Battery capacity and cranking survival

**MatrixPC** · 12-09-2004, 03:49 PM

Well, I have everything is up and running in my Matrix setup except 1 problem. It doesn't 100% cranking survival. I am running the Sproggy (similar to MK4.5), and I don't know exactly where is the problem.
Here is the spec for the Sproggy 3.3V@5A, 5V@15A, 12V@5A x 2.
One of the 12V rail is to power the mobo. The other 12V rail is powering the DVD-ROM and 7200RPM HD.
The problem.
- When cranking the computer just freeze. Battery is stock with 310CA and voltage drop to 9~10V during cranking which is within the operating voltage for the Sproggy.
- Replace the battery with 560CA and voltage is drop to about 10V. The computer is still runing during and after cranking (I still can hear winamp playing), but it only run for about 3~5 second then the PC freeze after the engine start.
How can I fix this?
I planing to use the spare battery and parallel via "Jump Cable" to see if this problem still exist. If it solve the "frozen" problem, will a bigger 900+CA battery solve the problem?

My Supra setup P3 600Mhz with Abit mobo power by the Sproggy (3.3V@5A, 5.0V@10A, 12V@5A) doesn't have a single problem. Well the battery in the Supra has 1000CA.

**fantomas** · 12-09-2004, 04:08 PM

swap out the sproggy from the matrix and put it into the supra and see what happens. if it survives that crank, then you know its the battery. if it doesnt it could be the psu.. and then take the sproggy from the supra and put it in the matrix. if that survives, its the psu, if it doesnt, its the battery.

**GReeToZ** · 12-09-2004, 04:09 PM

Hi, i have a small vauxhall/opel Corsa and naturally it doesnt have a big battery i just put a 2nd battery (12V 7A Lead-Acid) next to it run the plus wire from the car battery to the Plus on the seperate battery put a 10A diode in between it so the main battery wont discharge you're second battery when it dips under 12 volt. and just run the minus wire thru the 2nd battery doesnt need any diodes

you can also put a small 12V 1A battery in it but i wanted to be able to run my car pc for more then lets say 20 min with the engine off without using the main car battery

hope this helps i can just restart my car with carpc without it skipping or anything

my 12V 7A cost me about 20 euro's and a diode is about 2 or something a 12V 1A will be under 10 euro's i think

**MatrixPC** · 12-09-2004, 04:38 PM

Thanks guys, I will try swapping the whole computer between the Supra and the Matrix. The Supra setup isn't as powerfull as the Matrix so swapping the PSU along doesn't help much. Prior to complet the Sproggy in the Matrix, I used the one in the Supra to power it. It run fine but frozen during cranking.
Small SLA battery also an idea, but space is the problem.
The only big battery with lot of CA is the Optima Red Top, but I can't find it locally.
Any other idea?

**GReeToZ** · 12-09-2004, 06:47 PM

well a small sla 1A battery is not big at all, about (L*W*H) 10 by 3 by 4 Centimeters(atleast the one i saw) and i bet it could easily fit next to you're standard car battery

**eCar™** · 12-10-2004, 04:01 AM

Are you using the frame/body for your ground?

If so, try running a test from your PC's ground thru a voltmeter to your negative batt terminal. Then crank the car. See any voltage? It's best to use an analog meter, because some digital ones are a bit slow. Or an o'scope if you have one.

If you see a voltage spike, it points to bad starter ground. The starter usually gets it's ground thru the engine, and then the ground cable attached to the engine. If there is any resistance there some current may flow thru the body ground, to the engine, then to the starter. This can give you a drop in voltage at the PC, or anything grounded to the frame/body.

**MatrixPC** · 12-10-2004, 09:35 AM

Originally Posted by eCar™

Are you using the frame/body for your ground?

YES

Originally Posted by eCar™

If so, try running a test from your PC's ground thru a voltmeter to your negative batt terminal. Then crank the car. See any voltage? It's best to use an analog meter, because some digital ones are a bit slow. Or an o'scope if you have one.

Will do test that out. I have analog vol meter also an o'scope but I gota learn how to use it.

Originally Posted by eCar™

If you see a voltage spike, it points to bad starter ground. The starter usually gets it's ground thru the engine, and then the ground cable attached to the engine. If there is any resistance there some current may flow thru the body ground, to the engine, then to the starter. This can give you a drop in voltage at the PC, or anything grounded to the frame/body.

This part make me wonder a little about my electrical setup. Currently this car has "ground wires" installed (Just like big 3 wires in audiophile term). Basically the "Ground wires" just add more ground wire to improve existing (factory ground wire.)
Here is how the ground wires run all are 4GA.
- Wire 1: From batt neg to frame/body (along with factory wire.) left side
- Wire 2: From batt neg to tranny (along with factory wire.)
- Wire 3: From batt neg to throttle body (new wire)
- Wire 4: From thottle body to igniter coil pack (other side of engine).
- Wire 5: From igniter coil pack to frame/body right side

Does this "ground wires" setup create a bad starter ground?
How do I fixed bad starter ground?
- Run another "Ground wire" from the batt neg to the starter body/ground point? This option is easy.
- Run a "ground wire" for the PC/PSU instead of the frame. This option is PITA.
I would refer option one because it will fix the whole problem . Option 2 is just bandage solution because it fixed the PC/PSU problem but I may still have problem in other area.

**MatrixPC** · 12-10-2004, 09:41 AM

Originally Posted by GReeToZ

well a small sla 1A battery is not big at all, about (L*W*H) 10 by 3 by 4 Centimeters(atleast the one i saw) and i bet it could easily fit next to you're standard car battery

I will do some

regarding to SLA battery and heat in engine compartment. If SLA is fine in engine compartment then space is not an issue. If I have to put inside the carbine then that is a BIG issue (fume/space/.... ). SLA setup is my last option before I try other options available.

**MatrixPC** · 12-11-2004, 12:26 AM

Problem solved

- I test the negative terminal per eCar™ suggestion with an analog vol meter. No spike or whatever. So the problem is not the ground as one of my "ground wire" screw not too far from the starter.
- Took the setup from the Supra and hookup to the Matrix and try it. Guest what? Doesn't survive the crank. Now the problem for sure it that tiny little battery.
- Put everything in the Matrix back and run to Super Autobac cuz they have the Optima Redtop in stock. For those who doesn't know what Super Autobac is. Well it a Pep Boy of Japan. The one in Socal/Garden Grove is the only store they have in the States. If you guys want Japanese part (aka JDM), that is a place to get. Pay 108.82 bucks for the Redtop G35 and they put it in for me.
- When I put the fuse for the PC in, it turn on and load to window. Hold my breath and crank the car. Yup winamp still playing, turn the LCD on, switch couple song. Yayyyyyyy it WORKKKKKKK

Now I have to reorganize all the wires .....