Re: Info From A Lead Acid Battery On An Engine?

1 Lucky Texan wrote:

On Aug 17, 12:18 pm, Vladimir Vassilevsky <nos...@xxxxxxxxxxx> wrote:

eeboarder wrote:

Is it possible to get a run signal just from the battery?

Yes and No. It depends on the particular engine assembly.
The alternator generates the AC ripples which can be seen at the battery
terminals. You can even get the engine RPM by that ripples. However this
behaviour is stongly dependent on the particular engine and the
associated electrics, and this method won't work at all for some

Hmmm....maybe use the exciter circuit thru a bridge on-board and
detect when the voltage is equalized or , as someone said, perhaps
detect the change in current flow to/from the battery. have to create
a rectifier circuit that indicates the change in current flow, but it
could be built into your on-board power supply I guess.

This isn't 100% reliable either since the current flow depends on the engine RPM, the amount of electric load, the temperature and the charging state of the battery. In our days it is all controlled by the MCUs, so you can't take anything for granted.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant