Battery Capacity

[Bill Balme]

Last year on a thread here, I posted that I'd run a 1500W load on my 1100AH battery bank and that the inverter turned off after just 10 minutes when voltage dropped below 10.5V.

A year later... Same batteries, same load but having been attached to the dock for a season, owner having gotten a bit smarter(!) and having equalized the batteries just a couple of weeks ago, I got a better result... After 1 hour of the load (130A), the voltage started to fall and at 60 minutes I turned off the load when the voltage was 10.9V. Therefore better performance than last year. After recovering for 10 - 15 minutes, the voltage was back to 12.2V (Temperature was 65F)

I believe that 12.2V would indicate about 60% charge level, indicating total capacity at about only 350AH...

Question: Are these batteries shot? Is it a fair evaluation of AH capacity if one pulls at relatively high amperage compared to normal usage? Does the high load effectively lower the apparent AH capacity?

Appreciate your thoughts...