Dual Alternator install

[MichaelOverfield]

After a recent battery debacle I've been looking for ways to enhance electrical system reliability.. I found an article about adding the dual alternator set up for a 4th Gen, but it seems to be a bit of a mystery for 3rd Gen. Looking at it today seems some modifications to the fan shroud bracket would be needed, and I have yet to figure out how to electrically connect a second alternator, the 4 the gen has the wiring and just needs to be programmed with the ECM to use the second alternator.. I don't see such an option on 3 rd Gen. I was considering a 1 wire alternator and isolator where it would power separate battery and loads normally with and emergency tie option should the primary alternator fail. That would not be ideal, but given the electrical demands on this truck it would make me more confident in the middle of nowhere that I'm not going to get standed. Any thoughts on this idea, or experience doing this, assuming it's been done.

 

[Bob4x4]

Imho it will never pay off.Maintaining what you have is going to be the best way to go.Having worked on these CTD's for many years it is a very reliable system.

 

[MichaelOverfield]

Imho it will never pay off.Maintaining what you have is going to be the best way to go.Having worked on these CTD's for many years it is a very reliable system.

Thanks for your thoughts. I think at least the 220Amp alternator will be installed. Something is just weird about the fluctuating voltage and lights when the grid heaters cycle. Only reservation on the 220A alternator is the issues with the recall. If I get one I'm not sure how I know if it has the recall problems or not..

 

[MichaelOverfield]

So I have the 220amp installed. It's too warm to cycle grid heaters to notice the difference, but expect to see far less fluctuating. Speaking of, the reman unit may need replacement.. I think it's just the brushes getting seated, but it started with some voltage fluctuating, then stopped, but came back a couple of times... Not sure I trust it yet. I would normally get a new unit from my prior auto parts store experience, but in this case it was more than twice the cost.. next post: ideas about second alternator install..

 

[MichaelOverfield]

So, I have not given up on a second alternator, yet. To investigate I have 4th gen second alternator brackets on order, as well as fan shroud bracket. I got a close out serpentine belt for Dual alternators, cheaper than the single alternator belt! I found the electrical plug at Rock Auto.. I'll have the old alternator for fit checks.. now wiring, I think I know how to do it and ensure proper output, and no overload on the ECM. The field is determined by amperage, so if I were to connect same size alternators, fields ONLY in series, the amperage from the ECU will be exactly the same as for a single alternator. To ensure I can have reliability added I can add a 4PDT switch to enable this Dual mode for series connection, in one position, then the other would be single mode, where the DPDT switch in connected to one or the other alternator. This way one could fail electrically, and a simple switch change goes to isolate the bad unit and all is well on the other. As for unlikely bearing failure, a standard 1 alternator belt could bypass the second alternator if needed, but I doubt that would ever be an issue. I'll try to post some pictures when I get further with this project.

 

[brods]

I am not sure exactly what you are trying to accomplish, do you really need more power or just want a standby alternator? For simplicity you could just carry a spare alternator. By cobbling together your own dual system you are adding many more failure modes which will likely hurt reliability, not improve it. You will need non stock parts for repairs should something fail (like the belt) making roadside service more difficult and the second alt will make diagnosing electrical problems more complicated. So more money and costs for a more complex system with less reliability than stock. Not sure that sounds like a such a good deal.

 

[MichaelOverfield]

Brods, 4th Gen trucks have a 2 alternator option, the Ford Trucks have long had that option. The OEM 136A alternator is undersized, the massive voltage swings with grid heaters is a great clue. The 220A I put on seems to be working fine, now.. continuing to test it. With grid heaters this morning, it kept volts above 13.2V with heaters on, the 136A alt would let it drop to less than 12 Volts as the battery was doing the work. If one was to do several short drives in cold weather, with grid heaters, they'd be drawing down their batteries.. I think that is a poor design, my 1996 Saturn has a 134A alternator on a 1.9L gas engine, a 136A for the Cummins is way too small. The current production trucks have a standard 180A, with a second as optional, and can also have 2- 220A alternators... why? Because power demands and people want it. I'm not ready to swap trucks when the new ones are north of 70K!.. so I'm looking to get that kind of power capacity in my 3rd Gen. I plan to use OEM parts, for the 4th gen truck to make this work. I realize it will cost, but it won't be outrageous.. when I get the 4th gen brackets and start fit up.. I'll post more on that. I already have the dual alt serpentine belt, these are all standard parts for 4th gen trucks, so if it works, parts wont be an issue. More on next post on my investigation on wiring the alternators..

 

[MichaelOverfield]

So, I took the old alternator and investigated the internal connections to see if my theory on series field excitation might work.. and probably NOT. The wiring diagram from the service manual, and the RamBodyBuilder is grossly over simplified in this respect: The field windings are not directly and only connected to the ECM! There is a blurb about how the alternator will work via internal default regulation as needed.. well, yes, because it includes a transistor/diode and direct connection to the alternator output when operating. From what I can tell, the ECM sends a pulse to start the alternator (this triggers the transistor which connects the alternator output (connected to the battery) to the field winding, then can control that transistor to turn the field on or off as needed. So, what this means is there is no significant current draw for the field circuit.. the tiny wires would tend to affirm this observation... so I don't see significant risk in just having a second directly connected the same as the first. I'll be doing some additional testing on the old alternator to verify the operational characteristics of that connection. Now the 4th Gen trucks are pre-wired, and they need programming to enable the second alternator.. my guess is that allows the ECM to use either or both as needed for demand, and it would not surprise me if it idled one at low demand, and even time shared between the 2 as needed to match duty cycle.. I've seen some discussion of such a strategy for the Fords with dual alternators.

 

[MichaelOverfield]

Interesting.. one for field, one for sense.. according to this..

http://www.remyautoparts.com/The-Latest/2016/July/Chrysler-Application-Diagnostics-for-Alternator-w

 

[MichaelOverfield]

The Dodge 8W-20 Charging System Diesel, from the service manual and body builder guide shows ECM pin 40 as "GEN FIELD CONTROL" BR/GY, and "GEN SENSE" Pin 28 RD, both C1 Connector. That fits the Remy TB above, and makes it clear there will be no series connection.

 

[MichaelOverfield]

According to the service manual, the ECM uses pulse width modulation signal to the alternator to control alternator field and thus voltage. Seems that is a trigger input for the alternator. I read on several forums that successful connection of dual alternators in parrallel. As for the sense line, if connected to both alternators, the highest voltage will rule, and the pulse width adjustment will adjust as needed. Since all alternators have diodes, there is no reverse feed for current. It's looking like parrallel will work.

 

[MichaelOverfield]

This appears to be the patent for the Chrysler PWM method that began in 2008 for Chrysler, this patent was 2005. So the PWM sends a low voltage, VERY low amperage trigger to the alternator, that triggers a connect (transistor) to the battery/output to the field winding, other side of field is to ground.. and THAT regulates the voltage. I don't see how any harm is done if it triggers 2 same capacity alternators simultaneously, and there should not be a significant difference on the ECU trigger signal.

https://www.google.com/patents/US6912142

 

[MichaelOverfield]

Fig. 3, this is what we have, take out the 3rd wire to the ECU, "phase sense" and you have our control circuit. This shows the transistor, and diode that is contained in the brush holder assembly. The signal from the ecu drives current from output/battery through the field, then to ground. Fortunately we don't have "phase sense" if we did it would be impossible to drive 2 alternators, which would not be able to be synchronized. http://www.embedded.com/design/real...ontroller-driven-alternator-voltage-regulator

 

[MichaelOverfield]

Ok, I know this is all over the place, when I get it all figured out I'll do a how to with part and wiring instructions. So turns out the ECU does drive the alternator field, which means series connection is back in play, but it will require modification of on alternator to remove the internal connection to ground, and on the Denso style unit that appears to be pretty easy. More to follow with pictures on the bracket fit up and left fan shroud. It's looking very doable at this point.

 

[MichaelOverfield]

I'll be getting a new upper radiator hose for a 4th gen, but here you can see the Denso alternator with a fit up check. I have the 4th gen braket, I just need bolts, it fits perfectly, holes on block and fuel pump are right where they need to be. While it fits, it's tight. The cardboard between the alternator and induction was to check and verify clearance.. it cleared.. #ad

 

[MichaelOverfield]

Bosch original alternator won't work, connections interfere with the induction..#ad

 

[MichaelOverfield]

It's not a great picture.. this is the 4th gen left side fan shroud bracket. Will work with a couple of spacers on the lower end. This is needed to make room for the mounting bracket/alternator.#ad

 

[MichaelOverfield]

Denso style brush holder.. right side screw grounds the field winding.. to do a series connection I'll need to unground this and run a connector externally, seems like it will be pretty easy to do. #ad

 

[MichaelOverfield]

Side note, pictures from the first Denso reman alternator which will be returned.. it's a REMY, USA reman which was done poorly. The REMY replacement was a China reman, but looks in all respects brand new. Sad when the China unit is in all objective measures better. When I looked at​ the slip rings it was pretty clear what the problem was. They looked very worn and we're poorly sanded.. also it seems the diodes were not replaced, a stripped fastener makes that near certain, along with the connector, which is faded. At least the brushes were​ new!

 

[MichaelOverfield]

I will be working out the upper radiator hose issue, when I get a 4th Gen upper hose and bracket.. more on that later, those parts listed below as "TBD" for now. Don't run off and try this, yet.. still need to verify my wiring ideas, I have an actual Electrical Engineer that works on Automotive charging systems who has agreed to evaluate my ideas and let me know if it will work. His initial reply was favorable to running a dual alternator system with one controlling regulator. Below is the parts list.. so far..

Parts list (excluding mode switches/network, that will post later):


Alternator Bracket (XF7): MOPAR #: 04627793AA $ 59.72 (Moparpartsoverstock.com)
Alternator bolts (M10X1.5X105mm) (qty 2): MOPAR#: #: 06506337AA $3.20 (Moparpartsoverstock.com)
Bracket upper bolts (to engine block) (qty 3): $3 M-10 X 1.5 X 25 or 30 mm long (Lowes)
M-10 Washers (Qty 3): $0.50 (Lowes)
Bracket lower bolts (qty 2) (to fuel pump): M-8 X 1.25 X 40 to 50 mm long: $2 (Lowes)
M-8 Washers (Qty 2) $0.50 (Lowes)
Left Fan shroud Bracket: MOPAR# 68160116AA $64.70 (Moparpartsoverstock.com)
Mounting bolts (qty 2): M-8 X 1.25 X 50 mm long: $2 (Lowes)
M-8 Washers (Bag, QTY 20, use as needed to obtain correct fan shroud bracket fit): $2 (Lowes)
M-8 Nut, M-8 washer (or re-use existing, I needed one as I found one missing): $1.50 (Lowes)
Serpentine Belt MOPAR#: 04627589AA Gates #: K081298HD $ 28.79 (closeout deal) (Rock Auto)
Alternator, MOPAR #: 56029707AB, 56029707AA (About $400 new) Remy #: 11015 $129.79 + $ 50 Core ($179.79) (Rock Auto)
Upper radiator hose: TBD… Initial Continental# 66842 $15.95 (Rock Auto)
Bracket, Radiator hose: TBD… MOPAR# 68195735AA $6.58 (Moparpartsoverstock.com)


Electrical:


Alternator connector (2 pin): AIRTEX/WELLS# 1P1830 $12.50 (Rock Auto)
Alternator/Battery/Fusible link wire: OEM (68145075AB) wants $56 for this.. not reasonable.. so:
InstallGear 1/0 Guage AWG Power wire with In-line 250Amp ANL fuse holder: $13.85 (Amazon.com)
Dorman 85684 Conduct Tite GM Alternator Wire Boot: $6.13 (Amazon.com)
ABN Marine Battery Cable & Tinned Lug 1’ Foot in Red, 3/8" Inch Stud, 4-Gauge: $7.99 (Amazon.com)


Tools:


Serpentine Belt tool Kit: Gearwrench 3680 $41 (Amazon.com)
Serpentine Belt grabber tool: ATD Tools 8604 $22 (Amazon.com)


That's about $410 in parts, including the Reman 220A alternator.. (if you don't have the 220A to start with, you'll need a second 220A alternator as well). Considering the "option" on the new trucks is about $400-$500 assuming you can figure out how to order it.. that's pretty reasonable. With this kind of power, an inverter install and ability to power your house during a power outage becomes an option as well as other power options for mobile applications.. think of no need for a Generator when going RV, power tools in a remote work site.. as examples.