Battery Size?

[Cavey1638]

Dear All,

I have the original battery still in my 3.0l Z4 (2004). I want to change it to a slightly larger capacity one as I have a quality audio system that is demanding. I need to know if the car has any coding issues in relation to power management and charging the battery. I want to basically bin the lead / acid job for a newer AGM one.

Regards

Cavey

 

[WLH]

The original battery is an AMG and there are no coding issues. I have replace batteries a few times and I've never had any issues with making the exchange within 10 to 15 minutes. If you connect a trickle charger you won't even need to reset the clock which is the only issue that I've ever had. BMW dealers can supply the OEM AMG battery but most in the UK seem to go for the Bosch battery. I'm sure someone will post a specific recommendation.

 

[Cavey1638]

Thanks, although on mine it has a breather pipe which lead me to believe is a lead acid job. Anyway soon to be replaced with something with a bit more power.

Regards

Chris

 

[GuidoK]

AGM, calcium etc are all 'lead acid' afaik. (all based on lead and sulfuric acid; agm is a glass fiber mat between the plates, and calcium or selenium are additives to reduce gas). In general they all use the breather system. Dont forget to plug the side that isnt connected to the breather hose (usually there is a port on each side)
The original batteries were non agm for the pre fl z4's (that tech wasnt generally around back then), but bmw has been delivering agm batteries (only agm I think) for quite some time now.

You can fit different sizes in the boot; for the battery tray there are different size plates that you can click in:



Fitting a battery without a plate gives room for the biggest battery: 315x175x190mm (typical for a ~80ah battery)
The small/narrow plate gives room for a 278x175x190mm battery (typical for ~70-75ah battery) and the biggest plate gives room for a 242x175x190mm battery (typical for ~55-60ah battery).

I'm currently driving around with a small agm battery (save some weight, that saves me a diet :roll: ) but a bigger battery will last longer.
I have no idea how long my small battery will last. It's very dependant on winter useage.

Be sure to get a battery where the plus and minus are situated on the correct side (you can get them both ways!) and you need a 'B13' style bottom (hold down system) and standard recessed DIN terminals.

 

[pokeybritches]

I'm confused as to why you want more battery capacity for a sound system. If you're draining the battery faster than you're charging it, the issue is in your alternator. If your car can't handle the bursts of power required by the amp (for example, your lights flicker or dim every time the sub hits), you need a capacitor. General rule of thumb is 1 farad per 1000 watts.

 

[NeilP]

I'm confused as to why you want more battery capacity for a sound system. If you're draining the battery faster than you're charging it, the issue is in your alternator. If your car can't handle the bursts of power required by the amp (for example, your lights flicker or dim every time the sub hits), you need a capacitor. General rule of thumb is 1 farad per 1000 watts.

Caps put more stress on the electrical system than a battery with a larger reserve would.

OP is going down the better route for a lager reserve than adding a power cap.

 

[GuidoK]

Maybe listening to the radio while the engine is off, or on startup, when you first set your key to ignition and the other systems are starting up too. That usually can put a constant 30amp draw or so on it too.

My car already was equipped with the largest size battery from factory. Maybe bmw varies battery size with how many options are fitted on the car?

 

[Cavey1638]

Dear All,
Thanks for the replies. I have 2 x Hertz HDP amps, an Audison Bit One and an Audison Bit Play HD. There has been an issue around voltage drop and by old battery has the green indicator which is now black. I think its the original. Also as NeilP has mentioned a larger battery for my system is better than using capacitors. Guidok thanks for the entry will cut and paste that to my audio installer as my boot floor is now beyond my knowledge to remove the audio equipment. Further its a work of art and I don't want to mess with any of the plugs!

Regards

Chris

 

[NeilP]

Chris, while you're at it, upgrade the earth straps on both the battery and the engine. Keep the original ones in of course.

If you're in the market for a new battery, AGM technology is the way to go.

On a side note, how are you getting on with the Bit Play?

 

[Cavey1638]

Hi Neil,
There has been some teething problems with the Audison Bit Play in relation to the power up sequence. The Bit Play HD would hang as though stuck in some sort of boot up sequence. Paul at Source Sounds has spent some considerable time and at last with the latest software it has been sorted. In relation to the sound.... absolutely fantastic. Sound stage is amazing even in a convertible car!! Finding an audio installer who knows their subject and what the customer wants is the answer. Source Sounds (Sheffield) have gone the extra mile in relation to my install. When you start listening to old albums (Flac) and start hearing the quality of the recording with new ears that does it for me. In fact it shows the short comings of a lot of albums.

Would recommend it .....

Regards

Chris