Ammeter Jumping Up When Brake Pressed?

[mattlacey]

After replacing the regulator recently I thought I'd solved my electrical issues. The battery does seem to be staying charged, and the ammeter isn't dipping down, but it's not really going far (if at all) to the right either, I assume because the battery is topped up?|

It drops a bit as expected when I turn the lights on, but still maintains a slight +ve read. However, hitting the rear brake makes it jump right up to around the 3/4 mark, the needles flies so fast it's gotten stuck at the top more than a couple of times. What would cause that? Is it just the regulator making up for the extra power draw? I'm really not sure why it would do it for the brake light and not the others.

Where it jumps to the right in this video, is where I hit the rear brake: https://photos.app.goo.gl/FcnVvTbkWjhNKZ8s8

While I was playing with it just now I discovered the cause of more oil than usual being burnt off on Friday - rocker box cap has gone AWOL

[RalphM]

It will likely do the same if you press the horn as well it's due to the power for the brake light
drawing current from the battery direct not wired through the ammeter, so the regulator tries
to balance the charge and this does go through the ammeter so you see a higher reading.

[Roger Gwynn]

All is normal except the brake light, you have a short somewhere, after the switch

(admin edit - I think this is intended for this thread so I've moved it from 'Decompressor'...)

SG

[mattlacey]

Ah OK, that makes sense! Thanks

[Simon.Gardiner]

All is normal except the brake light, you have a short somewhere, after the switch

I agree with Roger - my ammeter moves a bit when the brake light comes on but nowhere near the end of the scale. Check to make sure you don't have a short somewhere in the brake light circuit.

SG

[mattlacey]

Just saw the moved post - thanks Roger, I'll take a look and see what I can find on the weekend.