Is it okay to install a physically smaller battery?

2015 HYUNDAI ELANTRA
60,000 MILES
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12CARPENOCTEM
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I just changed the battery on my mother's vehicle listed above. I picked up the new battery before looking at the size of the old one.

Although the website said the new battery was "guaranteed to fit", the new battery size is physically smaller than the old one. The new one has a group size of 47, the old one was a 91. But the new battery is rated at 630 CCA, which is greater than the old one (615 CCA).

I installed the new battery, and everything is clamped down securely and the car starts without issue. But this is the first time I've put a physically smaller replacement battery in. Will there be any problems from doing this?
Jul 2, 2024 at 6:56 PM
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CARADIODOC
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As long as the height is not much more than the old battery, there is no problem. If it's too high and is under the hood, it could short to the hood. Same when it's under a rear seat. As long as nothing metal is close to touching the terminals, you're all set to buzz off into the sunset. When clamped in place, the battery must be held firmly so it can't bounce or vibrate. That will knock the lead off the plates much faster than normal, especially when it gets to be a few years old. That normal flaking off of the lead can't be prevented, but any abnormal vibration, including from using a portable charger on a high setting, will shake that lead off faster, leading to early failure.
Jul 2, 2024 at 7:48 PM
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12CARPENOCTEM
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Thank you! Indeed, the hood closes with no problems. When I search for batteries for this year/make/model, I get a range of sizes, including the Group 47. I am guessing that there are a range of possible sizes that fit in this vehicle (some longer, some shorter), but still compatible since the voltage and CCA values are in range? The height and width seems to be the same, but the length is shorter.
Jul 2, 2024 at 8:13 PM
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CARADIODOC
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The cold cranking amps, (CCA), is on the lower end of what commonly comes as original equipment, but it is way more than enough. You can go to a new battery with a higher CCA rating, but it really doesn't gain you anything. A typical starter for a four-cylinder engine will draw roughly 100 amps. The rule of thumb used to be you wanted the battery to have a CCA rating of three times that. You have six times that, so you have plenty of extra capacity.

I apologize, but I should have included links to these articles for you to check out:

https://www.2carpros.com/articles/how-a-car-battery-works

https://www.2carpros.com/articles/how-to-replace-a-car-battery

If you're interested, you can find a lot more stuff here:

https://www.2carpros.com/articles
Jul 2, 2024 at 8:29 PM