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Hi Guys,
A srange fault has occured, Just finished servicing plugs and points and the old girl is really running sweet. I left the car for about a week went to get her out of the garage for a run out and found the battery absolutely dead. The battery was a bit passed it's sell by date so I invested in a new one. After fitting battery went for a run and the car was a dream with everything working ok. Put car back in the garage for a couple of days (you've guessed it flat battery again.) I have never had the car draw off current before and all that was done was a points and plugs service. What could I have done to cause this and how do I connect up a meter to check out draw off. There are only two fuses on the car.

Thanks

Terry

Perhaps it was just coincidence. What did the ammeter indicate:

while you were driving and reasonable road speed?

at idle?

at rest (engine off)?

Might not have been anything you did. It could be a defective battery - even brand-new. Before you do anything else with the car, take the battery back to the seller and have them charge and test it. If battery is OK, then you should look to the car.

For testing things like key-off draw, you'll need an automotive grade ammeter. Multimeters intended for working with electronics should NOT be used (directly). A plain old ammeter (or dash unit) is wired in series with the battery, but you can buy/rent handheld ammeters with a clamp-on pickup. Check with your local auto parts store and be sure to read and follow the included instructions.

Doesn't look like there is anything in the car except the starter switch or startix if you have one that isn't normally going thru the ammeter. If you've checked all the usual reasons or do not see any movement on the needle, then most likely a very low current leak.

Aside from the usual light bulbs being left on which would be easily seen and hopefully not the cause, one other known source of low current leaks is a carbon path in a switch or component. Sometimes a poor connection can cause one of the terminals to heat enough to turn surrounding insulator material into carbon. Can happen fairly quickly although usually there is a smell of hot material when it happens. A path to a nearby ground would then have a low current leak.

A high resistance in a switch could also cause a leak. Sometimes results in a drain thru a light bulb but with the resistance, not quite enough current for the bulb to be seen as on in normal light. Some hydraulic brake light switches have been known to do this.

Without obvious signs if it is a current leak, to find the source almost requires dividing the wiring feeding the car into sections and placing an ammeter on each feed until the area is narrowed down and component isolated and found.

Terry, I'm almost reluctant to mention it as I know you know your car quite well, but any chance that when you parked it both times you left it in reverse? Remember, reverse actuates the brake (backing) lights. Many a battery has gone dead from just leaving it parked for a while in reverse.

Thanks for all the info guys

I will try to take them in order. Firstly, whilst the car was running ampmeter indicated a charge. When at idle coming in and out wtih the cutout doing it's job.At rest with engine off and ignition switch off zero reading on ampmeter.

Secondly,no switches or lights on. No startix system. No smell at anytime from overheating switches.

Thirdly,Another battery that came off another car and fully functional also went flat after a day leaving it. No back up lights fitted as far as I know and checked it out by putting car into reverse ignition on and off.

Next stage I wil put an ampmeter into the circuit when I get one and then report back. I take it the way to test it is to dis-connect the hot lead from the battery and connect the meter to it and then back to the battery.

Thanks as always

Terry.

Terry, that's good information to help with the diagnosis and your data on the ammeter readings is normal, so nothing obvious to me. And FYI all 1934 Packards had a backing light as standard equipment; the circuit activates the brake light filaments.

Try this: with everything electrical turned off, remove the seat and battery cover, and remove the battery ground cable. Then in a near-dark condition just touch the cable to the post, looking for any small spark which would indicate an electrical drain.

Disconnecting the battery is a fine test to confirm the problem. But the car should now have a disconnect switch as well. Some of those wires go through wood and there could be a carbon track somewhere.

For anything higher than .25 amps a test light connected in series will confirm a fire hazard. After that a multimeter with ranges will work. Mine has 15 amps, .250 amps, and .0025 amps.

After you have confirmed a drain, on the right side under the dash is the trunk line for the interior lights. Cut the wire and install a 2.5 amp fuseholder. Then proceed to disconnect stuff until the drain goes away.

Good luck and don't give up until you find this problem.

Thanks Dave and Tim for the info.

Yes Dave I'm really getting to know my way around my car but I must confess that I have seen the reverse light switch on the A.E.A wiring diagram but incorrecty assumed that it would be a white lense lamp not red. Although my stop lights work there is no action from the back up lights when I put the car into reverse. Where is the back up switch located and how does the mechanical operation for this switch work?
Yes Tim I will stay at it as I hate mysterious faults and I have just received a heavy duty isolator switch as a present and will be fitting it in the next few days. I will be testing for any sparks off the battery tonight when it gets dark in the garage and report the results.

Terry, the backing light switch is mounted to the rear of the transmission. It's a simple plunger type of switch and is activated by the shifter rail in the top of trans. If the switch is there but doesn't function, it's very simple to disassemble and fix, just a couple of metal tabs to unfold.