These batteries are great! I have 8 12-Cs units in a 2x4 array yto give 48-volts for my Trace SW 5548. They replaced 8 MK Gel batteries. The Surrettes are real team players and workhorses. The MK's when used individually seemed to perform quite well, but for reasons unexplained, they were not team players. The Surrettes maintain their characteristics and charge uniformly which the MK's did not. I have MK's that start my boats, generator and power my electronics and they work fine and endure the severe cold environment. The Surrettes require greater care and maintenance, but the reliability is well worth the effort. Doing a hydrometer on 48 cells is a bit time consuming, but a small price to pay for the support they give me. So far, I have only equalized them once - as a preventative measure. They charge-up in textbook fashion and deliver the power they are rated to give. Great product, great buy - a world class product with world class support at the factory for consultation and documentation.

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