:thumbup: This is how we test battery plants for the Commonwealth radio system...but on a larger scale. These are large battery plants that generally cost in excess of $25,000. Depending on the battery stirng size, we place a known load on them (usually 500 amps at 52 volts), and measure the cell voltage every hour. They should drop to no less than 1.80 volts per cell with a 500 amp load after 4 hours.If you want to check the battery this is what I do annually for my bikes:
I pulled (remove from bike) the 4 year old Yuasa and made sure it was topped off with the trickle charger.
Then I hooked an 1157 bulb to the battery terminals (Draws abour 2.3Amps) and started the timer. I recorded the voltage every 15 minutes. My intent would have been to go no lower than 10Volts since that is pretty much "technically dead" for these kind of batteries.
Whatever bulb you use, you can use your multimeter to measure the amps drawn. Just put the leads in series between the bulb and battery. Make sure the meter is set for amps, and that the leads are in the right holes. There is usually a dedicated connection for the red lead when checking up to 10 Amps.
At 1 hr 15 min, the battery voltage had dropped to 9.8 volts. Since the Yuasa is an 18 Amp Hour battery, I would have expected it to last 6-8 hours if in new condition. Yes, I was surprised it only lasted 1.25 hours.
When I did that test last winter to the same battery, it lasted 4.5 hours, so it died fast in that last year of life.
So...I installed my spare.