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Bypass the Amp guage in my 69 440 GTX?
- Thread starter MrDee
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MrDee
Well-Known Member
I've only run into one guy who displays constant Richard Cranium tendencies on these forums and yes, it's this same guy.
- Local time
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- Location
- Framingham Massachusetts
ynst
Well-Known Member
in ANY ammeter charging system the ammeter is the LAST device in the charging circuit before you reach the battery.
EVERY load should be connected to the alternator side of the ammeter and ONLY the battery positive should be electrically connected to the other side of the ammeter.
With the system wired in this fashion, the ammeter ONLY measures the current flowing into the battery and not the total output of the alternator. On a fully charged battery, this current should be an amp or so and no more.
EVERY other "load" on the charging system is supplied to said loads PRIOR to the current flowing through the ammeter so, after the initial surge in current flow seen after the starter motor has partially depleted the battery, the ammeter will settle back to nearly zero as there should only be a trickle charge going into the battery.
If you have a heavy load on the alternator whilst running the a-c on high, the high beams on, the wipers going full tilt, etc., the alternator will be working overtime keeping up with all those loads BUT the ONLY time you'll see anything to indicate how heavily you are taxing the alternator is when the engine comes to an idle and the ammeter reads negative because the battery is, now, satisfying the loads that the alternator can't keep up with at an idle so the ammeter is showing you the reverse current rate.
So, the ONLY time you should see a pronounced positive needle reading with the engine running is if you are charging a partially depleted battery OR you have everything turned on except the engine, in which case, you'll see a negative reading.
Now, why would you see a high positive reading after starting the engine?
1. You have a bad cell in the battery. Charging it overnight just leaves an easily-depleted surface charge on the battery. To measure the battery without a load tester, first check the voltage at the battery THEN turn on the headlights for about 45 seconds AND THEN take another reading on the battery terminals. If the reading is suspiciously lower, replace the battery.
2. Your starter is drawing WAY too much current, possibly due to worn starter motor bushings and is depleting the battery to a greater degree than normal during the starting operation and your alternator will charge up the battery visible as a pronounced positive position of the ammeter which will slowly move back to just positive of center.
3. You have severely corroded bulkhead connector terminals, probably because the protective coating at the terminals has long-ago deteriorated and allowed moisture to get into the connection and corrode the terminals.
4. You have an aftermarket wiring harness without any protection on the terminals and they've corroded.
Temporary fix for corroded bulkhead terminals:
Remove the connector and pop out the terminal(s) and dip them in muriatic acid for a minute or two the wash them off with water. Carefully squeeze any loose female terminals to allow them to grip the male terminals tighter then snap the terminal back into the connector.
To remove a female terminal from the connector, place a tiny screwdriver into the open end of the terminal (there's a small notch in the connector for access to the locking tab) and carefully bend up the locking tab (seen above on the bottom of the terminal) and slide the terminal out. Carefully bend the locking tab back down before re-inserting the terminal into the connector.
The male terminal can be removed by carefully bending the pointed tang back towards the main body of the terminal and sliding the terminal out the back of the connector. Don't forget to bend the locking tang back before re-inserting the terminal.
When you're finished, pack the outside (under-hood side) terminals with heavy grease to prevent moisture from entering the connection and corroding the terminals.
EVERY load should be connected to the alternator side of the ammeter and ONLY the battery positive should be electrically connected to the other side of the ammeter.
With the system wired in this fashion, the ammeter ONLY measures the current flowing into the battery and not the total output of the alternator. On a fully charged battery, this current should be an amp or so and no more.
EVERY other "load" on the charging system is supplied to said loads PRIOR to the current flowing through the ammeter so, after the initial surge in current flow seen after the starter motor has partially depleted the battery, the ammeter will settle back to nearly zero as there should only be a trickle charge going into the battery.
If you have a heavy load on the alternator whilst running the a-c on high, the high beams on, the wipers going full tilt, etc., the alternator will be working overtime keeping up with all those loads BUT the ONLY time you'll see anything to indicate how heavily you are taxing the alternator is when the engine comes to an idle and the ammeter reads negative because the battery is, now, satisfying the loads that the alternator can't keep up with at an idle so the ammeter is showing you the reverse current rate.
So, the ONLY time you should see a pronounced positive needle reading with the engine running is if you are charging a partially depleted battery OR you have everything turned on except the engine, in which case, you'll see a negative reading.
Now, why would you see a high positive reading after starting the engine?
1. You have a bad cell in the battery. Charging it overnight just leaves an easily-depleted surface charge on the battery. To measure the battery without a load tester, first check the voltage at the battery THEN turn on the headlights for about 45 seconds AND THEN take another reading on the battery terminals. If the reading is suspiciously lower, replace the battery.
2. Your starter is drawing WAY too much current, possibly due to worn starter motor bushings and is depleting the battery to a greater degree than normal during the starting operation and your alternator will charge up the battery visible as a pronounced positive position of the ammeter which will slowly move back to just positive of center.
3. You have severely corroded bulkhead connector terminals, probably because the protective coating at the terminals has long-ago deteriorated and allowed moisture to get into the connection and corrode the terminals.
4. You have an aftermarket wiring harness without any protection on the terminals and they've corroded.
Temporary fix for corroded bulkhead terminals:
Remove the connector and pop out the terminal(s) and dip them in muriatic acid for a minute or two the wash them off with water. Carefully squeeze any loose female terminals to allow them to grip the male terminals tighter then snap the terminal back into the connector.
To remove a female terminal from the connector, place a tiny screwdriver into the open end of the terminal (there's a small notch in the connector for access to the locking tab) and carefully bend up the locking tab (seen above on the bottom of the terminal) and slide the terminal out. Carefully bend the locking tab back down before re-inserting the terminal into the connector.
The male terminal can be removed by carefully bending the pointed tang back towards the main body of the terminal and sliding the terminal out the back of the connector. Don't forget to bend the locking tang back before re-inserting the terminal.
When you're finished, pack the outside (under-hood side) terminals with heavy grease to prevent moisture from entering the connection and corroding the terminals.
ynst
Well-Known Member
Think of a charging system as if you were a plumber.
The alternator is a faucet with a hose attached.
Your hand and eyes are the regulator
A pair of equal-sized buckets represents your vehicle's electrical system.
Connect the two buckets together in the middle with a length of PVC pipe. The pipe is, essentially, your ammeter. One bucket will represent the vehicle's load demands and the other will represent the battery
Now, place the connected buckets on a level surface and fill each bucket with water all the way to the brim.
Now, let's start the car.
Take a coffee cup and remove a few cups of water from the "battery" bucket to simulate the drain of the starter motor. Now cover the battery bucket with Saran Wrap to prevent it from overflowing. Punch a very tiny hole in the cover to allow some seepage.
Turn on the faucet (to replicate a running engine operating your alternator) and fill the uncovered bucket back up so that it, in turn, fills the covered "battery" bucket back up. The flow of water through the connector pipe will gradually diminish as the "battery" bucket fills up just like the needle movement on your ammeter would represent.
Now, whilst doing that, with a drill, make a bunch of holes in the other bucket and keep filling the bucket with your hand on the faucet and your eyes watching the water level in the buckets. You want to keep both buckets filled to the brim.
The "battery" bucket will fill to the brim and the Saran Wrap will effectively shut off the flow of water into that bucket once it's full. A tiny bit will still flow because you poked that tiny hole in the Saran Wrap. That's your trickle charge.
As you continue to drill holes in the other bucket you are, essentially, replicating the addition of lights, wipers, heater, a-c, etc. and you'll have to increase the flow of water to keep both buckets full. The alternator's output amperage (current flow) will increase as you drill more holes.
Essentially, the bucket with the holes is SUCKING water (current flow) from the faucet and the "battery" bucket has stopped SUCKING water from the faucet because it's full.
The voltage regulator (your eyes to monitor the situation and your hand to control the flow) will limit the output so that the buckets don't overflow. If you reduce the flow of water (engine idling), the "battery" bucket will start draining back into the bucket with the holes in it (shown as a slight discharge at idle on your ammeter). If you increase the water flow again, you'll not only be refilling the bucket with the holes in it but you'll, also, be replenishing the "battery" bucket so you'll have flow back into that bucket as well (ammeter reading slightly more positive) until the "battery" bucket is full again.
If you shut off the flow of water (replicating shutting off the engine) the "battery" bucket will, now, start to try and fill the bucket with the holes in it.
The more holes you can plug up, the slower the water will flow through your ammeter (pipe) in the reverse direction. This is why your ammeter shows a discharge if something's turned on but the engine isn't running.
The alternator is a faucet with a hose attached.
Your hand and eyes are the regulator
A pair of equal-sized buckets represents your vehicle's electrical system.
Connect the two buckets together in the middle with a length of PVC pipe. The pipe is, essentially, your ammeter. One bucket will represent the vehicle's load demands and the other will represent the battery
Now, place the connected buckets on a level surface and fill each bucket with water all the way to the brim.
Now, let's start the car.
Take a coffee cup and remove a few cups of water from the "battery" bucket to simulate the drain of the starter motor. Now cover the battery bucket with Saran Wrap to prevent it from overflowing. Punch a very tiny hole in the cover to allow some seepage.
Turn on the faucet (to replicate a running engine operating your alternator) and fill the uncovered bucket back up so that it, in turn, fills the covered "battery" bucket back up. The flow of water through the connector pipe will gradually diminish as the "battery" bucket fills up just like the needle movement on your ammeter would represent.
Now, whilst doing that, with a drill, make a bunch of holes in the other bucket and keep filling the bucket with your hand on the faucet and your eyes watching the water level in the buckets. You want to keep both buckets filled to the brim.
The "battery" bucket will fill to the brim and the Saran Wrap will effectively shut off the flow of water into that bucket once it's full. A tiny bit will still flow because you poked that tiny hole in the Saran Wrap. That's your trickle charge.
As you continue to drill holes in the other bucket you are, essentially, replicating the addition of lights, wipers, heater, a-c, etc. and you'll have to increase the flow of water to keep both buckets full. The alternator's output amperage (current flow) will increase as you drill more holes.
Essentially, the bucket with the holes is SUCKING water (current flow) from the faucet and the "battery" bucket has stopped SUCKING water from the faucet because it's full.
The voltage regulator (your eyes to monitor the situation and your hand to control the flow) will limit the output so that the buckets don't overflow. If you reduce the flow of water (engine idling), the "battery" bucket will start draining back into the bucket with the holes in it (shown as a slight discharge at idle on your ammeter). If you increase the water flow again, you'll not only be refilling the bucket with the holes in it but you'll, also, be replenishing the "battery" bucket so you'll have flow back into that bucket as well (ammeter reading slightly more positive) until the "battery" bucket is full again.
If you shut off the flow of water (replicating shutting off the engine) the "battery" bucket will, now, start to try and fill the bucket with the holes in it.
The more holes you can plug up, the slower the water will flow through your ammeter (pipe) in the reverse direction. This is why your ammeter shows a discharge if something's turned on but the engine isn't running.
This isn’t the first trashing go-around. I had replied that Nacho was very helpful guiding me through some unusual wiring connections given that what I was installing wasn’t a stock feature. We had several back & forths due to my questions, Nacho was quite patient even providing some of his own drafted sketches, and got back to me timely. Every one of his recommendations worked perfectly. No condescending attitude, no inclusion of his background to try to make an impression. Copying advice from others? Who doesn’t? If one reads something in a manual, car magazine, or got advice from another, thereby learning from it, applying it, and later sharing it, is this a complaint?
CoronetDarter
Well-Known Member
Subscribed. Very informative videos, thank you.
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