Underhood versus Onan

[Davydd]

Why not both?

Cost for one thing and as Avanti said once you have a second alternator you may not use the Onan. Another thing is the more battery capacity you have the capability of an Onan as a battery charger is diminished and you can't run it enough to charge the batteries especially in a campground situation.

Then there is weight and space. The Onan weighs about 125 lbs.+ and takes up a lot of underbody real estate that can be used for other things. In my case 800ah of lithium ion batteries reside where an Onan would go. Most Bs are loaded to capacity and the Promaster's have to sacrifice other things like tank capacities to stay under weight.

As for air conditioning the results are still unsettled. Roadtrek made the initial grandiose claims with their system and proved to be bogus. At this time if you need air conditioning the most practical manner is to seek shore power. Advanced RV concluded with the Nations alternator it was a no go and with the much improved Delco alternator I think it is still rather foolish. They are testing a 48v Volta system installation but have made no commitment to that to my knowledge.

But with all, you still need to run a combustible engine in a campsite and that might not be permitted or feasible.

[cruising7388]

[QUOTE=Davydd;65308]I took it the alternator had to satisfy the engine and chassis needs first and the 40 amp limitation was a safe allowance left over. [/QUOTE

40 amp ceiling? That seems like an unnecessarily conservative safe allowance. I can't see the chassis side pulling more than 50 amps max. The engine alternator is rated at 220 amps cold and figuring a 25% hot derating we're still looking at around 175 amps hot.

[BBQ]

.

Can't wait for the good news from Volta.

[GeorgeRa]

I can’t wait for 250-500W, water cooled, 40-45dB, ICE tiny generator. Is it technologically possible - yes, marketing wise - no.

[Davydd]

[QUOTE=cruising7388;65331]

Originally Posted by Davydd

I took it the alternator had to satisfy the engine and chassis needs first and the 40 amp limitation was a safe allowance left over. [/QUOTE

40 amp ceiling? That seems like an unnecessarily conservative safe allowance. I can't see the chassis side pulling more than 50 amps max. The engine alternator is rated at 220 amps cold and figuring a 25% hot derating we're still looking at around 175 amps hot.

Hey that's Mercedes Benz. They know a lot more than us in their capability, electronics interaction and extreme conditions that may be encountered. And if it is hardwired into their computer electronics are you going to mess with that? But why screw around with the primary alternator when you can have a second alternator, the Delco 330 in my case, that I know can pull 280 amps hot for my house functions?

They are "Guidelines". I suppose one could hedge with forewarning.

[Boxster1971]

[QUOTE=cruising7388;65331]

Originally Posted by Davydd

I took it the alternator had to satisfy the engine and chassis needs first and the 40 amp limitation was a safe allowance left over. [/QUOTE



40 amp ceiling? That seems like an unnecessarily conservative safe allowance. I can't see the chassis side pulling more than 50 amps max. The engine alternator is rated at 220 amps cold and figuring a 25% hot derating we're still looking at around 175 amps hot.

The Sprinter has electric heat boosters and glow plug heaters that can draw way over 50A in cold conditions.


- - Mike
2012 Sprinter 3500 Extended converted B-Van by Airstream

[booster]

[QUOTE=cruising7388;65331]

Originally Posted by Davydd

I took it the alternator had to satisfy the engine and chassis needs first and the 40 amp limitation was a safe allowance left over. [/QUOTE

40 amp ceiling? That seems like an unnecessarily conservative safe allowance. I can't see the chassis side pulling more than 50 amps max. The engine alternator is rated at 220 amps cold and figuring a 25% hot derating we're still looking at around 175 amps hot.

I don't think you would see the 175 amps for long, if it got there at all hot, as it would continue to get hotter still. Most factory alternators that I have seen will get too hot if they are over about 50% of rated, and some not even that much. Disclaimer is that I have never dealt with an MB alternator.

Realistically, I think one could get 110 amps over a longer period of time from the alternator, and the van use would come off of that. Our Chevy runs about 10-20 amps most of the time, unless the heater/AC fans are on, or other high use like rear defogger. We can easily get to around 50 amps, I think, especially at night with the lights on. If you look at it under these terms, the 40 amp limit doesn't look all that bad.

You would have more available when the van stuff isn't on, but you would need a method of limiting the output of the alternator to prevent overheating, if it doesn't have internal provisions for it. If you set you output to the coach batteries to the high end of what will be available, you could pull too much when the van stuff is on, if you set it at the minimum, you lose charging capacity.

If the van had an old style, internally regulated, alternator on it, you could just put an external regulator on it to protect it and get the best of all worlds, but the new electronics won't let you do that.

So, basically, it just isn't as easy as it might appear, and MB is likely not as restrictive as they might appear.

Like GeorgeRa mentioned, I have been hoping for a long time, a small, continuous running, silent, low output generator to show up, as it just plain makes sense to me. Chose an output the will cover a days use, size the battery bank to cover a couple of days, and not worry about having a noisy Onan or running the van engine.

[peteco]

Originally Posted by GeorgeRa

I can’t wait for 250-500W, water cooled, 40-45dB, ICE tiny generator. Is it technologically possible - yes, marketing wise - no.

How about this:

https://www.wattfuelcell.com/uses/rv/

Looks like Hymer is looking into this. I hope they do better than they did with Ecotrek.

https://www.wattfuelcell.com/news/wa...ampaign=buffer

[GeorgeRa]

Originally Posted by peteco

How about this:

https://www.wattfuelcell.com/uses/rv/

Looks like Hymer is looking into this. I hope they do better than they did with Ecotrek.

https://www.wattfuelcell.com/news/wa...ampaign=buffer

I wish, folks are working on fuel cells for years, to be precise 218 years, so why we don’t have Fuel Cell vehicle flooding our highways yet - Fuel Cell History - Fuel Cell Today

I think that the Achilles heel is in energy source – primarily hydrogen (and methanol). Fuel cell is extracting electrons from hydrogen and oxygen chemical reaction. Oxygen is easy to get, the air. Hydrogen not so easy, could be stripped out from methane (natural gas) in a manufacturing plant and distributed to users. Or could be develop in situ from LPG in reactions requiring very high temperatures - 1800F.

These guys have a potential breakthrough https://www.redoxenergy.com/products,

Truma had a program for RV Vega Fuel cell, their site shows “Page not found”, meaning it is dead, but, nice video still floating in cyberspace

https://www.youtube.com/watch?v=-8bAQ_vxefk

[peteco]

Originally Posted by GeorgeRa

I wish, folks are working on fuel cells for years, to be precise 218 years, so why we don’t have Fuel Cell vehicle flooding our highways yet - Fuel Cell History - Fuel Cell Today

I think that the Achilles heel is in energy source – primarily hydrogen (and methanol). Fuel cell is extracting electrons from hydrogen and oxygen chemical reaction. Oxygen is easy to get, the air. Hydrogen not so easy, could be stripped out from methane (natural gas) in a manufacturing plant and distributed to users. Or could be develop in situ from LPG in reactions requiring very high temperatures - 1800F.

These guys have a potential breakthrough https://www.redoxenergy.com/products,

Truma had a program for RV Vega Fuel cell, their site shows “Page not found”, meaning it is dead, but, nice video still floating in cyberspace

Like most never-realized technologies; lots of promises, some research, hard to make a practical product, company disappeared before you can figure out what happened. I wanted to ask my gastro doctor today what happened to the promised little camera pill you swallow to do a colonoscopy instead of the traditional knock you out, scope procedure. I was unconscious before I could ask and he wasn't around when I came to.

[cruising7388]

[QUOTE=Davydd;65339]

Originally Posted by cruising7388

Hey that's Mercedes Benz. They know a lot more than us in their capability, electronics interaction and extreme conditions that may be encountered. And if it is hardwired into their computer electronics are you going to mess with that? But why screw around with the primary alternator when you can have a second alternator, the Delco 330 in my case, that I know can pull 280 amps hot for my house functions?

They are "Guidelines". I suppose one could hedge with forewarning.

I agree that to satisfy high current load requirements, a second alternator should be employed. But why not also borrow excess capacity from the engine alternator during periods when it is essentially loafing? From what I understand, the Galleria Li3 that is equipped with both the MB and a second Nations alternator does just that. As reported, when the Balmar regulator senses a lithium battery state that warrants going into a constant current boost mode, both alternator outputs are paralleled. When the regulator shifts to constant voltage, the alternators separate. During tests, the engine alternator contributed as much as 100 amps which would provide total charging capacity similar to the Delco. It's unclear how the output from the engine alternator is monitored to prevent overheating. But conceptually, this idea of paralleling alternators seems workable.

[avanti]

[QUOTE=booster;65342]

Originally Posted by cruising7388

ou would have more available when the van stuff isn't on, but you would need a method of limiting the output of the alternator to prevent overheating, if it doesn't have internal provisions for it. If you set you output to the coach batteries to the high end of what will be available, you could pull too much when the van stuff is on, if you set it at the minimum, you lose charging capacity.

Even that isn't necessarily true in a modern system. The same ECU that determines the instantaneous output of the alternator via the LIN also knows when the electric heater and glow plugs are on. It doesn't matter what the raw capacity of the alternator is. Very likely, it just isn't going to crank up the alternator unless there is a reason to do so, and (beyond the 40A), the ECU knows nothing about your coach battery. Could it measure it? Sure, but only if it could make assumptions about where and how the external load was connected, and the nature of that load (AGM battery? Lithium? inductive load?...). As I said, that load would look vastly different depending on which side of the battery-terminal shunt you connected your load. That is the purpose of the "40 amp" spec and the corresponding single approved connection point for drawing the load. It allows the rest of the system to be properly engineered. The 40 amps could have been much higher, but it isn't. I suspect that to do so would have required complex and hard-to-explain behaviors such as some kind of load-shedding strategy if too many high-current loads were present all at once, etc, etc. The spec is no doubt conservative, but it keeps things simple.

[Boxster1971]

Originally Posted by GeorgeRa

I can’t wait for 250-500W, water cooled, 40-45dB, ICE tiny generator. Is it technologically possible - yes, marketing wise - no.

To get only 250-500W seems like adding more solar would be a lot simpler. Once you have filled the available space on roof one could always add a side rack to expand the solar array. Something like the surf board racks in this thread on Sprinter forum.
https://sprinter-source.com/forum/sh...d.php?p=574804


- - Mike
2012 Sprinter 3500 Extended converted B-Van by Airstream

[booster]

Originally Posted by Boxster1971

To get only 250-500W seems like adding more solar would be a lot simpler. Once you have filled the available space on roof one could always add a side rack to expand the solar array. Something like the surf board racks in this thread on Sprinter forum.
https://sprinter-source.com/forum/sh...d.php?p=574804


- - Mike
2012 Sprinter 3500 Extended converted B-Van by Airstream

True, but the system GeorgeRa is referring to would be able to put out the 250-500 watts 24/7 and would net much more capacity per day than the same wattage of solar. That is the big upside to low output, quiet, power generation, using a battery bank as an accumulator/buffer.

[GeorgeRa]

Originally Posted by Boxster1971

To get only 250-500W seems like adding more solar would be a lot simpler. Once you have filled the available space on roof one could always add a side rack to expand the solar array. Something like the surf board racks in this thread on Sprinter forum.
https://sprinter-source.com/forum/sh...d.php?p=574804


- - Mike
2012 Sprinter 3500 Extended converted B-Van by Airstream

Mounting deployable solar panels on the side of the van in my view is not simple. In addition, solar harvesting is limited in time and weather. I have 300W on the roof and it is doing good job in good weather. If I would go the route of increasing number of PV panels I would most likely go by stacking them vertically on the roof which would give me 600W still useless in bad weather or at night.

I could buy a 450 watts portable generator, stripped it to the bone and reengineer it into a silent by stationary generator mount. This unit is 0.84 CF. I could build a double wall compartment with spacing of about an inch between the inner and the outer wall and provide the engine cooling with a pancake fan. Before actual use fill the compartment wall with water to block the sound. https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER

[booster]

Originally Posted by GeorgeRa

Mounting deployable solar panels on the side of the van in my view is not simple. In addition, solar harvesting is limited in time and weather. I have 300W on the roof and it is doing good job in good weather. If I would go the route of increasing number of PV panels I would most likely go by stacking them vertically on the roof which would give me 600W still useless in bad weather or at night.

I could buy a 450 watts portable generator, stripped it to the bone and reengineer it into a silent by stationary generator mount. This unit is 0.84 CF. I could build a double wall compartment with spacing of about an inch between the inner and the outer wall and provide the engine cooling with a pancake fan. Before actual use fill the compartment wall with water to block the sound. https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER

\

I wonder what the design life is on those type engines. I know a lot of the small pressure washer, edger, etc type 4 cycles are in the 300-500 hour range, which wouldn't be enough for this type of application. I think regular Onans are in the 2500+ hour range, and even they aren't continuous run units, as in 24/7 for many days on a regular basis. I would think you would need something at a minimum of 5K or 10K hours for this kind of application.

[GeorgeRa]

Originally Posted by booster

\

I wonder what the design life is on those type engines. I know a lot of the small pressure washer, edger, etc type 4 cycles are in the 300-500 hour range, which wouldn't be enough for this type of application. I think regular Onans are in the 2500+ hour range, and even they aren't continuous run units, as in 24/7 for many days on a regular basis. I would think you would need something at a minimum of 5K or 10K hours for this kind of application.

The reviews are not good for this unit, so I am not sure this would be the best option. A small Honda, Yamaha or Subaru would be a better option. A crankshaft free ICE generator could have a very long life, no side load on the cylinder but they are not available, hopefully yet.

[booster]

I think for generators, a linear travel heat engine of internal, or external combustion can be done, as the generated electric power can be taken of linearly instead of rotary. Basically a push-pull heat powered cylinder with a coil/core generator. No rotation will certainly make it easier to extend life.

[booster]

Linear engine generator

https://www.youtube.com/watch?v=QUbBqSu9Hdc

[GeorgeRa]

See some other examples:
https://www.youtube.com/watch?time_c...&v=0ZwZ7Con-Wc
https://www.youtube.com/watch?time_c...&v=u4b0_6byuFU