Every week, we answer your questions about what’s going on with your vehicle. Today we’re discussing a reader’s concerns about battery costs.
Dear, ask a mechanic,
My 2013 Hyundai Elantra’s battery failed recently and I had to boost it to start it. The garage where I took it to replace it told me that this car requires a more expensive special battery. There is nothing particularly unique about this car, why would the battery be any different? – Baffled battery
To better understand why similar-sized automotive batteries can have significant cost differences, it helps to know the differences between them. Traditional 12-volt car batteries haven’t changed appreciably from the type probably used by your parents’ first car. Most modern car batteries are now of a maintenance-free design (meaning the individual cells are sealed and cannot be recharged). Otherwise, it is still a âfloodedâ lead-acid battery, as the lead plates inside are submerged in a liquid mixture of sulfuric acid and distilled water.
The increase in the amount of electrical equipment in newer cars and the changes in the way the charging system works (performance is now often highly variable in the name of fuel efficiency) both place greater demands on the battery. . Add to that the need to tolerate the frequent and relatively deep discharge / charge cycles that are characteristic of vehicles with automatic stop-start systems, and an old-fashioned flooded cell battery simply cannot keep up.
As a result, automakers have switched to âAGMâ (Absorbent Glass Mat) style batteries in many newer applications. AGM batteries generally look the same as the Flooded style, and they still use lead plates and sulfuric acid to create the electrochemical reaction. However, they incorporate glass mats inside that work both as a sponge to contain the acid and act as a physical separator for the more tightly packed plates. This denser construction gives AGM batteries greater storage capacity, better tolerance to deep discharge, and better resistance to mechanical failure, but this comes at the expense (so to speak …) of higher manufacturing costs.
How does this relate to your Elantra? Automakers are always looking for opportunities to save money during production, so Hyundai wouldn’t have used this more expensive type for no good reason. The company obviously determined that the electrical needs of this model necessitated the use of this more powerful battery (although it didn’t have a stop-start), so it’s okay to use the same type as a replacement. Installing a conventional battery in which an AGM style is specified could result in significantly reduced life for the new battery, or even an inability to recharge quickly enough to continue to provide reliable starts.
Ask a Mechanic is written by Brian Early, a long-time Wheels contributor and Certified Red Seal automotive technician with over 25 years of experience. You can send your questions to [email protected] These answers are for informational purposes only. Please consult a certified mechanic before performing any work on your vehicle.