My dad recently bought an Everstart deep cycle battery from Walmart. After taking the caps off to check the acid levels, we noticed that the fluid just barely covers the top of the cells. Is that normal ?  I would think that the fluid level would be closer to the top.

Thanks
CVH

Good question most have no idea about.

I usually fill all my flooded batteries, whether golf cart, solar, man-lift, L16's, forklift, automotive, so that WHEN FULLY CHARGED, the level comes near the bottom of the fill cap entrance split ring.

Note ---after fully charged. Electrolyte EXPANDS significantly as sulfur ions are removed from the plates and into the 'liquid' during charging.

So, you need to check the battery state of charge with a hydrometer or optical refractometer [preferred], and record data, then charge the battery.

When charged the reading should be a specific gravity of about 1.260 [at least] to ~1.285, ---depending on many variables.

Also consult the manufacture's recommendations.

Don't waste time measuring SG after adding water, until after the battery has been actively charged and discharged and the electrolyte has had at least DAYS to fully mix, otherwise you will have an entirely meaningless reading.

Even after a week or two, if the battery hasn't been exercised heavily, the reading is still unlikely to be accurate.

So called 'electrolyte stratification' is a real concern of mine when doing careful analysis of our batteries. I'm still trying to find a way to solve it, and doubt I can since the issue has been well understood since the late 1800's.

One possibility is to insert a length of small diameter Teflon tubing and work it between the plates or around them to the bottom of the cell jar and extract electrolyte to measure from a location other than the surface.

Another is to penetrate the polyethylene jar at the bottom and seal a Teflon tube in the opening. A lot of 'engineering' issues involved.

An old book I found on battery chemistry and the info was confirmed in old catalogs, was a certain metal 'probe' that was dipped into the top of the battery into the electrolyte and the potential difference from it to one of the plates measured, to give an indication of battery condition. I purchased some of the metal several years ago but have yet to test it.

Now I may.

One thing that I should probably add is that the battery is labeled as " maintenance free "

But the battery has the normal pry-off caps.  I thought that maintenance free meant that you don't need to add water to them.

Are the caps vented?