jennifer911

What is the indicator to judge the full battery electrolyte (water) level? We were cleaning up the 997.2 trunk today and decided to have a quick look at the battery. It’s a Porsche oem Moll with 6 easily removable plugs. The water level was just barely above the plates so we figured it needs a top up. Because I’m the smallest, I got inside the trunk and using a flashlight looked straight down the cell holes. There is a suspended L-shaped strip in each cell. None of the assembled group had ever seen such a setup before. The consensus was to fill to the bottom of this L-shaped strip. Does this seem right? It will take quite a lot of water.

They are sending me off to get distilled water and beer. Hoping for an answer when I return. Surprisingly nothing in the search came up.

Bijan

Hint: Drink the beer and top up the battery with the distilled water

I think your judgement is correct as to proper level, the plates should be well covered but too much water may cause acid spillage from the battery

My experience with Moll batteries is that they last just over 6 years

jennifer911

Thanks Bijan, We also checked the Porsche’s stable mate a Lexus. It just took a drop in each cell for the water level to form a sort of cat eye shape. The oldest member of the beer drinkers said that back in the day that was a pretty universal style of top up indicator. The Porsche battery took a fair amount per cell and now looks to be the right height above the plates from what I can glean from the internets. I’m glad we caught this in time!

The Porsche got a new battery about a year and a half ago, about the same time I moved in with its owner. I put my battery tender (from my former car) on it if it’s not driven for a day or more. I’m hoping that more and better maintenance will make this battery last and not leave us stranded somewhere yucky.

ADias

If the plates were covered... why add water? In any case, make sure the drainage tube is attached correctly and draining outside the chassis, and the opposite side of the battery has a vent cap.

Also... make sure that the maintainer you are using works correctly and does not boil the electrolyte. A malfunctioning maintainer and too much electrolyte would make a perfect stormy mess.

jennifer911

Thanks, Adias, the German Mall battery is by no means maintenance free. The electrolyte level was just barely above the plates, well below the factory indicated level, so it did need some water. (Last fall we spent an extended time down in the desert, almost 110 degrees one day in Death Valley!)

Why are the electrical systems on Japanese cars so perfectly reliable and the OEM batteries appear to last forever? However, it seems that everybody I know with a German car has mystery electrical gremlins and very spotty battery life.

ADias

I've owned several Moll OEM batteries. I never added any water and I visit DV too and they last 6-8years, but I preventively change them at 6 years. As long as the plates are covered that's all that's needed - more than that, watch out.

the_buch

What's the difference between deionized and distilled water for this purpose? Thanks,

semicycler

Both are purification methods. The distillation process boils the water converting it to steam leaving the contaminates behind, then cools it back to very clean water. Double distilled water is used in labs. Deionizing water is a chemical process that removes charged impurities but can leave uncharged impurities behind like bacteria or viruses. Since most of the contaminates in water are charged, deionized water can be made very pure this way much cheaper than distilling can. But it only really matters for large scale purification processes. You can find cheap distilled water by the gallon at your supermarket or drug store for less than $1.

TLDR: used distilled water