Winter 12v strategy

Cold temperatures are NOT detrimental to a battery's longevity; quite the opposite in fact.
They will temporarily lose a bit of capacity WHILE cold but will recover once it warms up.

Using a battery tender is not a bad idea for long periods on non use but a little cold weather is not a good reason.
Since a hybrid doesn't use a conventional 12 V starter, that little loss of capacity isn't missed.

Won't hurt anything but won't accomplish anything either.

 

Yeah, I have to agree with Sam. If things are functioning properly, there should not be enough parasitic draw on the battery to cause issues when sitting in the middle of winter. That little battery just needs enough juice to start the system, and the HV battery takes care of the rest.

My car sat for a few weeks before I purchased it in November, the last two of which were some of the coldest we've seen here in Minnesota. It had the original battery from 2006 when I replaced it preemptively a couple of months ago. But if the battery tender buys you peace of mind, it's a worthwhile investment.

 

i have seen many weak 12 volt batteries bite the dust on a cold night. maintaining the charge can prevent that if you aren't interested in buying a new one

 

Yes and.......if the night was VERY cold, those batteries might have some useful life left in them.
But more than likely they are mostly SHOT and that is your clue that they need to be replaced.

That is especially true for a hybrid where the 12 V system doesn't need much amperage to boot up.

Improper use of a tender/maintainer can ensure that when it's time does come, your battery will finally fail out on the road somewhere away from the comfort of your own garage.

 

I'll stick with regular hook up to a smart charger, periodic assessment with an electronic load tester, and replacement say every 5 years, regardless of condition.