Well, I don't know, but *if* the correct convention for that ammeter
is to measure current supplied by the bateries to the vehicle (i.e.,
"+" means current flowing out of the battery), then your ammeter's
behavior sounds reasonable to me. Here's my interpretation of your
findings:
"Kelly, Robert" <Robert_Kelly@FCEINC.COM> wrote:
> With ignition OFF, main headlights ON, ammeter reads/moves to the POSITIVE
> range.
Big load, current flowing out of battery.
> With lights still on, engine running at low idle, ammeter reads a
> steady "0".
Charging at the same rate that the lights are discharging, so zero net
current flow at the battery.
> At anything over idle, ammeter needle goes to NEGATIVE.
With the engine revving faster, the generator supplies more current
than the lights draw, so the current starts to go negative at the
battery.
> The ammeter, when the vehicle is runing at anything over a low idle
> without lights on, appears to behave correctly, that is, the needle
> jumps to the far negative range for a moment then slowly settles
> back to the halfway point between 0 and far neg. range. With the
> lights on (under load) the needle settles back a little ways towards
> 0.
The charging current should reduce as the battery takes on charge.
Turning on the lights reduces the effective charging current even more
by robbing some of the charging current.
So, it might be backwards; I don't know what they meant by "+",
because I've only seen "C"/"D" meters in cars, but the behavior seems
consistent with a functional charging system, and it's conventional
in electrical engineering for power supplies with ammeters to indicate
positive current when they're supplying power (i.e., when your battery
is being discharged, if you think of it as a power supply), and to
indicate negative current if power is being forced into the supply
from an external source (often right before the magic smoke comes
out and the supply stops working :-).
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