14.5V = No Go for pw120?

wizardPC · 02-06-2004, 12:53 AM

My carputer works great, as long as the engine isnt running. The only thing different about my car when the engine is running is that the line that goes to my pw120 gets 14.5v instead of 12.7 when the engine is off.

I couldnt find any references to other people having similar problems.

I have had nothing but trouble with this setup this week, and I thought I had finally gotten everything working. Then I started my car and the PC died (which I thought was odd seeing as it is run off a second battery that is not involved in the starting process). I couldnt get the pc to start again until I turned off the car.

ARG!

Any suggestions?

starfox · 02-06-2004, 01:42 AM

While the car's running your altenator is powering the car electrical system. The altenator will supply ~14.4V which is enough to charge your car battery. There's a device called an ITPS which you can search for which is a low dropout regulator which might help to keep the voltage from jumping up too high (search and read, as running an ITPS is kinda a double edged sword).

Car and PC died means your car stalled and your pc wouldn't boot up? Or something else happened? If you're running a battery management system or charging circuit for your second battery i'd go check your car electrical system, might have a loose ground connection or something...

wizardPC · 02-06-2004, 02:12 AM

There are many problems with the ITPS, chief among them being the fact that it can only supply 60watts. Oh that reminds me I havent ever given any specs for this machine.
This is what is running right now:

Epia M10000
512MB Micron DDR266
30GB Toshiba laptop drive
Eluminix USB Keyboard
Lilliput USB Touchscreen
Deluo USB GPS
Orinoco USB Gold Client
All powered by a PW-120

apparently, many people have been able to get away without any regulation by using laptop components, so thats what I did. The fact that I have so many USB devices means that I cant (or at least shouldnt) use the ITPS due to its relatively low output.

shakes · 02-06-2004, 02:24 AM

wizard ... someone will have to double check me but i'm pretty sure the PW series supplies will take a max of 14v ...

so if you're giving it 14.5 the safety feature of it may be kicking in and turning the supply off.

stick a diode or something in there to get the voltage below 14 and se if it lives.

wizardPC · 02-06-2004, 02:45 AM

I have a potentiometer laying around here somewhere, I'll stick that on the power line and get it to 14v (with a multimeter first, of course) in the morning.

I'm gonna go to sleep now and try this in about 9 or 10 hours. I'll check here first to see if anyone else has come up with anything for me to try, or to tell me that putting a pot on the line is a bad idea.

Golf_MPIII · 02-06-2004, 06:27 AM

Hi
Be careful with the potentiometer, because the current that goes to your psu will also go through the potentiometer.
So if your psu draws, let's say 3 A @ 14V, you need a poti that stands at least 42W ! And that's a lot!

shakes · 02-06-2004, 10:44 AM

yes this is true ... it needs to be a high power pot ...

course if it fries no big deal as the pw70 will just shut off as it has been :-)

shakes · 02-06-2004, 11:26 AM

a potentiometer put in series with the pw-70 will indeed lower the voltage ... and they will both see the same current.

items in series have different voltage drops, same current ... items in parallel have same voltage drop, different current.

wizardPC · 02-06-2004, 12:13 PM

so where does one get a diode that is capable of handling something like this. I'm pretty sure that the little ones you can buy at Radio Shack aint gonna cut it.

(I am about to go outside and test this with my pot)

shakes · 02-06-2004, 12:41 PM

digikey ... the mbr6045 ... unless you have a good electronics store in your area

adamis · 02-06-2004, 01:02 PM

I used the PW-70 unregulated before I got the ITPS (for the shutdown features) and didn't have any problems with it. If I recall correctly the shutoff for over voltage was somewhere around 18 volts. I think this is mentioned in a PDF on Ituners website. It could be you have a bad unit perhaps...

This might be a dumb question but have you started the car with the computer off and then let the computer start? Instead of trying to make the computer survive a crank of the engine. What is this configuration for your tank circuit also? I had one in my car for a while but got rid of it because it was creating more problems then it solved, most of thos similiar as in it would reboot.

Another question, are you getting any life at all from the computer? Does the fan on the motherboard turn for a second or to and then stop? I have a PW-70 that I burned up on accident that would only power the MB for a second and then cut out.

One last thing is it could be the power supply is competing with other electrical systems in your car for the current. Although 4 or 5 amps isn't much if the powersupply isn't getting what it want's it won't work. Try connecting the PW-70 directly to your car battery instead of through your tank circuit and see if that works.

wizardPC · 02-06-2004, 03:04 PM

okay, its not a tank circuit, its a second battery--same battery as my car battery and they are charged by my alternator when the car is on. When the car is off, it disconnects the second battery from the car's electrical system to prevent anything attached to the second battery from draining the primary. Make sense?

I have tried to start the computer after the car is started, and the fan spins for about .01 seconds and then nothing. I then have to physically disconnect the power supply from the battery to get the pc to start again.

I just went outside and connected the pw120 to the primary battery and it worked with the car on. ARG!

I'm about to head to the audio shop that put in the second battery and ask them WTF is going on.

I may have to put another relay in there somewher so that the pc is powered by the seconday battery when the engine is off and the primary battery when the engine is on. This makes no sense to me since the batteries are connected when the car is on. If I have problems with one, I should be having problems with the other.

sigma957 · 02-06-2004, 06:08 PM

I have used an unregulated PW-60 for several months, and it works fine off the alternator. Unless you have a defective unit, I don't think the problem is your power supply.

wizardPC · 02-06-2004, 06:43 PM

okay, after my last post I went back outside and connected to the secondary battery and the PC worked with the engine running. Drove down the highway and got about halfway to where I was going (bout 10 minutes or so) and turned off the computer. Tried to turn it back on, and no go. Voltage was around 14.3

Get to the audio shop and go outside to show the guy whats going on. the PC worked when I cranked the car and he and I talked for a minute or two and I shut off the car, leaving the PC on.

I left the store about 10 minutes later and when I got back realjukebox had experienced a "serious" error and one of those "error reporting" message boxes was on the screen. I rebooted the computer, started the car, and left. About 3 minutes later, RJB experienced another error, as did streetfinder. I rebooted, and the same thing happened about 5 minutes later.

Because of that, I am nearly convinced that there is something wrong with my pw120. I dont think it is regulating the 5v and 3.3v properly, or at least within its tolerances. I bought one of those "universal laptop adapters" from radio shack about 20 minutes ago, and I will be using that the regulate the input to 12v.

EBJUSTIN · 02-07-2004, 01:22 AM

Quote: Originally Posted by wizardPC

okay, after my last post I went back outside and connected to the secondary battery and the PC worked with the engine running. Drove down the highway and got about halfway to where I was going (bout 10 minutes or so) and turned off the computer. Tried to turn it back on, and no go. Voltage was around 14.3

Get to the audio shop and go outside to show the guy whats going on. the PC worked when I cranked the car and he and I talked for a minute or two and I shut off the car, leaving the PC on.

I left the store about 10 minutes later and when I got back realjukebox had experienced a "serious" error and one of those "error reporting" message boxes was on the screen. I rebooted the computer, started the car, and left. About 3 minutes later, RJB experienced another error, as did streetfinder. I rebooted, and the same thing happened about 5 minutes later.

Because of that, I am nearly convinced that there is something wrong with my pw120. I dont think it is regulating the 5v and 3.3v properly, or at least within its tolerances. I bought one of those "universal laptop adapters" from radio shack about 20 minutes ago, and I will be using that the regulate the input to 12v.

I experienced the same problem when I What is the max current rating of the "universal laptop adapter"? See my sig for my 12V regulator solution...it took a bit of time to assemble but it works great and I don't need a tank cirucit during craking because the input voltage can be anywher between 8v to 20 and the output is a constant 12V