As electrolyte temperature drops maintenance voltage must increase to keep battery potential in stasis. An amperage inappropriately high at 80F may be perfect at 50F and inappropriately low at 30F
Several years ago I kept online records HERE on this forum of a generic 12 volt UNregulated 700 ma transformer. At 700 ma at 70F it maintained 13.45 volts. Th battery was a so-called deep-cycle Wal-Mart group 29
At 708 ma it maxed out. Temp was 50F and voltage had fallen to 13.18
In July voltage was 13.6(forgot the second digit.
Cell Activity was verified with a hydrometer.
During a narrow ambient temperature spectrum applied voltage was correct.
For 24/7 maintenance floating temperature is critical.
But battery tender products do an admiral job with temperature compensation. Within their amp hour capacity span.
Constant current maintenance is never appropriate. A 1,5% amperage to amp hour capability is acceptable.
