See if you can get one of these testers.
Tests the battery capasitance and your charging system.
It takes a lot of guesswork out of the pass fail procedure
Works great on my truck and car battery's also.
This one is probably obsolete as I purchased it 4 or 5 years a go.
Snip:
The BA7 from SOLAR provides quick, decisive battery testing for lead acid batteries rated from 100-1200 CCA, which covers everything from powersport to truck batteries. It features an operating range from 7-15 Volts and can test against several ratings systems, including CCA, CA, IEC and EN. It also tests a wide variety of battery types, including flooded, AGM, Spiral Wound and Gel Cell batteries. In addition to providing battery testing capability, the BA7 also enables testing of starting system performance and alternator output. It features reverse polarity protection and over-voltage protection for ease of use and operator safety.
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