Looks like my repaired battery tray and hell hole were christened by my new battery based on the white residue and light rust forming in the tray.

From what I’ve read in posts, I’m thinking voltage regulator and/or alternator as a probable cause. Any words of wisdom for someone new to electrical system troubleshooting and battery acid damage control?

Optima battery.

This is the age old problem with the 914 battery location. "in the day" battery acid ate through the fuel lines and caused fires and the rusted hell hole.
These days most people like to use the Optima battery-no leaking. It's worth the extra $$.

Put a volt meter on the battery. Should read 12.5-12.8 at rest, 13.0 at idle and 14.0-14.5 at 2500 rpms. Any more than that it's a regulator issue.

Optimas are a good thing for 914s.

Thanks for the Optima input folks. I remember reading years ago that maintenance-free batteries have no way to vent if they get over-charged by the electrical system if the voltage regulator goes on the fritz. No longer a problem these days?

Since they are gell filled, they don't overflow nor need to vent. They can take a charge higher charge than you would expect. But you really need to check the charging circuit.

Optima's are ~$125 at Costco.

I couldn't find an Optima battery locally. Anybody give me specific details on which battery, and where I can buy one? THANKS!

Mary, I bought my Optima (Red GRP 75/35) from Sears.
Mike

I prefer the Yellow Top, Marine deep cycle. It allows for full discharge with recovery. The one in the 911 has gone flat many times and still holds a charge.

I have an orbital which is a different brand but the same technology. It states on the battery that the voltage should never exceed 14.5 volts. I have gone through 2 of these and I believe the charging circuit may have damaged them (that and excessive drain) I think lead acid will tolerate the higher voltage but you risk boiling over problems. Lead acid is O.K. if you keep the area clean and no exposed unpainted metal.

Mary, check online at Optima for local retails, failing that. PP, AA, Pelican & some of the general online auto parts sellers can sell them & deliver. There was also another post on here last week re another battery dead issue, where a drycell battery was recco'd, so check that too (it was also available online.

Was your lead-acid a sealed variety? Interstate's are good, byt 914's are too rust sensitive & the acid eats the fuel lines (even the HO replacement type) - so the sealed gel or dry types are best/safest. Just check the charging as noted above & fix regulator, alt. or whatever is wrong (if anything), as boil-over may not be an overcharge since other things can happen to cause it.

... I think not! ...
Forget lead acid & fix the charging system or keep buying gel/dry batteries, as the body repair will cost far more, if not a total loss due to an engine bay fire when the acid eats your fuel lines & connections!

BTW - Here is a clean, neutralized & painted battery tray with no battery in there at all May 85 to May 09 (24 years) in my dry SoCal garage - this is what just the residual acid does even after cleaning/neutralizing!!!!

Click to view attachment

Disconect the battery while not in use and spray a baking soda solution around the battery tray and engine shelf and hell hole area below the battery as regular maintainence.Charge the battery outside the vehicle.

BTW - my pic above was with baking soda wash, spray down, etc. - it is NOT the Holy Grail Sir Galahad ~ ...How long does it take a sparrow to fly .....?

I remove and wash my PAINTED battery tray and hell hole once per year with a mixture of baking soda and water...I do a very thorough job of it...twice.
I have no paint bubbling and no rust.
That said...once the current battery dies...I will get a gel filled battery.

Rust occurs because there is moisture in the air...

Rich

Knowing the history of these cars and what lead/acid batteries can cause,a gel cell is cheap insurance. One of the first purchases I made for mine even tho' the battery installed was good.
Tom

I'm using an Orbital O6 battery from NAPA. It's an spiral cell like the Optima....between drives I keep a Battery Tender on it....

My main point is that if the charging system is not working properly and you are over charging a lead acid battery, then installing a gel battery is not a good solution. Fix or make sure the charging system is working properly before installing a gel battery. If you have circuits that drain the battery when the car is off, fix them. Gels are easily damaged by allowing them to drain excessively or overcharging. If running a lead acid, keep the area clean. and wash frequently.

I had a wire (d-) wire come disconnected on my 6 cyl conversion ...bad splice.
If you put 17.5 volts for an hour or so into a Optima it will boil over. The gell is green and was all over my trunk....apparently squirted up, hit the lid ....all over. Thank God the battery was no longer in the orginal position.

A dry cell is the hot ticket....of course it may explode under the same conditions from the lack of vents.