[DonRotolo]

Not sure what powerhouse teams do, but I second Indy Sam's recommendation above.

The CBAIII won't tell you a battery's state of charge, but it will tell you whether it is healthy or not. What it does is discharge the battery at a relatively low current (a few Amperes for a 12 volt battery - it is limited to 100 Watts continuous discharge) and tracks the battery voltage over time, until it reaches a 'safe' voltage (maybe 9 volts?), all automatically. You then compare the discharge curve to your other batteries, and the health of a given battery will become apparent.

It also gives you the battery capacity in Amp-hours, but use this carefully, because capacity is very dependent upon discharge current.