Car Battery

[Ranger_Vet68]

I might need to purchase a new car battery for my 2003 Z4 3.0i. Could someone please give me a recommendation and a GOOD strong battery that if my car sits for a while it will still keep its charge.

Thank you.

[David70]

Originally Posted by Ranger_Vet68

I might need to purchase a new car battery for my 2003 Z4 3.0i. Could someone please give me a recommendation and a GOOD strong battery that if my car sits for a while it will still keep its charge.

Thank you.

Buy a brand name battery, if they have two models pick the one that isn't the bottom and buy on specs (CCA). There are actually very few battery manufacturers but a huge number of brands. I have no issue getting the battery from O'Reilly, Autozone, or similar.

If your new car battery is discharging too quickly it is likely something using power or your car is sitting too long. Trying to find out what is using power can be difficult. I keep my car on a Battery Tender over the Winter and this is the best option. Another is a disconnect at the battery that shuts everything off (including radio presets). No idea if this is a good one but from a quick search - https://www.autozone.com/ignition/ki...E&gclsrc=aw.ds

[Ranger_Vet68]

Thank you for the info. I checked everything in my car that could be using juice and all I can think of would be the clock. But then again the clock doesn't turn on until you start the car. I thought about disconnecting the battery but then I would need to reset everything once I got back in the car. I'll see if I can chase it down. Oh and by the way. I was doing research for a battery and read it was better to go with an AGM.

[XMetal]

I would install the biggest AGM battery that you can fit in there. On an ///M, H6 is standard and you can fit an H7 in there and that's what I did. However, I'm not sure if an H7 would fit in a 3.0i. Look at what size you have in there currently and there should be a slot for the next size up for it.

If you don't daily drive your car, it's a good idea to hook up a battery tender every 2 weeks to top up the battery.

[3798j]

I went with Advance Auto's AGM. It has 850 CCA. It's identical in size, terminal location, and vent port location to the original battery...so installation was easy.

[pungo]

Unless it's a daily driver or at least a few times a week, a quality battery maintainer is a must for good battery health.

[rueyme]

if you don't mind spending for a really great battery, try antigravity. I have one in my car and super happy, has a backup reserve, kills the battery when it goes below a certain voltage, and weighs only 11 pounds! It also has a 5 year life rating on it

[CJW2OO4]

Last couple batteries I bought were Bosch ones from pep boys... they are hard to find now supposedly due to pep boys moving away from them due to cost

[KevinC]

There are only 3 battery manufacturers - doesn't matter what name is on it, it's from one of those 3.

As others suggest, I would go with AGM, and brand wouldn't matter, I would just seek out the best combo of price & warranty. I went with Duracell AGM, which carries a 4-yr full replacement warranty, from Batteries Plus. And yes, get a Battery Tender of some sort. I have an extra one that's available...

https://www.zpost.com/forums/showthread.php?t=1704227

[SD ///M4]

I bought an AGM battery from the local O'Reilly's because it had the same specs, size, vent, etc. and it was only a mile from my house. The Roadster doesn't get driven that often and mostly sits under a cover in the driveway connected to a CTEK battery charger.

The CTEK includes a pair of M8 eyelet connectors that work perfectly with the positive and negative battery posts in the engine compartment. The other end is a plug-in connector that allows for easy connect/disconnect from the main charger cable. You can also get an extension cable that gives you plenty of length.

[3798j]

Originally Posted by SD ///M4

The Roadster doesn't get driven that often and mostly sits under a cover in the driveway connected to a CTEK battery charger.

The CTEK includes a pair of M8 eyelet connectors that work perfectly with the positive and negative battery posts in the engine compartment. The other end is a plug-in connector that allows for easy connect/disconnect from the main charger cable. You can also get an extension cable that gives you plenty of length.

That's what I've done. As soon as I step from the car, I plug in the maintainer.