Dual Alternator install

[MichaelOverfield]

Michael, when I was researching ammeters for my truck, I decided to use a Hall effect current sensor rather then a shunt. While I have not yet completed the project (dual voltmeters and ammeters to monitor the charging system and battery use) I feel that they are much safer to install and maintain as opposed to a shunt, particularly with 300 amps going to it. Here is the one I found that I believe is up to the task. The company was also very helpful in tech support. IIRC, they are about $50 each and very easy to install. See info below--

http://www.inpowerdirect.com/docs/OM-23D.pdf

Thanks, I did look at similar units on Amazon. Certainly easier to install. One negative review pointed out they were subject to magnetic inerferance under the hood, in his case it was an issue.. since the first logical place for this sensor is pretty close to the alternator, initially ruled it out. That said there is a similar sensor on my Chevy Cruze, GM uses a computer stategy to monitor amps out of the Battery, it's on the negative ground cable, far from the alternator. It may be easier to have a slightly longer alternator to Battery cable and put these sensors behind the batteries one each side, over a shunt.. I will certainly consider this option.

 

[MichaelOverfield]

Michael, when I was researching ammeters for my truck, I decided to use a Hall effect current sensor rather then a shunt. While I have not yet completed the project (dual voltmeters and ammeters to monitor the charging system and battery use) I feel that they are much safer to install and maintain as opposed to a shunt, particularly with 300 amps going to it. Here is the one I found that I believe is up to the task. The company was also very helpful in tech support. IIRC, they are about $50 each and very easy to install. See info below--

http://www.inpowerdirect.com/docs/OM-23D.pdf

Do you recall where you purchased those meters? Amazon has a similar unit, but doesn't seem as quality, and about $24.

 

[seafish]

Contact Wesgarde (Simi Valley, Cal) at 805-579-9200 with the part #. They are distribute for inpower. I believe that there will a 2 week lead time. I have NOT bought mine yet.

 

[MichaelOverfield]

Tested the high side driver circuit today, initially it was driving a bit higher than the ECU signal (initially mostly due to no load, so I hooked it up to the second alternator field so it would drive under load), with both fields driven the second was still about 0.4 volts higher. [Knowing one field getting driven higher than the other would mean one alternator doing almost all the work, I sought a way to adjust this]* *(SEE POST #87, fields will self balance). The input resistance made no difference, even 2 - 15kOhm in series. Which from a circuit standpoint makes sense, that is a no current, voltage only input. Then I realized I had a plethora of diodes, about $5 gets you about qty 25 on Amazon. A diode has a voltage drop in the forward direction.. it turns out that got me within 0.01 volts, consistently, to make it more interesting found one of my meters was intermittently reading in error, fortunately I had a 3rd meter and figured that out pretty quick. Good enough! Now it will be the routing of the wires and such to take on. I think I'm going to stick with the shunt ammeters, I think the Battery mounts will work pretty well as a surface to install these shunts.#ad

 

[tvantuyl]

Nice that you were able to equalize the output of each alternator. Good pics, too.

 

[MichaelOverfield]

Nice that you were able to equalize the output of each alternator. Good pics, too.

To be specific, what I'm measuring in those readings above is field voltage, which assuming the alternators have same characteristics (they should), then it would follow they will have same output.. but that will be measured by the ammeters on each, when I get that far.

 

[Flash1034]

Most of this is hieroglyphics to me....but I sure am enjoying the thread and learning some things. Makes me glad I ordered the dual alternator system.

 

[MichaelOverfield]

Most of this is hieroglyphics to me....but I sure am enjoying the thread and learning some things. Makes me glad I ordered the dual alternator system.

Understand, it's a bit all over the place.. when I get the thing complete I'll organize the salient points.

 

[MichaelOverfield]

I've not given up, work demands of late have put the rest of install on hold, but I should get back to it in a week or so.

 

[MichaelOverfield]

To help those with 3rd Gen trucks older than 2008 who wish to try this, you do have a different circuit and style of regulation, see posts 27 – 30, and especially the REMY Tech bulletin posted as well. Here is that link again:
http://www.remyautoparts.com/The-Latest/2016/July/Chrysler-Application-Diagnostics-for-Alternator-w
If you have the “B” circuit, it is “high side” driven meaning the ECU/PCM is sending a positive pulse to the alternator field, in that case, you should be able to use the exact same regulation circuit I have described, only you have no need to do anything with the B sense, as you don’t have that in your system..
HOWEVER, if you are “A” circuit, you are “low side” driven, where the PCM/ECU alters the field GROUND, or low side, then you need to a completely different circuit for the second alternator.

I had exceptional help from David Swanson, at STI, and I’m going to copy what he said here, and try to attach the circuit design he proposed for a low side solution, this was before I clarified that mine was actually high side, which is where the simpler driver card came to be my solution.
From David’s e-mail:
“A” circuit, low side driven from PCM/ECU:

Buffer circuit to prevent excess current through PCM/ECU driving a second alternator:

“Q1 is a simple PNP transistor.. I would pick a 100V equivalent to a 2N3904… whatever that might be.



Q2 would have to be a lower Rds(on) MOSFET .. Again I would pick a 100V part… Not too low an Rds(on) because you are turning off Q2 with a 10k resistor… kinda slow…gate capacitance grows as Rds(on) goes down…

D1 should be rated at at least half the full on current. A 5A field would need at least a 2.5A diode…

Remember your switching elements are going to dissipate heat… Q2, D1. They may need some heat sinking. Under hood environment hot temperature ranges from 105C to 125C. That does not leave a lot of room for power dissipation in the switches.

I know I just gave you two opposing arguments… Low Rds(on) slows switching thereby increasing switching losses… High Rds(on) increases conduction losses… Engineering. J

A better gate driver might eliminate the first concern.

One more thing… You can put a switch in series with field 1 to disable the second alternator.”

 

[subsea]

Ok, best I can tell is the 220A uses the single field wire, internal grounded field regulation, which began in 2008. From the Remy technical bulletin I posted earlier, you'll have a system that uses 2 wire field regulation. The 220A would otherwise work bolt-in, no apparent changes in mounting brackets. So, if you want to do this, you would have to MODIFY the unit such that the field has both sides connected to your truck via the 2 wire connector. See the pictures of the Denso unit I posted earlier. The brush holder has 2 screws that hold it in, and connect the field windings. One goes to the connector, the other to ground.. you'll have to break the connection to ground ( insulate with plastic, etc. Then run a wire out to make that second connection. That I think would work.

I just had a look at my tech manual for my 2006 2500 Cummins, and it appears that the field is controlled by the high side, and the low side goes "direct to ground". Unless the manual is woefully inadequate and over simplifying things, the he should be able to just hook the high side wire to this Denso 220A alternator and let the alternator do the grounding, right? (assuming his year model has the same circuit as mine)

BTW, thanks for all the research. I will embark on a dual alternator install after I return home and fix all of these oil leaks.

 

[MichaelOverfield]

I just had a look at my tech manual for my 2006 2500 Cummins, and it appears that the field is controlled by the high side, and the low side goes "direct to ground". Unless the manual is woefully inadequate and over simplifying things, the he should be able to just hook the high side wire to this Denso 220A alternator and let the alternator do the grounding, right? (assuming his year model has the same circuit as mine)

BTW, thanks for all the research. I will embark on a dual alternator install after I return home and fix all of these oil leaks.

That would be the "B" circuit shown in that Remy technical bulletin. I'd verify using the test sequence also described on that bulletin. Should be a simple voltage measurement. The low side circuit has one wire at full battery voltage, otherwise you can be sure it's not low side, and is high side driven. Now I'd then verify there is nothing in the ground circuit side of your connector to ground side field winding. If it just goes straight to ground, then it would be a simple hook up, you'd use just the field side wiring, the B sense would have no connection for you. Otherwise I'd break the internal ground side field connection and run that side of the field out of the alternator and connect it to your existing harness. That way if there is any PCU/ECM monitoring of your alternator field on the ground side, it will continue to work. Not sure there is such monitoring, however, you should be able to trace the ground wire to be sure.

 

[MichaelOverfield]

Hoping to hook up the wiring this weekend. The connections will also permit operation with dual, or single, and selection of either alternator from inside the cab. The diagram is pretty rough, but it consists of a DPDT ON/ON switch, that selects either alternator in SINGLE MODE (does nothing in DUAL MODE). The second switch is a 4PDT ON/ON switch. In single mode it passes the field control and B+ Sense to the DPDT switch, where it connects to the selected alternator, just as it would be from the OEM. In DUAL MODE the switch connects the Driver input, ECU field together with the input to alternator 1, the driver output powers Alternator 2. The other contacts connect the B+ Sense from each alternator together and tie it to the ECU B+ Sense input. I added the diodes to the Field of each alternator, to prevent any inductive kick from the switching between alternators, there is a similar diode already in the Driver board output to protect that circuit, so it is redundant for Alternator #2, but I have like 25 of them, and they are cheap. These additional diodes protect the ECU from that inductive kick in single mode if changing the selected alternator while energized. I'll attach a diagram below:
=====================>

 

[MichaelOverfield]

Ok, ALMOST done with wiring. Might have been a bit faster had I not added so many other things at the same time. Figured out the shunt ammeters I bought won't work, they are wired to measure current between the loads and ground, impossible most places on a grounded system, and particularly impossible for an alternator which is grounded by mounting bolts! Tonight I should be doing a test run, without ammeters. I ordered new hall effect meters to install later. Here are some pictures:#ad

 

[MichaelOverfield]

Later today I'll be operational testing. It took hours to get the new belt on, I think that this belt had been on the shelf for awhile and was a bit stiffer than typical. I could write a small book on the assorted tools and techniques used to get it on.. the tensioner is almost completely retracted and spring fully compressed.. I expect it will loosen up a bit and be fine. Needless to say when finally done it was too late to run a test. For now I'll be manually measuring and calculating current across the shunts since the meters I have only work on the negative side. I did find some $7 panel voltmeters that will measure down to 0.1mV.. which I can make work. These are 300amp shunts, at 300amps they rate 75mV so 25mV per 100 Amps.. 20 amps is 5mV.. and so on, so I'll be able to determine amperage and practice mental math! Until those meters arrive and are installed, I'll measure manually with portable meters to verify each alternator is contributing.

 

[subsea]

While testing can you check the field amperage for the 220 amp alternator at full field (or just resistance in the field winding)? Kind of curious. My engine is coming back together and I will begin a similar project next week.

 

[MichaelOverfield]

While testing can you check the field amperage for the 220 amp alternator at full field (or just resistance in the field winding)? Kind of curious. My engine is coming back together and I will begin a similar project next week.

Field "resistance" on a meter is going to read near zero, it's basically a coil, and builds "resistance" with current flow. There is not significant difference in the alternators on the field coils, it builds the rotating field, the size of the rotor is larger, as is the case, fan, etc. The size and cooling (diodes, etc) allows a higher output.
From what if measured already, you have about 3-5 volts* on the field under typical loads, current not much, less than 5 amps.. the OEM wire for this is about 18 GA, which is informative as to design current flow. I should however be able to connect a meter and measure typical field current to get you real world data, and correlate that to output, while the panel meters won't provide the data, the shunts, with a bit of math should get me there, in theory. My multi meters can go up to 10 amps, and the field should be less than that for taking that data. (* The actual "voltage" is 400hz PWM 12V signals, but a typical meter is going to basically average that out, getting the 3-5 volts I was seeing, I'd need an oscilloscope to see real output, but it should not really be needed, as this generates the magnetic field, where the average, drives the current flow, then magnetic field.)

 

[MichaelOverfield]

While testing can you check the field amperage for the 220 amp alternator at full field (or just resistance in the field winding)? Kind of curious. My engine is coming back together and I will begin a similar project next week.

It's ALIVE! Working as intended, in all aspects. First data on FIELD current: turning on everything short of grid heaters, I could not get as high as even 1 amp. Confirmation it's going to be less than 5 amps on the field. Interesting, with my Dual Alternator setup, for the same demand the ECU output is half what it would have been, due to the driver card providing the other half. Picture of field current, first single Alternator, second dual.. same accessory load.#ad

 

[MichaelOverfield]

Dual Alternator WORKS for a 3 rd Gen! When I get some time I'll write up a summary and lessons learned (the hard way!).
Some pictures follow:

1. Dashboard switches
2. ST driver circuit installed in dashboard
3. Left (2nd) alternator output ( mV across shunt 25mV= 100amps), showing 2.8mV so about 11 amps.
4. Right (1st) alternator output, basically same both sides!#ad

 

[MichaelOverfield]

Here is the output curve: