I have a battery cutout switch on my AZU with 605cc engine. When I turn off the ignition, it takes 3 seconds or more for the engine to stop spinning. Is it detrimental to cut the supply from the battery whilst the engine/alternator are spinning even though the ignition is OFF ?
BobH

How does a battery cut out switch work?

I think I would prefer my engine to stop when I turn off the ignition!

Its a heavy duty switch which 'cuts' the battery +ve wire. Ie all systems are dead, but with the alternator still spinning, there is still electricity being generated.

bobh,
I seem to recall this type of cutoff switch, with alternator protection, being fitted to 2CV racers...
.
https://www.pegasusautoracing.com/docum ... =TECH00109

Would it not cut power to the exciter coil of the alternator, and therefore the alternator would not produce power?

Thanks Ken, you have answered my question in that a straight forward cut out switch would damage the alternator IF the motor was turning and the battery disconnected.

I'm confused. Are you saying that your engine runs on after switching off the ignition? (If so, the cause needs rectifying).
Also:
Why would you want to cut the battery feed while the engine is spinning/running? (Assuming that you're not using your van in some sort of motor sport, where the cut-out is for emergency use). (If it IS to stop it running on, you've already cut the ignition feed, so it won't make any difference).
As I said, I'm confused. What have I missed? (I was half asleep when I read your post, so it's quite possible that I've missed something obvious!)

Chevrons2, When I switch off the ignition, the inertia of the flywheel continues to turn the engine over for about another 4 seconds. Now 4 secs isn't long I agree, but time enough to cut the battery off (I always cut the battery when parking up at night or as a security measure). As has been answered, if the alternator is turning and generating energy, then if the battery is taken out of circuit, there is no where for it to go, then damage to the regulator could happen.

I must follow my old school motto :- "I bye my time" - funny how things turn out!

Can't really say I know what I'm talking about here, however, if you put a multimeter on the battery connectors, and start the engine. With engine running, does removing the connector to the exciter coil reduce the voltage being sent to the battery connectors.

I would hope so, as the alternator will only output power when the rotating armature windings are 'excited' . The alternator output comes from the 'field' windings which are stationary. These field windings produce alternating current which is 'rectified' to DC. The regulator controls the "excitation" and thus controls the power output from the field windings.

Note that I use the word 'power' as opposed to voltage and current, but to respond to the question, an alternator usually outputs about 14 volts to a battery which is nominally 12 volts.
BobH