This old (25+ years) battery charger I have has a start boost setting, a 10 amp setting, and a 2 amp setting. The meter reads plus to minus to 30 amps. If you put it on start boost, it will peg the 30 amp meter, but will also reduce down to 10 amps down after about 45 seconds to a minute on boos (unless you are actually boosting the battery and have a big draw). Its brought back about 1/2 of the questionable batteries I've connected to it by using the boost before it switches to the 10 amp charging.
I'm going to miss it when it finally dies.