T105s are a reliable 6V 225 Ah deep cycle battery
. We have 6.
Each pair is wired in series and each pair is connected in parallel giving a nominal 675 Ah at 12V. Ours are 7 years old and still fine. Keep them charged and topped always.
I check levels and specific gravity weekly. I also log draw and standing voltages several times a week. We also have nano pulses on ours. They seem to help with longevity.
You can either ignore your batteries and replace them yearly or look after them and get 5 - 10 years life.
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