Ignition HT circuit query

[Chris A]

6 minutes ago, NonMember said:

Normally, a battery "sucks in" electrons at the +ve terminal an pushes them out of the -ve one. This provides the electric current from +ve to -ve that you expect.

But what about when you're charging the battery? In this case the current flows into the +ve, meaning electrons are flowing out from it.

So yes, batteries can have the electrons going both ways.

So does this make them Bipolar? 

[poppyman]

1 hour ago, Chris A said:

So does this make them Bipolar? 

How come we have gone from batteries to the arctic?...........

[Mad4classics]

If you're interested and you want to visualise waveforms in the classic ignition circuit, there's quite a good simulation here : http://ltwiki.org/index.php?title=Adventures_with_Analog  called sparkignition.asc which is an LTSpice simulation file.

You need to download LTSpice software from Analog Devices website here:  https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html# to run it; windows or mac only I'm afraid.

Running the simulation gives the following; the green waveform in the picture is the ignition HT voltage while the blue is the primary coil current demanded from the battery - it flows both ways after the points open because of the resonance of the circuit. However, whilst the engine is running the net flow will be the charge current from alternator/dynamo into the battery.

David

[NonMember]

1 hour ago, Mad4classics said:

You need to download LTSpice software   ...   windows or mac only I'm afraid.

There are other Spice versions available for Linux, which may work, of you can run LTSpice under Wine, apparently.