Battery an Alternator

**UM_Fan** · 07-03-2005, 05:21 PM

It's been a week since I've had the computer up and running....with no problems with the car
Today I was cleanning my wiring (the car was off). I started the car...no problem. After I was done I went to start the car again...NOTHING
I took the battery out of my car and put my wife car battery in...I closed the windows and figured "let me start the car and replace the battery that way it will charge"
The car would not start with the SECOND BATTERY... WTF...I took my battery to a local auto part store to test..
The battery was good just uncharged...So left it there so they could recharged the battery...
The orginal battery of the when we purchased the car 3 years ago 60K miles.
But why would the car not start with the seconed battery

I was planning on purchasing a yellow top battery soon...but not this soon ($$$$$$$)
Here is what I got running:
Power Windows and lock
Epia 800
opus120
1 4ch JBL
1 2ch Sony

**jzgt** · 07-03-2005, 05:29 PM

Originally Posted by UM_Fan

It's been a week since I've had the computer up and running....with no problems with the car
Today I was cleanning my wiring (the car was off). I started the car...no problem. After I was done I went to start the car again...NOTHING

When you say cleaning up wiring, do you mean you were disconnecting and rerouting stuff?
- Jeff

**UM_Fan** · 07-03-2005, 05:48 PM

Originally Posted by jzgt

When you say cleaning up wiring, do you mean you were disconnecting and rerouting stuff?
- Jeff

Yeah, disconnected the power from the opus (Plug) and tie wraped all my cables. I didn't rerout anything
That was the only thing I "disconnected" ....Everything is fused.

4G-----140fuse----4G------3 way Disto Box (40fuse)----PC
4G-----140fuse----4G------3 way Disto Box (60fuse)----4Ch Amp
4G-----140fuse----4G------3 way Disto Box (80fuse)----2Ch Amp

**numbers** · 07-03-2005, 06:48 PM

I'm not saying that they're wrong, but you should rarely take the word of your local parts store as final. Your battery could be perfectly fine and it's your starter that has gone south. You just need to do some further testing.

**UM_Fan** · 07-03-2005, 06:59 PM

Originally Posted by numbers

I'm not saying that they're wrong, but you should rarely take the word of your local parts store as final. Your battery could be perfectly fine and it's your starter that has gone south. You just need to do some further testing.

I hear you...bro
Battery was bad...I bought a new battery and it turned on....no problem
Bought a red top battery....

$120
This project burn a nice small hole in my pocket ($$$$$$)

**jzgt** · 07-03-2005, 07:54 PM

I'm glad you got it working. Do you think you have a drain on the battery somewhere? That's weird that it didn't start with the 2nd battery from your wife's car...

- Jeff

**UM_Fan** · 07-03-2005, 08:29 PM

Originally Posted by jzgt

I'm glad you got it working. Do you think you have a drain on the battery somewhere? That's weird that it didn't start with the 2nd battery from your wife's car...

- Jeff

I guess I'll find out tomorrow morning.....
The car has 60K on it, I've never changed the battery...it was a stock battery.

**rudeboymcc** · 07-07-2005, 03:58 PM

sorry but what difference does it make to the computer if the batteery is red or yellow top? surely it doesn't take that much power?

**techy101** · 07-07-2005, 05:15 PM

the issue isn't just the computer. You have to remember that you're dealing with the entire electrical system in the vehicle. Starter, computer, accessories, stereo, etc... And how you plan to use these things. So if you were planning on using the system a lot with the car off, a yellow top is probably a better choice because it's a deep cycle, and you won't hurt it by running the system w/o the car on. But it costs more $$$.

**babazoid** · 07-07-2005, 06:45 PM

You really have to watch current draw. Chances are your car's alternator is rated somewhere from 80A to 120A depending on the size of your car and it's power requirements. The manufacturer isn't going to put an alternator in that has tons of extra capacity sitting around. Basically, if you have Air Conditioning, Power Windows, and other bells and whistles like that you can rest assured that you have a little extra current sitting there.

But surely you've used it all up -- TWO amps, plus a carpc will draw quite a bit of current (M1-ATX can draw 7A alone). If your battery isn't charged it's a tell-tale sign that you've overdrawn your alternator's current max and fried it -- so your car and all of it's electronics had to run off the battery... draining it.

And yes, there is a huge difference between batteries. When you say Yellow top and Red top I assume you are refering to Optima batteries. The Red top is designed for pure starter power, a better battery than normal however not ideal for electronics. The Yellow Top batteries are designed to withstand discharging better than a normal battery, and also take something like 40% less power to charge vs. a "stock" battery... placing less current demand on your alternator. From what I gather a typical battery can take up to 10% of it's Amp-Hour rating to charge. For instance, I added a 7.2Ah sealed lead acid battery to my car for my carPC -- so I know that it's taking an extra .7A of current to charge.

Anyway. Hope this makes sense. If you're running two amps I'd strongly reccommend getting a 1 Farad capacitor and also if you are looking to get a replacement alternator call your local car repair place to see if anyone will rewind your old one. Usually they can rewind an old alternator MUCH cheaper, and even add extra capacity while at it. Just don't add too much because the housing of your stock alternator wasn't designed to take 200A and it will melt!

I hope this makes sense and helps!

Mark