Why does GM insist on this ?

bandera · November 28, 2003

Got back from a hunting trip yesterday. Backed my 2000 Z-71 into the driveway to unload my 4 wheeler and all my other "junk". After cleaning everything up and putting away, I started to move my truck. Turned the key-nothing, just plain dead. Lights would shine about half brightness. Got my wife's car and jumped it off so I couild put it in the garage and put a battery charger on it. When I put the charger on it, the meter showed the battery was not taking a charge. It is the original battery (four years), so I figured it was time anyway, so I bouight a new battery. When I was removing the old battery, the positive terminal twisted off when I was trying to loosen the bolt ! I could see that it had been leaking for quite a while- the tray was all corroded and the cable was also messed up. I got some baking soda and cleaned it all up including down below around the fender area. Since I got a new battery it wasn't that big of a deal, BUT why does GM insist on that &*^*(+# design? It is hard to access the bolts on the side and that stupid 5/16 bolt head just begging to round off. That's why they put that larger round part around the bolt head-so you can put some channel locks or pliers on it to get it off. Any one out there that works for GM have a half way sensible answer for this?

k1500chevy97 · November 28, 2003

the side mounts really suck . Im thinking of switching mine over to top mounted cables

Ben · November 28, 2003

What you have is the IN-FAMOUS general motors postitive cable/battery problem.

Comes from that lead washer between the two lugs. It's one time use thing and should be replaced whenever the batt positive connection is loosened. If not, it crushes and allows the bolt to go too far into the connection to crack the battery case. Then it allows the connection to become intermittant to kill the alternator. Then it wicks acid into the cable and it continues to wick down to the starter and kill the starter.

I've posted many, many, many times and will again.

Here's the text, hot links and pictures:

================================================

....note that the brass nut is drilled out and just acts like washer. There are TWO OEM lugs on the battery terminal, then brass nut, then accessory lug (3 wires, two 50 amp fuse holder, one 30 amp fuse holder) and alarm power wire. Have since gone to store bought that looks very much like this one (it's shown on #1 Son's battery page).

Hot link to the thread on another forum

TEXT from that article:

That bad battery post design can/does kill alternators, batteries, starters, battery cables, and wreck havoc with other electrical circuits.

Think many don't know what Traveler and I are talking about. Here's an example of what is happening and the cause'n affect:

Take the battery positive cable lug and unscrew it from the battery (disconnect it). Manually hold the cable lug to the battery post. Start the vehicle. Now touch, remove, touch, remove the cable lug to and from the battery pos terminal. THAT is EXACTLY what happens when that stupid lead spacer crushes and allows the bolt to bottom into the battery pos post.

The alternator sees the battery, charges (provides oltage/current), then the connection goes away. Voltage at the alternator goes up (maybe several hundred volts, instantly...or almost that fast). Then when the contact is made again, the alternator will see huge load (maybe hundreds of amps, instantly...or almost that fast). This is called load dumping and will kill a good alternator in short order.

Above load dumping will also kill the battery in short order too. Over voltage and over current. Also will have high resistance terminal, meaning voltage drop, meaning current used at that spot. That current usage turns out to be heat...high enough to melt the battery case, which will allow battery acid to leak into the joint *AND* down the cable (cable acting like a wick and cable insulation acting like a hose...carrying battery acid down to the starter...starter don't like battery acid).

Another cause is that there is a lead spacer between the two cable lugs on the battery post. One time use, as 2nd time tightening the bolt will have the lead washer too short to provide resistance and allows the bolt to bottom out inside the batt pos terminal. That then cracks the batt case, allowing acid to leak...ditto above, ruining cable, starter, alternator, battery, etc. Throwing away the lead washer, cutting off the plastic from the lug blades (flat part only) and replacing the washer with stack of brass washers that won't allow the bolt to bottom is a fix.

All of the above then has this affect on the vehicle computer: turns it on and off. Or various components of the vehicle. Which one??? Who knows and not always the same one. Engine dies for no apparent reason. Doors lock and unlock for no reason. Window motors burn up for no reason. Lights turn on, off for no reason. After market alarms turn on/off and lose their programing. ETC, ETC, ETC.

Another way to avoid/manage the lead crush washer is to use a hardened brass bolt that is threaded whole length, that is longer than needed and a hardened brass nut. Put nut on and screw it to the bolt head. Stack up all of the lugs on the bolt, then screw the bolt into the battery pos terminal till it hits bottom, back off 1/2 turn. Now turn the nut down onto the stack of lugs while holding the bolt hex from turning (do not allow bolt to bottom into the batt terminal and only HAND tight). Tighten the nut till it's tight and makes good connection. This way you'll be able to keep that lead spacer and not have to cut off the plastic covers on the lug blades...

This avoids bottoming the bolt, which is one cause of acid leaks (cracks battery case), other is high resistance and the heat generated melting the batt case...causing acid leak.

Another potential is jumping another car while your engine is running. Here is hot link to that thread at hot link below.

HOW2 jump start without killing your alternator

JayMan · November 28, 2003

Ben: Thank #1 son good info there!

My folks bought a brand-new 1976 Chevy Monte Carlo with the big block. They "wisely" sold it a week before I turned 16

To prevent corrosion of those wonderful side post terminals, I finally put silicone dielectric grease on the new battery side posts, and a liberal amount on the new cables. Never seemed to have a problem after that.

My 1990 Toy 4Runner came, free of charge, with an old-fashioned battery that you had to top off once a month. It also came free of charge with a hugely overcharging charge system so battery acid GUSHED out the top vents of the battery.

Toyota Stealer claimed that was "normal" and refused to do anything about it.

I finally put in an AC Delco 78DT-84 that, although it bulged a bit, didn't gush acid and eat up the hood or fender. Changed the alternator, regulator, etc etc still did it.

"Oh what a feeling" my a**!