I have these on the lawn equipment battery, the import cat battery, just pulled a group 27 off the larger one. But truth is all.3 would be fine on the 27. And a 4th one on my whole house generator. It runs weekly to do a maintinace cycle. But i keep.the battery hooked up.24/7 battery seen to last way beyond what they should. Supossed to De-Something them too.