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pretty good discussion so far, lets talk a little more.....
Although the batteries are connected by various paths and with an added wire here and there can be improved for flow. My thought is that the passenger battery is the closest to the highest demanded load, glow plugs and starter.
Glow plugs are on when the starter is engaged, its a closer path and therefore satisfied at a higher rate from the passenger battery. Any though to the distance?
If it means anything, when a device has dual batteries or more and runs dead, I have swapped the batteries around and gotten limited life out of the device. No other changes.
Can I explain it? Nope, but it has worked, especially my home thermostat.
pretty good discussion so far, lets talk a little more.....
Although the batteries are connected by various paths and with an added wire here and there can be improved for flow. My thought is that the passenger battery is the closest to the highest demanded load, glow plugs and starter.
Glow plugs are on when the starter is engaged, its a closer path and therefore satisfied at a higher rate from the passenger battery. Any though to the distance?
That 2/0 AWG wire has a specific resistance of 0.000256ohm per meter of length.
The length of that wire can't be more than about 2m (9-10ft) in length so the total resistance is probably on the order of 0.0005 ohms. [5 ten-thousandths of an ohm]
If you tried to draw 1000A through that cable, you would see a voltage drop of approx 1/2 Volt
Since starter current can be as high (initially) as 600A, adding the glow plug current (100A) you could see 700A as a probable MAX.
So 2 parallel batteries would be providing around 350A ea (MAX)
350A through a 2 m long 2/0 cable would result in a voltage drop of less than 0.2V
Since the internal resistance of the batteries can be quite a bit more than the resistance of that cable, the connecting cable length is likely NOT significant.
Poor and/or loose connections in the cables + ground connections, plus burned starter solenoid contacts can significantly add to the total resistance of the network. resulting in low voltage at the starter during cranking.
If you have a new battery on one side and an older battery on the other side, the older battery (due to higher internal resistance) will not provide as much current as the new battery.
Battery internal resistance is generally much higher than the resistance of the connecting cables.......and rises with battery age and total (charge/discharge) cycles.
Considering voltage drop is minimal at the distance of 2m, say .5v with all the various connections. Given a set of batteries, brand new optimally connected, we constantly see the passenger battery failing before the drivers side.
Even if the connections aren't optimal (dirty, a little loose, not perfectly sized cables) and everything else considered.... distance, resistance, whatever. My thought is, like a faucet, I turn on full blast cold and then hot, it's not instantly warm, it's cold until some time has passed and it begins to mix. At the point I'm ready to finish washing and the water is just beginning to warm, I'm done. Very similar to flow I believe. By the time the drivers battery is providing it's fair share the demand is lower and the alternator has taken over.
Not sure how much flow has changed since I learned in 83'.
Well, if you want to discuss this in terms of plumbing, the starter and other loads don't care what temperature the electrons are at or how long they have been hanging around in the system, they care about the pressure and volume that comes out of the faucet, and that is constant once the valve is opened.
And this vehicle's plumbing lines are sized correctly when the vehicle comes off the assembly line. But as rust builds up in the hot plumbing line from the passenger battery over time flow will be diminished and pressure will drop. You can clean the rust off the accessible locations which will bring a good portion of the flow back, but it's easier to install a secondary hot water line and oversize it for mechanical strength and unforeseen issues in the original line. And although the additional line has the potential for additional flow, it is not needed since the faucet outlet has a limit to the pressure/flow relationship.
As I stated before I'm not an electrical engineer as I believe HB is, so I don't have the desire to go back and pull up all the research and calculations I would have to do to show the capability of the OE wiring, but years ago I did use Wire Barn's calculation apps to check out the design to try to understand why there are a number of people who had the passenger battery fail earlier. Many of us go through the procedure of cleaning connections up top, but maybe only 0.01% of us have gone to the point of cleaning the negative connection points down low. That 8ga wire calculates out fine for its short length, but I'm sure uncomfortable about it. And really concerned about the pathway as the vehicle ages.
It would have been more expensive to add the cable that I'm promoting should have be done at the factory, and I delt with enough with brake design in production vehicles to understand why it was done that way. But IMO it is the one untested way I can see to be the cause of the battery issue, and the weakest point in the layout. The only need to add cabling up top is because of the additional current going into the 6ga/2x 12ga fusible links from the larger output alternator to the passenger battery terminal.
On edit:
There used to be a good site years ago to help calculate what wire size you needed; these at Wire Barn are similar but will probably drive HB nuts. The first one is good to find the size wire based on the voltage, current and length.
The second page is good to sort out what multiple conductors get you. As an example, the factory alternator to passenger battery is a 6ga wire that also has 2 12ga fusible links spliced into its center. Now when we add a higher output alternator, what is the additional wire we need to run in parallel to handle the addional load. Based on the size of the alternator that can be a variable. 12ga, 6ga, 2ga .......
In an ideal world in the example on my truck I'm using a fuse to protect between the alternator-battery wire. Considering there are already fusible links in the circuitry I shouldn't be doing that. Since I've installed a 230a alt in place of the 110a stock unit what I should do is install another 6ga wire with 2 12ga fusible links spliced in the center, use interface all the same type of protection. I'm not following convention for alternative reasons, but it is the way it should be done. If I still had the 140a alternator in place, the additional wire should be a 8ga with a single 12ga fusible links spliced in. However, usually when you start to talk to people about using fusible links they tend to drift off.
As you've noticed from not burning up your OE wiring with the higher output alternator, the 140a unit stays under 110a at normal startup idle so you've been fine for these few months. But at some point you need an additional wire so provide both full support and protection for the extra 30a. The 36" 12ga wire from the alternator output post to the battery positive terminal will provide more then enough of a path, and the easiest way to provide fusing is with a setup used in my neck of the woods for boating and available through Amazon or a boating supply store. When I had a 140a unit in place I used a 40a to give me a little headroom so it didn't quick blow.
For the 1/0 cable you can get that made up at a NAPA store with 5/16" lugs for a reasonable price or order one through Amazon or eBay. NAPA is my normal go to place and they might even be willing to make a 12ga wire too. Usually anything smaller then 8ga I make up myself.
The 1/0 goes from the drivers frame connection to a boss to the right side of the crankshaft pulley as noted above in my truck.
The picture shows what I have with my 230a alternator, but the fuses are all the same as far as connection, which makes it simple to carry a spare in the glove compartment.
I am in the same situation as Mark_in_Co. My alternator went out so I replaced it with the 140 amp alt. I have not done any upgrades to the stock wiring yet. I know I need to, so I'll be trying to get these cables together while sh'e being torn apart for head studs.
If I buy the basic cable upgrade set from FICM repair (http://www.ficmrepair.com/index.cfm/...prod/prd29.htm) I wonder if the 1/0 wire they use from the alternator to the vehicle frame would be long enough to use in the location you recommend? Just a thought.
I'm still confused on the drivers frame connection location. Can you clear this up for me?
All of that wiring on FICMRepair is excessive, and is installed in addition to the mostly sufficient OE wiring. And the kit does nothing to improve the issue I'm concerned about. With a 140a unit you only need to Siamese a wire sized to carry an additional 30a to the passenger battery terminal. Between the two wires that should be under $20, plus either the fuse or fusible link setup.
Well, if you want to discuss this in terms of plumbing, the starter and other loads don't care what temperature the electrons are at or how long they have been hanging around in the system, they care about the pressure and volume that comes out of the faucet, and that is constant once the valve is opened.
And this vehicle's plumbing lines are sized correctly when the vehicle comes off the assembly line. But as rust builds up in the hot plumbing line from the passenger battery over time flow will be diminished and pressure will drop. You can clean the rust off the accessible locations which will bring a good portion of the flow back, but it's easier to install a secondary hot water line and oversize it for mechanical strength and unforeseen issues in the original line. And although the additional line has the potential for additional flow, it is not needed since the faucet outlet has a limit to the pressure/flow relationship.
As I stated before I'm not an electrical engineer as I believe HB is, so I don't have the desire to go back and pull up all the research and calculations I would have to do to show the capability of the OE wiring, but years ago I did use Wire Barn's calculation apps to check out the design to try to understand why there are a number of people who had the passenger battery fail earlier. Many of us go through the procedure of cleaning connections up top, but maybe only 0.01% of us have gone to the point of cleaning the negative connection points down low. That 8ga wire calculates out fine for its short length, but I'm sure uncomfortable about it. And really concerned about the pathway as the vehicle ages.
It would have been more expensive to add the cable that I'm promoting should have be done at the factory, and I delt with enough with brake design in production vehicles to understand why it was done that way. But IMO it is the one untested way I can see to be the cause of the battery issue, and the weakest point in the layout. The only need to add cabling up top is because of the additional current going into the 6ga/2x 12ga fusible links from the larger output alternator to the passenger battery terminal.
On edit:
There used to be a good site years ago to help calculate what wire size you needed; these at Wire Barn are similar but will probably drive HB nuts. The first one is good to find the size wire based on the voltage, current and length.
The second page is good to sort out what multiple conductors get you. As an example, the factory alternator to passenger battery is a 6ga wire that also has 2 12ga fusible links spliced into its center. Now when we add a higher output alternator, what is the additional wire we need to run in parallel to handle the addional load. Based on the size of the alternator that can be a variable. 12ga, 6ga, 2ga .......
In an ideal world in the example on my truck I'm using a fuse to protect between the alternator-battery wire. Considering there are already fusible links in the circuitry I shouldn't be doing that. Since I've installed a 230a alt in place of the 110a stock unit what I should do is install another 6ga wire with 2 12ga fusible links spliced in the center, use interface all the same type of protection. I'm not following convention for alternative reasons, but it is the way it should be done. If I still had the 140a alternator in place, the additional wire should be a 8ga with a single 12ga fusible links spliced in. However, usually when you start to talk to people about using fusible links they tend to drift off.
The part I don't understand is why use a fusable link over a fuse? To me it seams easier to replace a fuse then to have to splice in a wire when repairs are necessary. A fusable link is just a smaller gauge piece of wire spliced into the overall length....this piece would burn up instead of the whole harness. Is this correct? Or am I totally off base?
I'm still confused on the drivers frame connection location. Can you clear this up for me?
I pulled the air filter to find it yesterday. On my 06, it was below and inboard enough of the cold side intercooler pipe to get 13mm socket and a foot of extensions onto it.
I agree with everything you've said Jack. Adding the wire from drivers frame to block is a huge issue in my opinion as well, something that surprises me they under estimated.
The two wires from the higher output alternator are needed and by using the larger sized cable, the drop over time by degradation is less important.
The internal resistance of the battery is cumulative over time and the more charge/discharge cycles it seems is causing the premature failure over the drivers battery. What we haven't said yet is why that battery over the other.
You believe it to be the missing wire from drivers frame to block. You've had that wire in place for some time now and I saw the test strips you posted. Was the wire in place when the new batteries went in or is that the result of the wire added after?
I'm not an electric engineer, navy trained electronics guy, 32 years in the field and not even close to a smart guy... but the distance of the load to the supply has got to play into the equation. It is, I belive a combination of the issues.... distance, size of wires, internal resistance and ......
I'm curious to see if adding the drivers side wire were capable of diminishing the result of early failure.
I've always seen issues as a numbers game, same for the truck, doesn't matter if it's pressure, voltage or gallons.... the numbers don't lie, it's either there or it's not.
The part I don't understand is why use a fusable link over a fuse? To me it seams easier to replace a fuse then to have to splice in a wire when repairs are necessary. A fusable link is just a smaller gauge piece of wire spliced into the overall length....this piece would burn up instead of the whole harness. Is this correct? Or am I totally off base?
Your absolutely right. My understanding is that all the current protection in a parallel circuit (multiple wires in this case) should be of the same type, either all fusible links or all fuses, so they react the same way. And yeah they are a pain to replace.
And as you can see I'm violating convention in my own application. How many times have we ever heard of this current protection needing to be replaced? One in 500,000? IMO it's there for when there is a vehicle accident or other castastrofic issue. I just feel that when I talk about doing modifications in public I should state the correct way of doing it, but you guys can make your own decision.
My understanding is that you should be 4 sizes smaller in fusible link then the wire being protected. Ford did not follow this general rule by a wide margin. The OE alternator wire is a 6ga, so by convention the link should have been 14ga. However they used two 12ga links in parallel, and acts as a 9ga wire.
I probably should have also noted above in one of my posts that the chart I made up listing Powerstroke wiring sizes is conservative compared to the Wire Barn calculator sizing. My chart uses values I've used for decades at the vehicle testing division I was in charge of to add supplemental wiring for our data acquisition equipment and we never had an issue.
