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Mazda MX5/Miata alternator control


BarendB
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Hi Guys

Time for another question on my ECU install, the alternator in the 99+ MX5's have charging controlled by the ECU.

Now I struggled to find information here about this for the MX5's, but did find some info on Haltech's forums on how they control the alternator charging.


The base settings are listed below so people can follow this discussion without opening a base map:

Frequency: 250Hz
Start Duty: 75%
Minimum Duty 0%
Max Duty 100%
Gain 100
Target Voltage 14.7

Output Inverted


Please use a spare PWM output to the charge wire of the Alternator.

Use a 470ohm pull up to 12v on the chosen PWM output.
Please use the software settings previously mentioned.
Remember to check to voltage at each RPM site before racing!

I'm pretty sure this is not a problem to setup in Link, my question is more on the how I'll go about doing this, and what he means by "inverted output" and "470ohm pull up from 12v"

Thanks in advance

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Those settings above look like they are intended for some type of basic closed loop system.  We dont have such a function in our firmware.

I suspect you might be able to get reasonable results using a GP PWM table with Bat V on one axis and Eng RPM on the other.  The "inverted output" would be used to tell the output whether 100% in the table means "100% on" or "100% off" - you dont get the choice with a GP PWM table so you would just need to get your numbers the right way around.  Our aux outputs have a 1.5Kohm pullup builtin to the ecu so I suspect you wont need that.

You've seen these things right?: http://www.ebay.com/itm/222318261582

 

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  • 2 years later...

@o_dd Hey mate, I abandoned the idea of trying to control the Alternator with the ECU, just could not get it stable. I wen't through several trail and errors even bought an aftermarket control circuit that is suppose to control the charge etc...

My advice, source an alternator from a 1800 NA, those have the controller built in. Finding them second hand is bit hard, I just ordered one from my local parts store.

FYI I think this is what I bought... but as per the spec the regulator is built in.

https://www.repco.co.nz/en/brands/oex/oex-alternator-12v-80a-mitsubishi-style-mxa234/p/A1192640

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14 hours ago, BarendB said:

@o_dd Hey mate, I abandoned the idea of trying to control the Alternator with the ECU, just could not get it stable. I wen't through several trail and errors even bought an aftermarket control circuit that is suppose to control the charge etc...

My advice, source an alternator from a 1800 NA, those have the controller built in. Finding them second hand is bit hard, I just ordered one from my local parts store.

FYI I think this is what I bought... but as per the spec the regulator is built in.

https://www.repco.co.nz/en/brands/oex/oex-alternator-12v-80a-mitsubishi-style-mxa234/p/A1192640

Thank you BarendB
I wanted to control the alternator with Link.

I look for the alternator who taught me

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