i dont have a brand that is any better than any other they all are about the same. the agms as opposed the lead acid are significantly better. i get mine through baxter auto supply and have good luck. i have one yfz with a lithium battery and so far its been good going on 4 years old and still working. the lithium starts the machine every time but it hesitates when it is hot, it works it just seems funny but it has been like that since it was new and it will crank a little longer than the agm. as far as the blanket i just searched amazon and there were a few but i dont think they would fit in most battery boxes with out modification. unless you live in Alaska or Minnesota or some other equally frozen wasteland i would just wire in a battery tender.
I've been told elsewhere to leave a trickle charger like a batt tender on all winter but I've also heard not to charge a batt when it's below freezing. Is it ok to leave a batt tender on when it's under 32?
you might not want to leave a constant type tender on if you were going to be well below freezing for a while but the smart chargers wont do anything to harm the battery. it is constantly getting feed back and adjusting the charge. i live in southern oregon and we have temp down to zero or a little below pretty regular basis during the winter and i have never had a problem.
Stabilizes internal battery chemistry for
increased performance and longevity
Keeps the battery fully charged without
overcharging allowing the charger to be
safely connected indefinitely
Minimizes energy consumption when full
power is not needed
Charge LEDs dynamically track the
batteries state-of-charge when a load
outpaces the charge current
Intuitive visual diagnostic tool for detecting
reverse polarity, low-voltage or damaged
Automatically enables the charging port to
charge CANBUS systems Thermal Monitor
Internal temperature sensors adjust charge
based on ambient climate
this is page seven of the manual for the genius chargers. i have highlighted the section on temp for you. i have one of the tenders on my boat as well and it stays on there 9 straight months through the winter with no issues.