isolators, tanks, regulators, caps and Mitsubishi brand Alternators

**Jeff48** · 11-27-2004, 11:01 AM

I have done extensive research on this issue both on this board and others so those with a tendency to respond with

or

please try to restrain yourselves.

My car: 1994 heavily modified Mazda RX7 with and OEM 100+ amp Mitsubishi internally regulated alternator and a Optima Red Top.

My computer:
1.2Ghz CPU
512mb DDR Ram
20GB Hard Drive
8x dvd rom
USB GPS Hardware and Software
MediaCar software
Serial Port Datalogging Software
Zippy USB keyboard
USB FM modulator
7" XENARC TFT LCD Touchscreen
ITPS which, if necessary I will replace with an Opus 150W unit.

The problem: No cranking survivability and occasional intermittent short duration low voltage periods at idle which causes the computer to shut down.
At RPMs higher than 1000, constant voltage output between 13.5 and 14.3 volts.

The required solution: A secondary battery (either another Optima or the new Stinger{has a slightly higher resting voltage}). The secondary battery provides all power necessary through the cranking periods and low voltage transients.

The problem: How to charge the secondary battery while not allowing the main system to draw voltage from the carputer power source.

The Usual Fixes:
Isolators- Best alternative
Tank Circuits with the ITPS
Caps
External Regulators.

Why Isolators and tank circuits are not a possible fix: "Mitsubishi alternators do not play well with isolators". This is a quote from tech support at Phoenix Gold. Apparently the feedback system cannot support these solutions. A regulator will keep the main battery from being drained by the computer system when the car is off, but does nothing to keep the computer battery from being drained when cranking or under low alternator voltage periods.

THE QUESTION

Are there any solutions especially for Mitsubishi alternators that will allow the secondary battery to charge but not be available to the main system, and keeps the main system battery from being drained by the computer system.

**sapper6fd** · 11-27-2004, 08:40 PM

I dont know if this has anything to do with it at all, if not its a bit of UFI for ya, but all rotary engines cause a magnetic field, and the hight the RPM's, the sronger the magnetic field. If you put a compas in your vehical, the higher you rev your engine, the more off the neddle will get. Now I don't know if that could cause the voltage drop or not, but hey. Anyone else here have a Carputer in there RX7 or RX8 who has voltage problems?

**dtr** · 11-27-2004, 09:00 PM

I have a RX-7 With a Carputer, Epia M10000, Opus 90Watt, 250Gb HDD, 512 Mb RAM, Lilliput,Zippy EL610, GPS Receiver, Microtech ECU with Serial DataLogging, Yes it is very similar setup and no I am not Kidding I really am running this with no problems at all

**Jeff48** · 11-27-2004, 10:05 PM

Originally Posted by dtr

I have a RX-7 With a Carputer, Epia M10000, Opus 90Watt, 250Gb HDD, 512 Mb RAM, Lilliput,Zippy EL610, GPS Receiver, Microtech ECU with Serial DataLogging, Yes it is very similar setup and no I am not Kidding I really am running this with no problems at all

That is remarkably similar. What year is your 7 and are you running a stock alternator and alternator pulley.
Are you running off a single battery, if so maybe I just need to bite the bullet and go with the Opus 150.

**alti** · 11-27-2004, 10:33 PM

I am not an expert on this at all so forgive me if I am wrong but I remeber reading about tank circuits that were set up with a Diode off of the main battery in the line between the batteries. the diode should prevent current xfer from the secondary battery to the main but allow it from the main to secondary

**alti** · 11-27-2004, 10:38 PM

something like they are discussing here

by the way I used to have a 87' 7 with a aluminum moter that i got from mazda in like 99, man i miss that car

**IamMBS** · 11-27-2004, 11:33 PM

I'd get an OPUS 150

**4u2n** · 11-28-2004, 12:45 PM

Originally Posted by Jeff48

THE QUESTION

Are there any solutions especially for Mitsubishi alternators that will allow the secondary battery to charge but not be available to the main system, and keeps the main system battery from being drained by the computer system.

Yes there is a solutions on my homepage power controler with tank use and double relay

When not power on the main input from cigaret plug the system run on Tank battery and isolate from the car system.

When the system run on car system it charge the tank battery thru an resistor

The controler board is based on tank circiut and a part off ITPS

**Jeff48** · 12-07-2004, 10:57 PM

Well after analyzing all the answers and looking at various possibilities and eating all kinds of crapo from salesmen, I paid the $160+ and bought what I should have right from the start. OPUS90 is the rock solid solution to all my problems. 1 battery, no change to my electrical system etc. The OPUS has survived cranking to below 8.9 Volts and begs for more.

Do not waste as much time and effort as I have,

BUY AN OPUS PSU and enjoy your carputer.