Updated · Batteries
How a flooded battery works
A flooded battery, also called wet-cell or standard lead-acid, has lead plates sitting in liquid acid. It's the design cars have used for decades. Most sold today are sealed so you never add water, though some still have removable caps.
Flooded batteries do the job well in cars without start-stop and with a modest electrical load. They don't tolerate deep drains or heavy vibration as well as AGM does.
What makes AGM different
AGM stands for absorbent glass mat. The acid is soaked into fiberglass mats packed between the plates instead of sloshing around loose. That makes the battery spill-proof, tougher against vibration, and better at recharging quickly and handling repeated deep use.
Because it's sealed and doesn't vent gas in normal use, an AGM battery can sit in the trunk or under a seat, which is where many carmakers put it.
Cars that need AGM
If your engine shuts off by itself at red lights, the car has start-stop and most likely came with an AGM or an EFB, an enhanced flooded battery built for that duty. Many cars with heavy electronics, battery monitoring, or a battery in the cabin or trunk also use AGM.
Putting a standard flooded battery into a car designed for AGM is a common mistake. It may start the car at first, but it tends to fail early, and start-stop may quit working.
- Check the label on the battery you have now
- Look in the owner's manual under battery or specifications
- Ask for the original type when you replace it
Upgrading and downgrading
Moving up is usually fine. An AGM can replace a flooded battery or an EFB in most cars, as long as the size and terminals match. Moving down, from AGM to flooded, is the one to avoid.
Some cars also need to be told the battery type changed. That's part of battery registration, which many European models and some others require.
Where Texas heat fits in
AGM batteries generally hold up better to heat than flooded ones. A North Texas summer still shortens the life of both, so shade, clean terminals and a yearly test after the second summer matter whichever type you have.
When you call us for a battery replacement, give us the year, make and model. The technician brings the type your car calls for and installs it where the car is parked.