voltage regulator on my '72 VW bug died...battery was boiling acid into the cabin. Bad news

I am wondering if my voltage regulator is just starting to go out. when I tested it, the voltage was good, but 60 or so seconds of testing isn't very conclusive. not like my battery got hot driving around town. it was on hour 5 or so of 6 hours of driving. I am still going to see if they will exchange the battery, I don't trust it even if it turns out the voltage regulator is the issue. after getting that hot it has to be damaged a little

They replaced the battery without even testing it. I told them what happened and they looked up the receipt and just grabbed a new battery. They said if it does it again or it turns out it is the alternator and it messes this one up, you still have some time left just bring it back in and get another. I was shocked


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That is really good service! :) Sounds like not the first time they are dealing with this.

battery boilovers, repairs following, and precautionary measures taken
 

I had three VW's back in the day: a '64 Bug, and '72 and '73 SuperBeetles, all with the battery under the rear seats. I had no battery or electrical troubles with the latter two, but I did have a similar battery acid spillage/boilover with the older Bug.

When I bought it (in '71), the '64 had already damaged the floorpan with acid, which was repainted after a cleanup, but was still pock-marked. Soon afterwards, I had the regulator start acting up, and I perceived the smell of the acid, on my drive to the General Motors Training Center I was attending. I went back outside at lunchtime to see what I could do to temporarily fix the problem (I had already bought another regulator at a nearby VW dealership, during lunch), and the instructor and a few other students came over to see what I was doing.

The instructor furnished me with an acid-neutralizing chemical, and an acid-absorbent pad from his supplies, and my VW was "fixed" until I got home. Over the following weekend, I was able to rivet and seal in a new sheet metal plate under the battery, and place a sacrificial metal pan under the battery itself, to catch the acid if the problem ever occurred again, which it didn't.

On the SuperBeetles, I used plastic pans/trays under the batteries, with acid-absorbing pads inside, but neither ever leaked into them. Over the years, on various cars & trucks, I used a lot of those pads, used many plastic battery boxes (or painted the factory metal trays with POR), but most recently, I haven't taken such precautions on our vehicles. I rely on modern factory instumentation and periodic scan tool testing to find and fix battery problems before any battery boilover could occur.

Having made that last statement, can I now expect my X5's battery to dissolve the trunk underfloor, since I never visual inspect it (the trunk is filled with tools & supplies)?

Yes, it wasn't all that uncommon back in the day with mechanical voltage regulators ;)

For reference I just measured 14.4v at the battery, engine running and have been on the road for about 4 hours and no hint of battery heating up.
I'd be surprised if there wasn't at least a code set or light for overvoltage if not even some kind of overvoltage protection with a relay or the like.
I think the battery was overcharging because some of the plates got shorted and the voltage was too high for the remaining ones.

14.8 is a fully charged battery.[emoji106]
Get rid of that battery!
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@OP Is everything good now and are we for sure the problem was indeed the battery ? I wonder if this might somewhat of a brand specific problem ?

I dont think you can get over 12.6V on a fully charged car battery


When connected in a running car, yes you will see over 12, up to 14. But on its own, no

Not the best proof...I guess huh?
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