Running two amps in a 325i E36 Will that drain the Battery :S

[jmore1231]

Hi guys my friend recently upgraded his stereo system cause he is a rich ass and gave me some of his old stuff for free it included 2 sony amps one 4 channel 600 watt and one SONY XMZR602 2 CH Mono AMP. Ive already upraded the speakers in the car previously im running kenwood 3 way 5.25" speakers in the front and 4" Alpine 2 way speakers in the back as i didnt want to cut anything plus im running a 350watt RMS MB quarts Sub in the boot Also the headunit is a Pioneer DEH-5250SD its brand new even has 3 rca pre outs for full control.

All of this was installed about two days ago from my local autobahn even works and looks great but i have one question would all of these things drain my battery especially in a 1992 325i and if it isnt if i put 6x9's in back using a speaker adapter to replace the alpines would that push me over the thresh hold im just curious thats all .

[bksm311203]

Your amps will drain your battery after a while if you let the music play and your car isn't on. If you know how a car works, then you know it runs off your alternator and not your battery. your alternator in turn recharges your battery. so if the car isn't on so i can run, then it's not going to recharge and eventually die. Basically it's a big over sized rechargeable battery. If you would like to save even more power, then get yourself a capacitor to run with your system.

[jmore1231]

wow thanks for the info i never even new that i guess you really do learn something new everyday i feel like such a noob for asking the question now if you hadnt of told me that i most likely would have drained my battery in next few weeks.

So as long as the car is turned on as in ignition on then it should be fine. Ill get a voltage capacitor next week when i get payed thanks again

[sunbrn]

So as long as the car is turned on as in ignition on then it should be fine.

As long as your engine is running you'll be fine.

[restricted]

I recomend upgrading your alt to a 140 amp

[bksm311203]

yea, as long as the car is on you'll be fine. another reason why i said get a capacitor is because if your alternator is weak or has a low amp output, then when you have your system on and headlights, u might notice that they'll dim at times when putting your windows up and down.

[Mushu2663]

all a cap does is let the system hit the same note as the 1st...if u do not have a cap ur 1st note will always b louder bc that is when ur batt. has the most power.. so yes it will help wit ur lights and suck but no that is not what it is made 4

[TCarlisle]

Oh boy, are we really going to do the capacitor theory and debate again, and in the non-audio forum? Not like it hasn't been done a billion times already all over the Internet.

Anyways, putting the cap issue aside, if your alternator can stay ahead of your electrical system then you are fine. The alternator powers the engine and electronics to run the car, and then has some power left over to charge the battery. The battery drains to a degree when you start the car, and recharges when you run the car. So as long as their is enough power left after powering your engine & electronics to charge the battery back up then you are fine.

The audio system does not draw continuous steady power. It will draw more based on volume level and frequencies being produced. Bass draws more power than treble.

His system is rated at about 1200W between both amps. Not sure if that is peak or RMS, and no time to look up his model numbers to find out. Assume it is peak, because it probably is. He will on average be pushing 600-800W. Let's just say 750W since that is in the middle. He will be on average pulling about 20A of current.

In most cases, a car is designed electrically to have 40% headroom in alternator output. If he has the stock 80A, he has about 32A reserve power, so running 20A will bring him down to only about 12A reserve power. With this little reserve, he may or may not have problems depending on what accessories he has and what his driving conditions are.

If he has power seats, seat heater, etc. and runs them alot, and takes short trips and keeps RPMs low, it will probably leave him with a weak battery and have trouble starting once it gets cold out.

What I recommend is this. Play the music you play at the listening level you most often will use, then turn on all the cars high current drawing accessories -- rear defrost, AC, foglights, headlights & high beams, and put a voltmeter on the system and see what the voltage level is. It should stay in the low 13's. Operate the power windows and power seats and see if that dips the voltage below 13.0. If it does, the alt is not keeping up with the electrical system. Bigger alt will solve that problem.

Capacitor or second battery just provides reserve power so the alt doesn't get hammered by peaks in the music.

[lasmariaspr]

TCarlisle do you recommend the capacitor?
I'll be adding a sub in the near future.

[TCarlisle]

TCarlisle do you recommend the capacitor?
I'll be adding a sub in the near future.

No, I do not. They are expensive and IMHO unnecessary. A good amp has a power supply that keeps power in reserve.

[jmore1231]

No, I do not. They are expensive and IMHO unnecessary. A good amp has a power supply that keeps power in reserve.

Oh ok thanks for all the info youve helped me out alot im lucky i dont have the power seats, seat heater and i hardly run the actual heater only when driving at night which is usual once a fortnight not even that sometimes anyways the only features i use would be my power windows and headlights plus the stereo of course plus my AC belt is not attached atm so i havent used that in a fair while just to save on petrol really so im guessing i should be fine i drive mainly about 3 days a week 120kms in a day then maybe 20km on the rest but can really depend on what im doing i would say maybe a total of 500kms a week most of which is highway driving as well,

You also mentioned that its draws more based on volume level and frequencies being produced i tend to have my music quite loud as i like to get the most out of it so really it sits at about 30 to 34 thats out of 50 the only reason why that is because i have the loud option off as its just crazy and by the way plus there are freq settings for everything but atm i have the sub at 80hz, but then theres this setting called HPF its definately a frequency setting but im unsure what it does thats on at 80hz also the equalizer is set so that everythings in the middle for more of a natural sound.

Also my Mono amp is only 350watts Peak and that is not in RMS and the other 4 channel is 600 watts Peak also not in RMS so thats about 950watts in total i dont know if that changes anything as well This is actually quite complicated haha thanks again for your help so far

[TCarlisle]

I doubt you will have problems or need a bigger alt. As long as your electrical system is healthy, you should be fine. The only way to know for sure is to test with a voltmeter. It's a simple test and a voltmeter is cheap. You'll need a voltmeter one day anyways, and you'll need to know how to do this test too.

[jmore1231]

I doubt you will have problems or need a bigger alt. As long as your electrical system is healthy, you should be fine. The only way to know for sure is to test with a voltmeter. It's a simple test and a voltmeter is cheap. You'll need a voltmeter one day anyways, and you'll need to know how to do this test too.

Thanks again ill definately check that out when i get the chance next

[AReynante]

Would upgrading the Alt do anything in the realm of too many amps? If I'm planning on getting more electrical items later on, but I get the Alt first, will it damage anything?

*Sorry for jack