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Old 05-26-2018, 12:36 AM   #1
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Default Axial Flux generators

Just before they folded, Great West Vans was starting to offer rigs with underhood generators built by Mobile Electric Power Solutions. These are based on a technology called "axial flux generators". This is a very interesting approach that generates power using very simple brushless underhood generators with rotors containing permanent magnets. As I understand it, unregulated 3-phase power is passed via a 3-wire cable from the alternator to a custom electronic unit which converts this current directly to 120VAC. Another manufacturer using this technology is Aura Systems.

This technology seems to be very popular in military vehicles, and looks to have a lot of advantages, including good performance at low RPMs and good temperature characteristics. It has been around for awhile, and comes up from time to time in the RV world, but it has never seemed to have caught on. Does anybody have any insights as to what the pros and cons of this approach are?
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Old 05-26-2018, 05:01 PM   #2
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I recall a video about that...

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Old 05-30-2018, 05:24 PM   #3
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I recall a video about that...
I've got one of those things sitting out in the barn. We've been using it for a feed trough, but I could hose it off and it should be good as new. If anyone wants it, I'll let it go for $1,000,000. Firm.
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Old 05-30-2018, 05:27 PM   #4
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Does anybody have any insights as to what the pros and cons of this approach are?
I contacted both Mobile Electric and Aura before starting my current build. They're both pretty pricey. I don't recall what they quoted, but the difference between them and a couple of high output alternators was enough to scare me off.
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Old 05-31-2018, 02:58 PM   #5
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Does anybody have any insights as to what the pros and cons of this approach are?
We like this concept as a replacement for 'the RV generator' but prefer a system that directly outputs to our 'off-grid' electrical battery system . . . and for the time-being, that's 12 VDC. Yet, with a simple 12v charger, this approach has merit.
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Old 05-31-2018, 03:42 PM   #6
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We like this concept as a replacement for 'the RV generator' but prefer a system that directly outputs to our 'off-grid' electrical battery system . . . and for the time-being, that's 12 VDC. Yet, with a simple 12v charger, this approach has merit.
Yes, that is the approach I took as well. Literally everything in our rig is native 12VDC, except for the obvious high-current items.

But, the key phrase is "for the time-being". I brought this up in the context of this thread because if 48VDC makes sense, maybe 120VAC makes even more sense. The recent discussion about the apparent surprising efficiency of the current generation of "dorm fridges" adds credence to this. The idea of an ALL-AC van is interesting.

Obviously, one would need DC between the battery and the inverter/charger, but maybe some day that will be it. Some of the axial flux systems I referenced have integrated battery interfaces at various voltages.
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Old 05-31-2018, 04:46 PM   #7
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But, the key phrase is "for the time-being". I brought this up in the context of this thread because if 48VDC makes sense, maybe 120VAC makes even more sense . . . The idea of an ALL-AC van is interesting.
The time doesn't seem ripe for 48 volts. We'd like to avoid running parallel 12 & 48 volt systems. As our lithium-based house electrical system, including second Nations alternator, is completely separate (and never interconnects with) the vehicle system, we could have gone 48 volts. But until more 48 volt appliances are available, we'll stick with 12 volts, and its inefficiencies.

Speaking of ALL-AC, we have gravitated in that direction. We have 8 duplex outlets spread throughout our DIY Promaster 159" HT Class B with a Magnum 2812 inverter/charger running 24/7 (except when on shore power). We no longer shop for 12 volt power supplies for our computers, power tools, and other gadgets, instead, we just plug their supplied wall chargers into one of these distributed 120 VAC outlets. Yes, this arrangement carries a fairly steep 'overhead', say, 2kwh/day. But with a large array of solar (800 watts), that 2nd alternator and 500ah of lithium, why not?
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Old 05-31-2018, 05:22 PM   #8
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The time doesn't seem ripe for 48 volts. We'd like to avoid running parallel 12 & 48 volt systems. As our lithium-based house electrical system, including second Nations alternator, is completely separate (and never interconnects with) the vehicle system, we could have gone 48 volts. But until more 48 volt appliances are available, we'll stick with 12 volts, and its inefficiencies.

Speaking of ALL-AC, we have gravitated in that direction. We have 8 duplex outlets spread throughout our DIY Promaster 159" HT Class B with a Magnum 2812 inverter/charger running 24/7 (except when on shore power). We no longer shop for 12 volt power supplies for our computers, power tools, and other gadgets, instead, we just plug their supplied wall chargers into one of these distributed 120 VAC outlets. Yes, this arrangement carries a fairly steep 'overhead', say, 2kwh/day. But with a large array of solar (800 watts), that 2nd alternator and 500ah of lithium, why not?
What would be the components of your overhead estimate of 2kwh/day ?

Parasitic power and conversion inefficiencies on the Magnum?

Anything else?
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Old 05-31-2018, 07:06 PM   #9
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What would be the components of your overhead estimate of 2kwh/day ?
Our Battery Management System draws about 1 amp.

Our Midnite Solar Classic draws, when resting, about 1 amp. If we're tight on power (rarely), we have a breaker to disable this at night.

We've not documented the Magnum with absolutely nothing connected, but with the various 'things' that are always connected, it draws about 5 amps. These things include a router, a Ubiquiti WiFi modem/antenna, a WeBoost, an Asus file server (NAS) and various small chargers that we leave plugged in whether charging or not, a NovaKool R4500 frig which, when running, draws 4-5 amps, LED lighting of 1 amp, maybe more, one or more laptops/tablets . . . which can runs for hours at over 100 watts (8 amps).

Then there's the 125 amp hot pot which runs in 4 minute spurts, the 125 amp induction stove, again, limited time durations.

Truth is that we probably average closer to 3kwh/day. The good news is, during these long days at reasonable latitudes we can generate 4-4.5kwh/day.

But if we get hit with a couple of overcast days, it's either shore power or the 2nd alternator.
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Old 05-31-2018, 07:55 PM   #10
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Our Battery Management System draws about 1 amp.

Our Midnite Solar Classic draws, when resting, about 1 amp. If we're tight on power (rarely), we have a breaker to disable this at night.

We've not documented the Magnum with absolutely nothing connected, but with the various 'things' that are always connected, it draws about 5 amps. These things include a router, a Ubiquiti WiFi modem/antenna, a WeBoost, an Asus file server (NAS) and various small chargers that we leave plugged in whether charging or not, a NovaKool R4500 frig which, when running, draws 4-5 amps, LED lighting of 1 amp, maybe more, one or more laptops/tablets . . . which can runs for hours at over 100 watts (8 amps).

Then there's the 125 amp hot pot which runs in 4 minute spurts, the 125 amp induction stove, again, limited time durations.

Truth is that we probably average closer to 3kwh/day. The good news is, during these long days at reasonable latitudes we can generate 4-4.5kwh/day.

But if we get hit with a couple of overcast days, it's either shore power or the 2nd alternator.
OK, I was confused, I thought by overhead you were referring to the penalty for using 120v vs 12v devices and the requirement to keep the inverter running to support them...
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