dead batteries,ignition boxes, and melted wires

[cwhubb]

I was reading nacho-rt74's postings on dodgecharger.com forums and this guy is the only one that has ever explained why the mopar engineers went with the mopar style electrical system, it's actually a well thought out design, genius in it's simplicity. ol nacho knows his stuff. He explains it lay man terms and in basic electrical principals.

a quick synapse: dont use a battery that has a higher amp draw than the alt can keep up with, and of course the well known check any sources of resistance. cause resistance equals heat too much heat AND... can I have a coke with my fries.

Correction on the batt amp draw Hemi's right ,I meant to say the battery requires more amps from the alt to replace the drain from cranking

 

[Hemi Rebel]

Say what? Battery's do not draw amps. In a circuit the battery would be a power source. Whatever is being powered in the circuit that draws amps. The load if you will. Bulbs, blower/fan motors or the starter for instance. And, the less resistance in a circuit, the hotter it gets. Less resistance equals more current flow. No resistance equals short to ground, and that means fried wires. Dont believe me? Take a 3/4 wrench in your hand. Touch each end of it to your battery terminals. One side on positive, and the other side on negative. Then take a picture of the palm of your hand and post it on here so we can all see what brand of wrenches you have.

No, don't do that. I don't want to hurt anyone.

 

[cwhubb]

correction you're right I didnt mean draw amps I meant the bigger amp batteries take more amps/juice to recharge them, so with a wimpy alt it takes longer, and yes of course theres always resistance, just with a matched system its not enough resistance to cause over heating

Sorry this is a redundant post

 

[cwhubb]

I dont agree with your statement less resistance makes more heat. the longer the current stays in the circuit and harder it has to work due to resistance the more heat it creates, here's a point a to b example: Imagine your car is the current, you're driving down the highway (the circuit), theres light traffic (traffic equals resistance) you get from point a to b very fast, your car is running nice and cool. Next day on the circuit its bumper to bumper, very high traffic/resistance, it takes a very long time to reach point b and your cars over heating because of the extra load created by the traffic ( high resistance) and the time the current (car) was in the circuit (a to b route)

or think of digging a hole, nice soft loose dirt and you dont have to bust your ***, hard packed dirt you have to work way harder because of the high resistance caused by the hard pack and remain at the task a longer time causing you to bust your *** overheat and sweat like a pig.

 

[moparmarks]

Yep, Nacho is one smart dude. I actually met him at Carlisle a few years back. He wondered into my swap spot and after talking for a while I asked him if he was that dude on Moparts in Argentina. Sure enough.

 

[moparmarks]

the less resistance in a circuit, the hotter it gets. Hemi Rebel could you please explain this in terms that an electrician such as myself could understand?

 

[moparmarks]

Battery is not the main power source, the alternator is. The battery is a start up power source til the alternator takes over. Car will run forever on the alternator, it won't on the battery. Battery does draw current when it needs it.
Nacho found that is was better to connect added loads such as amps and lights to the alternator side of the main circuit rather than the battery side.
He also stated that our little 30amp alternators with 30amp main circuit have a hard time with big high cranking amp batteries.

 

[moparmarks]

Take a 3/4 wrench in your hand. Touch each end of it to your battery terminals. One side on positive, and the other side on negative. Then take a picture of the palm of your hand and post it on here so we can all see what brand of wrenches you have.

Actually resistance is the reason the 3/4" wrench got hot. Your 3/4" wrench is to small. Now use a bigger wrench, say one that will carry 400 amps and see if it gets hot. Same with a dead short. No resistance other than the conductor itself. If the conductor is not rated for the total current draw of the circuit then it puts up resistance against the current flow.
If you have a 400amp battery and put a 30 amp wire across the terminals then the wire will melt but if you put a 400 amp wire across the terminals the wire won't heat up.

 

[moparmarks]

Also not raggin on you. Just kinda bored.

 

[cwhubb]

exactly what I was trying to say! talking about your third post

 

[cwhubb]

I'd like to meet Nacho, seems like a nice guy.

 

[Hemi Rebel]

Take a 3/4 wrench in your hand. Touch each end of it to your battery terminals. One side on positive, and the other side on negative. Then take a picture of the palm of your hand and post it on here so we can all see what brand of wrenches you have.

Actually resistance is the reason the 3/4" wrench got hot. Your 3/4" wrench is to small. Now use a bigger wrench, say one that will carry 400 amps and see if it gets hot. Same with a dead short. No resistance other than the conductor itself. If the conductor is not rated for the total current draw of the circuit then it puts up resistance against the current flow.
If you have a 400amp battery and put a 30 amp wire across the terminals then the wire will melt but if you put a 400 amp wire across the terminals the wire won't heat up.

A wrench is made out of steel. A conductor of electricity, not a resistor. Simply because it isn't big enough to handle the amount of current flowing from a 400 amp battery does not change that fact. Its still a conductor.
The reason that much current is trying to flow through the wrench is because there is no resistance, or not enough in proportion to the amount of current from the battery.Which is why it gets real hot real fast. I can hook a test light up to the same battery and it does not melt down even thought he wire in the light is much smaller than the wrench. the bulb offers resistance in the circuit.
My response is in relation to a vehicles electrical system. I agree that size and length of wire has an effect on current flow in relation to the power source. The thicker or longer the more resistance in that wire. In a car there is no wire guage thick enough or long enough to handle what the battery can supply. even if your battery is in the trunk, a short to ground at the starter will cause the wire to melt. It will take a little bit longer, but its gonna smoke for sure. Unless you ran a wire that is really really thick. But then you would need more than a 400 amp battery to get it to crank over.

 

[moparmarks]

A wrench is made out of steel. A conductor of electricity, not a resistor. Simply because it isn't big enough to handle the amount of current flowing from a 400 amp battery does not change that fact. Its still a conductor.
Yes but not a very good conductor and not one rated to handle the current flow of that battery. There is no perfict conductor and all have some resistance.
The reason that much current is trying to flow through the wrench is because there is no resistance, or not enough in proportion to the amount of current from the battery.Which is why it gets real hot real fast. I can hook a test light up to the same battery and it does not melt down even thought he wire in the light is much smaller than the wrench. the bulb offers resistance in the circuit.
The reason current flows through the wrench because its the shortest path to ground. A test light is not a dead short like the wrench. It has a small resistive load that is not rated for more than it's conductor.
Turn on a 100 watt light then after awhile grab the bulb with your hand then til me the resistive load in the bulb didn't turn your skin to fried bacon.

 

[moparmarks]

The thicker or longer the more resistance in that wire.
Unless you ran a wire that is really really thick. But then you would need more than a 400 amp battery to get it to crank over.
Sorry but both of these statement make no sense

 

[Hemi Rebel]

The thicker or longer the more resistance in that wire.
Unless you ran a wire that is really really thick. But then you would need more than a 400 amp battery to get it to crank over.
Sorry but both of these statement make no sense

Im not trying to get into what conducts better, steel, copper or gold or whatever.keeping this simple.
A 100 watt bulb allows for more current flow than a test light bulb. thats why its hotter. But, a 100 watt house bulb works on ac not dc. lets stick to dc all hooked to the same power source. my test light is 13.5 ohms. a tailight is .7 and a headlight .2 or .3. the less resistance, the more current flow. hook each one up and after 5 minutes grab each bulb.
using the previous example of test light and wrench, with a test light hooked up in series to an amp meter, i have 150milliamps. The headlight bulb has 4.1 amp. more current, hotter brighter bulb.I wont even try it with the wrench. I like my meter.

 

[bigmanjbmopar]

Beer and nachos....sounds good to me...

 

[cwhubb]

Hemi, you say theres no wire big enough or thick enough to handle the batteries output,

not true, the positive cable handles it. all the pos cable is is a huge glorified wire, a wire that easily handles the batteries out put, albeit it wound, its still a functional wire.

 

[440roadrunner]

If nacho is claiming that the Mopar electrical system is a "well thought out" design, he's incorrect.

There has been TONS of info posted about bulkhead connector and ammeter failures, and even MOPAR knew about this a LONG time ago

Want proof?

Find some info on what is known as "fleet and taxi" wiring, which is added, heavier duty wire added for heavy alternators and in police, taxi, fleet vehicles.

Nach IS correct about one thing for better performance WHILE RUNNING and that is connecting heavy loads on the alternator side of the ammeter. BUT WHAT do you do if the car IS NOT running?

Let's just TAKE a "fleet" vehicle, a taxi, a plumbers' van, a PD car "back in the day." First of all, you can only hook so heavy a load at the alternator, because some of the older two way radios simply needed more current --and HAD to be hooked to the battery. But either way, if you hook a load to the alternator side, then when the car is shut off, and you want to run that load, that fan, that radio, whatever it is, the current will now have to go through the ammeter, through the bulkhead, and to the load. Guess what? burned up bulkhead and or ammeter wiring.

And his theory that you should buy no bigger battery than you really need to reduce load on the alternator is a really good proof that he's wrong. I don't advocate using 4 huge batteries in parallel, running them half dead, and then trying to charge them with a stock alternator through factory wiring, but you should be able to buy ANY (heavy) battery that will fit the factory tray and EXPECT the vehicle to perform OK.

RESISTANCE

Resistance goes UP with poor wire, such as non silvered copper, then plain copper, then aluminum, then other materials such as steel or iron, being the worst.

The THICKER the wire is the LESS resistance it has, not more

The LONGER the wire is the MORE resistance it has. ALL wires can be considered to be resistors. If you make them long enough, small enough, and run enough current through them, they will exhibit voltage drop -- a sign of resistance.

The MAD electrical article comes as close as any "rubber stamp" I"ve seen which explains the why and how of Mopar ammeter/ bulkhead problems

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Ferd an GM either quit using ammeters or went with external shunt ammeters for this exact reason.

 

[cwhubb]

that does sound good

 

[cwhubb]

he also said that the ammeter wasnt a heavy duty enough for fleet vehicles, all the lights, radio,and any other high draw additions should have a wiring by pass. He posted a by pass diagram for heavy electrical draw apps that run directly off the alternater side. What I mentioned and what Nacho is talking about is a production model, everyday driver.
In my original post I said it was a SYNAPSE of his article not all inclusive. you should read it, It's very good. and by the battery fitting the application he's talking about the electrical app not if the battery fits in the tray. if you put a heavy duty high amp battery in, the stock system cant handle it and you get the ammeter, bulkhead, over load problem.re-charging the extra amps of the heavy duty battery is the same thing as over loading the STOCK alternators charging capacity to run lights, radios, extra fans etc. any extra high drain load on the stock system needs the re-wire by pass.