When my tractor changed from a 40HP gas to a 55HP diesel, I built a 25 foot long set of jumper cables, #2AWG welding cable with solid copper clamps.
If I do not even have a battery in the tractor, those jumper cables easily start my tractor by jumping off the pickup.
They make the tractor act like the battery was moved from the pickup to the tractor.
Solid copper clamps are hard to find now,, I built my jumper cables in 1995.
I have two chargers I like
1) a Schumacher 150amp Battery Charger.
I do not keep a battery in my TroyBilt 8HP tiller, that 150 amp charger will easily start the tiller using the electric starter.
It is great not having a battery in the tiller, they only seem to last 2 seasons, and that equals about 20-30 starts.
2) about four months ago I bought this
[ame]https://www.amazon.com/gp/product/B08G446ZQ9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1[/ame]
It is an 8 amp charger/conditioner etc,,, I use it for the ATV, and batteries that have sat a while.
So far, I really like it, and it seems to be doing a good job.