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Old 14th November 2005, 06:26 PM   #1
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Default Car Power (for amps) help

Hey guys,
I have a rather old car (1988 560 SEL Benz) and the new soundsystem I installed in it is putting quite a strain on the alternator (dimming lights whenever bass hits). I already bought a 3 farad capacitor to help the strain but I was thinking...couldn't I just put in another car battery? I could just parallel a new battery to my old one. Any reason why this wouldn't work? Please let me know! Oh my soundsystem power drain is about 800W

-Segasonicfan
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Old 14th November 2005, 06:30 PM   #2
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Default YES!!

Not only can you put in an extra battery in parallel, you definately should. You might find that it is sufficient to prevent the lights from dimming and then you might get to return the capacitor. You could even put more than one extra battery. Note, that it is best to place the battery as close to the amplifier as possible.
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Old 14th November 2005, 06:37 PM   #3
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Default Re: Car Power (for amps) help

Quote:
Originally posted by segasonicfan
Hey guys,
I have a rather old car (1988 560 SEL Benz) and the new soundsystem I installed in it is putting quite a strain on the alternator (dimming lights whenever bass hits). I already bought a 3 farad capacitor to help the strain but I was thinking...couldn't I just put in another car battery? I could just parallel a new battery to my old one. Any reason why this wouldn't work? Please let me know! Oh my soundsystem power drain is about 800W

-Segasonicfan
What gauge cable are you running to the amplifier?
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Old 14th November 2005, 06:57 PM   #4
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Hey thanks so much Nafta

I'm actually using a bunch of amps: 1 Infinity 7520a, 1 Lightning Audio, 2 250W Crunch amps, and my pioneer in-deck receiver amp. I might also be adding my own amps to the system. As to the gauge of the cable, I'm using 20AWG to everything since I got a bunch of it bulk for a great price. It's coaxial and has great woven grounding insulation so I think it has great audio and power use (expecially cause it's solid).

-Segasonicfan
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Old 15th November 2005, 12:17 AM   #5
Stocker is offline Stocker  United States
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Wrong on all counts, if it's for power.

20 guage is way small for anything over a few watts. IASCA has a chart for this. You may be dropping as much as a couple of your 14 volts right across the wire, depending on the current. Not to mention the risk of fire. It would be an urban legend but I actually read the article myself... a fireman of all people had his car burn to the ground because of too-small power leads to his amplifiers and they heated up, melted the insulation, caught fire...

"they" tell us that current travels more on the outside of the wire "skin effect"... stranded wire = better for high current...

so you want MUCH bigger, stranded wire for power.

Another battery wouldn't hurt unless you install it wrong. Part of "wrong" is "without its own fuse within 18" ".

What you really want is a bigger alternator. I can't see stock parts from way back then being rated for lotsa watts for your sound system. Another battery is only a bandaid like the capacitor is a bandaid, and will be prone to the same not-helping effect, besides taking up more room. A new alternator is the solution to high current demands, and takes up almost no additional space.

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Old 15th November 2005, 02:33 AM   #6
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Thanks for your insight stocker. Unfortunately a new alternator isn't a possibility. The cost of a fitting my Mercedes with a new one wold be staggering-more than my soundsystem itself :/ And while the capacitors and the extra battery may be a bandaid, they are very good ones. Once the caps (and extra battery) are charged they should have enough power to pump out to the sound system for a while.

That's strange what you said about the gauge of wire though....I've never found the 20AWG to be heated in the slightest, even when running to the 250W amp. It doesn't make much sense to me that a hugher gauge would be required for safety when smaller gauges are run throughout my entire car at 12v running to everything from the original 10A soundsystem to the powerful window motors and other amps. I have a household heater that pumps out 1500W that has wire heating issues, but that's about double my soundsystem power and I've used less than 20AWG with it. I think something else must've burned that guys car down....

I always fuse the hell out of everything I have so I will definitely do so with the new battery. All my amps have at least one fuse a piece not to mention that the 12v battery and 12v signal lines are all fused (along with everything else) to my cars fusebox.

-Segasonicfan
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Old 15th November 2005, 02:45 AM   #7
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stocker is not kidding about the 20 ga coax for your main power to the amps-the cable is mainly used for low volt situations,not only is it going to sound worse it is dangerous-replace it with at least 4 gauge from batt to a disto near your amps and split it off with 8 ga.-for sub amp- or 10ga. to mid-high to ea amp,spend a few dollars it will sound better and you and your car will live longer.
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Old 15th November 2005, 05:52 AM   #8
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Well maybe it would improve the sound quality but I certainly don't think it's a fire hazard. I can't even find a 12v power line in the car larger than 24AWG and I would have to take about the entire dash (at the very least) to run wire directly from the new battery. So even if I do use 18AWG if will be connected to an internal 24AWG line or less coming from the battery not to mention the other 12v line coming from the remote which is also 24AWG or smaller.

-Segasonicfan
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Old 15th November 2005, 06:02 AM   #9
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new battery!i wonder if any battery will get fully charged ever.

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Old 15th November 2005, 06:09 AM   #10
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Wait, your power cable isn't even running straight to the battery?


This is basic stuff man, I hate to be so honest, but you should know better. Just the IDLE current from those amps is around the maximum that 24awg can handle, if you play any music, anything at all, you're exceeding the maximum current carrying capability of the power wire. 20awg can hold around 2 amps effectively (for power transmission) and around 10 amps safely. You're grossly exceeding both of those in your current setup. I don't know why can't find anything larger than 24awg in your car, my car has a 6awg coming off of the battery that goes straight to the starter, and a seperate 8awg coming off the battery that powers the windows, headunit, lights, etc. The power windows have ~12awg power, the headunit has ~16awg power...there are "large" cables all over. Your 20awg power is seriously a fire hazard, especially if you have it connected to a 24awg power lead in the dash.

Go in and run a 4awg cable straight from the battery to the trunk, then you can use a fused distribution block to split it to a few 8awg cables for your amps.
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