Increased Alternator Output at Idle - Opinions

[Nacho-RT74]

I liked the ammeter gauge, but they are source of problems. I don't want to run 100 amps into the dash and back out if I don't have to.

you are allways in danger to draw all the amps the batt is able to give untill wire, terminal or whatever around blows out on short.

if you have a thick wire will draw all the amps the wire is able to hold untill blow by what batt gives, no matter if you have a 40 60 or 100 amps ammeter gauge.

Note, the amps are given by what device requires... a short requires EVERYTHING from the source ( the batt ), except if the medium blows and cuts on that moment ( ie fuse link, thin wire, terminal etc... )

[flyinlow]

Reading with interest guys... all great stuff.    
I have a question though.  Given a situation where you have a high output alternator (100+amps) and the battery is in a serious discharged state, the car is cruising (alternator is at maximum output) and the draw on the alternator other than the battery recharge is minimal... wouldn't the fusible link on the battery side only allow so much current to go to the battery before blowing therefore protecting your factory 40 amp ammeter (assuming it's still wired as per factory and the fusible links blows before 40 amps are allowed to flow in the circuit)??  As I see it, the flow of electricity has to go from alternator to ammeter back out to starter relay (through the fusible link) then to battery in order to recharge the battery.  So, wouldn't the fusible link protect everything in the circuit starting at the splice all the way to the battery regardless of where the fusible link is in the path?    


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Yes the link would protect the battery from receiving a large current. however...all of that current would be going back thru a small charging wire (#12?) from the alternator ,thru the bulkhead connector twice and the factory alt. gauge before getting to the fusible link right before the starter relay.From the starter relay to the battery is a short distance in a much larger cable. Each of those earlier mentioned items is a Resistance to the 100 amps trying to go where 40-50 was meant to. What will give up first?
You can probably get away with this a few times, but it will eventually catch up to you.

[68neverlate]

Yes the link would protect the battery from receiving a large current. however...all of that current would be going back thru a small charging wire (#12?) from the alternator ,thru the bulkhead connector twice and the factory alt. gauge before getting to the fusible link right before the starter relay.From the starter relay to the battery is a short distance in a much larger cable. Each of those earlier mentioned items is a Resistance to the 100 amps trying to go where 40-50 was meant to. What will give up first?
You can probably get away with this a few times, but it will eventually catch up to you.

OK, I follow you... so what would you think of this then. 

I replace my stock alternator with a rebuilt 70 amp Mopar alternator having the smaller diameter pulley to assist low output at idle.  I know it probably won't keep up to demands at idle, but it should be better than the factory set up.  I run a new #10 wire from the alternator straight through the bulkhead, bypassing the bulkhead connector to the splice and then continue with that #10 on to the one side of my factory ammeter.  From the other end of the ammeter, I also run #10 wire through the bulkhead (again bypassing the bulkhead connector) to the fusible link (#14) and from there to the contact point on the starter relay.  In conjunction with this, I also run a #6 wire directly from the alternator to the same connection on the starter relay.  On this wire, I have a #10 fusible link and a diode restricting the flow of current to one direction only (alternator to battery).
 
Would you agree that the increased wiring capacity should reduce wire resistance issues and the bypass going directly from the alternator to the battery starter relay should take at least half the load off of the current going through the ammeter circuit.  The decrease in current going through the ammeter will affect the degree that the ammeter needle moves, but it should still deflect somewhat, showing what state your system is in (charge or discharge).  If the #10 fusible link blows on the bypass from alternator to starter relay, then all the current needed to recharge a seriously discharged battery will go through the ammeter again.  Because of the #14 fusible link, that circuit would never see 40 amps before blowing the #14 fusible link, thereby protecting the ammeter.  That's only if the #10 fusible link blows in the first place, which is unlikely given that it should be able to handle the maximum output of the alternator even if the battery is taking everything the alternator can put out.   

What do you think??

[Nacho-RT74]

These are my thoughts

In conjunction with this, I also run a #6 wire directly from the alternator to the same connection on the starter relay.  On this wire, I have a #10 fusible link and a diode restricting the flow of current to one direction only (alternator to battery).

this is bypassing the ammeter... and no reason for a diode. Both together will make weird readings at ammeter.

Would you agree that the increased wiring capacity should reduce wire resistance issues and the bypass going directly from the alternator to the battery starter relay should take at least half the load off of the current going through the ammeter circuit.  The decrease in current going through the ammeter will affect the degree that the ammeter needle moves, but it should still deflect somewhat, showing what state your system is in (charge or discharge).  If the #10 fusible link blows on the bypass from alternator to starter relay, then all the current needed to recharge a seriously discharged battery will go through the ammeter again.  Because of the #14 fusible link, that circuit would never see 40 amps before blowing the #14 fusible link, thereby protecting the ammeter.  That's only if the #10 fusible link blows in the first place, which is unlikely given that it should be able to handle the maximum output of the alternator even if the battery is taking everything the alternator can put out.   

What do you think??

as stated will affect ( if not totally neutralizes ) the ammeter reading.

Fuse link will start to blow mostly at the time being being of course the smaller the first to blow totally. I would ever use a 10 gauge fuse link. 16 or 14 MAX. If two fuse links being used, 16 MAX. SHORT WILL BE FEED BY BOTH WIRES at the same time, so will be like you have 14 gauge or even 12 fuse link in total. If you fit a 10 fuse link, plus 14, will be ALLMOST like a 8 fuse link... will take FOREVER to blown and damage will be even worst


one question... are you eliminating the stock wires from alt and bat going through the bulkhead ? or still using them ?

[flyinlow]

The #6 wire from the alt. to starter relay/w #10 link/ diode.....hmmm...
The wire is fine. The link is better than no protection, I used a fuse. The diode, I am not sure about . The problem is most diodes have a 0.7 - 1.0 volt drop across them forward bias. At least the smaller ones do. So which way would the power go? The voltage at the Dodie output might be up to a volt lower then what went thru the alt. gauge?

The problem with dual path wiring is this. If one of your two smaller wires breaks ,giving you an open in the wire ,you would not know it until the system was flowing a high amperage load. At that point the too small wire would get hot.

I think the way you talked about would show normal discharge readings,but only partial charge readings?  If I understand what you are thinking of doing.

[68neverlate]

Hey Nacho... appreciate your interest and feedback on this.          

I was thinking about what I posted yesterday on my way home last night and had a few more thoughts myself, but first to answer your question.  Yes, I was planning on eliminating the stock wires from the alt through the bulkhead to the ammeter and back out the bulkhead to the starter relay and replacing that all with #10 (passing it both times directly through the bulkhead - not using the bulkhead connectors).

So my thoughts... after posting yesterday, I remembered that current takes the path of least resistance.  With my suggestion to run a #6 wire directly from the alt to the starter relay connection point, when a battery wants current to recharge, even though a second path from the alternator to the starter relay exists (the #10 wire I mentioned I'd be running above), I'm convinced that most, if not all, the current wanted by the battery will travel through the #6 wire.  The reason is that it is larger and shorter (and therefore will have less resistance) than the longer and smaller #10 wire making up the secondary route through the ammeter.  I initially thought that about half the current wanted by the battery would still go through the ammeter, but now I'm pretty sure it will be almost nothing, if anything at all.  So I can see what you're saying about the ammeter not getting much, if any, current. 

My second thought about the path of least resistance is that if there is a significant demand on the alternator from both the battery AND the car, (at idle let's say so the alt can't keep up to demand), because the path along the #6 wire to the battery is the path of least resistance (the path on the #10 wire to the splice and on through the fuse box and through to whatever device is asking for the power will have more resistance than the shorter #6 bypass wire), the battery will win the battle for power from the alternator.  If that happens, it means the car systems will not receiving much power from the alt and will have to get the rest from the battery.  So, in that situation (battery wants power to recharge and the alternator is not able to meet the total power demanded by the car AND the battery), effectively what my suggested mods have done is transferred more of the load of car systems from the alternator to the battery, which is the exact opposite of what I'm trying to accomplish.  Would you agree with that reasoning??   

I have another simpler idea that I have to put some polish to.  I'll post shortly...

Cheers,           

[68neverlate]

The #6 wire from the alt. to starter relay/w #10 link/ diode.....hmmm...
The wire is fine. The link is better than no protection, I used a fuse. The diode, I am not sure about . The problem is most diodes have a 0.7 - 1.0 volt drop across them forward bias. At least the smaller ones do. So which way would the power go? The voltage at the Dodie output might be up to a volt lower then what went thru the alt. gauge?

The problem with dual path wiring is this. If one of your two smaller wires breaks ,giving you an open in the wire ,you would not know it until the system was flowing a high amperage load. At that point the too small wire would get hot.

I think the way you talked about would show normal discharge readings,but only partial charge readings?  If I understand what you are thinking of doing.

Hmmm... didn't realize that there would be a voltage drop on the diode.  I think you're right about the ammeter readings (normal discharge and partial charge)... although if you follow my last post, it's possible that there could be nothing at all on the charge side.  And yeah, I agree that as soon as one of the parallel wiring circuits go and there's only one left, the current flowing through the remaining circuit could easily cook it if you don't account for it. 

I do have a simpler solution in mind that I'm putting some final touches to.  I'll post that tonight and see what you guys think of that. 

Thanks for your continued interest... really appreciate hearing you opinions!        

[flyinlow]

If you look at why electricity moves thru thru system, it goes from highest potential or voltage to the lowest.( I am not trying to argue which way the actual electrons move )  Alt makes 14 volt potential to ground. If you turn on a light or run the wipers you have 14 volts to push the current. A low battery( enough to still start the car) would be around 12.0 Only a 2 volt potential for the alt. to push current into the battery and reverse the discharge reaction. In this case you are probably OK. A total flat battery (car jump started) 0 volts,is where the alt. has its full 14 volts to  push high currents into the battery. Depends on the resistance of the battery.
If you had a big enough wire to  handle 100 amps and  a 100 amp ammeter (cop car?) and you ran heavier gauge wire every where it was needed you would probably be alright. For my car that's up to 1400 watts (heat gun) going thru the inside of my car, when it does not have to.  I know you want to stay stock looking, however Ma Mopar used relays under the hood to keep the high current of the starter motor out of the cab.   

[68neverlate]

That all makes sense flyinlow.  My objective is to limit the high currents in the cab as much as possible too (that's why I'm making the headlight circuit mods that John Kunkel suggested with relays), but also make it safe for when higher currents do pass through the cab due to a higher capacity alternator, excessive demand or a faulty charging system (dead battery or dead alternator).  I'm trying to accomplish this through fuses, upgraded wiring capacity and a parallel run.  And ideally, I'd like to do this with as little visual alteration as possible (stay with a stock alternator if at all possible). 

The more I get into this, the more I'm realizing that staying with a Mopar alternator may not be possible.  I'm going to see if the electrical shop I'm dealing with can build me a special Mopar alternator that looks stock but can produce 80 amps at max output as well as providing at least 40 amps at idle.  If they can, then I might be able to make the mods described below work.  So, this is the simpler solution I was talking about earlier today.  Interested to hear what you guys think.

Starting at the 80 amp alternator mentioned above, I use #8 wire to replace all the wiring from the alternator through the bulkhead (bypassing the bulkhead connector) to the splice to the ammeter and from the other side of the ammeter through the bulkhead (again bypassing the bulkhead connector) to a #14 fusible link with the other side of the fusible link connected to the contact point on the starter relay (basically, just upgrading the stock wiring to #8 and bypassing the bulkhead connector).  Now, for the parallel run.  Run a parallel #8 wire from the splice through a 30 amp fuse to the battery side of the ammeter.  One further modification... install another 30 amp fuse between the splice and the alternator side of the ammeter.  This should permit up to 60 amps (30 down each route) to flow from alternator to battery or battery to splice without blowing any fuses.

This mod should essentially half the current going through the ammeter circuit.  If the alternator makes 40 amps at idle and the car asks for 80 amps, the 40 amps shortfall will travel from the battery to the splice.  Because there are two routes for this power to get the the splice (ammeter route and the bypass), each would carry about 20 amps (wire size is the same on both).  Neither carries more than 30 amps, so the fuses are fine.  The 40 total amps should pass through the fusible link without blowing it, the car gets what it wants... the ammeter is receiving half of what it would otherwise, but it is still enough to cause the needle to deflect to the correct side, therefore telling you what state your charging system is in (charge or discharge).  It won't read the correct current, but it will tell you what state it is in. 

Now for the two extreme conditions, dead battery and dead alternator.  Assume the car asks for 80 amps and the alternator is completely dead.  All 80 amps will flow from the battery through the fusible link to the junction of the two parallel routes.  This time the battery is pushing 80 amps down the line.  If the fusible link does not blow on 80 amps, the #8 wiring will be fine because it is rated at much higher than 80 amps.  When the 80 amps arrives at the junction of the two parallel routes, it will half (40 amps) down each one.  Because the fuses are rated at 30 amps, they should both blow, protecting the ammeter.  If the battery is dead and the alternator is trying to push maximum current to the battery (assume car is asking for minimal power) then the same result occurs (both 30 amp fuses blow) protecting the ammeter.

Thoughts??      

[ChargerST]

I pictured it like this. It should work but it I'm not sure how accurate the ammeter would work as current would more likely flow through the bypass if the two lines don't have the same resistance (what's the internal resistance of the ammeter?).

Your mod is basically a fused shunt. in theory you can achieve the same result (although not fused) if you connect the two ammeter posts with a thin wire - it would take some load (like 10A) off of the ammeter.

[68neverlate]

Yup, that diagram pretty much puts a picture to my very wordy explanation last night!   

The only thing that I was picturing different is that I wouldn't be using the ammeter to connect to the battery side of the circuit with the bypass (trying to keep the current away from the ammeter to keep the heat down).  I'd be connecting a short distance away from the ammeter.

I follow what you're saying about the bypass taking more of the current because of the resistance of the ammeter.  It's important to ensure that each path takes half the current to maximize the efficiency of the bypass.  I think that's pretty simple to fix though... once the resistance of the ammeter is known, a resistor of the same value can be added to the bypass circuit.  With that change, each circuit would have the same resistance and, therefore, should carry the same amount of current.  I'm guessing the ammeter resistance would be quite low.

I have to give credit where credit is due... I looked back after writing this all out last night and noticed that my solution is very similar to the mod set out by Psycho Chryco earlier in the thread.  A slight variance on connection point of the battery side for the bypass and a few fuses is all that sets them apart.  And I'm sure if you look hard enough, other members have maybe made similar mods, so the idea isn't new.

Interested to hear if anyone knows the impedance of the factory ammeters so the correct resistor can be placed into the bypass circuit, although, I think I'd confirm my own ammeter reading to ensure the correct resistor size is selected. 

Thanks for the diagram ChargerST... I gotta get more savvy with the graphic part of this stuff so I can save a few keystrokes (and you guys some reading time)!           

Interested to hear from anyone else on any shortfalls/deficiencies that they can see of this latest mod...       

[68neverlate]

Apologies to Chryco Psycho... for ambi-dextering your name.  I can't even get my credits straight...    

[Nacho-RT74]

just one note... no matter what you do...all the power demand will go through the cab because the MAIN splice is inside the cab. There is not a way to change that unless a heavy mod or make a full relay setup all around. Being that the first and unvariable true, there is not something wrong on a heavy wire going into the cab.

once again, with a perfect iddle capacity of the alt you won't need ever to take care of the full alt capacity EXCEPT on a death batt, but since the alt you are getting you won't have ever a death batt, so don't worry about the full alt aoutput ever, trust me. I think you are overthinking this.

try first without the wire going to starter relay and if you are not satisfied, then go ahead with that extra wire, but I'm sure you'll be satisfied.

I kept the original wires simply for stock look, but I run 8 on alt side and 10 on batt side ( beside the stock ones still in use ) to the extras/parallel... I used those wires simply because a Coronet 76 I removed all the wiring had those and I reused for my car.

I call them PARALLEL just because I'm not removing the stock wires under the tape, but MaMopar didn't ever used those on the bulkhead bypass, and just used the ones through firewall even with 100 amps leece neville alts

[ChargerST]

I was thinking about adding an 8g or 6g wire from the the alt directly to the battery but switched with a heavy duty relay (100A). Then mount a small relay trigger switch inside the cabin. If I ever have a dead battery I just switch on the alt-battery connection to recharge the battery. That way there would be no current going through the ammeter. After the battery is charged I would switch off the connection and the ammeter would work again.

It would be even better if the relay would be switched on automatically by some sort of amperage sensing device (triggers the relay if it senses a certain amount of current at the + pole of the battery - starter motor shouldn't be a problem as it isn't used when the engine is running). A warning light could be added as well to tell the driver that the ammeter is not functioning momentarily as the battery is recharged. 

[68neverlate]

Thanks for the feedback Nacho... appreciate you keeping your hands (and brain  ) in this.   

I understand what you're saying with the power coming into the cab... I'm not really reducing anything because I'm increasing it (80 amp alternator compared to the original 46 amp) more than I'm reducing it (10 amps for headlights that will now come straight off the alternator with the headlight relay mod).  So, my main goal is to just make everything safe and still have the use of the ammeter to tell me the state of the charging system (it's not important to me to have an accurate reading on the ammeter, I just want to know what state it's in and if it's an extreme condition).  I think the mod stated should do that.

I got some news on the alternator front today... I talked to the head tech at the electrical shop and he was pretty confident he could build me a Mopar alternator that looks stock that meets the 80 amp max output and 40 amps at idle specs I gave him.  He said I wasn't on the hook for it if it didn't generate the minimum 40 amps at idle.       If he can't satisfy the specs, I'm probably going to have to break down and go with a different alternator.  Hopefully he comes through...

Now, I looks like I have a wiring project to get started on   ...

[flyinlow]

Looking at you diagram , I think your new ,larger direct routed wires will work. Still would leave the original fusible link near the starter terminal. If you ran a 75 or the 80amp Mopar alt. you are talking about and did have to jump start a flat battery, just let it idle for awhile before you hit the road. This is always a safer course with a low battery anyway. In case the engine stalls you are somewhere safe with the vehicle. After 15 minutes of so I would think you would be good to go. You could turn the headlights on if they where powered from the alt. directly reducing the power available to run thru the car to the battery. The best way is to recharge the battery before driving the car.  At work I can not take off if the the battery's are Charging at a high rate ,would have to wait until it drops or the better way and sometimes faster way is to have  maintenance swap in fresh battery's first. Don't want an overheated battery or thermal runaway in flight .
Good luck.

[68neverlate]

I was thinking about adding an 8g or 6g wire from the the alt directly to the battery but switched with a heavy duty relay (100A). Then mount a small relay trigger switch inside the cabin. If I ever have a dead battery I just switch on the alt-battery connection to recharge the battery. That way there would be no current going through the ammeter. After the battery is charged I would switch off the connection and the ammeter would work again.

It would be even better if the relay would be switched on automatically by some sort of amperage sensing device (triggers the relay if it senses a certain amount of current at the + pole of the battery - starter motor shouldn't be a problem as it isn't used when the engine is running). A warning light could be added as well to tell the driver that the ammeter is not functioning momentarily as the battery is recharged. 

This would be really cool (the detection of the low battery and automatic switching of the power)!  The direct link from alt to the battery is kind of where I was going in my first suggestion, however, I started having second thoughts about it when I thought it through a bit further.  I became concerned that I may be creating some further problems.  My first concern... the battery may win the battle for power over the car systems because there would be less resistance in the direct circuit from the alt to the battery than there would be from the alt to the systems in the car.  Second, if the systems in the car are not being satisfied by the alternator, it may attempt to draw the power from the battery.  It's even arguable that the new path provided via the direct bypass might have less resistance between the alt and the splice coming from the battery side of the ammeter than the factory path from alt to the splice.  If that's the case, you may be pushing all the power to car systems through the battery side of the ammeter, which may blow the fusible link, or worse yet, cook the wiring or the ammeter.     

I really like the idea of automatically detecting the low battery and having an automated switch to redirect power away from the ammeter and to the battery.  I'd just be concerned that it may create other problems while the battery is recharging.  I'm not sure these things are a concern or not, but it bothered me enough to rethink my original plans.  For what it's worth my friend...     

[68neverlate]

Looking at you diagram , I think your new ,larger direct routed wires will work. Still would leave the original fusible link near the starter terminal. If you ran a 75 or the 80amp Mopar alt. you are talking about and did have to jump start a flat battery, just let it idle for awhile before you hit the road. This is always a safer course with a low battery anyway. In case the engine stalls you are somewhere safe with the vehicle. After 15 minutes of so I would think you would be good to go. You could turn the headlights on if they where powered from the alt. directly reducing the power available to run thru the car to the battery. The best way is to recharge the battery before driving the car.  At work I can not take off if the the battery's are Charging at a high rate ,would have to wait until it drops or the better way and sometimes faster way is to have  maintenance swap in fresh battery's first. Don't want an overheated battery or thermal runaway in flight .
Good luck.

Thanks flyinlow... all really good practices to be sure.  I hope never to have to recover a fully discharged battery without charging it outside the vehicle first, but if I'm stuck and have no choice, I'll remember what you said.  I particularly like what you said about turning on the headlights to cut down the amount of power that's available to recharge a completely discharged battery.         

So, you did say "batteries" in your post... right?  Exactly how many batteries do you have in that trunk anyway??     

[flyinlow]

So, you did say "batteries" in your post... right?  Exactly how many batteries do you have in that trunk anyway??    

No trunk, electronics bay , was talking about being at work . A lot of commercial airliners used two 14V. nickle cadmium batterys in series for the 28V DC part of the electrical system.  Just one battery in the trunk of the Charger.   I guess Charger would be a good name for an electric car. 

[John_Kunkel]

I was thinking about adding an 8g or 6g wire from the the alt directly to the battery but switched with a heavy duty relay (100A). Then mount a small relay trigger switch inside the cabin.  

Why use a switch? I would run the #6 wire directly from the alternator lug across the core support to the battery. The ammeter won't be accurate but it should still show some charge/discharge.

[68neverlate]

No trunk, electronics bay , was talking about being at work . A lot of commercial airliners used two 14V. nickle cadmium batterys in series for the 28V DC part of the electrical system.  Just one battery in the trunk of the Charger.   

Wheew... that's a relief!  I thought for a moment there you had gone over to the dark side... trading your internal combustion for electric!       There would just be something terribly wrong with one of our cars rolling down the road to the whine of an electric motor rather than a ground-pounding big block!     

I guess Charger would be a good name for an electric car. 

Put the Charger on the charger!!   

[Nacho-RT74]

any late 70s alt is able to provide 40 amps alt at iddle. In fact Beck Arnley 78 amps replacements are spec'ed in that way. Now diff is try to build your stock 60's alt on those spoecs what will be really cool

to feed headlights relays you can feed ( and in fact will be the right way to the right amm reading ) from alt stud OR any portion of the wire on alt section of charging system.

However if you decide to fit a wire line between alt and starter relay, you are already modifying the ammeter reading so won't care at the end where you source the relays because its already bypassed.

[68neverlate]

I got some news on the alternator front today... I talked to the head tech at the electrical shop and he was pretty confident he could build me a Mopar alternator that looks stock that meets the 80 amp max output and 40 amps at idle specs I gave him.  He said I wasn't on the hook for it if it didn't generate the minimum 40 amps at idle.       If he can't satisfy the specs, I'm probably going to have to break down and go with a different alternator.  Hopefully he comes through...

An update on the alternator front... I just got my alternator back from the electrical shop and it looks great!        
All stock paint and look with a custom stator that puts out 100 amps and a whopping 50 amps at idle!!  All the while, looking completely stock.   

I'm really impressed with these guys... they sent alway to Toronto to have the stator custom built and then painted up and assembled everything when that came in.  All the power with the stock look...  I can hardly wait to get it in.  Still haven't started the wiring mods... life interupted those the past couple of weeks.  Hoping to get at it this week.  Looking forward to hearing the big block fire up again!   

[Nacho-RT74]

GREEAAAAT, some chance to get me built one for me ?

just teh stator is good enough, I can keep the rest of my pieces and built by myself

[68neverlate]

GREEAAAAT, some chance to get me built one for me ?

just teh stator is good enough, I can keep the rest of my pieces and built by myself

Anytime Nacho, you just say the word and I'll put the order in for you!   

Of course, shipping from me to you might cost you as much as the stator....