The Ford Barn

Ron McIntyre · 07-23-2025, 01:56 PM

New wiring harness. Battery takes a charge. Seems every 2 days battery is dead. What can cause this.

Marshall V. Daut · 07-23-2025, 02:15 PM

Tap the top of the generator cutout with a small hammer or wrench to unstick the points. They may be stuck and are draining the battery.
Also ensure the brake light is off when leaving the car for the night.
Marshall

Y-Blockhead · 07-23-2025, 02:41 PM

Quote:

Originally Posted by Ron McIntyre

New wiring harness. Battery takes a charge. Seems every 2 days battery is dead. What can cause this.

In addition to what Marshall said, IF you have a modern alternator, one or more diodes in the rectifier may be bad.

Ron McIntyre · 07-23-2025, 02:44 PM

Thanks everyone

joncrane · 07-23-2025, 03:02 PM

Battery may be kaput. How old is it? Freeze in the winter?

nkaminar · 07-23-2025, 03:05 PM

Sponsored Links (Register now to hide all advertisements)

A lot of Model A owners end up putting battery disconnect switches in their cars. It will save the battery and is a safety thing.

With the battery disconnected, use the ohm setting on your multimeter to see if there is a drain to ground. Disconnect one thing at a time to discover which item is causing the drain.

Also what Jon Crane said.

Marshall V. Daut · 07-23-2025, 04:42 PM

Get into the habit of checking the ammeter after shutting off the engine. If the needle dips into the negative side and stays there when the ignition key is turned off, something is drawing current. Stuck cutout points usually take an hour or two to completely drain the battery, while a stuck brake light may take one or even two days to do the job. Although unlikely, if the instrument panel light is left on, it, too, will eventually drain the battery. Those lights are not real bright, so if you only drive your Model A during the day, you might not even notice that the light had been inadvertently turned and left on.
Marshall

Keith True · 07-23-2025, 05:15 PM

Has this only happened since you put the new harness in?

ModelA29 · 07-23-2025, 06:01 PM

Quote:

Originally Posted by nkaminar

A lot of Model A owners end up putting battery disconnect switches in their cars. ......

Our Tudor has a cutoff switch. The PO mounted it by the starter so you need to open the hood each time when you take it out for a spin or put it away for more than a day or two.
I mounted this one in our Coupe. It's through the wood floor board (flush with the wood). I just lift the mat to turn it on or off. The connector for my Battery Tender is right next to it.
https://www.summitracing.com/parts/sum-g1442

JoeCB · 07-23-2025, 08:17 PM

I had a slow drain, turned out to be a misbehaving "Pop - Out" ignition switch. Pushed in OK but saw still "on" . Drain was elusive because of position of breaker points. A turn- around to MR Crabtree for a rebuild solved the problem
Joe B

07-23-2025, 01:56 PM	#1
Ron McIntyre Senior Member Join Date: Sep 2011 Posts: 194	Battery killed after 2 days New wiring harness. Battery takes a charge. Seems every 2 days battery is dead. What can cause this.

07-23-2025, 02:15 PM	#2
Marshall V. Daut Senior Member Join Date: Apr 2011 Location: Davenport, Iowa Posts: 2,627	Re: Battery killed after 2 days Tap the top of the generator cutout with a small hammer or wrench to unstick the points. They may be stuck and are draining the battery. Also ensure the brake light is off when leaving the car for the night. Marshall

07-23-2025, 02:44 PM	#4
Ron McIntyre Senior Member Join Date: Sep 2011 Posts: 194	Re: Battery killed after 2 days Thanks everyone

07-23-2025, 03:02 PM	#5
joncrane Member Join Date: May 2010 Location: rochester Michigan Posts: 85	Re: Battery killed after 2 days Battery may be kaput. How old is it? Freeze in the winter?

07-23-2025, 03:05 PM	#6
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 5,860	Re: Battery killed after 2 days Sponsored Links (Register now to hide all advertisements) A lot of Model A owners end up putting battery disconnect switches in their cars. It will save the battery and is a safety thing. With the battery disconnected, use the ohm setting on your multimeter to see if there is a drain to ground. Disconnect one thing at a time to discover which item is causing the drain. Also what Jon Crane said. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

07-23-2025, 04:42 PM	#7
Marshall V. Daut Senior Member Join Date: Apr 2011 Location: Davenport, Iowa Posts: 2,627	Re: Battery killed after 2 days Get into the habit of checking the ammeter after shutting off the engine. If the needle dips into the negative side and stays there when the ignition key is turned off, something is drawing current. Stuck cutout points usually take an hour or two to completely drain the battery, while a stuck brake light may take one or even two days to do the job. Although unlikely, if the instrument panel light is left on, it, too, will eventually drain the battery. Those lights are not real bright, so if you only drive your Model A during the day, you might not even notice that the light had been inadvertently turned and left on. Marshall

07-23-2025, 05:15 PM	#8
Keith True Senior Member Join Date: May 2010 Location: Epping N.H. Posts: 3,423	Re: Battery killed after 2 days Has this only happened since you put the new harness in?

07-23-2025, 08:17 PM	#10
JoeCB Senior Member Join Date: Nov 2018 Location: Farmington MI Posts: 366	Re: Battery killed after 2 days I had a slow drain, turned out to be a misbehaving "Pop - Out" ignition switch. Pushed in OK but saw still "on" . Drain was elusive because of position of breaker points. A turn- around to MR Crabtree for a rebuild solved the problem Joe B