Dave: Have your battery checked for a bad cell.
>Fellow sworkers:
>
>I have been fighting an electrical gremlin in my TR for the past
>several days....
>
>So a digital voltmeter across the battery after a thorough off-line
>charge shows 12.6 volts at rest, falls down a coupla volts during the
>start operation, then goes back to 12.6 or so. Putting the same DVM
>from ground to the D terminal on the E reg. shows 14.5 (about what I
>would expect). The charge current (according to my schematic) goes
>from one of the A terminals through the ammeter thence to the batter
>+ive term. This is where I need some help. Shouldn't the voltage
>across the battery be in the 13.8-14.2 range just after starting? The
>ammeter shows current flow but the voltmeter shows quiescent battery
>voltage, and even I know you cannot charge a battery unless the E
>applied is greater than 12V. Do these lovely Lucas ammeters have a
>shunt just for this purpose and maybe mine is open circuited? As
>usual, any and all info is appreciated.
>
>Replies to foxb@macom.com will get read before those to AOL, FWIW.
>
>Cheers,
>Barry W. Fox 65 TR4A CT51681L
> <<<<<<<<<<<<<<<<<< End Snip >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
>Barry,
>
>Sounds to me like the ammeter is bad. The battery is connected to
>your D terminal via the ammeter and if the voltage is not the same
>then either the ammeter is bad of there is one heck of a load on the
>system (not likely since the voltage differential is 2.5 volts.)
>
>Do this experiment:
>1) disconnect the battery for safety reasons unless you want to
> replace the wiring harness.
>2) Disconnect the wires from the ammeter and connect both to one
> terminal (either terminal.)
>3) Reconnect the battery.
>4) Retest the system and see if the voltages are now the same.
>
>If they are then you need a new ammeter. I haven't seen a bad
>ammeter but it could happen if there was a short circuit at one
>time or another. You can operate the vehicle with the ammeter
>hooked up this way indefinitely but you would not have an ammeter
>(as so many cars on the road have.)
>
>Good luck
>
>Dave Massey St. Louis, MO USA
>
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