What battery can I put in? 55Ah? 60Ah? 75Ah or more?

[Boble]

I'm about to buy a new battery, what are the pros and cons of buying a battery with more Ah than the regulator? Is bigger always better?


My car is a 76 super beetle equipped with the latest version alternator w/integrated regulator. If I remember correctly it gives 55Ah(?).

[bluebus86]

[ashman40]

The '76 Beetle Owners Manual shows the recommended battery rating:

While "45Ah" is one way to measure (electrically) the capacity of the battery... most modern automotive batteries are rated in Cold Cranking Amps (CCA) or sometimes Cranking Amps (CA). This is more practical as the battery is primarily for starting the engine and CCA is a rating of how much current is available as a surge of power to crank the engine. Once the engine is running and the charging system is providing current it works to provide power to the car's electronics and power to recharge the battery for the next start. As long as your battery's CCA rating is the same or higher than the recommended CCA for your car you will be fine.

From what I can find, the recommended minimum CCA for the 1600cc Beetle engine is 365CCA. That is actually a very low value for modern maintenance-free batteries . The smallest CCA rated batteries I can find are around 450CCA. Most batteries are in the 750-1000CCA range.


The real challenge will be to find a "Group 42" size battery. This is the correct sized battery that will fit safely under the rear seat. From what I have seen Group 42 is NOT common and no longer available at most FLAPS. Often, it must be special ordered.

Another option is to look at using a battery with side mount terminals. This would allow you to use a slightly taller battery and avoid shorting the terminals on the bottom of the seat. You will need to change the battery cables to ones w/ side mount terminals at the end. This route does open up battery groups that have a much higher CCA rating. This is desirable if you plan to draw power from the battery while the engine is OFF.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Boble]

Thanks for very good and comprehensive answers! Useful info.

[Ricksurfin]

I just bought a new battery. I wanted to stay with the original size as I didn’t want to deal with issues of mounting and figment, so I went to Autozone as they still stock the 42-DL battery.

[ashman40]

There is nothing wrong with buying a new Group 42 battery. It is a drop in fit and modern maintenance-free batteries typically last 3-5yrs.

But if you plan on keeping your Beetle for longer than that, the new breed of Absorbent Glass Mat (AGM) batteries are better is so many ways. My last one lasted nearly 10yrs and this is not a fluke as others have reported the same. They provide more CCA in a smaller package. They can also be mounted sideways or even upside down. My new truck came from the factory with an AGM battery.

My point is if you are considering a new battery, don't dismiss the newer batteries just because they don't come in Group 42 format. A longer lasting battery also means one less dead lead-acid battery to recycle (better for the environment).
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[bluebus86]

my plain old maintenance free battery in my VW van lasted 15 years, it was amazing.

Bug On, Van On!
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Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[clarkd]

I also need a battery for my 72 super beetle. Does anyone have an AGM battery installed they would recommend? I have an odyssey battery (pc925) installed in another older vehicle and I'm happy with it. I bought it because it would fit in a small battery box and had SAE posts. Since I'm not limited by size in the VW, I'd like to find an AGM that works, but is a lower priced than the Odyssey.

[Boble]