Small voltage stepper upper doodads?

Been driving an '81 RX-7 for a while because summer.  It is an altogether pleasant, if slow, experience, with one issue.  The alternator is fairly low output.

The issue is that I have an Innovate MTX-L in it for to satisfy my inner DAQ nerd.  If I use the headlights, wipers, and blower fan, the alternator cannot keep voltage up enough to keep the Innovate happy and it goes into heater mode when driving, or the dreaded E9 when at idle.  Same for using the A/C under any condition when at idle.

I am wondering if there is not a cheap/simple transformer kinda device I can use that will guarantee that the unit sees over 12.5v even if the woefully underpowered alternator can't keep up.

Be real nice if I could use the defogger right about now...

A bigger alternator would be nice but that would bump the car from Prepared to Mod when I take it to its occasional rallycross.  I am perfectly content with the OE bandaid of using a giant battery to cover up periods of insufficient charging.

The problem is that you need to trade amperage for voltage to do that.   

And the reason you don't have enough voltage to begin with is that it doesn't put out enough amperage, especially at idle.

In reply to Russian Warship, Go Berkeley Yourself :

I get that, but at the same time, if the thing needs 4a at 12v instead of 3a at 14v (or whatever the math is) then that is fine.  I am not worried about insufficient charging, I only want to keep the voltage to the Innovate over a certain level so it does not shut off, which will kill the sensor.

I mean, I know a Boost-A-Pump will do it but that is a bit crazy just to keep a gauge happy 

Does the Innovate need to stay powered-on all the time? Could just use a separate battery for it when tuning.

To answer your question though, yes, and they're called boost converters. It may or may not be easy to find one, but look around on Amazon.

In reply to kb58 :

Must be powered up if the sensor is in the exhaust stream or the sensor will die a rapid death.  Anyway, as Clarkson put it when describing the Skyline GT-R, I'm a bloke and gotta have all the esoteric gauges.  Heck, it is why I bought an Autometer Dash Control for my Volvo.  I can see what the rear diff pump is doing, transmission temperature, shock valving, fuel pressure... if a computer in the car has a sensor for it then I can see it.  It even calculates horsepower and can run a 0-60 time right there in the instrument cluster.

A quick search while I sit here waiting for the car to unfog shows that it should not be too terribly difficult to find or even make.  Thanks!

There are 12 Vdc voltage regulators that do what you want, typically the output is a steady 12 Vdc but you may find one that has an adjustable output that you could dial up to 13 Vdc, input is 10-36 Vdc in the example below.

Something like this.

I wonder if a small super cap battery in parallel with your existing battery would cover those low moments.  Do you have actual current draws?

In reply to Stampie :

It isn't low "moments" though... it is when too many accessories are on.  Like driving in the rain and everyone starts driving really slow and ram air is no longer sufficient to push air through the defrost vents and I have to turn the fan on.

Yes it is perverse that I gotta go 75 to be able to see 

I mean, the obvious solution  is to fix the alternator problem...

In reply to Keith Tanner :

I did submit a rules allowance for Prepared to allow uprated alternators, or conversion from generators to alternators, because the class also allows other electrical component additions or upgrades and this may tax the stock units.  Didn't go through.

There is only so much one can do with 45 amps   The thought had crossed my mind a time or two that it might make sense to swap in a bigger alternator then put the stock one in for competition, it takes less time to change than to change one wheel.  But that is also more stuff to do that takes away from fun, and besides, the only issue is keeping the one little gauge happy.

In reply to Pete. (l33t FS) :

Are there still alternator guys in your area that could maybe upgrade the guts for you?

Maybe that's a grey area rule wise, but isn't being able to see the course kind of a major safety concern?

I don't have anything I'd consider helpful. I'm just disappointed that an alternator upgrade bumps you up a class. If that's not a recommendation for throwing out some rules, I'm not sure what is.

RevRico said:

In reply to Pete. (l33t FS) :

Are there still alternator guys in your area that could maybe upgrade the guts for you?

Maybe that's a grey area rule wise, but isn't being able to see the course kind of a major safety concern?

I HAVE an "upgraded" alternator for the other car.  I took it right back out again because it does absolutely no charging below 2000rpm or so.  Worthless

If it is raining hard enough that you need defrost, we don't run.  Not that it matters because I can use the blower just fine as long as I don't also have the headlights and wipers on.

Really, competiton is a minor thing, I only have issues on the street under very specific circumstances, and I like the stockness of it all.  Upgrading the alternator would require peripheral alterations and pretty soon it is a bastardization of hacks and mods, which is the opposite of what I want to enjoy.  So in a way I am happy that the rule change request didn't go through.

+1 on a boost converter, especially for just one gauge.

If upgrading the alternator isn't allowed, how about tweaking the voltage regulator? Won't help the full load situation but will help to have AC without leaving a brick on the gas pedal. 

Agreed with tweaking the regulator if that is possible on one of those alternators. Also whats the wb grounding? The innovate are VERY sensitive to that and I always ground at battery negative.

What's the full load current of the wideband when the WB is in full heat mode? 

Maybe? DTJ1524S15 https://www.mouser.com/datasheet/2/942/SF_DTJ15-1708603.pdf only 1A though

Choices get thin for higher currents...

What you need is a voltage stabilizer. They are used frequently in marine (boat) applications. It will solve the problem.

Would LED headlights bump you up in class?

A DC-DC converter is the droid you're looking for.

If the upgraded alternator does not charge below 2000rpm there is something wrong with it.

zordak said:

If the upgraded alternator does not charge below 2000rpm there is something wrong with it.

That may be related to the pulley sizes needed to keep the alternator and belt happy at the 7K redline.

The thing is, you have neither an excess of volts OR amps.  Trading amps for volts is only going to work if you've enough, and you don't.  The problem is, you're using too many Watts (Volts x Amps).  You need a bigger battery or an alternator upgrade.

Back when I was tuning the Haltech, I was running the software on an old laptop that had about 5 minutes of battery life.  My solution  was to throw a marine deep cycle battery in the passenger footwell, connect an inverter, and run the laptop off of 120-VAC.

Stampie said:

Would LED headlights bump you up in class?

No, but the only LED headlights for 7" Round are insanely bright, and have really poor patterns, so kind of worthless on the street.

In reply to Pete. (l33t FS) :

You're not giving me much to work with here.

In reply to Stampie :

*shrug*

As long as I don't get it wet, or drive it after midnight, everything is fine