Sprinter Van second alternator install for mobile-48v-system

[user21]

I've build this one https://www.mobile-solarpower.com/mobile-48v-system.html
I want to add alternator charging for it

where in Florida or neighboring states I can find someone who ca do this
I've tried looking at companies in www.vanlifeoutfitters.com/directory for the Florida state

but most don't do it or are not doing it if it is not a victron based system

anyone knows someone good who can install a second alternator for sprinter van ?

 

[justinm001]

What alternator? I just bought one like this, should be delivered any day. I believe for sprinters they make dual brackets.

American Power High Output Alternator: 160HFTAN4H848S9C

www.americanpowerinc.com

 

[user21]

this looks like a good one, at the moment I don't know the best models, was hoping a specialized shop would recommend and install one that is the best to have from performance and reliability

on this website I saw they sell a kit https://www.vanlifeoutfitters.com/store/nations-wakespeed-secondary-alternator-kit-12v-24v-48v
not sure how good it is, but I'm also looking for a builder/service provider who can do this type of work


who is going to install yours ? what state ?

 

[justinm001]

That's a good kit, I'll basically be doing the same. I'll likely need to install mine myself or maybe find someone to install the alternator for me and I'll do the wiring. No sure if there's any installers. Most on here DIY hence the name. I'm in Columbus Ohio and there's a few local shops that might do it.

Luckily for you they make kits like that so if I were you I'd call around

 

[user21]

I did call and sent emails, for some reason they don't do it if it's not a victron system or don't do it at all
there is one guy that said will take a look but it is silence for now as he said he needs time to research

 

[justinm001]

Victron doesn't make alternators or regulators...

 

[user21]

what I mean is that I tell them that my 48v system is not victron based but self build and point to this https://www.mobile-solarpower.com/mobile-48v-system.html and they say if it is not victron we are not touching it, which is bizarre

I'll have to keep looking

 

[justinm001]

what I mean is that I tell them that my 48v system is not victron based but self build and point to this https://www.mobile-solarpower.com/mobile-48v-system.html and they say if it is not victron we are not touching it, which is bizarre

I'll have to keep looking

No one even uses Victron batteries so it wouldn't matter. Likely they won't touch it because they think it's a junky system and would be more issues than it's worth.

Many wouldn't touch 48v systems regardless. Keep trying to find someone local

 

[Buzz Lighting]

I did call and sent emails, for some reason they don't do it if it's not a victron system or don't do it at all
there is one guy that said will take a look but it is silence for now as he said he needs time to research

I have a Sprinter van and currently considering swapping over to 48v’s and installing a second 48v alternator. I’m planning on eliminating solar completely and removing the two 50A Orion XS that I have installed in parallel. I currently have 920Ah’s installed with all the Victron goodies so it won’t be too hard to convert it. I’ll need a new inverter, swap out the batteries and install a 48v to 12v step down converter.

I would recommend having MB install the second alternator. They know what they’re doing and it has to line up perfectly or you’re going to run into trouble if not done right. I got quoted $1100 for them to do it and then I would wire the rest. As mentioned they do sell bracket kits that make the install a bit easier.

I would reconsider using that inverter and consider using a Victron inverter that are made for the marine and RV market. There is a lot of movement when going down the road with these mobile vehicles and they’re built to take that beating. Same reason why stranded wire is preferred over solid Romex in these environments.

You’re probably getting push back from these installers as it would be hard to integrate the alternator regulator with that type of inverter. Depending on what alternator you choose you will still need a regulator to communicate with the system for charging hence why they prefer you to use a Victron system. Way easier to integrate it with the Victron Cerbo for communication. WakeSpeed and Zeus are two common ones that are regularly used. There is also third one that I can’t remember the name at the moment.

Also consider going with the newer Arco alternator with their Zeus regulator as they are way better built and easier to program the Zeus regulator. However, also a bit pricier.

Attached is a good video on how to install it but it has a lot of good info on the process and they get into a lot on the subject.

Hope this helps.

 

[justinm001]

I have a Sprinter van and currently considering swapping over to 48v’s and installing a second 48v alternator. I’m planning on eliminating solar completely and removing the two 50A Orion XS that I have installed in parallel. I currently have 920Ah’s installed with all the Victron goodies so it won’t be too hard to convert it. I’ll need a new inverter, swap out the batteries and install a 48v to 12v step down converter.

I would recommend having MB install the second alternator. They know what they’re doing and it has to line up perfectly or you’re going to run into trouble if not done right. I got quoted $1100 for them to do it and then I would wire the rest. As mentioned they do sell bracket kits that make the install a bit easier.

I would reconsider using that inverter and consider using a Victron inverter that are made for the marine and RV market. There is a lot of movement when going down the road with these mobile vehicles and they’re built to take that beating. Same reason why stranded wire is preferred over solid Romex in these environments.

You’re probably getting push back from these installers as it would be hard to integrate the alternator regulator with that type of inverter. Depending on what alternator you choose you will still need a regulator to communicate with the system for charging hence why they prefer you to use a Victron system. Way easier to integrate it with the Victron Cerbo for communication. WakeSpeed and Zeus are two common ones that are regularly used. There is also third one that I can’t remember the name at the moment.

Also consider going with the newer Arco alternator with their Zeus regulator as they are way better built and easier to program the Zeus regulator. However, also a bit pricier.

Attached is a good video on how to install it but it has a lot of good info on the process and they get into a lot on the subject.

Hope this helps.

If you're removing solar then why switch to 48v? You're only saving a few bucks in wiring. With solar 48v makes sense as you get 4x the solar on the mppt.
The wakespeed integration to Victron doesn't do anything. It just send the status to Victron so you can see it. Super nice but doesn't help the installers as it still needs wired and programmed.

 

[SolarRich]

They won't touch your system because if your van burns up you will blame them. They don't want to take the responsibility for your work which could be poorly done and could cause a fire.

 

[Buzz Lighting]

If you're removing solar then why switch to 48v? You're only saving a few bucks in wiring. With solar 48v makes sense as you get 4x the solar on the mppt.
The wakespeed integration to Victron doesn't do anything. It just send the status to Victron so you can see it. Super nice but doesn't help the installers as it still needs wired and programmed.

I’m not doing it to save money and more for convenience, efficiency and fast charging. We have a 12v fridge/freezer combo unit, rooftop AC with a heat pump, induction cooktop, Starlink permanent mount, central vac and 120VAC heat tape under the van for the tanks and drain lines just to new a few high powered items. We basically use up power at will and not trying to be conservative in any way or change our habits. We use our van year round so we use a lot of power. Being able to quickly charge the battery bank within a few hours is important for us and the reason that I would convert.

400 watts of solar on a Sprinter van for a 48v system isn’t worth their literal weight up there and space that they take up. If I had a Class-A, Schooly or TT that would be a different story. Trying to make that work up in series to get up 5v over the battery voltage is also another PITA and they reason that I would just remove solar. I’m not trying to fabricate something to put more panels up there either.

Lastly, if I’m going to install a second alternator - I might as well go for the 48v one versus a 12v one. There are benefits of the regulator communicating with Victron and DVCC enabled.

Something important to consider is protection from a battery’s BMS shutting down while the alternator is still running. This will make for a very bad day as that is a lot of voltage that will end up somewhere. Victron does have an ATC relay built into the Lynx BMS that will shut down the alternator. With no Lynx BMS, you can also add a Balmar APM switch that will absorb that surge. It’s basically a surge protector.

 

[azazel1024]

I’m not doing it to save money and more for convenience, efficiency and fast charging. We have a 12v fridge/freezer combo unit, rooftop AC with a heat pump, induction cooktop, Starlink permanent mount, central vac and 120VAC heat tape under the van for the tanks and drain lines just to new a few high powered items. We basically use up power at will and not trying to be conservative in any way or change our habits. We use our van year round so we use a lot of power. Being able to quickly charge the battery bank within a few hours is important for us and the reason that I would convert.

400 watts of solar on a Sprinter van for a 48v system isn’t worth their literal weight up there and space that they take up. If I had a Class-A, Schooly or TT that would be a different story. Trying to make that work up in series to get up 5v over the battery voltage is also another PITA and they reason that I would just remove solar. I’m not trying to fabricate something to put more panels up there either.

Lastly, if I’m going to install a second alternator - I might as well go for the 48v one versus a 12v one. There are benefits of the regulator communicating with Victron and DVCC enabled.

Something important to consider is protection from a battery’s BMS shutting down while the alternator is still running. This will make for a very bad day as that is a lot of voltage that will end up somewhere. Victron does have an ATC relay built into the Lynx BMS that will shut down the alternator. With no Lynx BMS, you can also add a Balmar APM switch that will absorb that surge. It’s basically a surge protector.

Out of curiosity, is that all the roof space? I've mostly looked at transits, and the extended length ones it seems like you could probably cram 1000w up there with the right panels and mounting system, even with AC on the roof (better to put it on the back door though as that frees up enough space for another 200w of solar on the roof top). 800w shouldn't be hard to get up there. Now, for ~12kwh of battery and as much as it sounds like you are using, it isn't necessarily going to put a huge dent in that. Though with (currently) 1.2kw of charging, ~800w is a decent fraction of that.

5v over battery voltage should only take 2s:2p with the right 200-250w panels. And very easy with any kind of 4s setup (or even a 3s setup).

You know your setup, wants and needs wayyyy better than I do. I am more curious than anything. I am a few years out from actually undertaking getting a Transit and undertaking a camper conversion. I am likely to do this as two steps. First is dipping my toes for something to have fun with a couple or a few weeks a year for a few years. The next is the retirement, all the bells and whistles van implementing the lessons learned with the earlier one. My about to be wife and I are only 42. That is a solid 15(+, I hope not much +) years from retirement. My oldest is 17. Her youngest is about to be 10. So, it'll be a few years before we are empty nesters. We both love to travel. We also love parks and nature. Her requirements are some sort of bed to sleep in. It can't get really cold inside. She needs a place to go 1/2 with some privacy if needed. And needs to at least take a hot shower every day. A hot 2 or 3 minute shower is fine. I'd like everything, except the heat/hot water, to be electric. Looking at a diesel heater to keep the van warm, and a 6-gallon marine diesel water heater that can take a 300w 12v heating element to utilize excess electricity for water heating.

At least for us, we aren't likely to be mobile every day. A lot of times it is going to be driving to a spot and parking there for a couple or a few days. Not necessarily with an electric hookup. I really don't want to have to fire up to van and let it recharge the batteries for an hour or three every day. I have considered a small suitcase generator as the backup to solar for parking in the shade or just using tons of power. Such as lots of A/C use. My little Sportsman's 1000 doesn't take up much space, isn't very loud, and is relatively fuel efficient. ~600-700w constant load to recharge batteries would take a while, but that is also just fine to run it for hours to support cranking the A/C and charge the batteries slowly if the sun isn't shining much. A gallon of gas gets about 9hrs of 80% output on the generator (I hate pegging it higher than that for hours on end).

I would of course want an alternator charger system too. I guess I was thinking more like a single Orion 50. Though I was also looking at more like a ~5kwh battery bank for the van.

Though I might want a lot more than that on the retirement van, as I am thinking the future wife and I are likely to spend 3-4 months of the year on the road in retirement (probably 6-8 weeks, times two).

 

[justinm001]

I’m not doing it to save money and more for convenience, efficiency and fast charging. We have a 12v fridge/freezer combo unit, rooftop AC with a heat pump, induction cooktop, Starlink permanent mount, central vac and 120VAC heat tape under the van for the tanks and drain lines just to new a few high powered items. We basically use up power at will and not trying to be conservative in any way or change our habits. We use our van year round so we use a lot of power. Being able to quickly charge the battery bank within a few hours is important for us and the reason that I would convert.

400 watts of solar on a Sprinter van for a 48v system isn’t worth their literal weight up there and space that they take up. If I had a Class-A, Schooly or TT that would be a different story. Trying to make that work up in series to get up 5v over the battery voltage is also another PITA and they reason that I would just remove solar. I’m not trying to fabricate something to put more panels up there either.

Lastly, if I’m going to install a second alternator - I might as well go for the 48v one versus a 12v one. There are benefits of the regulator communicating with Victron and DVCC enabled.

Something important to consider is protection from a battery’s BMS shutting down while the alternator is still running. This will make for a very bad day as that is a lot of voltage that will end up somewhere. Victron does have an ATC relay built into the Lynx BMS that will shut down the alternator. With no Lynx BMS, you can also add a Balmar APM switch that will absorb that surge. It’s basically a surge protector.

It makes zero sense for you to go 48v. There's no more power with 48v vs 12v, just lets you use smaller cables. What size inverter are you planning? If 5k+ then maybe 24v makes more sense.

The regulator has nothing to do with voltage, the Zeus/wakespeed works with all voltages you just need an alternator with an external regulator.

If you go 12/24v you can run DC converters like the Victron XS and not have to worry about the alternator over voltage or anything else. You can also get a sterling APD to protect the alternator for voltage spikes.

I don't think DVCC will help as I'm pretty sure that Victron can't send commands to wakespeed. DVCC works to combine multiple devices and is meant for MPPTs so they work together. Its been a while since I used my wakespeed, but new alt is coming in today so I'll be able to play around with it soon.

Just FYI I have 12 and 48v systems in my rig, all with 24v chassis. My 48v is ideal because I have 5kw of solar on the roof and 10kw in inverters.

Charging from shore is the same regardless of voltage.

 

[justinm001]

I’m not doing it to save money and more for convenience, efficiency and fast charging. We have a 12v fridge/freezer combo unit, rooftop AC with a heat pump, induction cooktop, Starlink permanent mount, central vac and 120VAC heat tape under the van for the tanks and drain lines just to new a few high powered items. We basically use up power at will and not trying to be conservative in any way or change our habits. We use our van year round so we use a lot of power. Being able to quickly charge the battery bank within a few hours is important for us and the reason that I would convert.

400 watts of solar on a Sprinter van for a 48v system isn’t worth their literal weight up there and space that they take up. If I had a Class-A, Schooly or TT that would be a different story. Trying to make that work up in series to get up 5v over the battery voltage is also another PITA and they reason that I would just remove solar. I’m not trying to fabricate something to put more panels up there either.

Lastly, if I’m going to install a second alternator - I might as well go for the 48v one versus a 12v one. There are benefits of the regulator communicating with Victron and DVCC enabled.

Something important to consider is protection from a battery’s BMS shutting down while the alternator is still running. This will make for a very bad day as that is a lot of voltage that will end up somewhere. Victron does have an ATC relay built into the Lynx BMS that will shut down the alternator. With no Lynx BMS, you can also add a Balmar APM switch that will absorb that surge. It’s basically a surge protector.

Also if I were you I'd look into CIGS panels, they're light and stick right on the roof. Solar is free power that's there as long as the suns out. I run 200w of panels on my 12v system and it's amazing to keep that topped off with all the idle consumption. If you can toss 500w+ it'll really help when you're not driving.

 

[azazel1024]

Also if I were you I'd look into CIGS panels, they're light and stick right on the roof. Solar is free power that's there as long as the suns out. I run 200w of panels on my 12v system and it's amazing to keep that topped off with all the idle consumption. If you can toss 500w+ it'll really help when you're not driving.

That was part of my thought too about it. Not sure why you wouldn't keep some kind of solar. Unless you need to use the entire roof, there are options that weigh effectively nothing.

What I am looking at would NOT be light or small, but it would certainly be worth it for what I am thinking, I am also planning on a 12v* system, so just running all of the panels in parallel, even at 1000w wouldn't be a problem. Just some bigger cables. So, shading shouldn't be any kind of real concern. For 100lbs of panels up on the rack, okay. That is also a lot of power. Depending on what we end up doing, what a final build might look like, etc. I am also thinking I'll probably throw at least 320w of folding panels in the van and some long cables. A lot less power, but then if I want to park in the shade, I can just go setup the panels 50 feet away in the sun. Or if parking in the sun, I can rock a third more power.

But I'd also just be looking at 2kw inverter for an induction cook top and a couple of outlets for anything I'd want to use that takes 120v. Everything else, A/C included, I'd want to run off 12v (or 24v).

*24v may end up making more sense in the end though.

 

[justinm001]

That was part of my thought too about it. Not sure why you wouldn't keep some kind of solar. Unless you need to use the entire roof, there are options that weigh effectively nothing.

What I am looking at would NOT be light or small, but it would certainly be worth it for what I am thinking, I am also planning on a 12v* system, so just running all of the panels in parallel, even at 1000w wouldn't be a problem. Just some bigger cables. So, shading shouldn't be any kind of real concern. For 100lbs of panels up on the rack, okay. That is also a lot of power. Depending on what we end up doing, what a final build might look like, etc. I am also thinking I'll probably throw at least 320w of folding panels in the van and some long cables. A lot less power, but then if I want to park in the shade, I can just go setup the panels 50 feet away in the sun. Or if parking in the sun, I can rock a third more power.

But I'd also just be looking at 2kw inverter for an induction cook top and a couple of outlets for anything I'd want to use that takes 120v. Everything else, A/C included, I'd want to run off 12v (or 24v).

*24v may end up making more sense in the end though.

Unless you're running 5000w+ of power 12v makes the most sense. There's some reasoning where it can be cheaper (lots of solar/MPPTs, long wire runs, no 12v equipment) but generally its better. There's a lot less devices that support 48v and everything is complicated. You're also losing efficiency when converting to 12v for those loads.

Plus it's better to have multiple MPPTs because of shading so 12v helps and you're not needing to get 55v+ from strings.

Even if you have a couple hundred watts it makes a huge difference. You'll always have devices consuming a bit of power here and there so having something that makes a few watts offsets that and helps keep the batteries balanced.

 

[user21]

I have a Sprinter van and currently considering swapping over to 48v’s and installing a second 48v alternator. I’m planning on eliminating solar completely and removing the two 50A Orion XS that I have installed in parallel. I currently have 920Ah’s installed with all the Victron goodies so it won’t be too hard to convert it. I’ll need a new inverter, swap out the batteries and install a 48v to 12v step down converter.

I would recommend having MB install the second alternator. They know what they’re doing and it has to line up perfectly or you’re going to run into trouble if not done right. I got quoted $1100 for them to do it and then I would wire the rest. As mentioned they do sell bracket kits that make the install a bit easier.

I would reconsider using that inverter and consider using a Victron inverter that are made for the marine and RV market. There is a lot of movement when going down the road with these mobile vehicles and they’re built to take that beating. Same reason why stranded wire is preferred over solid Romex in these environments.

You’re probably getting push back from these installers as it would be hard to integrate the alternator regulator with that type of inverter. Depending on what alternator you choose you will still need a regulator to communicate with the system for charging hence why they prefer you to use a Victron system. Way easier to integrate it with the Victron Cerbo for communication. WakeSpeed and Zeus are two common ones that are regularly used. There is also third one that I can’t remember the name at the moment.

Also consider going with the newer Arco alternator with their Zeus regulator as they are way better built and easier to program the Zeus regulator. However, also a bit pricier.

Attached is a good video on how to install it but it has a lot of good info on the process and they get into a lot on the subject.

Hope this helps.

thank you for the knowledge

so my steps would be something like this ?
- buy Arco alternator (do you have a link)
- buy Zeus regulator (do you have a link)
- ask MB dealer to install the alternator

how about the "programming" part, does that happen automatically if to use a Victron inverter ?
I need to do some reading

 

[Buzz Lighting]

It makes zero sense for you to go 48v. There's no more power with 48v vs 12v, just lets you use smaller cables. What size inverter are you planning? If 5k+ then maybe 24v makes more sense.

The regulator has nothing to do with voltage, the Zeus/wakespeed works with all voltages you just need an alternator with an external regulator.

If you go 12/24v you can run DC converters like the Victron XS and not have to worry about the alternator over voltage or anything else. You can also get a sterling APD to protect the alternator for voltage spikes.

I don't think DVCC will help as I'm pretty sure that Victron can't send commands to wakespeed. DVCC works to combine multiple devices and is meant for MPPTs so they work together. Its been a while since I used my wakespeed, but new alt is coming in today so I'll be able to play around with it soon.

Just FYI I have 12 and 48v systems in my rig, all with 24v chassis. My 48v is ideal because I have 5kw of solar on the roof and 10kw in inverters.

Charging from shore is the same regardless of voltage.

It make 100% sense to me because of the 48v second alternators capacity to charge the battery in a couple of hours while driving down the road at full bore. The Arco’s have a true 12, 24 or 48v source field which you can use 100% of it, are way better built IMO and have more access for cooling than the others do. Take a look at the video when you get a chance. They talk about the true source voltage field around the 1:02:30 mark.

I’m totally convinced on removing the solar panels as we would prefer a small rooftop deck instead. I would only keep a 100A panel for charging the chassis battery. I currently have a smaller 30A panel solar trickle charger when no tied to shore and a regular 120 VAC BatteryMinder when on shore or generator. I understand that it’s free power but the alternator is also free power. (After you’ve paid for it just like the solar panels)

I don’t plan on idling the van to charge the batteries as that is not good for a Sprinter diesel van and MB Upfitter guidelines restrict charging from a second alternator at idle. DVCC is meant for all charging devices in a system and uses the batteries BMS to control everything if you set it up that way.

I would upgrade to a 48v Victron Multiplus II 5kVa. Why go the 3kVA route for a few dollars less and be able to run a few higher powered appliances without the power assist function. I already have all the bigger gauge wires in place already with no plans on downsizing that.

 

[Buzz Lighting]

thank you for the knowledge

so my steps would be something like this ?
- buy Arco alternator (do you have a link)
- buy Zeus regulator (do you have a link)
- ask MB dealer to install the alternator

how about the "programming" part, does that happen automatically if to use a Victron inverter ?
I need to do some reading

I have an Ext 24 ft Dually Sprinter van and giving you advice from that perspective.

Attached is a link for the Arco alternator and Zeus regulator. Again, IMO they are better built and allow for more air to cool it down than other manufacturers. Others have mentioned idling the van but that’s not something that you want to do with a Sprinter diesel van if that’s what you have and not recommended by MB.

My use case as mentioned is for quickly charging our battery bank when on the road in a few hours. Our AC is also 120 VAC so it can draw down the bank and especially if we have the heat pump going in cooler weather. Right now we can get about 8 hours along with everything else running.

The Zeus has an app that you can do the programming on and if you decide on Victron then that’s done via the Cerbo.

Kit available here but you can try to shop around for cheaper pricing:
https://trek.systems/collection/alternator-charging/high-output-alternator-kits/

 

[justinm001]

It make 100% sense to me because of the 48v second alternators capacity to charge the battery in a couple of hours while driving down the road at full bore. The Arco’s have a true 12, 24 or 48v source field which you can use 100% of it, are way better built IMO and have more access for cooling than the others do. Take a look at the video when you get a chance. They talk about the true source voltage field around the 1:02:30 mark.

I’m totally convinced on removing the solar panels as we would prefer a small rooftop deck instead. I would only keep a 100A panel for charging the chassis battery. I currently have a smaller 30A panel solar trickle charger when no tied to shore and a regular 120 VAC BatteryMinder when on shore or generator. I understand that it’s free power but the alternator is also free power. (After you’ve paid for it just like the solar panels)

I don’t plan on idling the van to charge the batteries as that is not good for a Sprinter diesel van and MB Upfitter guidelines restrict charging from a second alternator at idle. DVCC is meant for all charging devices in a system and uses the batteries BMS to control everything if you set it up that way.

I would upgrade to a 48v Victron Multiplus II 5kVa. Why go the 3kVA route for a few dollars less and be able to run a few higher powered appliances without the power assist function. I already have all the bigger gauge wires in place already with no plans on downsizing that.

You can get massive 12v alternators, my understanding is there isn't much difference. For instance instead of replacing my 24v/270a alternator with a 24v/450a (50dn with 50dn+). I'm going with the 48v/160a. On paper it sounds like the 48v is better but just looking at their specs I'll never be able to pull above 100a at 57v and even then it'll overheat. While the 50dn+ I can pump all 450a constantly as it's 100% rated and oil cooled.

There's tons of high output 12v alternators 300a+

Alternator power isn't free at all. At best it's 750w/hp. It's a noticable fuel and power drain, even with my huge 12.7 engine. My fuel gauge switched to idle consumption so I can see the difference instantly. This is regardless if driving or idling.

Switching from MP 3kw to 5kw you'll burn about 10w more idle so 37w vs 27. I have 3 quattro 5000s in my rig. It's also less efficient at lower wattage. There's an efficiency chart online. I can't remember if it includes idle or not but was a massive difference. You'll be burning almost 1kwh per day just sitting on. 200-300w of solar would cover these losses.

 

[azazel1024]

You can get massive 12v alternators, my understanding is there isn't much difference. For instance instead of replacing my 24v/270a alternator with a 24v/450a (50dn with 50dn+). I'm going with the 48v/160a. On paper it sounds like the 48v is better but just looking at their specs I'll never be able to pull above 100a at 57v and even then it'll overheat. While the 50dn+ I can pump all 450a constantly as it's 100% rated and oil cooled.

There's tons of high output 12v alternators 300a+

Alternator power isn't free at all. At best it's 750w/hp. It's a noticable fuel and power drain, even with my huge 12.7 engine. My fuel gauge switched to idle consumption so I can see the difference instantly. This is regardless if driving or idling.

Switching from MP 3kw to 5kw you'll burn about 10w more idle so 37w vs 27. I have 3 quattro 5000s in my rig. It's also less efficient at lower wattage. There's an efficiency chart online. I can't remember if it includes idle or not but was a massive difference. You'll be burning almost 1kwh per day just sitting on. 200-300w of solar would cover these losses.

You beat me to the punch on a lot of that.

DCC alternating charging is not free at all. Diesel engines are more efficient than gas engines, but the additional load on the engine is not all that much more efficient than a good inverter generator on watt hours per gallon of gas. You are looking at likely 8-11kwh per gallon of diesel or 7-10kwh per gallon of gas at highway speeds for DCC charging. At lower engine speeds and idle, you are likely looking at between 3-5kwh per gallon of gas, possibly worse since you'd be idling a big engine just to turn the alternator.

At a minimum, I'd consider at least throwing a couple of 100-200w folding solar panels, or a 300-400w folding panel (so long as the Vpower is high enough to charge the battery) in the sprinter and lay it out to charge while parked. 1000w of panels on the roof somewhere sunny can save you a gallon of fuel...per day.

And OP has what they have, but converting what you can to 12v (or 24 or 48v) so you can leave the inverter off most of the time is also going to save a lot of power. With my future build, the only thing I am planning for a vehicle system that uses 120v is going to be an induction cook top. A couple of outlets for convenience things that are used intermittently. Like a coffee grinder. Maybe a blender. Possibly a small TV. Just flip a switch to turn on the inverter and not deal with ~25-35w of idle power consumption sucking down 500+wh of power every day. But maybe 25-50wh of idle use per day.

And DC HVAC units are (mostly) all much more efficient than 120v AC units, plus the lack of idle power consumption. You can easily squeeze 15-30% more cooling or heating out of your batteries than what a 120v unit can manage (depending on duty cycle of the unit).

*EDIT* To add, if you are using a heat pump to heat the vehicle, and charging it using a DCC, you are likely burning more diesel than if you have a diesel heater in the van instead. A bog standard Chinese diesel heater is around 70% efficient (some of the better ones are closer to 80%). Even an optimist diesel cycle engine is going to be close to 40% efficient. A 120v heat pump in a mobile setup is likely to move at most 2.5x more heat than the power it uses (less the colder it gets). Which gets about 120% efficiency for that diesel!

Except you have to figure in 5-8% losses for converting the mechanical energy into electrical energy in the alternator. 2-4% losses for the MPPT charger. 8-12% losses charging the batteries themselves. Idle power consumption of the 120v inverter. And then the inverter losses themselves (likely 8-12%). You are optimistically looking at 70% efficiency out of the energy of that diesel if you are relying on DCC to power the 120v HVAC.