Anyone swap a stock Delco 22Si alternator for a Delco 28Si alternator on a QSB 5.9?

I know I'm starting yet another thread, but while related to other issues, this is a different question.

I want to increase alternator output but don't want to go with an external regulator. The stock 22Si is mounted with a J180 short frame and like many of the QSB installations there are remote oil filter lines that run above the alternator with minimal clearance. I have heard it is possible to swap the 22Si for a 28Si. I've got a single wire 22Si and there are single Wire 28Si with remote battery sensing.

I've asked at sbmar.com but so far no answers there and was wondering if anyone here has done it?

Hi Dave

I replaced my stock Cummins alternator for a 210A Leece Neville on my Cummins 6.7. Same remote oil and fuel filter issues as your 5.9. We had to adjust the mounting rotation (tension rotation) due to the larger body, but it did fit using the existing mounts and belt. I was going to switch to the 28si, but the tech I was working with suggested the Leece-Neville. It was designed for high output at idle for vehicles such as buses and ambulances which have a high draw at low rpms.

We also used 4/0 cable from the alternator to the electrical bus bar. I have not connected the remote sense wire and don't see a need to do so at this point.

We just left Reid Harbor this morning with the house bank down -320AH. It was cold and raining, so we used heat and hadn't run the genset the evening before. At idle, soon as the voltage controlled relays closed the charging circuit to the alternator, the alternator was charging the bank at 150A plus handling 30A of load.

Thanks for the feedback.

You mentioned relays... I want to use some relays to control the DC-DC chargers I am using. The issue is finding a good power source to use as a signal. One thought is to find out where the key-on power goes and see if I can tap into that. However, that likely means running a bunch of wire. I also thought considered using the power than runs to the Engine start battery solenoid in the after lazarette. That gets energized before I start the engine when I flip the breaker in the pilothouse. On engine shut down, I turn off the Engine solenoid breaker along with the other items that are used when only running the engine such as windlass, thrusters, etc...

Since the wires running to the solenoid are very small, I am thinking of splicing into those and creating a small amp bus bar and running power and ground from that to power a couple relays. A normally closed and a normally open.

“At idle, soon as the voltage controlled relays closed the charging circuit to the alternator, the alternator was charging the bank at 150A plus handling 30A of load.”

Check the alternator case temp the next time you do this. 180A from an alternator for any length of time can overheat it, particularly at low engine rpm’s where the alternators cooling fan isn’t spinning very fast.

You should keep the alternator case temp below 225 F.

David

David
Does not a thermally regulated alternator adjust for temperature vs output? In the cool PNW I’ve seen some near max internally regulated alternator outputs for hours on end in a well ventilated ER.

Of course this opens the non marine internal vs external regulated discussion, remembering that non marine applications account for virtually all alternator designs and applications.

sunchaser said:

David
Does not a thermally regulated alternator adjust for temperature vs output? In the cool PNW I’ve seen some near max internally regulated alternator outputs for hours on end in a well ventilated ER.

Of course this opens the non marine internal vs external regulated discussion, remembering that non marine applications account for virtually all alternator designs and applications.

Click to expand...

A Balmar external regulator with temperature probe does cut output to keep case temps down. But the poster above doesn’t have an external regulator. I think he may need one.

Years ago while full time cruising I had a Balmar aternator and regulator with the temp probe. After a couple of days at anchor with little solar input due to clouds, I would start up the propulsion engine to cruise to another anchorage. The 440 Ah house bank was down by 150 A.

The 100A rated alternator was initially putting out 100A, but after 15 minutes or so the regulator cut back to 50A because the temp probe sensed that the alternator was overheating.

I checked the case temp with an IR gun and when the regulator cut back, it was 220 or so. After cutting output in half it settled down near 200.

So any alternator feeding a big battery bank and especially a Li bank, can overhear if not temperature controlled.

David

DavidM said:

“At idle, soon as the voltage controlled relays closed the charging circuit to the alternator, the alternator was charging the bank at 150A plus handling 30A of load.”

Check the alternator case temp the next time you do this. 180A from an alternator for any length of time can overheat it, particularly at low engine rpm’s where the alternators cooling fan isn’t spinning very fast.

You should keep the alternator case temp below 225 F.

David

Click to expand...

Your point is well taken. I really wanted to run down and check the winding temps at that point, but we were underway fairly quickly after startup. Just needed to pull a couple of lines away from the mooring buoy and off we went. A missed opportunity for sure. This alternator is rated for 257F, but 225F or below is certainly a good operating envelope.

I have measured alt temps on this unit when underway at 7knts with a 145A load. Case and winding temps were under 150F. I had to measure three times to make sure because it seemed very low. Pacific Northwest waters and good airflow in the ER.

If I change to external regulation, I'll have a better way to look at alt temps in real time.

Ron

So today, as I was trying to figure out why I kept getting the AP "Current Limit" error, I was checking my batteries and charging currently. (This was before I knew what that error meant). I couldn't check the amount of amps coming out of my stock alternator (rated at 130amps). However, I was able to check battery voltages and how much my Orion XS DC-DC charger was sending from the Thruster Bank to the House Bank. Early on, it was kicking out between 46-48amps. So the Alternator was sending an unknown amount of amps to the Thruster bank, the Orion was then sending almost 50 amps from the Thruster to the House bank. I was able to do a quick temp check of the alternator and it was running at about 125F. The engine was running only about 1300 rpm as I was limping back to the dock. At my normal cruising RPM, I would imagine the alt temp would be higher. It is rated at 200F, but I doubt if that is a continuous rating. As the Orion decreased the amount of amps sent to the House bank, the load would decrease on the alternator. I had a chance to look at the Orion's output as I get back into the harbor and it had decreased the amps sent to the house to around 30amp.

I have the Orion to immediately start charging the house bank from the Thruster bank if the Thruster bank is at 14.3 volts. I also set a "delayed start" of 13.9v and set the delay at 5 minutes. It sounds odd but I was concerned about the thruster bank. So, I want the engine running for a while after startup before the Thruster bank starts to share the alternators bounty with the house bank. My thinking is that it is shortly after startup that the windlass and thrusters are going to be used and the thruster bank may be down some.

Anyway, it worked well. The thruster bank came up to over 14v pretty quickly and after using the thrusters for a couple short bursts and then when the Orion kicked on, the Thruster bank was holding at around 13.9v. Eventually, by the time I got back to the dock over and hour later, the Thruster Bank was again at 14.0v.

5 hours later back at the dock, after having sat with no charge, the thruster bank was still at 13.0v So my initial impression is that the Thruster bank had been beat up by the charger failing and very deeply discharging the batteries. However, after having given the Thruster bank 24hours of Bulk/Absorb/Float charging from shore power (I temporarily re-routed the charger to the thruster bank) it seems to have recovered.

Yes. I have a 28si on my QSB 5.9. It is very tight, but it fits. If you already have the 22si you already have the J180 short arm mount. Some QSBs had a 19si and the mount has to be swapped (available from Cummins).

The 28si comes in a couple of variations, 160 and 180A. I chose the 160A as the output curves show it putting out a bit more at idle, and this was what caused me to remove the Balmar after only 10 hours use. The 160 puts out approximately 90A at the QSB 600 rpm idle.

The internal voltage regulator will derate if it overheats, but the internal voltage regulator is also bad at charging a house bank. These are designed to recharge a starting battery in a bus, then keep bus 12V loads supplied. You can cheaply convert the 28si to external regulation (an alternator shop will do it for ~$100). The Wakespeed WS500 is the premium external regulator (and perhaps the Zeus, no personal experience with that one).

If you use the alternator temp function of these regulators, it will definitely cut back on charge soon after starting. My 28si will do about 120A continuous after reaching steady state heat, resulting in about 100A into the battery. The engine and alternator themselves consume around 20A. That means that choosing the 180A version is of no benefit. The real limit on these things is cooling, not max output - my alternator was bench tested by the shop that converted it at 178A max output.

I have about 20 days of continuout traces of volts, amps, field drive, temperatures, etc. now captured with my app, and understand its operation pretty well at this point.

That is really helpful. I really do know next to nothing on engines in general.

Initially, I am interested in just doing a swap, at some point I may consider going to external regulation. Baby steps though.

Is this the power curve you were talking about?




If so I see what you mean about the lower amp alternator actually performing better at low rpm. I believe I read somewhere that rpm ratio on the QSB5.9 with the Delco 22,24, and 28 alts was about 2.7:1? Does that sound right? If that is the case, this curve would indicate that at idle (600rpm engine or 1,600rpm alt), the 200amp alt will hardly produce any current. The curve would then support your 90amps at idle and the 180 amp alt would be about 1/2 that.

I cruise typically at 1400-1450rpm. That would be an alt rpm of 3800-3900 maybe? At that rpm, the difference between the 160A and 200A is about 40amps. At that same rpm, the difference between the 160A and 180A is only maybe 10amps? So given those numbers, I can see why you chose the 28Si 160amp. It makes a lot of sense.

If I was going to feed a hungry Lithium bank at cruise, the 200amp would be better as long as it was externally regulated. Since I am looking to feed the house bank through a DC-DC charger from the Thruster bank, the 160amp would make more sense.

Another example of how smart all you guys are. I would have just gone with the 200amp just because it is "bigger" than the 160A or 180A

DDW said:

Yes. I have a 28si on my QSB 5.9. It is very tight, but it fits. If you already have the 22si you already have the J180 short arm mount. Some QSBs had a 19si and the mount has to be swapped (available from Cummins).

Click to expand...

Another question for you, do you know what the part number is for the pully on the 28SI alternator the Cummins QSB5.9? I know that it is the same as is on the 22SI, but I would like to put a new pully on the new alternator keeping the 22SI as a spare. I just am having a heck of a time finding a part number. sbmar.com's forum has ghosted me and I know I can buy the pulley from sbmar.com, they don't give a part number for it.

I do not, as I took it off the 19si. Whatcom Electric in Bellingham did the work, they can probably fix you up with a pulley. I had the same problem with the Cummins parts people, the pulley isn't listed. You cannot use any K8 pulley though, for the Cummins it has about 1/2" extra extension to get the alignment right.

When I swapped the alternator mounts, SBmar would not give me the part numbers either, wanted to sell them along with their expertise in installation (2 bolts) for $600. I did find the PN and bought them from Cummins for $150.

@DDW thanks. Yeah, the other compounding factor is that Cummins uses different part numbers than Delco. It is amazing how difficult it is to simply find out what pulley is used on the 22si, 24si, and 28si alternators by Cummins on their QSB5.9L marine engines.

I did find a table on the Delco website that lists the pulleys that can be used with the 28SI 160amp. It gives specifications for each. So in theory, I should be able to take my calipers and see what the width and diameter are of my current pulley on the 22Si and compare it to the 8 groove pulleys from Delco's list. Then armed with the Delco part number, I should be able to find one for about $40.

Last night I pulled the trigger on a 28Si 160A alternator. $291 including tax.

dhays said:

I know I'm starting yet another thread, but while related to other issues, this is a different question.

I want to increase alternator output but don't want to go with an external regulator. The stock 22Si is mounted with a J180 short frame and like many of the QSB installations there are remote oil filter lines that run above the alternator with minimal clearance. I have heard it is possible to swap the 22Si for a 28Si. I've got a single wire 22Si and there are single Wire 28Si with remote battery sensing.

I've asked at sbmar.com but so far no answers there and was wondering if anyone here has done it?

Click to expand...

In case you are not considering an external regulator because converting the 22si may be difficult, I have recently done it and it was much easier than I thought. I searched for many hours on the internet to understand what needs to be done and then did it in about 30 minutes once the alternator was off the engine. I wanted to keep it simple and already had a spare 22si, so chose to keep it. I will be running the Balmar 618 external regulator with an alternator temperature sensor. If interested in the details, reply and I will post pictures of how to do it.

Update - Just saw your last post.... Never mind.... 28si it is.

Skag said:

In case you are not considering an external regulator because converting the 22si may be difficult, I have recently done it and it was much easier than I thought. I searched for many hours on the internet to understand what needs to be done and then did it in about 30 minutes once the alternator was off the engine. I wanted to keep it simple and already had a spare 22si, so chose to keep it. I will be running the Balmar 618 external regulator with an alternator temperature sensor. If interested in the details, reply and I will post pictures of how to do it.

Update - Just saw your last post.... Never mind.... 28si it is.

Click to expand...

Thanks @Skag
At this point, I don't think I will do external regulation, but I certainly may be interested in the future. If so, even if you did a 22Si, I likely will have some questions on the process in general. @DDW did external regulation on his 28SI as well.

One of the reasons I want to get a new pulley for the 28Si is that I can hang onto the 22Si as a back/spare.

Understood. For future reference and the benefit to anyone else considering modifying a 22si, below is one method to do it:

The most difficult part to this is to fabricate a spacer in place of the existing regulator. The brush assembly mounts on top of the regulator, so removing it requires a spacer to keep the same position of the brush assembly. I bought a small piece of 10mm fiberglass board on eBay. Using regulator as a template, drilled holes to match and than used a grinder to make the shape shown below.

To prevent binding up the brush wire, grind the spacer a bit so wire is not trapped/crushed.

Wire up the brush assembly so that one brush is + (this will be the field from the external regulator), the other is to be grounded. For the +, re-use the existing connection as shown and use the same insulator that was used on the bolt holding the old regulator.

The brushes need to be pushed back in and held in place with a paperclip (see pic, but I had to flip the paperclip to install) for re-assembly. Once rotor is re-installed, pull the clip to release brushes.

I chose to run an extra ground that was likely not needed because the brush is grounded through the hold down bolt to the case. Picture below is what it should look like before re-assembly (brush holder mounted on top of spacer and one brush run to field +, the other grounded).


Re-install stator and install/tighten nuts. Than install rotor/top case and you are done.



Disassembly is straight forward, I had to use a mallet to lightly tap the case once the four long bolts holding the case together were removed. You will need to remove the "diode trio" (pic below) and discard. The diode trio is used to power the internal regulator, hence no longer needed. The large diodes/rectifier and heat sink will remain.

Be careful to not damage the brushes by having them retracted and held with the paperclip when re-installing the rotor.

All that being said above, I have not run my alternator yet. If anyone else has feedback on this modification, I'd like to hear it.

@Skag I'm impressed.
Of course to me, alternators are some form of deep, arcane, black magic that I don't understand so I don't know enough to be impressed or appalled. ;-)

Nice writeup on the "deregulation". A shop will do it fairly cheaply if you don't want to get your hands dirty.

On the pulley, the ID and OD are important, but also the offset of the K8 groove pattern. As I said it is offset forward about 1/2" for the Cummins. A normal pulley mabye can be spaced, but the result has to match the belt position.

If you had the choice, you might use a slightly smaller OD pulley. Can't go too small or you will over speed it, but the cooling suffers from running our Cummins at 1200 rpm all day.

I'd be afraid of changing it. The one thing that worries me the most is removing and then re-tensioning the belt. I simply haven't ever done it on this engine. So it will be a bit of a learning curve for me (as in so many things).

DDW said:

Nice writeup on the "deregulation". A shop will do it fairly cheaply if you don't want to get your hands dirty.

On the pulley, the ID and OD are important, but also the offset of the K8 groove pattern. As I said it is offset forward about 1/2" for the Cummins. A normal pulley mabye can be spaced, but the result has to match the belt position.

If you had the choice, you might use a slightly smaller OD pulley. Can't go too small or you will over speed it, but the cooling suffers from running our Cummins at 1200 rpm all day.

Click to expand...

I was down at the boat today and took measurements of the pully on my 22Si alternator and they matched with the DelcoRemy #10499362 pulley. So I ordered one today. Just under $50 including shipping. So maybe I can work on that next weekend. Hopefully I'll have both the 28Si and the pulley by then.

Here is what the battery voltages looked like this afternoon when I left the boat. Notice the thruster and genset batteries. The thruster bank has been without a charge source since Friday morning. No drain on it, but it still is at a 12.9v resting voltage. I think that is pretty good.
OTOH, the genset battery is at 12.34v. Not terrible but I think I may put a trickle charger on it periodically. When I'm out on the boat using the generator, its alternator should keep it happy. The battery is a 8 year old group 27 AGM from West Marine.
The other issue is the temps of the house bank. It is a LOT higher than the other batteries and is only getting a float charge.

DDW said:

I chose the 160A as the output curves show it putting out a bit more at idle, and this was what caused me to remove the Balmar after only 10 hours use. The 160 puts out approximately 90A at the QSB 600 rpm idle.

Click to expand...

Why is the output at idle important? Isn’t your cruise rpm much higher?
Just curious.

guy with a boat said:

Why is the output at idle important? Isn’t your cruise rpm much higher?
Just curious.

Click to expand...

Good question. For me part of what I want is the increased amps while using the thrusters and windlass, both of which occur at idle. The power curve of the of the 28i 220A shows that at my idle speed, it would produce almost no current yet the 28si 160A would produce about 90amps.

At my cruise rpm however, the 200A would produce 40amps more then the 160A. However, as the voltage of the batteries go up, the output goes down, so there would likely be much less of a difference after a short time at cruise.

At least that is my idea.

guy with a boat said:

Why is the output at idle important? Isn’t your cruise rpm much higher?
Just curious.

Click to expand...

I have a Cummins QSB, and it consumes about 15A just to keep it running. A largish alternator consumes another 5 - 10A in the field. The result (with the Balmar alternator) was a net charge of around -20A at idle. This sagged the voltage pretty quickly down to around 12.4V, then then engine control would alarm with low voltage (as it expects a positive charge when it is running). I'd have to cycle through the menus on the stupid Mecruised display and reset it, also the alarm is forwarded via N2K to the Raymarine system which also alarms and also had to be silenced. This is at 600 rpm idle. At 650 it was enough to at least maintain 0 charge and 12.8V bus. I contacted Cummins about setting the idle up to 650 or 700 but apparently this required an Act of Congress and could not be done (local mechanic and Cummins corporate agreed).

At 600 rpm idle, the Delco ($280 vs $1300 for the Balmar) put out 90A.

dhays said:

Good question. For me part of what I want is the increased amps while using the thrusters and windlass, both of which occur at idle. The power curve of the of the 28i 220A shows that at my idle speed, it would produce almost no current yet the 28si 160A would produce about 90amps.

At my cruise rpm however, the 200A would produce 40amps more then the 160A. However, as the voltage of the batteries go up, the output goes down, so there would likely be much less of a difference after a short time at cruise.

At least that is my idea.

Click to expand...

What you will find is after 10 minutes both alternators will put out the same amperage, as both will derate due to heat. At least if the regulator is working properly. They have the same fan and cooling capacity, and cooling is the steady state limit. So the maximum spec is an illusion, however the idle spec is real.

DDW said:

What you will find is after 10 minutes both alternators will put out the same amperage, as both will derate due to heat. At least if the regulator is working properly. They have the same fan and cooling capacity, and cooling is the steady state limit. So the maximum spec is an illusion, however the idle spec is real.

Click to expand...

That is my hope. At the very least it should get me a lot more than my 130amp 22si is currently.

I got an email today from the outfit that I ordered the pulley from. They said that it turns out it is out of stock and are refunding my CC. So I ordered another one from another company for a total of $10 more making it $58 total with tax and shipping instead of the $48.

I'm getting about 100A steady state, hot, after house and engine loads, into the battery from my 28si (with WS500 external regulator), with temp limit set to 100° C. You might see less because I'm pretty sure the internal regulator will run the accept voltage too low, but you should still get a lot. Pushing the temp a bit makes a difference - I'll see 110A if I was willing to run at 105. The hotter it runs though, the quicker it dies.

Let me know if the pulley works - I want to get another 28si backup, but it will be useless as a backup in the remote reaches of SE AK unless it has a pulley on it.

DDW said:

I'm getting about 100A steady state, hot, after house and engine loads, into the battery from my 28si (with WS500 external regulator), with temp limit set to 100° C. You might see less because I'm pretty sure the internal regulator will run the accept voltage too low, but you should still get a lot. Pushing the temp a bit makes a difference - I'll see 110A if I was willing to run at 105. The hotter it runs though, the quicker it dies.

Let me know if the pulley works - I want to get another 28si backup, but it will be useless as a backup in the remote reaches of SE AK unless it has a pulley on it.

Click to expand...

Yeah, I will let you know. I think the pulley will arrives before the alternator. The Alt is coming on a slow truck from PA

DDW said:

I'm getting about 100A steady state, hot, after house and engine loads, into the battery from my 28si (with WS500 external regulator), with temp limit set to 100° C. You might see less because I'm pretty sure the internal regulator will run the accept voltage too low, but you should still get a lot. Pushing the temp a bit makes a difference - I'll see 110A if I was willing to run at 105. The hotter it runs though, the quicker it dies.

Let me know if the pulley works - I want to get another 28si backup, but it will be useless as a backup in the remote reaches of SE AK unless it has a pulley on it.

Click to expand...

I have both the alternator and the pulley now. Unfortunately, it won't be until maybe this next weekend that I can get down to the boat to check on the fit of the pulley. One of the things that I discovered is that I believe I am going to have to use the spacers from the 22si that go between the pulley and the alt on my new alternator and pulley. The spacers that came with the new alt I don't think will work with with the pulley. I'm guessing there are specific spacers required. So I won't know until I get the old pulley off the old alternator to check it out.

I am not able to find the information as to what spacers are required. I was hoping that I could keep my 22Si as a ready spare for the 28Si. However, that won't work as well if I need to transfer the spacers from one to the other. So I'd like to find spacers.

dhays said:

I have both the alternator and the pulley now. Unfortunately, it won't be until maybe this next weekend that I can get down to the boat to check on the fit of the pulley. One of the things that I discovered is that I believe I am going to have to use the spacers from the 22si that go between the pulley and the alt on my new alternator and pulley. The spacers that came with the new alt I don't think will work with with the pulley. I'm guessing there are specific spacers required. So I won't know until I get the old pulley off the old alternator to check it out.

I am not able to find the information as to what spacers are required. I was hoping that I could keep my 22Si as a ready spare for the 28Si. However, that won't work as well if I need to transfer the spacers from one to the other. So I'd like to find spacers.

Click to expand...

The spacers are just washers (of a specific width)? Those can be had from McMaster or others, or made yourself (provided you have a lathe ).

DDW said:

The spacers are just washers (of a specific width)? Those can be had from McMaster or others, or made yourself (provided you have a lathe ).

Click to expand...

yeah, my thought was that likely no-one would know, so I will try to find something that matches. That is why I have calipers on the boat!

So I just got back from making that alternator swap. It went well, but I ran into a couple issues.

The pulley on the 22Si is fundamentally different than the pulley I got for the 28Si. The width of the 8 groove section was identical as was the diameter. However, the pulley on the 22Si didn't have spacers but the pulley itself had the "spacers" cast or machined into the pulley itself. So, no spacers to measure. Furthermore, it isn't just a matter of measuring the total width of the old and new pulleys and getting spacers to make up the difference. The rim width of the two pulleys is different. So I ended up using the old pulley on the new Alt and it worked just great. I'd like to figure out what spacers would be needed, but It will work.

The second issue is that the Ground connection points on the 28Si on in a different location than the 22Si. There was not enough clearance to get the ground screw out due to the remote oil lines that pass above it. I had to take off the bolt holding the top mounting arm so I could swing down the Alt a 1/4" so I could get the ground cable attached, then I reattached the top arm.

I used an impact driver to get the pulley nut and the mounting nuts off. That made that easy. My son-in-law recommended that after taking the belt off the old alt, to use a zip tie to hold it in place so the serpentine belt stayed in place while it wasn't under tension. That ended up being real helpful.