volts on the gauge. Some douche must have come by and turned the power switch on and left it for me. Nice. My own fault for not locking it tho. I know for certain that I turned the switch off before I left the bike.

Harley tech came over from the shop to jump me off a power pack (Snap-On if it matters).  He hooked negative lead first, then positive lead. I was always taught the reverse-that you connect positive lead first, then negative (on negative ground systems).

Did he do it right/correct?  Discuss.

I always do it your way Dennis, just my 2 cents

Negative last on, first off. That's the way I have always done it.

I connect the positive cable to the good battery then to the dead battery.  Then the negative cable to the good battery and then to a ground on the frame of the vehicle with the dead battery.  That way it won't spark near the dead battery in case of any explosive vapor in the area.

Probably doesn't matter with an AGM battery since they don't vent a lot of hydrogen gas, but that is just a guess.
The proper way to prevent explosions is to connect the positives first then the negative on the donor battery then a ground somewhere distant from the battery on the dead vehicle.

ThumperDeuce beat me to it.

Quote from: ThumperDeuce on September 09, 2013, 08:34:56 AM
I connect the positive cable to the good battery then to the dead battery.  Then the negative cable to the good battery and then to a ground on the frame of the vehicle with the dead battery.  That way it won't spark near the dead battery in case of any explosive vapor in the area.

That's the way I was taught has an apprentice years ago.  Bob

 

I have witnessed a few battery explosions  (not by me  ) due to hooking both cables directly to the last battery (especially in hot and poorly ventilated conditions after a charge cycle attempt). Very loud and lots of acid spray.

Quote from: ThumperDeuce on September 09, 2013, 08:34:56 AM
I connect the positive cable to the good battery then to the dead battery.  Then the negative cable to the good battery and then to a ground on the frame of the vehicle with the dead battery.  That way it won't spark near the dead battery in case of any explosive vapor in the area.

ALWAYS! The ONLY way to do it, AND whether it "Matters" or Not, Helps keep you doing it Right, (Makes it almost Second Nature if you will) and away from picking up any Bad Habits.

Quote from: Hogman on September 09, 2013, 11:01:41 AM

Quote from: ThumperDeuce on September 09, 2013, 08:34:56 AM
I connect the positive cable to the good battery then to the dead battery.  Then the negative cable to the good battery and then to a ground on the frame of the vehicle with the dead battery.  That way it won't spark near the dead battery in case of any explosive vapor in the area.

ALWAYS! The ONLY way to do it, AND whether it "Matters" or Not, Helps keep you doing it Right, (Makes it almost Second Nature if you will) and away from picking up any Bad Habits.

Clamp one positive end of the cable to the positive terminal on the dead car's battery and then attach the other positive end to the positive terminal on the good battery on the other car. Connect one negative end to the good battery at the negative terminal and then clamp the other negative end to the engine block or a solid part of the car's frame to establish a ground. Try to find a spot as far from the battery as possible. You may also connect it to the negative terminal on the dead battery, but this should be a last resort if you can't find another spot. Connecting to the dead battery to complete the circuit could cause a battery explosion, although it's unlikely.

This is a copy and paste from an article I read but it is how I have always done it. Just using their words to explain my procedure.

Not to complicate things "but" be sure the ground current is direct line to the battery when "electronics are concerned. I use my rear footboard mounting bolt and starter terminal and not the battery. Easier than accessing the battery too. For example a wild feed through an electronic component because it is in the path to ground (or the battery) can smoke the delicate circuits. In other words use or go the chassis, not a wiring harness or lighting ground point.

For example (a little off topic but for demonstration purposes), welding on a chassis where heavy current can pass through bearings or electronics will cause damage. Always ensure the current path does not pass through bearings or cause a surge to electronics. Disconnect the battery to prevent the latter example.

The NEG is always the last on first off, unless your working with an old Pommie POS that had a Positive Earth System.

Well, Thumper deuce, Truck and anyone else that used that method are all correct.  FWIW, exploding batteries are a myth I tell you.  Can't happen, never has happened, and even if it did, how much damage could it do?


[attachment removed after 60 days by system]

Quote from: Rags722 on September 09, 2013, 02:29:51 PM
Well, Thumper deuce, Truck and anyone else that used that method are all correct.  FWIW, exploding batteries are a myth I tell you.  Can't happen, never has happened, and even if it did, how much damage could it do?

Had one blow up in my face. My face was maybe a foot away. It blew the whole lid off of the battery. It can happen with lead/acid battery's.

Edit: Guess I missed the sarcasm.

Funny thing about this thread that no one understands the basic reason why ground is the last to connect and the first to disconnect.. If everything is done right it really don't make a damned bit of difference.. Expelled gases will ignite and blow up a battery no mater which which way it is hooked up if there is a spark close to the battery vent..  I've blown 2 batteries up but not from hooking em up or disconnecting them.. The root cause was a non electrical spark..

Max

 
"I've blown 2 batteries up but not from hooking em up or disconnecting them.. The root cause was a non electrical spark.. "

Makes me curious as to a further explanation for your (non electrical sparks)

Quote from: moscooter on September 09, 2013, 04:01:19 PM

"I've blown 2 batteries up but not from hooking em up or disconnecting them.. The root cause was a non electrical spark.. "

Makes me curious as to a further explanation for your (non electrical sparks)

First time was a bench grinder. Second was a disc grinder..

Max

QuoteFunny thing about this thread that no one understands the basic reason why ground is the last to connect and the first to disconnect.

I know, but you go first.   

May I? 
Negative on last, off first, so that an accidental touch of any frame material will not cause fire works due to a dead short across the battery. Surprisingly easy to happen . . .

Quote from: Hogspitt on September 09, 2013, 06:35:30 PM
May I? 
Negative on last, off first, so that an accidental touch of any frame material will not cause fire works due to a dead short across the battery. Surprisingly easy to happen . . .

That's basically it.. The 2 batteries are isolated.. When connecting the positive first you don't have a return path to ground if the ground cable isn't attached and the positive cable should bump any part of the frame while connecting.. Once the positive lead is connected, accidental touching of the ground lead does not produce high current flow.. It's also the reason you connect the ground cable last when installing the battery. If you connect the ground first installing a battery, there is a chance that the wrench you use to tighten the positive terminal could short against something since it would be at 12 volts if the ground cable is attached first..

Still I'll pull the seat and make sure the positive side is tight without disconnecting the negative side.. Just make sure the wrench don't tough anything cept the  terminal.. And no.. You won't get electrocuted..

Max

QuoteMay I? 
Negative on last, off first, so that an accidental touch of any frame material will not cause fire works due to a dead short across the battery. Surprisingly easy to happen . . .

   have a 

When a battery blows the top off it is pretty loud.  Two years ago we were in the Blackhills and stopped to look at a map.  Got ready to go and the wife hit the starter button on her heritage and Kaboom.  She about jumped off the bike.  I pulled the seat and the whole top had blown off.  Jumped on my bike and went and got a new (AGM) battery and a box of baking soda and a jug of water.  Luck would have it the acid didn't eat the chrome or paint on the bike.  I would hate to be looking at the battery when that happened.