Hello,
since I heard from the controlled BMW alternator I 'beared' some DIY ideas:
» I guess it would make sense to find a stronger alternator which is able to prive more current (Ampere) because charging times are shorter.
»The lowest cost solution would be some switches which are connetced in that way that alternators field is turned off when vacuum is high (less pressure in manifold) or even cheaper an idle switch. If voltage is beneath a certain value the altornator is feeded as usually.
» A more elgant (but cheap) way would be to modify the field voltage. If field voltage is low than the alternator is producing much current, if field voltage is high, less current.
What's about of a 2 levels of field voltage?
- 7-10V if injector PW = 0 and TPS = idle (engine 'brake') --> maximum current This could be done by a simple fixed voltage regulator like LM7807...
- ~14.5 during cruising so that a minimum of charging is done. I don't know if it's possible to design a fixed voltage booster. I read about voltage boosters which can rise voltage for e.g. 2.0V. I guess field current is small --> no problem with simple ICs. But I don't know if there exist ICs which provide a special amount of voltage independend of incoming voltage.
The opposite function of LM78xx.
Plus some componentes (Z diode...) and the 'controlled' alternator should be ready....
I guess we have not to be afraid in voltage peaks. Older alternators were 'controlled' mechanically by contacts.
Hello AXMonster,
if you tried the circuit in AX then I remember that the battery alarm light on dashboard does not show each alternator failure (as I found it on the hard way). Maybe this is the same reason you reported with the diodes.
I don't know if your 'new' injectors are P&H type. I know the older BOSCH Mono jetronic SPI with a low Z injector. BOSCH added a resistor (5 Ohm or 10Ohm??) to lower current. If you want I can ask a well educated AX/106 guy with MA3.0 ECU.
If it's possible it's better to pick up the signal before the driver because there is is nearly a square wave.
»Horst