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2017 159, w/dual sliders. SF Bay area
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Discussion Starter #1
I'm mulling the options for AC. I'm not sure how often we'll use it and I expect it'll be one of the last things we do. I don't want a generator. I was watching a video comparing the Hymer to the Travato and learned that Hymer's A C unit is run from the second alternator. they call it the under-hood generator, but we all know what they mean.

This means that you get AC when on shore power or if your van is idling. I like this idea. What would be the downside to this setup? I've read that the second alternator hangs pretty low, but there is a 3rd party skip plate available to protect it.
 

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It depends on how you would set it up, but the roadtrek doesn't directly power the AC from the second alternator; it charges the batteries which the AC runs off of through an inverter. On paper it's a clever system. However their implementation has been plagued with issues since day one. I've heard people say they build quality and the parts selection may have something to do with it. You can for sure do your own setup, but the cost is high.
 
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ThomD,

You will have to really want/need the set up. I have the set up, AC, second alternator, and skid/engine guard.

like you, we do not use the the AC that often but, when we do it is worth the trouble and extra expense as we have 3 fur kids.

The install of the Nations second Alternator (Hymer and Roadtreck both use this kit) is no small deal. Unless you are a mechanic. You do loose clearance with alternator and further clearance loss with the guard. Clearance is after skid plate is approximately 6" and you will not want to go with out it as even a curb hit would do major damage.

We run our AC off our Lifepo4 battery so no need to idle the engine when parked. When driving in extreme hot weather we just turn on the second alternator and run the AC for the dogs. We actually use the second alternator mostly to charge our battery on non sunny days.

Hope this helps

Dave
 

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Problems and a lot of cost for little gain. Even with thousands invested in a big lithium battery bank you arent running the AC long. And that kind of consistent load on any battery system is shortening its life.
 

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We run our AC off our Lifepo4 battery so no need to idle the engine when parked. When driving in extreme hot weather we just turn on the second alternator and run the AC for the dogs. We actually use the second alternator mostly to charge our battery on non sunny days.
Dave,

My understanding of the system in the Aktiv is that they have AGM batteries in addition to the Lithiums. In that system, I could never tell what charged what when.

IIRC the Fit RV people had the second alternator dedicated to Lithium batteries, I believe because the charge characteristics were different and they didn't want to do a battery-to-battery charger.

Thom, you may want to look at their blog entry for this. They describe a misadventure where the belt installation for the alternator failed and it cut the radiator hose :eek: And they had "professionals" install it.

https://www.thefitrv.com/rv-tips/ou...ithium-battery-solar-alternator-and-inverter/

I have three dogs too, and am considering a Lithium retrofit once the technology is mature. In the meantime I'll just use a generator, but I'm considering hacking my own "Volt-Start" system with one of the remote-start systems just because. (I'm a software engineer with embedded system experience)
 

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Discussion Starter #6
Thanks everyone.

James and Steph (ok, mostly James) do have lots of interesting content. They have been very influential in my journey so far - Promaster good, Travato bad. I mean, they have to keep their mountain bikes on the outside of the van! Heathens.
 

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What would be the downside to this setup? I've read that the second alternator hangs pretty low, but there is a 3rd party skip plate available to protect it.
We, too, have the Nations second alternator installed. But unlike the cautious Dave (Not Home), we have only the factory installed plastic 'splash' guard installed.

We haven't had a problem except when we removed the plastic splash guard to . . . (see below)

Thom, you may want to look at their blog entry for this. They describe a misadventure where the belt installation for the alternator failed and it cut the radiator hose . . .
. . . again, for the second (or is it third?) time patch/fix/repair the radiator hose 'sliced' by the second alternator added serpentine belt. Amazing how, within less than 30 minutes after removing the splash guard . . . we managed (in the dark) to drive over an exposed short stump . . . which tore all the alternator wiring out. Fortunately we were able to perform surgery and get both the alternator functional and the radiator hose 'patched' (our emergency hose fix was a series of worm hose clamps forcing the longitudinally sliced radiator hose together . . . 5K miles and this temporary fix is still holding).

My understanding of the system in the Aktiv is that they have AGM batteries in addition to the Lithiums. In that system, I could never tell what charged what when.
And, Ziggy, you probably will never be able to tell what is happening with an Aktiv . . . as Hymer keeps their wiring and system diagrams 'top secret'. You're truly 'flying blind' with a Hymer . . . it seems their philosophy is . . . create a system for the ignorant, tell them how to turn it on, but give them no meaningful or quantitative metering that they might misinterpret . . . make it fully automatic and idiot proof.
 

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It's the future -- whether technology is mature enough for your budget or vehicle is the main question. I think is just a matter of time.

These systems work better on Mercedes Sprinters because they come from factory with a second alternator bracket option. RAM really needs to include this option on PM, or better yet offer a second HD alternator from factory.

For what it's worth, Xantrex just introduced an integrated system that should be competitive against a diesel generator when installed in a Sprinter. I haven't seen details or cost yet, but would estimate around $10,000 for 600 Amp-hours of lithium battery bank capacity. A couple of van manufacturers have already jumped in.


http://www.xantrex.com/email/egen/flyers/coachmen-flyer-web.pdf


One design feature I would change is make it operate at 48-Volts nominal, but Xantrex stuck with 12 Volts, which I think is questionable with a 3,000-watt inverter (even higher surge). Current level is crazy high, and why larger systems for luxury bus conversions operate at 48 Volts.
 

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We haven't had a problem except when we removed the plastic splash guard to . . . (see below)

. . . again, for the second (or is it third?) time patch/fix/repair the radiator hose 'sliced' by the second alternator added serpentine belt. Amazing how, within less than 30 minutes after removing the splash guard . . . we managed (in the dark) to drive over an exposed short stump . . . which tore all the alternator wiring out. Fortunately we were able to perform surgery and get both the alternator functional and the radiator hose 'patched' (our emergency hose fix was a series of worm hose clamps forcing the longitudinally sliced radiator hose together . . . 5K miles and this temporary fix is still hooding)
It would seem that a radiator hose guard might be more essential than a skid guard then.
 

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Problems and a lot of cost for little gain. Even with thousands invested in a big lithium battery bank you arent running the AC long. And that kind of consistent load on any battery system is shortening its life.
mrshowtime3,

Maybe I'm missing something, are you speaking from experience? Did you install the kit? do you have a Lifepo4 bank?

What are you referring to when you say "And that kind of consistent load on any battery system is shortening its life"? Even with a small Lifepo4 bank the load is fractional C discharging, well below .5 C. This kind of discharging has no effect on a Lifepo4 house bank.

How long you can run the AC is only a mater of the size of your battery and the type and size of your AC. In our case we have a 11,000 btu 12v AC. It has a brushless motor and has no in rush on start up. the AC cycles and draws on average about 50amps at 12v. when I run the alternator it puts out 100-140amps at idle. We have a 9Kw battery bank so we can run the AC with the engine off for hours!

We have had no problems to date only benefits. Is it expensive? Absolutely, it adds up real quick even if you build it your self. Going down this road is the full meal deal and once you start you are committed. Its is only recommended for the most adventurous.

Cheers,

Dave
 

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Are either of these dealers setting up a second alternator on a diesel engine? When I build my rig the second alternator was not an option for the I4; has that changed?
 

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Discussion Starter #13
We have had no problems to date only benefits. Is it expensive? Absolutely, it adds up real quick even if you build it your self. Going down this road is the full meal deal and once you start you are committed. Its is only recommended for the most adventurous.

Cheers,

Dave
Hi Dave,

Do you have a build thread? If not, can you give a quick overview?
 
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