I'd have to check the specs on the units we use, but we use them in our fleet of over 50 trucks. The ones we use plug into an accessory port. (cig lighter)
Our fleet consists of all 12 Volt systems with an annual average mileage of about 7,000 miles, many with less than 1,000.
We've noticed stronger starting and we've bought fewer batteries since using them.
They are currently installed on anything from 2.5 Ton trucks to a 1999 John Deere tractor. We had a 24 Volt Blazer, but turned it in before we got the chargers, so I can't say how that would have worked.
I'd say it would be worth a shot. Let it sit for a week, check voltage. Plug it in for a week, check voltage.