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Alternator Controller behaviour

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On 10/04/2020 at 8:14 PM, Island Time said:

Ideally a reg that is completely voltage adjustable, and has temp sensors for the alt AND the batts, and hopefully a ramp up period to save on belt wear. Plus a hot rated alt. That's the ideal, but as you have discovered, its not inexpensive to do.

I had this on my old motor, although only with a 75amp balmar alt.

On the new D240, it comes with a 115 amp alt with temp sensing - it reduces output if to hot. However its a stupid reg, set voltage, although it has voltage sensing to allow for diodes etc.  I have added one of these http://nordkyndesign.com/product/nordkyn-electronics-vrc-200-charge-reference-controller/ it uses the standard alt voltage sense wire to control the alt, and makes it fully adjustable.

It keeps the temp sense for the alt as standard and has a battery temp sense option. Works great for anyone with a D2 series volvo...

Wow, that is a very interesting unit!

So instead of directly controlling the field voltage/current it varies the sense voltage and thus the internal regulator output?

I guess it depends on how good your internal regulator is , temp cutback etc, not  Hitachi super dumb.

I went the other way and found reliable (medium  duty, well cooled) automotive alternators, got rid of the internal reg, and

fitted off the shelf programmable ext regulators. I see he mentioned  the 10SI, a good alt but not in the same street as the Bosch, IMO.

Mainly owing to ease of modification and ease of external cooling. Plug n play.

Bearing in mind this is for DIYers that want to save decent amounts of money and want duplicates on standby for backup.

Balmars temp sense lead $60US. Nordkyn $20US

Zener diode in lead is a couple of bucks.


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ok update for the thread. got in touch with mr man that made these units and he gave me some advice on how to adjust them for a higher voltage. now set at 14.5v @20deg c, will try this for a few days and see how I go. 

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7 hours ago, lateral said:


Zener diode in lead is a couple of bucks.


That's a clever idea as long as your not expecting great accuracy from a simple circuit.  You could do it with a normal diode as well and no need to have a bias current?  More parts though.

Don't forget to check max operating temp of the diode your using as well.  Most are 150 degree-ish rated or less.

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