Aftermarket Amplifiers...

[blndweasel]

Hey folks,

I'm having a helluva time with my charging system.

I have a basic question for all of you...

1. What is the total RMS wattage of the amplifier(s) you are running in your Ti.

2. Are you running the stock Alternator?

3. How is your battery not dying all the time?

I have the 10-speaker stereo setup, and I am using the OEM amplifier, as well as an Infinity Basslink which advertises a 200 watt RMS draw. Under what I would consider "normal" conditions for a stereo (I'm not blasting it, just listening to some bass with a good kick) I consistently drain my battery.

Checked for shorts, bad grounds, etc, it's not that. Basically I think my alternator needs rebuilt. But I'm wondering how closely BMW designed the charging system according to the electrical system's average load. 80Amps isn't that big for a car alternator, and my guess is the amplifier I installed could be drawing as much as 20Amps. And it's pushing the alternator past it's capacity to charge the battery. When I disconnect my amp via the fuse, the system charges just fine.

It's like impossible to find a higher capacity alternator for the 318ti, I've looked and there's nothing in the stock casing. Since I hate paying other people to do things, I'm thinking of buying another Valeo alternator (90 or 105 A) and changing out the internals to the stock 318ti casing.

If I can avoid this with a simple alt rebuild, I'll stick with the stock unit. Thoughts? There have to be folks running bigger sound systems than me here...

the blonde weasel

[Will'sBimmer]

I am running a 500 watt amp. I play the music pretty loud and with my speakers on all the time. I also sometimes play the music or watch movies while the car is off. I have the stock alternator and my battery never runs down or even seems to get low. I would just get another alternator. I believe if your alternator was working you wouldn't be having any problems.

[stormos]

I had a 960 watt amp driving all my ti speakers with a bosch silver battery. never caused me any issues and i had the dde rings, stereo and blowers on 24/7

[cooljess76]

Have you checked your alternator's output with a multimeter? What was the voltage? Test it with the amplifier completely disconnected and then check it with the system running. You should have 13.8-14.4v going to the battery. If not, check your main engine ground behind the passenger front wheel well. It's connected to the right motor mount and the chassis. Mine had a bad connection and was arcing. I found it after replacing 3 alternators and 2 batteries. GL

[tiFreak]

you could get a capacitor, my friend had this one with his 1000w amp and 2 12" subs and his battery never got run down

[blndweasel]

Originally Posted by cooljess76

Have you checked your alternator's output with a multimeter? What was the voltage? Test it with the amplifier completely disconnected and then check it with the system running. You should have 13.8-14.4v going to the battery. If not, check your main engine ground behind the passenger front wheel well. It's connected to the right motor mount and the chassis. Mine had a bad connection and was arcing. I found it after replacing 3 alternators and 2 batteries. GL

Right, I read your other thread about the Alternator mysteries... I will be sure to check those grounds if I'm in there.

From the sound of it considering what other people are running, I'm going to assume it's just worn brushes on the alt. I'll just have to tear her open and check the carbon stacks.

Thanks for all the replies!

tbw

[blndweasel]

Originally Posted by tiFreak

you could get a capacitor, my friend had this one with his 1000w amp and 2 12" subs and his battery never got run down

A capacitor only helps in situations where the speakers/amps are drawing so much current at once that the charging system under supplies the amplifier and it shuts down. i.e. hitting a big 20hz bass note on a 1000W amp, or something like that.

alternator sizing has more to do with averages... average draw over a period of time resulting in overall charging or discharging of the battery.

it sounds like my alternator isn't putting out what it should, so I'll go for a rebuild.

[classicronnie]

weird i was just about to make a thread about this , my battery costantly dies and i only have about 500rms and i also got a 2 farad cap, how can i fix this problem

[thesk8nmidget]

i used to run a 1200 watt amp and 2 12's constanly. never had a single problem with my battery.

i would also do it with my car not running.

i would say as well alternator or battery

[classicronnie]

which alternator should i buy?