I have been doing some research on various AGM 12VDC batteries for mobile use. Much of this online research was centered on where the battery was made, warranty, weight, recharge cycles, reviews if they were available. cost and working time. I was focusing on 100ah 31 series for the most part. My main performance goal is to provide 80amp power for a ALS-500M amplifier: Optima Yellow Top D31A - Mexico with 2 year warranty 300 charge cycles $343 NorthStar NSB-AGM-31 - USA, 400 charge cycles. 75lbs, with 4 year warrant $360 ODYSSEY PC 2150T 31 series - USA, 400 charge cycles, 77.8 lbs, 4 years warranty $390 NPP npd12-100ah - China, 1 year warranty, 65lbs $170 (also a few more China companies in the same ballpark) In most reviews the QA of the USA companies far exceeded the others. Optima has a heavy marketing campaign but may be second best in value. The actual lead content for the the Type 31 batteries for NorthStar and Odyssey really stands out at 99.99% and speaks to the quality. I tend to not go with the low end China built products and am hedging toward the NorthStar product. I was wondering what others have done with research and experience?