When to change battery?

[mr_z4mc1m_oz]

Ok so my Z4MC is a 2008 model and still has the original battery. Car has 62k kms.

My battery light and some other lights flashed flashed for a couple of seconds while I was driving it the other week. I had recently been overseas for 4 weeks so disconnected the battery while I was away. Did it have something to do with the battery disconnection, or should I be replacing it?

I check the voltage last night, results were:

11.9 with car off.

14.1 to 14.3 with car on and all lights, hazards and air conditioning on fall.

I would appreciate any comments.

Thanks

[StickMon]

9 year old battery? I would say it's had a good run.
5 years is more typical.
Make sure to get a size H6. Some auto chains list H5 for the ///M, which is incorrect.

[mr_z4mc1m_oz]

Originally Posted by StickMon

9 year old battery? I would say it's had a good run.
5 years is more typical.
Make sure to get a size H6. Some auto chains list H5 for the ///M, which is incorrect.

Yeah that's what I think. I'm just going to get a genuine BMW battery. $500 here in Australia.

[David70]

Originally Posted by mr_130i_oz

Yeah that's what I think. I'm just going to get a genuine BMW battery. $500 here in Australia.

There's no point in doing this, BMW doesn't make batteries and all of the extra cost is the "BMW" on the label.

[mr_z4mc1m_oz]

BMW quoted me for a 70 AGM battery

[racerbruce]

Originally Posted by mr_130i_oz

Ok so my Z4MC is a 2008 model and still has the original battery. Car has 62k kms.

My battery light and some other lights flashed flashed for a couple of seconds while I was driving it the other week. I had recently been overseas for 4 weeks so disconnected the battery while I was away. Did it have something to do with the battery disconnection, or should I be replacing it?

I check the voltage last night, results were:

11.9 with car off.

14.1 to 14.3 with car on and all lights, hazards and air conditioning on fall.

I would appreciate any comments.

Thanks

The beloved Z4M cannot be towed, it must be placed on a flatbed truck. The significant cost and inconvenience, plus the safety risk(s) associated w/a failed battery can be mitigated....I replace the batteries in all of my cars every 4 years on duration.

[StickMon]

Originally Posted by David70

There's no point in doing this, BMW doesn't make batteries and all of the extra cost is the "BMW" on the label.

^WHS. 100% surcharge for the BWM sticker.
They run about $175 U.S. here from the major chains.
I think that's maybe 220 OzBucks?

[mr_z4mc1m_oz]

Originally Posted by StickMon

^WHS. 100% surcharge for the BWM sticker.
They run about $175 U.S. here from the major chains.
I think that's maybe 220 OzBucks?

Online prices for non genuine seem to range from $270 to $380 AUD.

BMW want $560, but my mate that works there can get it for $500.

[Finnegan]

Originally Posted by StickMon

^WHS. 100% surcharge for the BWM sticker.
They run about $175 U.S. here from the major chains.
I think that's maybe 220 OzBucks?

Yes. Bingo. Totally overpriced.

With a battery of that age don't be surprised to find a lot of corrosion on the battery cables unless you've been super diligent about cleaning/protection. I let one of our batteries go 7 years. Big mistake. I spent a good several hours addressing the corrosion issues on cables. A new set of cables is, IIRC, 500-600 USD, not cheap, not easy, not fun.

I've now added a 6M check/corrosion prevention approach to the care/feeding schedule.

[mr_z4mc1m_oz]

Originally Posted by Finnegan

Yes. Bingo. Totally overpriced.

With a battery of that age don't be surprised to find a lot of corrosion on the battery cables unless you've been super diligent about cleaning/protection. I let one of our batteries go 7 years. Big mistake. I spent a good several hours addressing the corrosion issues on cables. A new set of cables is, IIRC, 500-600 USD, not cheap, not easy, not fun.

I've now added a 6M check/corrosion prevention approach to the care/feeding schedule.

I double check tonight, but I don't think there is any signs of corrosion on the battery or cables.

Aren't these voltage readings perfectly normal?

11.9 volts when car switched off

14.1 to 14.3 volts when car on with everything turned on i.e. lights, high beams, air con full blast, stereo on, interior lights on.

[antennahead]

Originally Posted by mr_130i_oz

Ok so my Z4MC is a 2008 model and still has the original battery. Car has 62k kms.

My battery light and some other lights flashed flashed for a couple of seconds while I was driving it the other week. I had recently been overseas for 4 weeks so disconnected the battery while I was away. Did it have something to do with the battery disconnection, or should I be replacing it?

I check the voltage last night, results were:

11.9 with car off.

14.1 to 14.3 with car on and all lights, hazards and air conditioning on fall.

I would appreciate any comments.

Thanks

I had a new battery installed after a new alternator a year or so back. I sometimes go a day or two between driving the car. This battery would not hold a good charge, was at 11.9 resting and 13.8 to 14.2 when driving. I was scared it was going to leave me stranded, swapped it out for a new O'Reilly AGM. The new AGM battery never drops below 12.3, even after sitting for days. It charges at 14.4 up to 14.7 if the car has been sitting for a few days and I'm running stereo, AC, etc. Fully charged it hits and holds 12.6 unless I let it sit for a while. You got great service out of that original, don't start getting all the weird computer crap happening because of a low voltage situation. I'd get a new one soon.

[antennahead]

Originally Posted by mr_130i_oz

I double check tonight, but I don't think there is any signs of corrosion on the battery or cables.

Aren't these voltage readings perfectly normal?

11.9 volts when car switched off

14.1 to 14.3 volts when car on with everything turned on i.e. lights, high beams, air con full blast, stereo on, interior lights on.

Actually I believe each cell should be 2.1 volts, or 12.6 fully charged......... but I have been wrong once before

[pungo]

The way to acuratly measure the voltage is to charge the batt with a good quality agm charger, then disconnect the batt and let it sit at least overnight, then measure the voltage. Chart voltage chart for AGM batt

[mr_z4mc1m_oz]

Originally Posted by pungo

The way to acuratly measure the voltage is to charge the batt with a good quality agm charger, then disconnect the batt and let it sit at least overnight, then measure the voltage. Chart voltage chart for AGM batt

Attachment 1672469

When we tested it yesterday (car off) I hadn't started the car in 1.5 weeks and the charge was 11.9.

Therefore based on that chart it seems like its at 30-40%.

So sounds like time to change battery

[StickMon]

Another reason not to let the battery get weak is that our cars have a very bad reaction.
The car won't tell you that the battery is weak. It will go into limp mode and tell you that all manner of things are wrong with the fly-by-wire throttle system (EML).

[mr_z4mc1m_oz]

Battery ordered.

[chickdr]

Originally Posted by mr_130i_oz

Battery ordered.

What did you go with? Hopefully you just got one from the local parts store instead of wasting cash on the BMW battery. $500 AD is highway robbery....

[David70]

Originally Posted by StickMon

Another reason not to let the battery get weak is that our cars have a very bad reaction.
The car won't tell you that the battery is weak. It will go into limp mode and tell you that all manner of things are wrong with the fly-by-wire throttle system (EML).

As someone that rarely drives his car (at most on the weekends) I use the Battery Tender to help save the battery and the alternator. When I start the car the battery is fully charged and there is very little for the alternator to do. Should help the alternator last longer.

[wdb]

Originally Posted by David70

As someone that rarely drives his car (at most on the weekends) I use the Battery Tender to help save the battery and the alternator. When I start the car the battery is fully charged and there is very little for the alternator to do. Should help the alternator last longer.

^^^ This. Me too. I even got a deal on an "official" BMW trickle charger!

[bosstones]

Just replaced mine last year.....for my 07 (06 build). Replacing is the safer thing to do at the age of your battery.

I went w/ an AGM from O'Reilly per other suggestions. Not sure if they have O'Reilly in Austrailia, but it saved quite a bit for the same battery.

[RossBMWZseries]

StickMon suggested that you should get a H6 battery. I was running a H5 since October because Autozone indicated that was OEM size. I just found out that the H7 actually is the same size as the OEM battery my Z4M had when I got it back in 2011. So just recently I got the AGM battery from Autozone (H7) and fits perfectly fine, obviously more cold cranking amps.

[StickMon]

Now that we have firm confirmation I'll probably go H7 next time around.
More Power !!!