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voltage drop problem, what battery to buy?


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michigan_tech 
Member - Posts: 32
Member spacespace
Joined: September 16, 2008
Location: Michigan, United States
Posted: November 17, 2009 at 9:16 PM / IP Logged  
Hello all,
I just installed a Sundown 1500D amplifier in my car along with a Sundown 50.4. I checked the voltage at the amp and its sitting at 11.5 V, with the amp gain turned ALL THE WAY DOWN! I can't even here the subs. The stock battery in my 2008 Commander just isn't hacking it. Which battery do you recommend I purchase that can still fit the tray?
Here are a few things to note:
1. A H/O alternator is out of the question. It requires fabrication, and no direct bolt in is currently available (the ones that advertised as being so are false and don't put out dirt at idle).
2. A second battery is out of the question, believe it or not, I don't have the space for it.
I'm not made of money either, so can we keep this somewhat cost affective? They will be drawing a tone of current considering the woofers hooked up to it are hungry and are wired for .75 ohms. Let me know what you guys think.
i am an idiot 
Platinum - Posts: 13,606
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: November 17, 2009 at 9:35 PM / IP Logged  
If you can not hear your subs, you must have one or more of them wired out of phase with the other(s)
michigan_tech 
Member - Posts: 32
Member spacespace
Joined: September 16, 2008
Location: Michigan, United States
Posted: November 17, 2009 at 9:40 PM / IP Logged  
No, its nothing like that. I can hear my subs easy, but I can't turn the gain up on the am without massive voltage drop (1.5 V). I need to get me a big beefy battery. But what kind will fit my 2008 Commander that can take the pull from a Sundown 1500D @ .75 ohm and a Sundown 50.4 bridged at 4 ohm?
whiterob 
Copper - Posts: 351
Copper spacespace
Joined: July 22, 2007
Location: United States
Posted: November 17, 2009 at 10:08 PM / IP Logged  
A new battery isn't going to be doing much good. The alternator is what powers the electronics in your car when the engine is running. So it is going to be the most important part of the charging system. Getting another battery is not going to give you a big improvement in your voltage.
The first thing I would look at is doing the "big 3" upgrade. I would also check the voltage at the battery and compare it to the voltage at the amp. If you have too big of a difference you may have a bad ground for your amps.
michigan_tech 
Member - Posts: 32
Member spacespace
Joined: September 16, 2008
Location: Michigan, United States
Posted: November 17, 2009 at 10:32 PM / IP Logged  
whiterob wrote:
A new battery isn't going to be doing much good. The alternator is what powers the electronics in your car when the engine is running. So it is going to be the most important part of the charging system. Getting another battery is not going to give you a big improvement in your voltage.
The first thing I would look at is doing the "big 3" upgrade. I would also check the voltage at the battery and compare it to the voltage at the amp. If you have too big of a difference you may have a bad ground for your amps.
Hello whiterob,
Perhaps I wasn't as clear in my initial post, but here, I'll clarify this again.
1. I CANNOT in any way get a H/O alternator. There are no direct bolt-ins available that work. They all have really low idles and take like 4000 RPMs to get up to where they need to be constantly. I'm not doing the whole fabricating route either.
2. The difference between the battery and and the amplifier is about 1 Volt, and the amplifier dips about another .5 volts when you crank it up. I'm trying to replace about a 2V differential then when I actually turn the gain up. I should be able to pull that with a big battery.
3. I also am considering running the ground right to the battery instead of the chassis. I do not, however, think it is smart for me to run the power directly, as I'd rather have it fused.
tommy... 
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Joined: December 10, 2004
Location: United States
Posted: November 17, 2009 at 11:27 PM / IP Logged  

Did you pick up on "The Big 3" comment...? Just curious...What size power wire did you run...? You defitnely need to keep it fused...voltage drop problem, what battery to buy? -- posted image. You can use your meter to verify a Good Ground.  The upgrade is cheap and easy,so why not...! After the upgrade is done...Then check voltage and go from there...! Here is a cool site to breeze through... http://bcae1.com/ ...

And the sticky for the upgrade... https://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1 

...and for the ground... https://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1

M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
michigan_tech 
Member - Posts: 32
Member spacespace
Joined: September 16, 2008
Location: Michigan, United States
Posted: November 17, 2009 at 11:45 PM / IP Logged  
tommy... wrote:

Did you pick up on "The Big 3" comment...? Just curious...What size power wire did you run...? You defitnely need to keep it fused...voltage drop problem, what battery to buy? -- posted image. You can use your meter to verify a Good Ground.  The upgrade is cheap and easy,so why not...! After the upgrade is done...Then check voltage and go from there...! Here is a cool site to breeze through... http://bcae1.com/ ...

 And the sticky for the upgrade... https://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1 

...and for the ground... https://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1

Yes, I have already upgraded the big three with 0 gauge. Everything is 0 gauge, all the charging system and the wires running to the back (12 V). That 12 volt is in a distro block and is being split to both amps, 0 to the sub amp, 8 to the 4 channel.
oldspark 
Gold - Posts: 4,913
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Joined: November 03, 2008
Location: Australia
Posted: November 17, 2009 at 11:57 PM / IP Logged  
A bigger battery will not reduce your voltage drop.
If its your distro block, then replace it.
(Let me guess - it's a bling type with an ammeter? And guess what - it's a resistance/shunt ammeter and not a Hall Effect or similar? Now wth do people want to know what amperage they are using if they lose voltage because of it - because knowing amperage is more important than power output? Or maybe it has thermal breakers or fuses that have the same effect instead of magnetic breakers.)
Your best solution is double up on the big-3; that should halve your voltage drop. Or triple for one-third.
After that it gets academic - you are losing so much output because of the undersized alternator...
EG: you get 44% MORE output power by running at 14.4V instead of 12V (usually more in practice).
tommy... 
Gold - Posts: 1,901
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Joined: December 10, 2004
Location: United States
Posted: November 18, 2009 at 12:00 AM / IP Logged  
Odyssey and Northstar are a few brands a buddy uses for his competitions(group 31's...) I got a few for him this past year...Couldnt even find them for awhile...They said miltary was buying them up...! What size is the stock battery in those(group #)...There really is no upgrade for the alternator in those ...huh...? What about a "factory" upgrade alternator...(just throwing it out there) On a side note...Did you fuse the 8 gauge extension seperately(from the dist block)...?
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
michigan_tech 
Member - Posts: 32
Member spacespace
Joined: September 16, 2008
Location: Michigan, United States
Posted: November 18, 2009 at 12:12 AM / IP Logged  
oldspark wrote:
A bigger battery will not reduce your voltage drop.
If its your distro block, then replace it.
(Let me guess - it's a bling type with an ammeter? And guess what - it's a resistance/shunt ammeter and not a Hall Effect or similar? Now wth do people want to know what amperage they are using if they lose voltage because of it - because knowing amperage is more important than power output? Or maybe it has thermal breakers or fuses that have the same effect instead of magnetic breakers.)
Your best solution is double up on the big-3; that should halve your voltage drop. Or triple for one-third.
After that it gets academic - you are losing so much output because of the undersized alternator...
EG: you get 44% MORE output power by running at 14.4V instead of 12V (usually more in practice).
Can anyone else verify this? I thought for sure that having a better battery would definitely help out and keep the voltage more stable around 12 V.
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