I have a Dodge PU with a Cummins. It requires 2 batteries to heat the
preheat plate and to crank it. 30 deg weather and it cranked real slow.
Took it to Wallyworld where I purchased the batts 2 years ago and they
never even checked them. Replaced and said your 3 year warranty just
restarted! No charge. I was impressed!
Of course, sometimes it doesn't take much to impress me!
Gordon