Volts or Amps?

This is the R100RS SOBoxer.
Starting it on 24 volts (1) did for the fairing mounted tick-tock and
Motorworks want £50 for a replacement so I find myself perusing a dizzying
array of alternatives in the Demon Tweeks motorsport cat. This got me to
thinking about replacing the slightly vague voltmeter, which raises a
question. Do the panel think that an ammeter might be more useful than a
voltmeter?

(1) or it could have been the dodgy regulator

 

Ammeter, for definite.

It wasn't ;-))

 

Ammeter everytime for me. Yes, the voltmeter might tell you
the battery is low, but the ammeter will let you know this
is going to happen sooner ie if the battery ain't charging
well enough it's going to run out before too long. It was
the best instrument I ever added to my Bedford CA
Dormobile...!

That's my tuppenyworth (how DO you spell that) anyway, thank
you and goodnight...

Nick

 

Is what I was thinking. Now what is the wiring plan?

 

From memory, main feed (usually brown on BMC/Rootes era vehicles) to
starter solenoid (battery side terminal) from regulator routed via a 30A
ammeter wired in series.

==oo--------(A)------[reg]
solenoid meter regulator

 

Have both. Do without the clock.

 

Well I'm thinking about a full stack including artificial horizon, brakeline
pressure and world time in several major capitals. Of course I wish a Boost
Gauge was needed.

 

All you really need is needle, ball and alcohol.

 

Will an artificial horizon stop me falling over (embarrassingly) if I
put my foot where a drain cover isn't at the lights? If so, I NEED one!
Pot guards are wonderful things...

Seriously though - heck that WAS serious - how are you going to fit an
ammeter in the same place as the voltmeter? That'll be some rewiring
job...


Regards,

Simonm.

 

Ammeters don't have to pass all the current to be measured through
the meter. You can implement an ammeter by placing a low-resistance
shunt in the circuit to be measured, and run light-gauge wires from
that shunt to a remote voltmeter. E.g., use a 10 milliohm shunt, 1A
of series current thru the shunt generates 10 millivolts across it.

 

Eh? First aid kit, something to play with, and bottle of booze? Makes a
certain sense.

 

No, you fool. Turn and slip.

 

I know that. It's a question of _what_ you end up measuring, and to do
it well takes a lot of care.

You'll have to run at least one extra wire, possibly two. There's a
multi-way plug between the fairing and the main loom, for example, which
will affect the resistance of the meter loop. If you bypass it, that
means a new pair of wires going from fairing to close to the battery -
not ideal. I guess you'd have to fuse both legs. There's also the matter
of finding the right shunt, and a place to put it...

The BMW voltmeter might be wildly inaccurate, but at least it's
reasonably consistent, and gives me a good indication of the state of
the battery, and if I've left the grips on by accident.

Regards,

Simonm.

 

I wasn't actually advocating an ammeter over a voltmeter. I personally
would take a voltmeter over an ammeter if forced to choose.

 

big fat wire from solenoid to ammeter and back to solenoid, connect
everything except the starter through the ammeter.

 

Is what I was thinking, which kind of puts me off the idea. Don't fancy a FO
cable run all the way up to the fairing panel.

 

I used something similar with my standby generator at my old place. I
monitored the voltage drop from the genny to the change over relays.
Then made up a cheap and cheerful digital AC Voltmeter to monitors it.
After a while I would know how much current was being drawn by the
deepness of the note of the exhaust noise.

 

Probably looking at 3m (ish) of 30A cable. Would be a piece of piss to
do and undo if neccessary.

 

Ah; cheap tyres.

--

Dave

GS 850 x2 / SE 6a
SbS#6 DIAABTCOD#16 APOSTLE#16? FUB#3
FUB KotL OSOS#12? UKRMMA#19

 

Temp gauges for the engine, gearbox and backend.

--

Dave

GS 850 x2 / SE 6a
SbS#6 DIAABTCOD#16 APOSTLE#16? FUB#3
FUB KotL OSOS#12? UKRMMA#19