I did a home inspection not long ago on a home that was completely off the electrical grid. It was one of the more fascinating homes I've done. In addition to the solar panels, wind turbine and assorted other advanced renewable energy technologies, it had a bank of industrial batteries.
Now these are not part of your everyday home inspection. 
Since I was a certified Home Performance Specialist for the state of Idaho, I have a fair amount of experience with alternative energy and energy efficient housing, so I got the job. That's one of the advantages of being the nerdiest of the inspectors in the area - I get alot of the fun projects.
Anyway, I had to inspect and test these batteries. My client was concerned (rightfully) that the batteries may have issues adn he didn't want to get left in the dark if they failed ocmmpletely.
I contacted the manufacturer, Trojan Batery and they were kind enough to work with us to get voltage tables and specifiactions to make sure we got accurate answers. The inspection process is pretty simple:
• Examine the outside appearance of the battery. The tops of the batteries andterminal connections should be clean, free of dirt and corrosion, and dry.
• I f fluids are on the top of a flooded/wet battery this may mean that the battery is being over-watered. If fluid is on the top of a battery this means that the battery is being overcharged and the performance and life will be reduced
• Check battery cables and connections. Replace any damaged cables. We did have several cables that were damaged.
Then it was time to test the batteries. This is actually an easier process than you might think but you need to have the right tools and the training to handle these batteries safely.
1) Get a voltmeter and a graduated hydrometer
2) Charge the battery set fully
3) Wait 1-2 hours after charge is completed (or knock the surface charge off by turning on a light bulb for 2-3 seconds - which is what we did)
4) Measure and record individual battery voltages (w/ voltmeter - I used my multimeter) and/or individual cell "specific gravities" (w/ hydrometer). Batteries connected in series do not need to be disconnected from each other to record battery voltages.
5) Run equipment until the battery performance drops (hopefully this only takes 0-15 minutes)
6) Turn off all equipment.
7) Measure and record individual battery voltages (w/ voltmeter) and/or individual cell "specific gravities" (w/ hydrometer) again
8) Reference the voltage/gravity chart
9) Identify any battery(s) that are significantly lower on the chart AND drastically different than other batteries in the set
It turns out that the batteries were pretty well done. since these are industrial batteries, the were quite expensive to replace but absolutely necessary for this house.
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