The Ford Barn

1929tudor · 09-26-2010, 11:42 AM

Still working on my car so I'm only able to take it around the block each week to test things out. I have to charge my battery each week because it keeps going dead. Once charged I can get the car started and drive around the block. Sitting all week it looses charge. Other than the obveous bad battery or bad cells is there something to check to see if something is draining it. When I turn the key off from running it shuts off the car and with the key off it won't start naturally so I know the switch is working. Lights are off and horn is off all week so i know they aren't on. Any help would be great. Oh the battery is only a couple years old. I have an alternator, would that somehow drain it without anything on. Thanks

BRENT in 10-uh-C · 09-26-2010, 11:50 AM

Yep, the alternator typically has a self-exciting regulator that creates a constant drain on the battery. Install a cut-off switch on either the battery or even a small one on the terminal coming from the backside of the alternator.

.

Kurt in NJ · 09-26-2010, 12:11 PM

A battery can have an internal problem that causes it to go dead, try a week of the battery disconnected and see if it goes dead on it's own.

The alternator could have a diode problem, and it is possible that the regulator also has a small drain on the battery when sitting, try a week of the alternator unhooked

Cars that originally have the most common alternator that is used for conversions use a regulator that gets a "turn on " signal from the ignition switch, the "one wire" type alternator can have a regulator that always steals a little electric from the battery so it is ready to turn on.

There could also be a problem with the stop light switch.

Do you have a volt meter that has an "amps" setting?

Have you tried a test light between the batt terminal and the cable, if it lights something is "on" (this will work on old cars without computers, clocks, and radio memory)

I don't have a shutoff switch, and am still using the original generator and expect the battery to still start the car after several months of sitting ---but I see many people with alternators are using shutoff switches ---just be carefull of the ratings and quality of the switch if you decide to use one, many are designed for 12V and will not last when used for the higher demands of a 6V system.

A lead acid storage battery doesn't like being totally discharged too many times, you can take it to 1/2 charge hundreds of times, but totally dead 20 times may be enough to make it bad, or loose much of it's capacity.

johnbuckley · 09-26-2010, 12:51 PM

a master switch to isolate the battery completey is always a good idea, ( useful from saftey point of view as well as as stopping any unintentional drain when car is left unattended)

Tom Endy · 09-26-2010, 02:01 PM

Regardless of how old the battery is, it may have one or more defective cells. My advice is to invest in a hydrometer, available at any parts store, and they are inexpensive. Each cell of a fully charged battery should have a specific gravity of 1280. If one or more cells is lagging, it is an indication of a defective battery. The hydrometer is a big eye dropper looking device that pulls the water out of each cell and a floating element inside indicates the specific gravity.

Another way to tell, as you have an alternator, is that the ammeter should return to zero after some amount of driving. If it is always showing charge it is an indication the battery is not taking the charge. When the battery is fully charged the ammeter should read zero.

An alertnator has a series of diodes in it, usually six, that rectifies the AC voltage to DC voltage. The diodes have a back resistance that can drain the battery over time on a Model A left sitting. The ignition key does not shut things off as in a modern car.

Most of us have installed a fuse on top of the starter. If you lift this fuse it shuts everything off except for the power going to the starter switch. Whenever I secure my car for the day I lift the fuse and stand it on its head at one end of the fuse clip.

The diode modification in a Model A cut-out switch can also drain the battery over time.

It is always a good idea that anytime you exit the car to look at the ammeter to check that the needle is sitting on zero. The ignition may not have turned off and the points are closed, or the brake switch may be stuck. Best to know that before you leave the car.

Tom Endy

1929tudor · 09-26-2010, 02:28 PM

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Thanks everyone for your great relpies. Good info I will use.

Paul from Maine · 09-26-2010, 04:38 PM

Quote:

Originally Posted by 1929tudor

Still working on my car so I'm only able to take it around the block each week to test things out. I have to charge my battery each week because it keeps going dead. Once charged I can get the car started and drive around the block. Sitting all week it looses charge. Other than the obveous bad battery or bad cells is there something to check to see if something is draining it. When I turn the key off from running it shuts off the car and with the key off it won't start naturally so I know the switch is working. Lights are off and horn is off all week so i know they aren't on. Any help would be great. Oh the battery is only a couple years old. I have an alternator, would that somehow drain it without anything on. Thanks

I have a Model T with an alternator. When I shut down the car, if I listen closely I can hear a very quiet high pitched hum. When I shut off the master switch, it stops. My battery has never gone dead because I always shut off the master. I never have investigated it further, but I suspect the alternator. I never heard the hum when I had the generator installed.

Herb Concord Ca · 09-26-2010, 06:18 PM

Like Tom says if you have an alternator, you will likely have a draw on the battery. My 6 Volt pos ground alternator draws about 200ma.
As Tom also says, best to install a safety fuse on the starter that the suppliers sell ( if you don't have one), and when your done driving the A for the day pull the fuse, that's what I have done for over 15 years.
Regards,
herb

ford1 · 09-26-2010, 11:04 PM

ive never had any problems with the 3 wire alt, ive had lots of trouble with the 1 wire draining the battery, same with the alt with the reg, the 3 wire is not "hot" until the key is turned on and then activing the charging system in the alt, put a new batt in the car and see if it goes dead, if it does its not the batt

09-26-2010, 11:42 AM	#1
1929tudor Senior Member Join Date: May 2010 Location: indiana Posts: 135	battery keeps going dead Still working on my car so I'm only able to take it around the block each week to test things out. I have to charge my battery each week because it keeps going dead. Once charged I can get the car started and drive around the block. Sitting all week it looses charge. Other than the obveous bad battery or bad cells is there something to check to see if something is draining it. When I turn the key off from running it shuts off the car and with the key off it won't start naturally so I know the switch is working. Lights are off and horn is off all week so i know they aren't on. Any help would be great. Oh the battery is only a couple years old. I have an alternator, would that somehow drain it without anything on. Thanks

09-26-2010, 11:50 AM	#2
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,509	Re: battery keeps going dead Yep, the alternator typically has a self-exciting regulator that creates a constant drain on the battery. Install a cut-off switch on either the battery or even a small one on the terminal coming from the backside of the alternator. . __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

09-26-2010, 12:11 PM	#3
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,158	Re: battery keeps going dead A battery can have an internal problem that causes it to go dead, try a week of the battery disconnected and see if it goes dead on it's own. The alternator could have a diode problem, and it is possible that the regulator also has a small drain on the battery when sitting, try a week of the alternator unhooked Cars that originally have the most common alternator that is used for conversions use a regulator that gets a "turn on " signal from the ignition switch, the "one wire" type alternator can have a regulator that always steals a little electric from the battery so it is ready to turn on. There could also be a problem with the stop light switch. Do you have a volt meter that has an "amps" setting? Have you tried a test light between the batt terminal and the cable, if it lights something is "on" (this will work on old cars without computers, clocks, and radio memory) I don't have a shutoff switch, and am still using the original generator and expect the battery to still start the car after several months of sitting ---but I see many people with alternators are using shutoff switches ---just be carefull of the ratings and quality of the switch if you decide to use one, many are designed for 12V and will not last when used for the higher demands of a 6V system. A lead acid storage battery doesn't like being totally discharged too many times, you can take it to 1/2 charge hundreds of times, but totally dead 20 times may be enough to make it bad, or loose much of it's capacity.

09-26-2010, 12:51 PM	#4
johnbuckley Senior Member Join Date: Jul 2010 Location: United Kingdom Posts: 1,441	Re: battery keeps going dead a master switch to isolate the battery completey is always a good idea, ( useful from saftey point of view as well as as stopping any unintentional drain when car is left unattended)

09-26-2010, 02:01 PM	#5
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: battery keeps going dead Regardless of how old the battery is, it may have one or more defective cells. My advice is to invest in a hydrometer, available at any parts store, and they are inexpensive. Each cell of a fully charged battery should have a specific gravity of 1280. If one or more cells is lagging, it is an indication of a defective battery. The hydrometer is a big eye dropper looking device that pulls the water out of each cell and a floating element inside indicates the specific gravity. Another way to tell, as you have an alternator, is that the ammeter should return to zero after some amount of driving. If it is always showing charge it is an indication the battery is not taking the charge. When the battery is fully charged the ammeter should read zero. An alertnator has a series of diodes in it, usually six, that rectifies the AC voltage to DC voltage. The diodes have a back resistance that can drain the battery over time on a Model A left sitting. The ignition key does not shut things off as in a modern car. Most of us have installed a fuse on top of the starter. If you lift this fuse it shuts everything off except for the power going to the starter switch. Whenever I secure my car for the day I lift the fuse and stand it on its head at one end of the fuse clip. The diode modification in a Model A cut-out switch can also drain the battery over time. It is always a good idea that anytime you exit the car to look at the ammeter to check that the needle is sitting on zero. The ignition may not have turned off and the points are closed, or the brake switch may be stuck. Best to know that before you leave the car. Tom Endy

09-26-2010, 02:28 PM	#6
1929tudor Senior Member Join Date: May 2010 Location: indiana Posts: 135	Re: battery keeps going dead Sponsored Links (Register now to hide all advertisements) Thanks everyone for your great relpies. Good info I will use.

09-26-2010, 06:18 PM	#8
Herb Concord Ca Senior Member Join Date: May 2010 Location: Concord CA Posts: 635	Re: battery keeps going dead Like Tom says if you have an alternator, you will likely have a draw on the battery. My 6 Volt pos ground alternator draws about 200ma. As Tom also says, best to install a safety fuse on the starter that the suppliers sell ( if you don't have one), and when your done driving the A for the day pull the fuse, that's what I have done for over 15 years. Regards, herb

09-26-2010, 11:04 PM	#9
ford1 Senior Member Join Date: May 2010 Location: oroville ca. Posts: 1,554	Re: battery keeps going dead ive never had any problems with the 3 wire alt, ive had lots of trouble with the 1 wire draining the battery, same with the alt with the reg, the 3 wire is not "hot" until the key is turned on and then activing the charging system in the alt, put a new batt in the car and see if it goes dead, if it does its not the batt