Rick's Free Auto Repair Advice

What you should know about your AGM car battery

Important facts about your AGM car battery

Many new cars are equipped with an AGM car battery. See this post to learn how they’re different. They provide many advantages over traditional flooded lead acid starting/lighting/ignition (SLI) car batteries. But they’re also more expensive and if you don’t treat them right, they’ll fail early and cost you a bundle to replace. Here’s what you need to know about your AGM battery

You can’t use your old battery charger

AGM batteries require a completely different charging routine and it’s low and slow. Most older batteries chargers are designed to provide fast charging. If you use an old battery charger on an AGM battery, you’ll overheat it and kill it.

You can’t test an AGM battery with an old battery tester

Since AGM batteries have lower internal resistance, they’ll provide false readings. If your tester doesn’t have an AGM Mode button, don’t use it to test an AGM battery.

Never replace an AGM battery with a flooded lead acid battery

First, late model vehicles regulate charging with the PCM/ECM and the software is written specifically for an AGM battery. It won’t properly charge an SLI battery.

Second, the PCM/ECMs in late model cars track the battery’s condition. The computer adapts the charging routine as the battery ages. When you replace a failed AGM battery, you MUST reprogram the PCM/ECM to tell it you’ve installed a new battery. If you don’t, it will think you’ve still go the old battery and it won’t charge the new one properly

Also, if you have a start/stop system and install a standard SLI in it’s place, you can expect this. Yeah, KABOOM!

exploded car battery

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat


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