Re: charging frozen batteries
If they have been on some solar charge, or if they were left fully charged, it is possible that they are fully charged already, hence going from bulk to float without absorb. If you have a battery temperature sensor, it may be telling the charger to ramp down the charge current.
A battery with anything but pure water in it won't freeze at 27f. 50% charge won't freeze until nearly -20, fully charged won't freeze until well below -50f.
Check each cell with a hydrometer or volt meter.
Ps, we routinely leave batteries over the winter @ -40 with out trouble.
Second, don't charge a frozen battery,,, but I don't think yours are frozen.
Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!