4.3 Possible Battery Charging Issue ?

[pcdabbler]

Just treated myself to a cigarette plug in digital voltmeter and tried it in the RAV. It shows something strange, and I'm not sure if it's meant to behave like this ? On start up, the voltage is showing 14.2V, i.e. charging the Battery, and all is well. However, once on a drive, I'm seeing large swings in voltage, it drops suddenly to around 12.5v and stays there. After several minutes, it starts to increase again., then drops to 12.5V. Is there some sort sort of clever charging monitor on the Rav, or is this a dodgy alternator/Reg/Recifier ? There's no error lights on the Rav at all. And I've confirmed the cheap DVM readings at the Battery with a Fluke DVM to show the same swings.

Thanks,

Alan.

[shcm]

Perfectly normal for a 4.3 and probably not a faulty alternator. Yes, you've guessed it, the charging is semi "intelligent"(?). It is supposed to help fuel consumption (all be it slightly) amongst other things.

[pcdabbler]

Thanks for that (relief) ! hoped that's what it was. Too smart for it's own good !

[shcm]

Description attached also applicable to diesels and not just the 1AZ-FE and 2AZ-FE petrols like it says at the top of the pdf.

alternator.pdf

[pcdabbler]

Now that's impressive ! I'm used to constant output alternators and shunt regulators. So the Rav has a variable field Alternator and The ECU controls the alternator output for maximum efficiency.