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The 996 was on the battery tender last weekend (normal if I'm going to be gone for several days); I drove it on Tuesday and everything was 5x5. Yesterday, it stayed in the garage; today, I went out to head to work this morning and heard the click-click-click we all know and despise. How the battery went from a full charge to too flat to start in a day? No idea, but I took the 80's time machine (my '96 Corvette) to work instead.
I had time to head home at lunch, so I figured I'd pull the battery and have it tested by the fine folks at AutoZone...and this is what I found:
No external forces were applied to the terminal to make it that wonky...it hasn't been shorted, and it hasn't been overcharged; to my knowledge, those are the only reasons a lead-acid battery will swell.The battery case isn't distended as is usually the case with thermal runaway; if it was, I'd chuck my battery tender and test my alternator - but the ONLY symptom is the terminal separating from the battery.
I suppose the other possibility is crappy construction - this was a 5-year-old X-brand battery that I believe was already in the car when I purchased it.
Maybe someone before you carried the battery around with one of those straps that hooks over the terminals so that it was cracked some time ago but finally now gave up the ghost.
When electrolyte leaks from the battery, it reacts with the lead terminals to form lead sulphate (the white powder); if copper is present, hydrated copper sulphate (the blue-green powder) is also produced. This was a sealed (maintenance-free) battery; there shouldn't have been ANY electrolyte present at the terminals.
What I find most surprising is that I was working around the battery less than 2 weeks ago. There was no visible corrosion at that time and the terminal wasn't jacked up. Whatever happened to make the terminal pop out and cause the charge to dissipate happened without the last couple of weeks.
When electrolyte leaks from the battery, it reacts with the lead terminals to form lead sulphate (the white powder); if copper is present, hydrated copper sulphate (the blue-green powder) is also produced. This was a sealed (maintenance-free) battery; there shouldn't have been ANY electrolyte present at the terminals.
What I find most surprising is that I was working around the battery less than 2 weeks ago. There was no visible corrosion at that time and the terminal wasn't jacked up. Whatever happened to make the terminal pop out and cause the charge to dissipate happened without the last couple of weeks.
Your post title says it all - I've never seen this either. IIRC the cables are pretty tight (not much, if any, slack). Any track use or rough roads where there might have been unusual pressure on the terminals? I'm assuming the battery was clamped down tight.
......you had me at "5 year old brand x battery". That's a long time. I have Walmart Maxx series battery in my '99 996 and my '04 C5, mainly b/c they are open 24 hours. I've had just about every brand there is. As you may know the C5's are snowflakes when it comes to the battery voltage. They have been great in both cars.
I am certain that most if not all the batteries today are absolute junk vs the batteries we had 15 years ago. Too much recycled junk in them these days. They simply don't last.
I had a battery fail in both my 996 and 997. And both failed with no warning whatsoever. I think these cars draw more when not in use than any other car I've had.
Congrats on getting 5 years out of it. You should have that sucker gold plated...
When a cell in the battery goes the resistance goes up. When the car pushes amps through the battery it heats up and the case expands. When the car is turned off the distorted case is left. The battery had to vent somehow. The same effect can be caused by bad voltage regulation. All car batteries, sealed or not, have a venting scheme so they don't become bombs.
5 years is a good run on a battery these days. Change batteries every 3 years and you can almost guarantee never to be stranded due to a battery failure. Excluding some other failure that drains it of course!
I had a side terminal battery in a Chevy Blazer that failed similarly one time. The lead plug where the cable screwed in just spun in the side of the battery. As I was trying to disconnect the cable the whole lead plug just fell out of the battery case.
The battery had a 9/2011 production stamp. It also had two outgassing vents; one was plugged and the other was properly vented. I'm guessing the vents were either improperly molded and they weren't actually allowing any hydrogen to escape - but that's just a WAG.
Glad it didn't burst or otherwise cause any trouble - I'm feeling like I dodged a bullet...
*edit* Professor Google provides more info: the + grid corrodes over time; they call this grid growth. Eventually, the plates reach the bottom of the cell, and further corrosion has nowhere to go but up - so the terminals eventually get pushed up out of the post seal.
Professor Google provides more info: the + grid corrodes over time; they call this grid growth. Eventually, the plates reach the bottom of the cell, and further corrosion has nowhere to go but up - so the terminals eventually get pushed up out of the post seal.
That is interesting information and explains a few things!
11-17-2016, 05:31 PM
I've never seen THIS before (battery failure)
