I just put in a computer with a power supply that doesn't like going bellow 11 volts and cuts out when I start my car. It's not the battery because I just replaced it. The other one was really old and had white corrosion on it.
Is this normal to drop that low or is my voltage regulator or starter going bad?
Do you guys just get another regulator to put in line with a computer and have one you'd recomend? I have a mini itx MB with a variable input voltage picoPSU. I also have a 1 farad cap on my system too.
I need to get this sorted out to put in the megasquirt =)

The starter can draw a ton from the system. I've never paid attention to any voltage drop across the rest of the vehicle, but it wouldn't surprise me

Ive had mine drop to as low as 9v while cranking. This was while I was working on the car with the hatch open for at least 2 hours.

Put the PSU after the cap.

Thanks for the quick replies...
I measured the same voltage off the cap too which is in the hatch, so I'm guessing theres a lot of power going to the starter. The battery I just got has like 800cca or something crazy.
I was hoping the picoPSU would handle this but I guess not. I'm pretty good with electronics so I'll probably just build a VR.

This is normal. You need at least 9.6v to start a car, if it drops below that while cranking then most likely you have a bad batter or an excessive draw somewhere. What I would recommend is a delayed turn on for what ever you turning on. It is not good for the equipment that your trying to run to have that "surge" of power when the car actually starts, hence why some new cars delay turning on their headlamps(spec. the HID systems) to prevent them from being damaged.

Originally posted by Slo2g
This is normal. You need at least 9.6v to start a car, if it drops below that while cranking then most likely you have a bad batter or an excessive draw somewhere. What I would recommend is a delayed turn on for what ever you turning on. It is not good for the equipment that your trying to run to have that "surge" of power when the car actually starts, hence why some new cars delay turning on their headlamps(spec. the HID systems) to prevent them from being damaged.

You are 100% right. The 9.6v drop while cranking can be used as a general spec. for pretty much all cars.

So I found out that I ordered the the wrong PSU, this is going to be the new one (works 6-24v)
http://www.logicsupply.com/products/m3_atx
I could probably make the old one work with a capacitor across the +/- and a diode (maybe 5A?) in series on the plus side with the cathode facing the cap. So it would only pull power from the cap if battery power dropped below 12v. I might try this if I add anything else to the system.
The new PSU should be pretty sweet, and give me more options.