Battery Discharging

C

Capuano

Member
1940 Deluxe/Flathead V8. Replaced generator with MAC 40 amp alternator. Replaced headlights with halogen and running and stop lights with brighter bulbs.
1939/1940 Fords use dash voltmeters. Operation is fine during day but at night voltmeter goes into the red zone indicating discharge. I am not sure if it is a battery, alternator or short in the wiring. Previous owner disconnected hot water heater and clock light for some reason indicating an original problem. With everything off and the battery cutoff switch on a reading in the negative battery wire with a clamp on amp meter indicates 100 milli amps. This must indicate that somewhere in the negative side wiring is shorted to the frame before the switch to that circuit. Is there a means to check wiring before the switch to find short? Any suggestions?
 
If I am understand you correctly sounds like at least two different problems. Halogen lights can pull a lot of power, so that could well be your nighttime issue. On the power drain, 100 mAmps does not sound like a wiring short, sounds more like something is pulling a small amount of power like a radio memory (just an example). Might try disconnecting circuits to isolate it.
 
You didn't mention whether your system is 6 or 12 volts. Regardless, a 40 amp Alternator is on the small size for capacity especially if your are using high-end lighting, heater, etc.

Unless you put a switch on it, an electric clock will use a small amount of current all the time and if the car sits for long periods may run-down the Batt. These are typically twin-coil operated clocks and they take periodic pulses of electricity to re-wind themselves.

Aside from checking for shorts and proper grounding, I recommend checking that new Alternator. If you're not using the original Voltage Regulator and the new Alternator has an internal voltage sensor, the Alternator may have a defective sensor in it or the external voltage sensor wire may not be connected to the right location. I had similar problem to yours .... in my case I have a 55 amp Alternator and the sensor wire was connected to the Alternator's output post instead of at the starter Solenoid where it could "read" the systems actual voltage draw. I made the correction and everything is now bright, gauges are happy and it charges even at idle rpm.
 
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40amp alternator will easily handle halogen bulbs an bright bulbs. I know this as I run halogen headlights with a 20-25 generator (can't remember which one) on my daily car, at this time of year head lites on all the way to work and on journey home.
I'd be checking that alternator and charging circuit, sounds like it's not giving what it's ment to.
Martin.
 
Lets get a voltmeter on that battery....
Voltage with engine off
voltage with engine running
voltage engine running with light on

i had a set of model a halogen on my hot rod and a 40 amp generator wouldnt keep up with them.......
 
Check the connections on the ignition switch that the voltmeter, temp gauge and oil pressure gauge are ALL CONNECTED TO THE LOAD SIDE OF THE IGNITION SWITCH. I have seen the effect of connecting those gauges to the battery side of the ignition switch - drains the battery. Defective diode in the alt will also drain the battery, but http will reduce the output off the alt. Disconnect either terminal from the battery and connect a voltmeter across the disconnected battery cable and the disconnected battery terminal. Start disconnecting the alt, oil pressure sender, horns, lights and other devices until you see the voltmeter drop to zero. You will find it. How about the radio - 12 v?. If so, it could have a direct wire to the battery to maintain station settings. All of these components could add up to the mil amp loss that you are experiencing. Happy Holidays to ALL.
 
BUBBAS IGNITION said:
Lets get a voltmeter on that battery....
Voltage with engine off
voltage with engine running
voltage engine running with light on

i had a set of model a halogen on my hot rod and a 40 amp generator wouldnt keep up with them.......
Click to expand...
This is interesting, how van my 20somethin amp gen be fine with halogens, and your 40amp can't keep up?
One of my customers cars (Morris Minor) has a 35amp alternator on his, we fitted this to go along with other modifications (upgrades) this includes halogen headlights, bright bulbs in back, CD stereo system, heated front and rear windscreens. His 35amp alternator keeps up fine.
Are the output of charging systems not measured in a universal way? Maybe along the lines of, here in Britain it's measured as an average out put and over your side, measured at peak output?.
This maybe nonsense just a guess, trying to work out the apparent different charging abilities of my mentioned points above.
To the op, you state that your battery gauge indicates discharge, does your battery actually go flat? Does the battery gauge red zone actually meen discharge? Or just lower volts? Don't know about the battery gauge, and what the colour zones really meen. An amp gauge actually shows charge and discharge, my experience is with amp gauge systems.
You need to systematically go through the above testing procedures to see what's really going on.
Martin.
 
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There are a lot of different quartz halogen bulbs being used for conversions, what bulbs are you using? I have quartz halogen bulbs on my A, 15 amp generator, battery never goes dead, never charged except by driving, last battery lasted 16 years

I have fouind that most alternator ratings are cold amps, generator ratings are hot amps, so a 32-35 amp generator( most likely what your car had originally) makes about the same amps as a 40 amp alternator when it's hot, and to make the same amps the alternator will have to spin faster, this means you need a smaller pulley on the alternator than the generator had, and much tighter belt tension

Your 100 ma draw is most likely the alternator, many of the voltage regulators used in the delco conversion alternators are sourced from the cheapest source, only have 1/3 the componets inside the regulator of an original delco one

You need a way to measure the amp and voltage output of your alternator, and the electrical needs of your car, then you should be able to pinpoint your problem ---some modern digital meters may not like the flathead ignition system---on my A I had to move the meter behind the door to inside the car, or use old analog meter
 
Thanks to all with possible means to resolve. I will try these in the new year. I had returned the alternator to the manufacturer and they sent me another which did not resolve problem. They suggested taking to Auto Zone to check. Auto Zone could not check since it was 6 volts. Interesting. Could not find current draw of halogen headlights but believe they are 30 watts which would be roughly 5 amps each. Other bulbs are in candlepower so it is unknown. I guess I could use clamp on to measure current draw for each.

With slightly discharged battery the maximum current measured with a clamp on meter on the single wire with engine running was 14 amps. That is the same max current measured when using the battery charger.

Again thanks to all and I have exploratory work to do.
 
scooder said:
This is interesting, how van my 20somethin amp gen be fine with halogens, and your 40amp can't keep up?
One of my customers cars (Morris Minor) has a 35amp alternator on his, we fitted this to go along with other modifications (upgrades) this includes halogen headlights, bright bulbs in back, CD stereo system, heated front and rear windscreens. His 35amp alternator keeps up fine.
Are the output of charging systems not measured in a universal way? Maybe along the lines of, here in Britain it's measured as an average out put and over your side, measured at peak output?.
This maybe nonsense just a guess, trying to work out the apparent different charging abilities of my mentioned points above.
To the op, you state that your battery gauge indicates discharge, does your battery actually go flat? Does the battery gauge red zone actually meen discharge? Or just lower volts? Don't know about the battery gauge, and what the colour zones really meen. An amp gauge actually shows charge and discharge, my experience is with amp gauge systems.
You need to systematically go through the above testing procedures to see what's really going on.
Martin.
Click to expand...

The halgon lights are kinda like electric fans in the respect they all draw different amounts of amps..
I have seen some that take 10 amps and others that take 40-50 amps. Depends on the quality of the lamps etc...:confused::)
 
BUBBAS IGNITION said:
The halgon lights are kinda like electric fans in the respect they all draw different amounts of amps..
I have seen some that take 10 amps and others that take 40-50 amps. Depends on the quality of the lamps etc...:confused::)
Click to expand...

10amps - 50amps! That's a damn big difference. Never new that.
Martin.
 
Kurt in NJ said:
There are a lot of different quartz halogen bulbs being used for conversions, what bulbs are you using? I have quartz halogen bulbs on my A, 15 amp generator, battery never goes dead, never charged except by driving, last battery lasted 16 years

I have fouind that most alternator ratings are cold amps, generator ratings are hot amps, so a 32-35 amp generator( most likely what your car had originally) makes about the same amps as a 40 amp alternator when it's hot, and to make the same amps the alternator will have to spin faster, this means you need a smaller pulley on the alternator than the generator had, and much tighter belt tension

Your 100 ma draw is most likely the alternator, many of the voltage regulators used in the delco conversion alternators are sourced from the cheapest source, only have 1/3 the componets inside the regulator of an original delco one

You need a way to measure the amp and voltage output of your alternator, and the electrical needs of your car, then you should be able to pinpoint your problem ---some modern digital meters may not like the flathead ignition system---on my A I had to move the meter behind the door to inside the car, or use old analog meter
Click to expand...

Thanks for the generator to alternator amp info.
We never finish learning.
Martin.
 
Capuano said:
Thanks to all with possible means to resolve. I will try these in the new year. I had returned the alternator to the manufacturer and they sent me another which did not resolve problem. They suggested taking to Auto Zone to check. Auto Zone could not check since it was 6 volts. Interesting. Could not find current draw of halogen headlights but believe they are 30 watts which would be roughly 5 amps each. Other bulbs are in candlepower so it is unknown. I guess I could use clamp on to measure current draw for each.

With slightly discharged battery the maximum current measured with a clamp on meter on the single wire with engine running was 14 amps. That is the same max current measured when using the battery charger.

Again thanks to all and I have exploratory work to do.
Click to expand...

So does the battery go flat?
Martin.
 
BUBBAS IGNITION said:
The halgon lights are kinda like electric fans in the respect they all draw different amounts of amps..
I have seen some that take 10 amps and others that take 40-50 amps. Depends on the quality of the lamps etc...:confused::)
Click to expand...

Yep, I have had enough issues with them that I don't like using them (I know, I know, there are folks that love them!) I just don't think they are worth the hassles, but that's just me.
 
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