Battery Replacement

[bananabun]

I'm trying to replace the battery on the Z4MC, but having trouble figuring out what to get. Did a search on here and found a pretty resourceful spreadsheet, but seems like there's some discrepancy between what members suggest and the fitment guide from the various stores.

https://docs.google.com/spreadsheets...J7A/edit#gid=0

For example, the H6 AGM is recommended as a good fit, but the same store suggests only H5 for the car. Similarly, O'Reilly has changed part numbers and I'm confused on what's what now.

Is there a 'preferred' option for Z4MC owners that will fit without adjustments, and is worth the price? Thanks!

[RobMCoupe]

H6 AGM is perfect. In fact, this battery is compatible with many BMW models.

[XMetal]

H6 AGM is what comes with the car. If your car sits around a lot or want some extra insurance, a H7 will fit as well

[bananabun]

Thanks for chiming in, guys! Ordered the H6 AGM and will have it installed during Inspection 1 service this weekend.

[racerbruce]

Originally Posted by bananabun

Thanks for chiming in, guys! Ordered the H6 AGM and will have it installed during Inspection 1 service this weekend.

Did your battery fail, or are you replacing pro-active?

[bananabun]

Originally Posted by racerbruce

Did your battery fail, or are you replacing pro-active?

Just being proactive.

[StickMon]

Pretty much all of the major auto parts chain's computers and web pages pull up an H5 for the ///M, and they're all wrong.

[bananabun]

Originally Posted by StickMon

Pretty much all of the major auto parts chain's computers and web pages pull up an H5 for the ///M, and they're all wrong.

That is correct. Advance Auto and O'Reilley's both had a wrong size listed. H6 AGM is the best fit.

[racerbruce]

Originally Posted by StickMon

Pretty much all of the major auto parts chain's computers and web pages pull up an H5 for the ///M, and they're all wrong.

I replace on duration every four years....my commute is only five miles one-way daily and this accentuates premature battery failure. The risk(s) of battery failure and being stranded, requiring a multitude of costs, and the safety risk(s) is simply not worth it.

[chickdr]

Originally Posted by racerbruce

I replace on duration every four years....my commute is only five miles one-way daily and this accentuates premature battery failure. The risk(s) of battery failure and being stranded, requiring a multitude of costs, and the safety risk(s) is simply not worth it.

Mine pretty much sits in the garage and goes out a few times a year. 5yrs has been my threshold for the first two batteries(both died at almost exactly 5yrs.).

[Rick Hunter]

By utilizing a battery tender whenever my car sat for a few days, I was able to stretch my 1st battery to the 8 year mark. I could have stretched it out more, but proactively swapped it out.

Battery Tenders FTW.

[inTgr8r]

^whs!!!
Makes a HUGE difference in the life of a battery.

[chickdr]

I use a tender as well, but just hook it up and charge the battery once a month.

[inTgr8r]

Originally Posted by chickdr

I use a tender as well, but just hook it up and charge the battery once a month.

I leave mine on all the time. (Not a DD)

[Swashplate]

I used a Odyssey PC1200MJT and pried the metal case off. (per Odesseys call center instructions) Then I took a piece of Delrin and milled it to match the OEM battery bottom. Then bonded that Delrin plate to the battery. Presto! I have a small lightweight battery with the oem mount. No tender but I do drive once a month min.

[Pineland resistance]

Carquest agm h6 or h7's are great and relatively inexpensive. I've put them in bmw's for years as long as the computer is reset my original exide battery lasted 10 years of daily driving.

[saintex]

I was looking for a replacement and ended building my own.
10 Ah 480CA. It will start my S54 enough times in a row to overheat the starter.
5 pounds.
16-A123 26550 LiFePO4 cells in a 4s 4p configuration, full Battery Management System board.
Not particularly budget oriented but 40 pounds lighter than stock.

[chickdr]

Nice. I will be interested to see how long it lasts. What was the cost?

[saintex]

About 300$ cad plus my labour. Not cheap cuz it was small volume and my first attempt. A123 cells are supposed to be able to do 1000s of full discharge cycles without losing any capacity. Since September they still still hold 100% capacity.

If you want to compare check out lithiummoto.com and a few other makers out there.

[XMetal]

A recent alternator incident with my X5 and I was able to limped it home (10 miles) running only on my AGM battery - this was at night during rush hour in stop/go traffic with headlights running and all In situations like this, I will gladly take the 50lb hit on my 100AH AGM battery over a 10AH lithium ion! A small light weight battery is great when everything is working perfectly. But not everything works perfectly all the time. The engineering side of me wants some buffer zone (lots of buffer zone) - as much as possible. I'm glad I stuffed an H8 AGM in there when BMW only called out an H7 flooded battery for it.

I'm going to stuff in an H7 AGM into the Z on the next go 'round.

[saintex]

No kidding!
It's not for any car. It's a performance thing. Weight matters in a sports car. People change their seats to save 50# .

[Hawkeye]

Originally Posted by saintex

No kidding!
It's not for any car. It's a performance thing. Weight matters in a sports car. People change their seats to save 50# .

It is easier than going on a diet after all.