Posted by: Ors

Jumpstarting...again - 04/12/06 03:35 AM

Okay, I'll freely admit that I don't understand a whole lot about how cars work. I posted a question about jumper cables and correct method of hooking them up a few months ago, but I'm really confused about what happened yesterday. I left my lights on (darn warning buzzer didn't work!) and I had a friend agree to let me use her car to jumpstart mine. I hooked up positive to positive and negative (live) to ground (dead). I had her run her car at high idle, and within a twenty minute period, tried three times to start my car...but nothing. I then took the cables off, and reattached them, this time connecting negative to negative (I know, possibility of exploding battery). My father in law (as I said in the last post) swears this is the correct way to do it, although I'd never done it that way. Within a couple of minutes, my car started right up.


Do I do it the "wrong" way and risk battery acid in the face because I know it works for my car? 'Cause I know the "correct" way didn't work.

I don't get it. <img src="/images/graemlins/confused.gif" alt="" /> <img src="/images/graemlins/confused.gif" alt="" /> <img src="/images/graemlins/confused.gif" alt="" />
Posted by: Eugene

Re: Jumpstarting...again - 04/12/06 11:37 AM

Your not supposed to make the last connection at the battery because you could make a spark too close to the explosive gas.
If you couldn't get good power connecting to an engine ground then you may have a dirty connection somewhere.
Posted by: harrkev

Re: Jumpstarting...again - 04/12/06 02:33 PM

The problem was likely that one of your connections was not good. Some people say that the last negative connection should be made to the chassis itself to reduce the posibility of explosion. There is some merit to this, but you can ignore it if it is a windy day. The advantage of the direct connection is that there is less resistance. The lead in top-post terminals is rather soft, and the teeth of the clamps can grip right in and make a great connection easily.

If you attach the calbes to the chassis, you have to make sure that the cables touch metal and not paint/grease/rust.
Posted by: Ors

Re: Jumpstarting...again - 04/12/06 06:57 PM

If you couldn't get good power connecting to an engine ground then you may have a dirty connection somewhere.

On my very first car, I always grounded it to part of the frame. Is that thinking correct? Just as long as it is grounded, somewhere?
Posted by: Eugene

Re: Jumpstarting...again - 04/12/06 08:40 PM

The starter is bolted to the engine as close to the engine block/starter is the best place. Grounding to the frame of the car you have to go through a ground cable/strap to the engine which is a potential point of bad connection. You usually have a large ground strap from the engine to the body and then a large negative battery cable from the battery to the engine block. So connecting to the frame your going through whatever bonds the frame to the body then the strap from the engine to the body.
\My very first truck was 1988 chevy which we got from a repo auction and someon had improperly installed a body lift. We found that the large negative battery cable was left disconnected since it wouldn't reach and it then melted the small negative battery cable. When we foudn this we took the body lift back off and reconnected the large egative battery cable but didn;t think to check the connection. Since it had been disconnected for sometime the connection point had been exposed and started to rust, then reconnecting it on top that rust didn't help any. I couldn't get it to crank one day and wiggled the battery cable and it started, then disconnected the cable from the block and found all the rust trapped under it and cleaned it up good and it was fine for many years to come.
Posted by: Grits

Re: Jumpstarting...again - 04/13/06 01:01 PM

What guage wire were the jumper cabels?

Smaller diameter wire will not carry the current needed to jump off vehicles. A large diameter cable will carry the load needed to start another vehicle.

When most folks buy jumper cables they purchase the cheap ones. Invest in a good quality pair of jumper cables and save yourself some headaches along the way.
Posted by: Anonymous

Re: Jumpstarting...again - 04/13/06 03:36 PM

Yes that thinking is correct - but even the paint at the connection point can weaken the current sufficiently to make a bad connection so look for bare metal - or go directly for the battery terminal
Posted by: 311

Re: Jumpstarting...again - 04/13/06 04:20 PM

Problems making the connection to ground at remote locations on the vehicle is a sign of a ground problem. You need to correct this, not just put the ground clamp on the battery. Find the connections that ground the vehicle parts together., i.e. engine to body strap, hood to body (if you've got one). disconnect these. Clean with sandpaper, wipe with a solvent (acetone or alcohol) and reconnect. Be sure that they are tight. These straps & wires were put there for a reason (reduction of static in your radio, for one). Don't ignore them.
Posted by: Arney

Re: Jumpstarting...again - 04/13/06 04:21 PM

So, I guess one question for you, Ors, is whether your car's owner manual suggests a place to clamp that negative cable and if that's where you clamped. Just because the cable is connected to something metal doesn't necessarily make it a good grounding point, as others have pointed out.

Posted by: 311

Re: Jumpstarting...again - 04/13/06 04:25 PM

If the headlight warning buzzer doesn't work, check to see if the interior light comes on when the door is open. ???! On my car, the buzzer circuit needs to know when the door is open so it can warn you about the headlights. When my door switch failed, the interior lights & the warning buzzer stopped working. Fixed door switch, interior lights & buzzer fixed!
Posted by: Ors

Re: Jumpstarting...again - 04/15/06 02:10 AM

That is an interesting point, because my interior light doesn't always come on. I don't see a pattern to it myself, but it is worth investigating the connection between the two.

Thanks for that bit of advice!
Posted by: Ors

Re: Jumpstarting...again - 04/15/06 02:23 AM

That is a good point too. A favorite expression in our family is "RTFM"..."Read The ****** Manual".

Guess I should take that sagely advice. <img src="/images/graemlins/ooo.gif" alt="" />
Posted by: atoz

Re: Jumpstarting...again - 04/15/06 03:02 PM

You need to make sure that when you hook the cable to the car that it is touching BARE metal. Most cars have painted parts so what you have to do is scratech off the paint to allow the clamp to touch bear mettal. I have found this the case in almost all the times I have had to jumpstart a car.
Posted by: Dean

Re: Jumpstarting...again - 04/16/06 04:42 AM

This is why I like Optima batteries. They do not have liquid acid in them. They also have low internal resistance so they put out alot of amps for starting and then re-charge fast. That way they stay in good condition. I also appreciate that they seem to stay cleaner and when I open the hood I don't get that acid fume smell.
Posted by: Eugene

Re: Jumpstarting...again - 04/17/06 01:40 AM

How long do those last? I found a thread or two from people saying they only got a couple years out of them but I always thought they lasted longer than that.
Posted by: David

Re: Jumpstarting...again - 04/18/06 04:03 PM


I may be wrong, but it seems from your description that you left the circuit open in the wrong place. You should have attached the negative cable to the negative terminal on your (dead) battery, then grounded the other end to the boosting (live) car, in the manner of your choosing.

The connection sequence I ALWAYS use when jumping a car is this:

1 - Live/boosting positive (usually, with engine running)
2 - dead positive
3 - dead negative
4 - live ground (either to the battery, or another appropriate ground on the running engine)

You initially reversed #3 & #4, which left no way for a circuit to be completed with your dead battery...until you connected the negative cable to it, as well.

I've made the same mistake in the past...until I finally learned to do it "by the numbers".

Also, a good heavy-gauge set of jumper cables should be in every vehicle you own. I use mine to help out others more often than not, but nothing else will do when you need them!

Glad you got up & running.

Posted by: MartinFocazio

Re: Jumpstarting...again - 04/19/06 01:05 AM

A few things about jump-starting.

1. Avoid it in the first place, if at all possible. A 100% depleted battery will never perform properly again.

2. Remember that you're moving HUNDREDS of amps through a relatively small cable - as a result you need utterly SOLID metal-to-metal connections.

HEre's a good guide:
Posted by: Arney

Re: Jumpstarting...again - 04/19/06 04:17 PM

I learned to connect the cables the other way, with the ground at the dead battery end. To double check, I looked at the owner's manual for my two cars, and they both say to ground the dead battery end. I've jumped cars this way, and obviously you've jumped cars your way, so both ways allow current to flow. Of course, when in doubt, follow your own car manufacturer's instructions.

I recently found this outstanding webpage on car batteries. There's a lot of great information on here and from what I've read so far, it all looks authoritative. E.g. I didn't really realize that your car's alternator could burn out or blow a diode from trying to recharge a completely dead battery because it's not designed to. So, even after getting a jump start and driving around for a while, you might disable your recharging system and soon end up with a dead battery again. That possibility had never occurred to me before. Anyway, check it out.