TheSamba.com :: View topic - What battery can I put in? 55Ah? 60Ah? 75Ah or more?

Mon Sep 03, 2018 3:01 pm

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(?).

Mon Sep 03, 2018 3:58 pm

Boble wrote: 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(?).

The battery storage capacity is not dependant on the charging system out put. You may put as high capacity battery as you need in the Bug, so long as the battery fits. It is very important that the battery is securely clamped to the chassis, in a roll over a loose battery can be deadly. and it is also extremely important that the rear seat springs can not ever make contact with the positive battery post and wire ends. Bugs have caught fire cause of seat spring contact. In high school it happened to a friends bug, big guy got in back seat, and that pushed the seat spring into the positive terminal, shorted, got hot, started the seat stuffing on fire. ruined the seat, nearly he lost the car, flames! Flaming seat was tossed out of the car in nick or time.

A higher capacity battery allows you to run a stereo or other accessory for longer with the engine off, gives you more margin to start the car as batterys do self discharge over time, so if the battery has more capacity, it can sit longer and still start the car, BUT allowing the battery to discharge too much is really hard on battery life. If car sits long, say a month between drives, or stored over winter, then put a trickle charger on it, or recharge every month to assure longest battery life.

So higher capacity is not really needed, unless you plan on extra electrical loads that you want to run with engine off. but the battery must be able to be secured and clear the seat, with a cover to protect it from seat springs.

If you want a huge thumper stereo, that takes lots of amps, eventually if the stereo draws too much, (say 60 amps, and you only have a 55 amp alternator) you will need to up the alternator to a high amp unit, for even if the engine is running, a huge thumper stereo system might exceed the capacity of the alternator, amd that will draw down the battery regardless of battery capacity, even with engine running! But that would be some huge stereo. Youd go deaf I would think!

Bug On, Charge On!

Mon Sep 03, 2018 8:58 pm

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.

Mon Sep 03, 2018 10:35 pm

Thanks for very good and comprehensive answers! Useful info.

Tue Sep 04, 2018 5:24 am

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.

Tue Sep 04, 2018 5:51 am

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).

Tue Sep 04, 2018 7:56 am

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

Bug On, Van On!

Tue Sep 04, 2018 12:00 pm

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.

Wed Sep 05, 2018 1:43 pm

clarkd wrote: 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.

Just bought a Bosch S5 A05 AGM 60 Ah battery for my beetle today.

It's the original size (242 x 175 mm footprint). Hopefully it's good stuff, at least the price indicates that...

Don't know if you will be able to get Bosch batteries in USA?