What kind of battery charger should i get for my Hummer h3
That all depends on how many amps you want it to put out, a float charger is one that is designed to just maintain a good battery if it is going to sit for an extended period of time, a automatic charger is a charger that can start out at its rated amperage then as the battery charges it slowly cut s the rate back to a trickle rate of about 1 amp but you can't leave these on for an extended period as it can run a battery dry of electrolyte, a boost charger has a high setting the can boost a battery for a short duration to aide in a fast start of a discharged battery, but todays charging systems cannot recharge a discharged battery without damaging the alternator, so use wisely. I hope this will give some idea on what type you need.
Electronic chargers are complete crap. If they work at all they will quit after a short while. Get a quality analog charger and it will last you for decades.