Yukon battery giving me troubles

[Narkonus]

I was driving my truck tonight, and i noticed the console lights were dimming on me. I looked at my voltometer (i believe that's what it's called) and instead of being at just past 14 like normal, it was dipping to about 10.5. I hit my accelerator and the gauge raised back up to 14. As soon as i hit the break again it dipped to 10.5 again. The battery hasn't died, and it still starts, but it just has a severe dip in power when i hit the breaks. When i started the truck up after sitting for about three hours, the voltometer read 14 again. I live in Michigan, and it's real cold outside, but i don't know if that has anything to do with it. I've got a 760 watt amplifier powering two 10" subwoofers in the Yukon, but i've had that going for 6 months without previous trouble. I also had that same setup in my Saturn for two years before i got the Yukon without experiencing this. Could my alternator be bad? My battery? Any ideas? Any help would be very much appreciated.

Thanks for your time.

[Bish]

Clue us in on what year/model.

[Narkonus]

1997 Yukon. Only thing i've added is the amp and subs that i mentioned, and a pioneer deck. But this is the first time i've had trouble in the six months i've been driving they Yukon.

[Guest 007FL]

Sounds to me like a loose belt or a bad voltage regulator. Easy diagnosis, take it to Walmart or Autozone and tell them you Think your battery is going bad. They'll put a tester on it and tell you right off what the problem is.

[Narkonus]

My belt looks good, not much wear on it. I bought a new battery and put that in there, thinking that maybe the old battery just couldn't hold a charge or something. I'm still having the same problems though, even with a brand new battery. I don't think it's my alternator because the battery will charge back up when i'm accelerating, it just won't hold that charge for very long. Any ideas?

[Ben]

Do a search on battery positive post. You most likely have infamous GM battery positive post issue.

 

Side post batteries with two cables have a crush spacer that is one time use thing. Second time tightening the bolt will have the crush washer not allow sufficent resistance and the bolt will go too far into the positive post hole, cracking the battery case.

 

That sets up cycle that will ruin batteries, alternators, cables, starters (wicks down the cable) and wacky electricals.

 

Intermittant connection on top of the acid leaking out.

 

And or you jump started another while your engine was running. Kills alternators, which then kills battery and goes into vicious cycle.

 

Oh heck, here's the info again from my files:

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

 

 

....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 text from 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 another vehicle without killing your own alternator