That is the way battery ratings work.)

I know. Such a small battery is not suitable for any forced air heating
system.

doug, a brand new, fully-charged Grp 27 battery will give up about 50 to 60
amps before it is dead. Even more when going to flat dead. That Espar ran
that brand new, fully-charged Grp 27 battery flat dead in about 6 hours. Flat
dead.

of course, it was not 68* outside. More like low 40's.