pianotuna wrote:
phemens,
The reading I've done (which may be incorrect) suggest low slow charging may be possible at -20 c (-4 f)
Tonight it will be -33c here.
Yes, I've heard that as well. My use case is really on the borderline of the threshold for regular charging (getting down to below 0c occasionally, with risk of battery core temp falling into that 'danger zone'), and that's for a couple of weeks at the end of the season (maybe longer is we start extending). Since we're not there to make adjustments during the week, the safest option for me is the waste tank heater running all the time. At 6a/hr, I only really get a drawdown after the sun doesn't send enough juice to the solar panels, so maybe 14 hrs which is 84 ah to recover, which is more than acceptable given my battery reserves. While we're away apart from the heater, there's the residential fridge and usual parasitic draws, so the system keeps up without breaking a sweat.
