Ammeter heat question

[megavites]

I decided I wanted to do the easier ammeter bypass in my 67 Sat by bolting together the feeds and taping up really good.
My question is would you expect them to get warm?
Roughly, 100degs?
I would expect due to resistance in the system, some heat is expected, but it surely is not enough to melt anything and would be the same even if it was left hooked up to ammeter.
For just this modification, would leaving these taped up behind the dash after experiencing this 100deg or so warmth be acceptable?

 

[SIX225]

I've heard of the ammeters burning up, but I think the real issue of the all problems is that the connectors in the bulkhead corrode. Current is still passing throught the bulkhead if you just tie the wires together at the ammeter. If you're bypassing the ammeter, you should really just bypass all the ammeter wiring through the bulkhead. Personally, I like the functionality of the ammeter and would rewire it with appropirate gauage wire for your alternator directly to the ammeter and likely fuse it too.

 

[Dana67Dart]

The heat is directly proportional to the load.

At the ammeter wires if the battery is low of on its way out the wires will get warm, if the headlights are on they can get warm.
If you have extra non stock loads, fuel pump, electric fans, sound system, higher wattage than stock headlights, etc then you are pulling more wattage through the wire, than stock and it will warm up even more.

The simplest way to bypass the ammeter is to rout a heavy wire with a fusible link in it from alternator to starter relay post (assuming it is that way on your no a body car)

Leaving the rest of the stock wiring alone. That way you have two bulkhead connectors to Cary the load from battery or alternator into the car.


I would clean up the connectors at the bulkhead regardless, tighten up the terminals and check again.


Did you use any type of grease at the 2 terminals you tied together? You might have introduced a resistive connection there by using the wrong type of grease.

 

[67Dart273]

Lots and lots of variables
1...Wiring is old, and under that fancy molding around the wire eyelets are crimp connectors, subject to damage from corrosion and heat damage
2...The wiring was always marginal, and if you've added higher wattage headlamps, stereo, big alternator, etc, the load is increased.
3...Even if the wiring is OK, "it might be" that oxidation on the eyelet surfaces + the type of bolt (plated) reduces conductivity even though connection is tight

100F is not hot. Barely above human body temp.

What you REALLY must do MINIMUM if you want to bypass the ammeter

1...Yes bolt the ammeter wires together BUT!!!
2....Inspect and repair the bulkhead terminals. Absolute MUST
3...Run a bypass direct from battery to alternator through a fuse or breaker. Depending on alternator output, use big wire, no8 min. is good for up through 60A, or parallel about 3 no 10 wires

"One wire" alternators must use much larger oversized output wire, because the sense circuit is over the same wire, and voltage drop becomes very important

 

[megavites]

@Dana67Dart , @67Dart273 ,
car has no additional accessories. Stock headlights. (added crackedback headlight/relay wiring) and 60amp ALT.
-bulkhead connectors where examined, cleaned and di-electric grease added.
-will run bypass from ALT to Starter relay (8GA with 12Ga fusible link) to reduce load thru bulkhead.
I'm debating if i just hook ammeter back up. (connections looked good)
I know i have increased resistance from alt thru volt reg., adding about .25V additional at battery, which i will address with wire replacements.

I was just concerned about the heat felt at the connection, which wasn't much, at the end of the day.

 

[Dana67Dart]

My stock 67 dart has a wire bundle under the dash about in line with the ignition switch.

When driving at night if I grab the bundle there is warmth to it.

I'm not sure if it is heat from the steering column leaking from the engine compartment or the heater or the wires themselves. But I suspect it's the wiring, since I don't notice it during the day.

 

[Mattax]

My question is would you expect them to get warm?
Roughly, 100degs?
I would expect due to resistance in the system, some heat is expected, but it surely is not enough to melt anything and would be the same even if it was left hooked up to ammeter.

No. It should not get warm.
There are only two factors in play; resistance and current.

The resistance may be higher, lower, or the same as when they were connected to the ammeter. It depends on where the resistance is. If the ring terminals are oxidized., if the wire and crimp to the terminals has been damaged, these will cause the same resistance regardless of whether they are attached together or bolted to the ammeter studs.

The current moving through the circuit is the same whether the two wires are connected together or connected to the ammeter.
The only current that should be going through that circuit is when power is needed to start the car, and when the battery is getting recharged.*

Starting will draw no more than 5 or 6 amps though the circuit.
Recharging will draw anywhere from 10 to 20 amps very briefly and then quickly go down to roughly 5 amps, and then eventually zero.
If you see more than this on the ammeter, then the problem is not the circuit, but a high load problem.
With the ammeter disconnected, you can put a clamp type ammeter on the line. (Do not support the meter clamp with the circuit wire!)

On the other hand, if the ammeter is indicating normal operation, and the connectors are getting warm, then there is excessively high resistance.

*There are a couple of exceptions; clock circuit and convertible top were sometimes tied in at the ammeter.

 

[1969383S]

50+ Years later it will get hot! This should alarm any vintage car enthusiast! Replace all the wiring period!

Some Folks just do not get it! The few here that help patch up some posters issues should always have a disclaimer, JMO!