DiyMobileAudio.com Car Stereo Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
hi guys, question, if my alternator is on limit to hold on to music, but i dont want to put second one and dont want to put extra battery,
if there will be different if i put 2 or 3 or 10 farad capacitor? if bigger capacitor will help or it can help only on peaks not all the time?
 

·
Registered
Joined
·
643 Posts
First off, what kind of voltage drop are you seeing at the amp? This would indicate if you even have an issue. Also what is the rated max wattage of your system and what size wiring are you using? How/where are you grounded? All these factors impact voltage.

A 2 3 or 10 capacitor isn't going to help you, let alone a 500F cap in this case.

For holding your voltage during an extended bass note, the only true option is to produce more power. The only way to produce more power is an alternator. You can consider upgrading your existing to a HO aftermarket version and not have to install a second one.

A battery can help with its extra reserve power, but you'll still see a dip in voltage as a battery floats at about 13v. And at some point you may have too many batteries for your alternator to be able to charge.

The only cap worthwhile is something like a 500F like the XS Superbank. But this isn't going to solve your issue of voltage drop on a burp and a second battery would do a better job at helping. The superbank is for that initial attack and to give your amp the power it wants immediately, which then the bat/alt take over when they 'catch up' to the power demand. But this works your alt even harder as it's having to put that power back into the superbank constantly. If your alt actually isn't enough for your system as-is, you might actually see a dip in voltage because the alt can't keep up with charging the cap.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
i have 65A brand new alternator ( its a 1965 volvo amazon car) so there is not to many power needed :)

i have 2 amps, one will be 4x110 rms 4 oh and other will be 450 rms 4 oh.
using 4AWG wire for each amp. will ground it to cars body lest than 10cm from amp
 

·
Registered
Joined
·
47 Posts
I would check the fuses on your amps and add them up. Compare that to your 65 A alternator. My guess is that will not make the juice for you to have those amps run trouble free. A lot of factors such as how loud and what music can impact your actual current draw.
 

·
Premium Member
Joined
·
3,564 Posts
I would check the fuses on your amps and add them up. Compare that to your 65 A alternator.
...
I thought that the fuse define the upper limit?

He needs an ampere meter to measure real current draw, which will never be higher than the sum (of all fuses).

The OP probably can run it find with the volume rotated more anticlockwise, and likely can get trouble if it is run all the way clockwise at 11.

Ideally that current (ampere) measurement can be done at two or three volume levels... soft, normal, and loud.
 

·
Registered
Joined
·
47 Posts
I thought that the fuse define the upper limit?

He needs an ampere meter to measure real current draw, which will never be higher than the sum (of all fuses).

The OP probably can run it find with the volume rotated more anticlockwise, and likely can get trouble if it is run all the way clockwise at 11.

Ideally that current (ampere) measurement can be done at two or three volume levels... soft, normal, and loud.
I have used the total fuses of the amplifiers as a general guide when considering potential loads that the battery/car might see. Of course if you have an amp that's 1 ohm stable and you run it at 2 ohms that will make a difference in current draw.

Where would you measure this safely with a DMM? I guess you might need something heavier duty. At the incoming side of the power and ground distribution blocks? I'm very interested in doing these type of tests and really better understanding the effects the audio system has on the car.
 

·
Premium Member
Joined
·
3,564 Posts
I have used the total fuses of the amplifiers as a general guide when considering potential loads that the battery/car might see. Of course if you have an amp that's 1 ohm stable and you run it at 2 ohms that will make a difference in current draw.
...
Adding fuses works in a worse case scenario sense, and it still over estimates it as amps only blow fuses when something has failed in them.

But how much will a 1-ohm differ from a 2- or 4-ohm load at 1000W?
Input current is a function of output wattage, and that is more of a function of volume than of the output impedence.
If the volume is at zero, then the output is at zero, and the input is a bit more than zero, but still low.


...
Where would you measure this safely with a DMM? I guess you might need something heavier duty. At the incoming side of the power and ground distribution blocks? I'm very interested in doing these type of tests and really better understanding the effects the audio system has on the car.
Ans: I would measure it around the cable...

 

·
Registered
Joined
·
13 Posts
Discussion Starter #8
so you think best is to put all in the car and than test it in real life?
fusses are 2x25A and 2x30A
 

·
Premium Member
Joined
·
3,564 Posts
so you think best is to put all in the car and than test it in real life?
fusses are 2x25A and 2x30A
Best? Compared to what?
It is the only way to get an accurate idea... but you could do it on a bench with a resistor and 1W RMS and it should be close.

Or just run it an if the lights are not flickering like a discotheque it is ok.
 
1 - 9 of 9 Posts
Top