Test for borderline battery

[Hydros]

OK, here's some info,

The high amp batteries will show good with a voltmeter and may even show good with a load test. The best way I have found is one or both of these two:

As you charge your batteries, look at each cell to see if all cells show the same amount of bubbles. Do this several times, like once an hour at a med charge. If a cell is not bubbling like the others, then that's the bad cell. (of course, wear eye protection, batteries can and do pop or explode.

Another way and to double check, is to do all your charging, wait a few hours and use a hydrometer to check each cell, if you find one way off from the others, that's the bad cell. You must wait a few hours for the bubbles to die out.



   Hydrometer

A volt meter is a good tool, and it will tell you if a battery is:
charged,
undercharged or
really bad.

What you want is a tool that will help you find out if a battery is:
good,
borderline and
bad.

Never buy/use one of those small cheap hydrometers. I guess a good one cost around $5-$10.00 these days.

If this sounds new it's not. This is a good, solid test. Just don't add water just before you check the cells. If your cells are low, add water, charge, wait, then test.

To be honest, I forget the name for the measurements, I know the number your looking for is 50 in the difference of each cell. Anything over 25 is borderline and 25 or under is most likely OK.

[Hydros]

You'll need the kind of battery that can have the vent caps removed. Plus you should always remove them when charging anyways.

Take the hydrometer and press on the rubber ball, then stick the hose way into each cell, slowing draw up the acid, keeping the tool vertical. Check the scale readings, now slowly press on the rubber ball flushing the fluid back into the cell. If you pressure too hard too fast, the acid may shot out of the tool and splash on your clothes and face.

If you see particles floating around or it the fluid is clouded, it means the battery is on it's way out, or that cell is bad if the others look fine.

This is pretty much it, cheap, fast and simple and after 30 years of dealing with lead acid batteries (which IMO are still the best, for hoppers) this is the best way to test to see if your batteies are good.

NOTE: I did not state fully charged.  

[Hydros]

Now on to using a volt meter to test for charged, undercharged or really bad battery.