Ask a Mechanic......Expensive Battery Elantra
Today we’re discussing a Reader’s concerns about battery costs.
Every week, we answer your questions about what is going on with your vehicle. Today we’re discussing a Reader’s concerns about battery costs.
Dear Ask a Mechanic,
The battery in my 2013 Hyundai Elantra recently failed, and I had to boost it to get it started. The garage I took it to to replace it told me that this car requires a special battery that’s more expensive. There’s nothing particularly unique about this car, why would the battery be different? – Battery Baffled
To better understand why similarly-sized automotive batteries might have significant discrepancies in cost, it helps to know the differences between them. Traditional 12-volt car batteries haven’t changed appreciably from the type your parents’ first car likely used. Most modern car batteries are now a maintenance-free design (meaning that the individual cells are sealed and can’t be topped-up). Otherwise they’re still what’s known as a “flooded” lead-acid battery, because the lead plates inside are submerged in a liquid mixture of sulphuric acid and distilled water.
The increased amount of electrical equipment in newer cars, and changes in the way that the charging system operates (output is often now highly variable in the name of fuel efficiency) both put a greater demand on the battery. Add in the need to tolerate the frequent, relatively deep discharge/charge cycles that are characteristic of vehicles with auto stop-start systems, and an old-school flooded cell battery simply can’t keep up.
Consequently, automakers have switched to “AGM” (Absorbent Glass Mat) style batteries in many newer applications. AGM batteries typically look the same as the flooded style, and they still use lead plates and sulphuric acid to create the electrochemical reaction. However, they incorporate glass mats inside that function like both a sponge to contain the acid, and act as a physical separator for more tightly packed plates. This denser construction provides AGM batteries with greater storage capacity, improved tolerance to deep discharging, and a better resistance to mechanical breakdown, but it comes at the expense (as it were…) of higher manufacturing costs.
How does this all relate to your Elantra? Automakers are always looking for opportunities to save money during production, so Hyundai wouldn’t have used this costlier type without good reason. The company evidently determined that the electrical needs of that model required the use of this more powerful battery (despite it not having stop-start), so it’s correct to use the same type as a replacement. Installing a conventional battery where an AGM style is specified could lead to a greatly reduced service life for the new battery, or even an inability to recharge quickly enough to continue providing reliable starts.
Ask a Mechanic is written by Brian Early, a longtime Wheels contributor and a working Red Seal-certified automotive technician with over 25 years’ experience. You can send your questions to firstname.lastname@example.org. These answers are for informational purposes only. Please consult a certified mechanic before having any work done to your vehicle.