Ammeter

[David.H]

Chitti - the 1932 AG- IS RUNNING! I am getting 8.5volts at the battery, but the ammeter refuses to acknowledge that fact! The dynamo I think must be working!
All the wiring is newly replaced, so error must have crept in! Any ideas where to start?

[Tiger]

Just about to complete a rewrite on a Ruby.
I already know my ammeter is dodgy.
Sorry to be obvious but what’s the reading with the engine off ?
Wondering how good is your multimeter.
With limited information it sounds like ammeter fault.
Was it working before wiring?
Regards
Tim

[Bob Culver]

Digital meters often go haywire near a running Seven engine. The cheapest moving coil are useful on pre elctronic cars but accuracy poor. Can calibrate from a digital meter.

Attempting to read highish amps on a multimeter often ends in a blown meter (or internal fuse). The meter resistance often alters the current anyway.

[David.H]

Engine off ignition on shows small discharge. Lights on suitable discharge.
With engine running ammeter shows discharge & warning light stays on, but dynamo is charging according to the voltage at the battery the dynamo is putting out a healthy charge. My thought is that a wire to the ammeter is off/ incorrect. ......

["Slack Alice" Simon]

Sounds like the control box isn't clicking in - so the charge isn't getting back to the ammeter, and the light stays on.

[David.H]

Thanks, I will check it out (peer at it & give it a tap !) & see if the wires are connected? ,!
David

["Slack Alice" Simon]

Re-reading the thread - it doesn't sound right.

As I understand it, the voltage is limited by the battery.  7 ish volts at the battery is ok, but I think 8 is too much.

The dynamo can give much more, but the battery itself limits the output to the nominal battery voltage.

And the dynamo output only reaches the battery - if the wiring is correct - via a closed cut out.

So check everything against the wiring diagram.



But, before that, make proper earth connections.   Do not rely on anything like the body or clips that attach things to be good contacts.

I use a couple of distribution points - bolts with heavy duty wires direct to the battery, one at the front and one at the rear, and then separate cables from these to electrical items.

In particular, to the control box and the instrument panel (breaking my rule about direct connections because I don't think there is much of importance needing a good earth on the panel....the indicator module has its own connection), and if I feel it necessary, to the distributor and coil.

I use over-spec battery cables to a gearbox stud and the starter, and the engine spins faster than I have ever heard one before, sounds like it is on 12 volts.

[David.H]

Battery earth is very good...all new. before I renewed the wiring the ammeter went positive, so I think it is something I have done....I will re-check against the diagram!
Thanks to all, I'll report how I get on....no hot wires though- which is good!