Kinderlehrer's wrote:
> Thanks, I think you got the point in your first
> response - even in my generator equipped TR-3, the
> ammeter reads to the + side most of the time,
> meaning I have current to spare, meaning an
> electric fan is not going to sap any more horsepower.
> Unless you want to atart calculating the requirements
> for the extra weight.
Bobk,
I don't know about the TR3, but in my TR6, the
ammeter is wired such that it shows current flow
into and out of the battery, excluding the starting
circuit. I am pretty sure that the TR3 ammeter
would be wired in the same way.
Thus, what the ammeter tells the driver
is whether the battery is charging (+) or
discharging (-). If the battery is neither
charging or discharging, the ammeter should read
right in the middle.
What this means is that in a properly functioning
electrical system, "most of the time" the ammeter
should read right in the middle. If most of the
time your ammeter is reading (+) it means either
* that your battery is not accepting a charge
well (and should probably be replaced), or
* that your car isn't being driven long enough
between starts to fully recharge
As somebody else mentioned, if your ammeter
generally reads (-), this means that your
battery is discharging at that moment, and if you
continue in this way long enough, your battery
will be completely discharged, and your car
won't start next time you try!
On my ammeter-equipped TR6, this is the behavior
I see: (This is the correct behavior, as I
understand it.)
When I first get in my car in the morning, and
turn the ignition to "on" (the car is not yet
running), the ammeter shows (-). This is because
various electrical components are now on (warning
lights). When I turn the key to "start" the
engine starts, and after a few seconds the ammeter
kicks way to the (+) side since the battery is now
slightly discharged, and the alternator is charging
the battery. (I typically don't have my lights,
wipers, or other high-power electrical components
on at this point.) As I drive along, over the next
two minutes, the ammeter will slowly drop from the
(+) side back to the center of the scale, as the
battery gets fully charged. It will then stay
right there in the center while driving, since the
battery is fully charged, and the alternator is
supplying all the current needed to run the electrical
components in use (including the spark plugs.)
If while driving I turn on my lights or a
directional signal, the ammeter will "blip" to
the (-) side when the component first comes on,
recenter while the component is on, and then
"blip" to the (+) side when the component is
turned off. I won't go into the details of why
this happens, but it is a "surge" of current
being provided either by the battery, or being
"absorbed" by it.
--ken
'70 & '74 TR6 Daily Drivers
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
|