Properly hooking up dead battery.

[lupindub]

So about a month ago I had my car jump started by the AAA guy and he hooked it up as such - Positive terminal my car, Positive terminal + Negative terminal his car and then finally NEGATIVE terminal my car. The manual states that whichever battery is dead (my car) should have the negative terminal hooked up to a ground. So I am wondering why you need to do it as such when it worked just fine the way the AAA guy did it?

[mdm]

By connecting to the car ground (any large metallic uninsulated piece) you are indirectly connecting the cable to the battery's negative terminal, as the negative terminal is connected to car ground.

The reason why it is not recommended to connect directly to the negative terminal is that making or breaking this connection often creates a spark. The battery may produce and release hydrogen when charged. You don't want to ignite this hydrogen with a spark.

EDIT: I just checked the FRS manual and the picture there shows the jumper cable connected to car ground close to the battery. That's not ideal, you obviously should connect to the ground away from the battery

[lupindub]

Originally Posted by mdm

By connecting to the car ground (any large metallic uninsulated piece) you are indirectly connecting the cable to the battery's negative terminal, as the negative terminal is connected to car ground.

The reason why it is not recommended to connect directly to the negative terminal is that making or breaking this connection often creates a spark. The battery may produce and release hydrogen when charged. You don't want to ignite this hydrogen with a spark.

EDIT: I just checked the FRS manual and the picture there shows the jumper cable connected to car ground close to the battery. That's not ideal, you obviously should connect to the ground away from the battery

Yep, problem is the jumper cable only splits off (positive and negative terminal) so far so it kind of has to be close to the battery. Do you have any good recommendations for a ground?

[mdm]

Originally Posted by lupindub

Yep, problem is the jumper cable only splits off (positive and negative terminal) so far so it kind of has to be close to the battery.

I see. Wouldn't call it a properly constructed jumper cable, but on the other hand it's an "abundance of caution" rule, imo. After all, batteries rarely explode even though many people ignore the rule or use jumper cables with terminals close to each other.

Originally Posted by lupindub

Do you have any good recommendations for a ground?

Any solid unpainted metal part that is a part of or directly connects to the chassis or engine should work, as long as 1. it is covenient to clamp to, 2. it is not moving or is not too close to a moving part.

In the FRS/BRZ engine bay, depending on how far the negative cable can reach, I would go for one of the exposed bolts on top of suspension struts, or one of the bolts on those rods (or whatever you call them) that go from the suspension strut area to the center-back (I mean the bolts on the center-back end of the rod). Because of the engine configuration few metal part of the engine are accessible, so I probably wouldn't try connecting to the engine. Maybe one of the two bolts in the center of the engine, where the air intake tube goes would work, or in the front of the alternator, those the latter maybe to close to the engine belt for comfort. But I'd rather stick to those on top of suspension struts or on the rods.

[JoeC]

I've always hooked everything to the battery terminals for the last 30 years just like my dad taught me. He learned from his dad. I'm glad we're all still here. Next thing, someone's probably gonna tell me I need to turn off my diesel truck when taking fuel or resting my hand on the gear shifter is gonna wear out the transmission after 350,000 miles.

[Packofcrows]

Originally Posted by lupindub

...he hooked it up as such - Positive terminal my car, Positive terminal + Negative terminal his car and then finally NEGATIVE terminal my car.

Its just for safety to reduce likelihood of sparks. His battery has charge, yours did not.

Some people connect the negative (black) good battery terminal to the bad car but not on the terminal. They usually put it somewhere on the car where there is paint peeling. I do it the way my father showed me too like the above member and also connect red to red and black to black.

Black (negative) terminal is always grounded to the chassis anyways. Take a look at your battery and follow its connections.

[mdm]

Originally Posted by JoeC

I've always hooked everything to the battery terminals for the last 30 years just like my dad taught me. He learned from his dad. I'm glad we're all still here. Next thing, someone's probably gonna tell me I need to turn off my diesel truck when taking fuel or resting my hand on the gear shifter is gonna wear out the transmission after 350,000 miles.

There are many of rules like that: supposedly important for safety but followed by few.

For example, when fueling, one should never go back and sit in the car, because of static electricity. I always sit in the car when fueling. Though I admit afterwards I usually touch a metal part on the pump before touching the nozzle to discharge electricity away from fuel fumes, especially on dry days.

[Ultramaroon]

Originally Posted by JoeC

I've always hooked everything to the battery terminals for the last 30 years just like my dad taught me. He learned from his dad. I'm glad we're all still here. Next thing, someone's probably gonna tell me I need to turn off my diesel truck when taking fuel or resting my hand on the gear shifter is gonna wear out the transmission after 350,000 miles.

Really? You brag about this? Do you also hate on people that use jack stands and seat belts?

[Packofcrows]

^^^ @Ultramaroon

Water level issues?

[Ultramaroon]

Originally Posted by Packofcrows

^^^ @Ultramaroon

Water level issues?

Yup. Yet another reason to keep those cells topped off.

[JoeC]

Originally Posted by Ultramaroon

Really? You brag about this? Do you also hate on people that use jack stands and seat belts?

not bragging. just saying that's the way I was taught to do it and it's the way I've seen every other person do it. I even said I was thankful that we're all still here.

[HunterGreene]

I've done both (all terminals, or black to ground on car being jumped) and never had any real issues. It just is a matter of looking at the battery and making sure the connections are in good condition. Also being willing to keep an eagle eye on the connections and being ready to jump in there and remove a connection if things start to look a bit sketchy.

[mdm]

Originally Posted by HunterGreene

Also being willing to keep an eagle eye on the connections and being ready to jump in there and remove a connection if things start to look a bit sketchy.

Well that might help if the problem is battery overheating due to incorrect connections, as that process is not necessarily immediate (by the way, one car's manual I saw also suggested connecting the negative cable to a piece of metal not to battery terminal but the reason they gave was to prevent battery overheat, and I do not understand why).


If you have hydrogen ignition, you won't be able to do a thing, it goes pretty quickly. Maybe not as quick and disastrous as this one ;-) but still.:
[ame="https://www.youtube.com/watch?v=AfnvFnzs91s&feature=player_detailpage#t=95 "]CNN: Challenger Disaster Live on CNN - YouTube[/ame]


The only reason why people have been doing it for years without problems is that the likelihood is small. People drive without a seatbelt for years too.


Still it costs nothing to clamp on a piece of metal on the chassis instead of the terminal, and even if hydrogen ignition is unlikely it's consequences would be serious. So I'd follow the manual if I ever needed to jumpstart my vehicle.

[Ultramaroon]

Originally Posted by JoeC

not bragging. just saying that's the way I was taught to do it and it's the way I've seen every other person do it. I even said I was thankful that we're all still here.

Oh, my bad. I need to calibrate my sarcasm filter.

...I'll just take a seat over here.