My batteries are currently full and in storage mode, but one is the multi plus putting almost 14.9v into my batteries when absorption is set to 14.4v
Temperature compensation. You're at 7C, the charged voltage is for 25C. The compensation figure, being negative, is the reduction in charge voltage as temperature increases.
Doing the maths, the increase is 18* the compensation value, which comes out close to 3C.
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