# Opus = Best, but will ITPS suffice for low end?

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• 03-19-2004, 05:41 PM
Soul
Hello all, i'm new here and reading allot :)

but i do notice that everybody is talking about watt and not about current (A)
I calculated my total watts with this
http://www.mymp3car.com/MP3Car/PSUpower.asp
I get total of 85 Watt so i think my setup would work with an opus 90 watt
but i see that my 12volt rail is gonna need 3.65A does the 90 watt opus deliver this ?
I know the 150 watt version 'only' has 5A at the 12v rail

I know that P = U * I but i don't know the exact watts that the opus gives on the 12volt rail so i can't calculate the exact amount of ampere i would get at 12 volt rail

or am i missing something ? :p

edit:
Just found opus 90 watt specs and the 12 volt rail only has 2.5A so that wouldn't work, i think.
• 03-19-2004, 08:02 PM
The diode and battery trick is possible but there is a problem. Since the diode lowers the voltage to the sealed battery by a volt or so it lowers the charging voltage to the sealed battery. If your alternator cranks out 14.5 volts when running and the diode sucks a volt then the sealed battery will only see 13-13.5 volts.

This is barely enough to charge the battery in my experience. I did however have the sealed battery setup to charge only when the car was running so if I drove the car only a few minutes a day it wouldn't have enough time to charge.

I figured that if I set the sealed battery to charge even if the car was off then I would be constantly draining my battery because of the voltage difference. Bottom line it can be done but takes some work.
• 03-19-2004, 09:54 PM
cybermob2
Quote:

The diode and battery trick is possible but there is a problem. Since the diode lowers the voltage to the sealed battery by a volt or so it lowers the charging voltage to the sealed battery. If your alternator cranks out 14.5 volts when running and the diode sucks a volt then the sealed battery will only see 13-13.5 volts.

This is barely enough to charge the battery in my experience. I did however have the sealed battery setup to charge only when the car was running so if I drove the car only a few minutes a day it wouldn't have enough time to charge.

I figured that if I set the sealed battery to charge even if the car was off then I would be constantly draining my battery because of the voltage difference. Bottom line it can be done but takes some work.

someone else had mentioned a rechargeable battery (what size i wonder?), which sort of makes sense... quick charging (on 12V)... not necessarily for a tank setup, but for maintaining adequate voltage while cranking. makes sense... it only needs to support for what? 2 seconds?

btw... here are the numbers on my electrical system:
OFF: 12.05±.05V
ACC: 11.8V±.05V
ON Position: 11.66 - 11.76 (varies on amt of accessories on)
CRANKING: <2sec @ 9.6V±.1V
Running: 14.4-14.6V

whats the prognosis doc?
• 03-19-2004, 10:45 PM
cybermob2
ok i've got a plan.

i've realized this:
1. i want the computer on only when choose, not everytime i start the car.
2. i want the computer to shut down automatically when car is turned off.

so, after researching the "fake UPS/XP" shutdown controller (someone please verify that this works), i've decided i'm going to scrap saving for an opus, dodge the ITPS, and rather go with a "press to turn on" route.

so, with a pw70, i'm guessing with no ITPS, i'm gonna need 12V regulation. what do i need to do to regulate and condition the 12V power line properly? thx.
• 05-17-2004, 01:55 AM
yunusyu
Opus does all that for you...itps and pw70 are all in an opus..so choose
OPUS or (itps & pw70...a tank would not hurt either if u want it to work at crank :))
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