Ammeter bypass

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ir3333

ir3333

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How did the ammeter bypass affect your battery voltage?
After the bypass is installed the old connections through the
bulkhead are no longer in the charge circuit....did your battery
voltage go up a bit?
 
Mine did, but I also put on new alternator so not sure how much it actually helped.
 
tryin' to wrap my head around this modification.
..basically it just splits or reduces the load through the bulkhead?
 
It gets rid of the ammeter in the circuit, which itself is a known weakness in the system. And it bypasses the bulkhead connector, which isn't a good way to run that kind of amperage. Which is why you can often find burned or melted terminals at the bulkhead.

As far as increasing battery voltage, it shouldn't. Or at least not much. You probably eliminate some losses by getting rid of the less than great bulkhead connection, but that's minor. The real benefit is from eliminating the ammeter, which can kill the charge circuit and can cause fires, and the high amperage connection at the bulkhead, which can cause fires as well. It's a more of a safety and reliability improvement than an efficiency improvement.
 
..but you can't get rid of the bulkhead flow by just running the alternator to the battery.
...the bulkhead will still supply some load
 
Why not add an 8 ga wire from the battery to the alt. Ammeter will still work but with less sensitivity. This also reduces the current through the bulkhead
 
My understanding is that the cars entire electric charge must go through the ammeter in order for it to function properly.

A volt meter, on the other hand, will tell you the system voltage when measured from anywhere in the system.

Then again, even when the ammeter is functioning properly it doesn't give you a hell of a lot of information, so maybe you don't care and just want to reduce the load through the bulkhead.
 
yes...i think that is the point.
For those with a large normal load (air conditioning,hi output stereo etc.) the bypass will prevent some of the current from going through the firewall,dash and ammeter.
 
Yeah, if I was running A/C and a boombastic system I'd probably bypass the ammeter all together. Too risky, in my opinion, to have high loads going through 40+ year old wiring with poorly designed connectors.
 
a common problem is overcharging the battery and boiling it over.This can be caused by a failed voltage regulator,poor ground,voltage drop through bulkhead etc.A steady charge as low as 15 volts will eventually boil your battery over and may not be seen until it's too late.
..how could we protect the electrical system from this type of failure????
 
I did this by pass last weekend on my 73 Swinger and it works great but have a bigger problem. Since doing the by pass my car will not shut off, even after removing the key. The alt. is good because with battery pulled she still runs just as smooth, but I have to place a ratchet against the starter relay stud, then touch the iron manifold, cancelling the current to shut her off. I know, very bad thing to do, but only did twice, just to make sure that is what shut her off. I have heard everything from ignition switch, ballast resister, alt. Has anyone had this issue?
 
dbs1473 said:
I did this by pass last weekend on my 73 Swinger and it works great but have a bigger problem. Since doing the by pass my car will not shut off, even after removing the key. The alt. is good because with battery pulled she still runs just as smooth, but I have to place a ratchet against the starter relay stud, then touch the iron manifold, cancelling the current to shut her off. I know, very bad thing to do, but only did twice, just to make sure that is what shut her off. I have heard everything from ignition switch, ballast resister, alt. Has anyone had this issue?
Click to expand...


What changes have you made in the wiring? You have a factory alternator / regulator or a Delco, etc?

You may have created some kind of feedback loop.

Try getting the car running, the unplug the ignition switch connector where it exits the column
 
ir3333 said:
How did the ammeter bypass affect your battery voltage?
After the bypass is installed the old connections through the
bulkhead are no longer in the charge circuit....did your battery
voltage go up a bit?
Click to expand...

If anything the bypass should LOWER charging voltage, that is, it was charging too high before the bypass. The common problem which I've preached a lot on here is voltage drop in the harness, that is the wandering path the voltage regulator IGN terminal takes on the road to the battery. This includes the ignition switch, switch connector, bulkhead connector and ammeter.
 
GMachineDartGT said:
... Ammeter will still work but with less sensitivity. ...
Click to expand...
Probably so little sensitivity that you won't see the needle budge.
I ran the underhood bypass, but w/ a shunt diode that builds up enough voltage drop to move the needle (~0.75 V for 3/4 scale). Unlike a simple resistor, as current increases beyond 30 A, the voltage drop barely increases. See my post "Modernized Engine Wiring ...". But unless you understand physics, you will likely make a mess in fooling with such high currents.
 
My thought was that the reading at the battery would be higher with the charging circuit no longer going through the bulkhead.
..and would also be higher than the reading taken by a meter supplied from the dash.
 
ir3333 said:
My thought was that the reading at the battery would be higher with the charging circuit no longer going through the bulkhead.
..and would also be higher than the reading taken by a meter supplied from the dash.
Click to expand...


Here's how the voltage drop problem works. It is "key" with the voltage regulator IGN terminal which is where the VR reads voltage as well as gets power for the VR and field. The collective drop through the harness terminals and connections DROPS the voltage from the battery down to the VR. So the VR is seeing a reduced voltage. BUT the VR is designed to provide a setpoint AT THAT TERMINAL. So the VR ramps up the alternator until the VR IGN terminal is 14V AKA whatever the setpoint is. Now the voltage at the battery goes high because of the drop in the harness. The charging voltage the battery sees is the difference between the harness drop and the VR setpoint. If you have 1 volt drop in the harness, then you have 14 +1 at the battery.

Now you have UPGRADED the voltage drop and eliminated it, so the battery voltage and VR setpoint BECOME CLOSER. If you have "zero" drop in the harness, then the VR IGN terminal and the battery will be exactly the same voltage

Don't forget ground..........if there's a drop between the neg battery terminal and the VR mounting flange THAT drop will add to the battery voltage.

ALSO REALIZE that just adding a big jumper between the alternator and the battery DOES NOT ELIMINATE all the drop.

You can still have ground side drop..........

and with an original harness, and if the only change is a jumper from alternator to battery, you still have the "drop path".........

Starter relay..........fuse link........bulkhead connector.........ammeter..........ignition switch connector.........through the switch......back through the ign switch connector,........back out the bulkhead on the "run" line.
 
67Dart273 said:
What changes have you made in the wiring? You have a factory alternator / regulator or a Delco, etc?

You may have created some kind of feedback loop.

Try getting the car running, the unplug the ignition switch connector where it exits the column
Click to expand...
I do believe it is a stock alternator, the only thing I did was the by pass and new ignition switch, which didn't shut the car off. Just so I am sure of things, red wire black wire from ammeter spliced, soldered and sealed then spliced to 10 gauge wire, ran through the fire wall, then come together connecting to a 16 gauge fusible link, then connected to starter relay, then a 10 gauge wire from battery stud on alternator to 14 gauge fusible link connected to starter relay, did I miss something? If I pull the bypass wire from the starter relay and the pos. bat terminal she shuts off, and she starts right up and runs smoothly, I am sure either I missed something or I caused a short some where.
 
What happens as I suggested? Running, pull the ignition switch connector loose. It should die. We HAVE had members with new defective switches
 
dbs1473 said:
I did this by pass last weekend on my 73 Swinger and it works great but have a bigger problem. Since doing the by pass my car will not shut off, even after removing the key. The alt. is good because with battery pulled she still runs just as smooth, but I have to place a ratchet against the starter relay stud, then touch the iron manifold, cancelling the current to shut her off. I know, very bad thing to do, but only did twice, just to make sure that is what shut her off. I have heard everything from ignition switch, ballast resister, alt. Has anyone had this issue?
Click to expand...
Wow Dude!
 
67Dart273 said:
What happens as I suggested? Running, pull the ignition switch connector loose. It should die. We HAVE had members with new defective switches
Click to expand...
Never bought one of those bad but I bought many brand new parts that were bad; starters, a hub bearing from Advance Maiden friggin China totaled out my 02 four-door Ram I was second owner of I should have sued over that. Alternators I'm sure I could think of some more but generally most everything lately is garbage and it's mainly crap from overseas
 
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