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Matthew Wright

Bad Battery Behavior?

By November 3, 2008

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Dear Matthew,
I had a question about jump starting a car. I was asked today to help a woman jump start her car. I obliged and had jumper cables in my car. I hooked everything up as instructed. For the black cable on the dead-battery car, I attached it to the piece over the battery (that I thought was metal). The car would not start. It turns out the piece over the battery was not metal. Anyway, another guy came over and attached the black cable to the negative terminal of the dead battery and the car started right away. Is this bad? I haven't seen any instructions that tell you to do this. Finding a piece of metal was hard and if attaching the second black cable to a battery is an option, why doesn't anyone tell you to do it this way? Thanks for your help!! -- Bill Straderman

Chivalry is alive! You're a better man than most, Bill. These days people would rather rush to Wal-Mart than help a stranded motorist. As for the battery danger, it's a toss up. Clearly the best connection for jumper cables is at the battery terminals. So why do most instructions tell you to attach the negative cable to the car's chassis rather than the negative battery post? These days, batteries are maintenance free and sealed for life. No loose caps or spilled juices. Not too long ago, however, the acid in car batteries could easily escape through the caps in the top of the battery used for adding water. It's not the acid itself, but the gases that were the problem. A leaky battery could have a cloud of gas around it. A spark near the battery could cause fire or explosion. Thus the danger. To avoid the spark near the battery, attach the cable somewhere else. These days, the chances of a fire are even slimmer than the slim chance back in the day. It's still probably a good idea to attach the cable to the chassis. Safety first!

November 4, 2008 at 2:00 pm
(1) maplewoodtransmission.com says:

Like the old saying goes, “its better to be safe than sorry”. I would rather find a place on the chassis than to have battery acid explode in my face!!!

November 4, 2008 at 7:00 pm
(2) lvguaranteedauto.com says:

I alway connect the negative to a metal on the engine or body. I car seems to react better than the battery terminal

November 5, 2008 at 6:02 pm
(3) Jon says:

Call me terrible, but I always hook up the positive clamp to the positive terminal and the negative clamp to the negative terminal. It’s much easier that way and since I’ve never seen any exploding battery gas in my life, I figure I’m safe enough.

November 7, 2008 at 6:30 pm
(4) Cactass Dupree says:

I learned a new one the other day. I always try and help a stranded person by carring a set of cables. The Roofing Foreman that I work with called in need of jumpers. I was 50 miles away. Seeing him later in the day I remarked: You must have got some jumpers? He said: Nope I Redneck jumped it. I asked what that was? He took a battery out of another truck, had his helper sit in the dead truck with the key turned to start. He then flipped the good battery over pos. to pos. and neg. to neg. It started right up. I said your lucky it didn’t blow up.

November 7, 2008 at 11:37 pm
(5) Matt says:

Wow, that’s a new one on me. I’m all for using redneck methods, but this takes the cake.

November 12, 2008 at 5:21 pm
(6) john says:

connecting jump leads direct to your battery with your ignition on can cause electrical spikes througth the vehicles electronic systems…..as a tech i see more of this on modern car systems. putting the black lead of your jumper to the body dissipates any voltage surge through the vehicles body. Its the safer option if you can take it..

August 12, 2009 at 10:40 pm
(7) U NO HOO says:

My suggestion is, if you must attach to battery terminals, attach cables to dead battery first, then to charged battery.

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