Is it helpful to put slow charge on equipment like chipper that may sit more than used?Define "battery"? What kind?
If you're talking about a smaller lawn tractor type (UR1) class, around 30 amp hours capacity, you'd only need a 4 amp charger to bring it from dead to full in eight hours.
If it's a car or truck battery, the math still applies. A 100 amp hour battery needs 12 amps for 8 hours for a full charge.
The real question is why is the battery dead?
A conventional lead acid battery self discharges at a little less than 1% of it's remaining charge per day. Even after 6 months, it won't have enough juice to crank and crank and crank, but it will crank fast enough for 20 or 30 seconds to get something started.
A conventional lead acid battery is pretty much junk after being flattened 5 or 6 times. They are meant to provide high output for starting, not to provide power over time. Deep cycle batteries are designed for that application, that's why they're used in solar power applications.
If you're discharging a battery ( hopefully a deep cycle ), on a daily basis, ( hence the need to re-charge in 8 hours ), $45.00 for the one from Amazon isn't bad for a charger that has a brain, and will charge the battery both quickly and as gently as possible.