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Discussion Starter · #1 ·
I gave my '21 Forester the once over this week and noticed the battery water level was about 1/4' below the Upper line of the positive side of the battery case. I was unable to see the water level thru the case on the negative side. The case was simply too opaque. The only way I was able to see the water level on the positive side was to hold flash light against the side of the battery and look for the water shadow on the front side. That did not work on the other side. Even after opening the caps on the top, figuring out if the water level was okay by looking down into the battery was inconclusive. The water was above the plates, but hard to figure out if it was "low" enough that it needed more. So I added a tiny amount on the positive side and called it a day. Plus I spent more time cleaning the caps and threads than anything else. Dirt really settles into those threaded holes and had to be carefully cleaned so none fell into the water as I took those caps off and on. The pic below is after cleaning.

Okay, now that I have all that belly aching out of my system, are there any tips for accurately checking the water level that I'm overlooking? Or is what I went thru simply the nature of the beast with Subaru's Q85 battery? Thanks.

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I think the answer is not to overthink it. As long as the plates are fully covered, you are OK. The closer to even you can get the level, the better, as this ensures a uniform pH (you are diluting the acid with water) cell to cell. Overfilling promotes liquid droplets on the outside of the battery if you flood the venting system.
 

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2007 Forester Sports XT 4EAT
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@Oldguy2 it's been awhile since I added distilled water to a battery, we're running AGM batteries in all our vehicles now!

As I recall, you add distilled water until it touches bottom of each fill tube. It will take VERY little distilled water!

Bobby...

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Discussion Starter · #4 ·
Thanks, using the bottom of the fill tubes is what I ended up actually doing. The upper/lower guides on the outside of the battery were useless as I was not able to see the fluid level thru the thick plastic casing. Although I must say the fill tubes are very narrow, like a roughly a 1/4 inch wide, making it tough to look down into the battery to inspect the water level. Most other FLA car batteries I've owned had capped water holes probably twice as wide as this one.

This is the 1st Subaru I've owned. I posted my frustration to see if there was some other trick experienced Forester owners used to verify the water level on this battery's unique design.
 

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My understanding has always been that you should look down into each cell with the caps removed. There are molded-in plastic flanges inside each cell, which if the water level is high enough, form a meniscus of water (a curved top surface of the liquid, like in a test tube) that greatly changes the appearance of the reflection you see shining a flashlight down into the open cell. Low cells have a flat top surface of the water.
 

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@boureesub yes, "in name only"!

I've read if the top of the plates are exposed to air... get dry, the battery will be damaged, as in, it will never fully recover, even if distilled water is added. The battery will continue to work, but the CCA will be reduced.

Bobby...

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Discussion Starter · #8 ·
Call my crazy, but I do love a challenge. Here is the simple solution I came up with to make it easier to verify the water level inside this particular battery design. I made a jig out of wood (clean Popsicle sticks in this case) that matches the distance from the top of the battery case to upper water level marker. Pics tell the story. The unexpected benefit was how much easier it was to judge the height of the water level inside the battery as the lighter colored wood reflected off the top of the water much better than the black plastic battery frame when you shine a flashlight in the hole. I realize wood is not a good material to use long term around battery acid, but I'm a happy camper for the time being.

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@Oldguy2 when you look into the filler hole, there a ledge. I believe it will appear "round" when the water is at the correct level.

Watch that battery acid... electrolyte! Any splashed on your clothes will become holes after they go thru the wash! I lost a favorite flannel shirt that way! :(

Bobby...

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