I found Upgrading Honda Accord Group 51 battery to a larger one but it answered one of my questions.

2012 Honda Civic LX, 1.8l

Battery stock size is 51R, but they only get about 4-500 CCA. We live in frigid Idaho so we get below freezing temps every winter.

I need to replace both alternator and battery. A online Costco search only recommends 24f, not even a 51R. Which they can be wrong. But it got me thinking because it can be 700 CCA. She has a subwoofer that came with the car, she's not sure if she'll keep it.

  1. Will a 24f fit into the engineered 51R space?

  2. Will I need larger battery cables?

  3. Should I get a better alternator to match the bigger battery with higher CCA?

  4. How will the more powerful battery (and/or more powerful alternator) affect the fuses?

  5. Or should I just tell her to sell the subwoofer and go with the original specified 51R battery and alternator?


  1. I thought it had normal basic stock battery; nay it's an AGM. They previous owner must upgraded it to a Duralast Platinum 51R AGM, 435 CCA, 540 CA, 75 RC, 41 Ah., probably to take care of the subwoofer electric needs.

  2. I've seen some posts of other civic owners who installed bigger batteries and they say it's tight but they fit. Group 24 may fit, but 35 is supposed to fit better. So I don't know. The 51R size does leave a lot of space around it.

UPDATE: 2 photos

BTW, her car is not a start-stop type.

Is this a capacitor?

enter image description here

enter image description here

1 Answer 1


The battery should be the 51R for your Civic. You cannot put a 24F in its place, because the 24F is bigger in every dimension.

    24F     51R
L   10.75"  9.375"
H   6.75"   5"
W   9"      8.75"

Your main problem with getting any battery with a higher CCA or reserve capacity, it's going to have the same problem. You can't just stuff more power into the same size. More juice = bigger size ... period.

While I'm not an audiophile, I can tell you if your daughter is having a problem with there being too much bass and not enough power to go around, you could always get a capacitor to cover what the needed power when needed. This is how most people solve the issue with overblown stereo systems. I do not know what size, type, color, or whatever you'd need, but it should solve the stereo issue.

If your actual issue you're trying to solve is ensuring the vehicle will start in the morning, then do like most people do in the great northwest ... install a block heater in the car and plug it in at night. Myself, having lived in Montana for a large portion of my life can tell you, it's a lifesaver ... or rather a battery saver. Plus, you'll have a warm car not long after firing it up ... added bonus.

As far as the other stuff you stated, you wouldn't need larger cables. Alternator usually doesn't suffer, but getting a higher amperage output never hurts. More powerful battery will not affect fuses.

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