Great West goes electric

[avanti]

Great West finally got up their new website, showing their 2016 Sprinter Legend and ProMaster Classic models.

http://www.greatwestvans.com

The basics are mostly unchanged, but now that they are settled in their new digs, they seem to be gearing up for a rework of their technical systems. The most notable thing so far is that they are offering the option of a 3KW engine-driven generator from MEPS:

http://www.meps.com

What is interesting about this is that it appears to be a true AC generator, which should make for a nice clean installation. The MEPS website has interesting performance data for many of their systems, although the 3KW unit seems to be a fleet-only item.

I suspect that Sterling is evolving their systems incrementally, and may be planning to position themselves as the cost-effect alternative for folks interesting in all-electric solutions and other high-tech systems. Their MSRPs are pretty attractive, especially the ProMaster. I hope they continue their willingness to work with customer-driven customizations. If they can do that on a cost-effective platform that also continues to offer the latest technologies, they may carve out an attractive niche for themselves.

 

[gerrym51]

sounds cool

 

[booster]

I have always wondered why the manufacturers had chosen to use 12 or 24 volts of DC for the engine generators. That said, they can't really be an AC generator like we know because there is no constant speed to give frequency. But, they certainly can generate the higher voltage, get all the benefits of smaller wiring and then invert it to 110AC pretty easily. Since most of the manufacturers are going directly to the coach batteries with the engine generator, they aren't tied into the 12v anyway. Just think, you could have 10 gauge wire from the engine to the charging area, instead of lots of very heavy 4/0 cable.

 

[avanti]

I found the following in a FAQ about the MEPS system:

There are three main components to the system:

1. The Alternator: is a 3-phase AC, 6-pole, high-output alternator at half the weight of others on the market and is located under the hood next to the vehicle alternator.
2. The ACU: only weighs around 18 Lbs and about the size of a toaster (senses, monitors and protects the alternator and converts the 3-phase power coming in from the alternator to pure sine wave). It is typically located in a protected area in the rear of the vehicle
3. Automatic Idle Control: regulates the idle to respond to increased/decreased consumption requirements and is typically located on the drivers side dashboard (About the size of a pocket calculator).

So, it looks like they are sending unregulated 3-phase AC to the controller box that reforms it to pure sine wave AC.

This makes a lot of sense--looks like a real innovation.

 

[booster]

That is interesting, and also makes a lot of sense. It must be some interesting electronics to do it all, and keep it under control. A system like that make so much more sense than wiring for hundreds of amps of 12v power. The only downside I could think of would be the availability of deadly voltage under the hood, where folks would expect it.

 

[Davydd]

Avanti,

The MEPs literature infers replacing your "failure prone" (MEPs' words) inverter/battery system or Onan generator. What exactly are they implying? That you do not need a high battery capacity system and inverter but would simply idle your engine? I understand a direct replacement of the Onan in function. Will they still offer high capacity batteries and inverter with this? How do they envision its use? Our second alternator functions only while driving to charge batteries (so far after 15,000 miles) and I only see engine idle charging as emergency backup.

Freedom from shore power has increasingly pushed us toward more primitive campgrounds especially in the national parks with no generator use restrictions which means also no engine idling. I even found the Espar diesel-firing for heat to be a bit embarrassing in Big Bend Chisos Basin CG next to tent campers. So we turned it off and burrowed into our sleeping bags in overnight freezing temperatures.

They are clarifying their name and branding. Also noted they have four captain chair model options. That's new isn't it? They are up to 8 dealers in their listing. They only had 3 in 2011. Dale Borstad at Lake Region RVs got a deserving shout out on the web page.

 

[booster]

I think they are directly addressing the "normal" Onan installation and the Roadtrek lots of batteries and inverter to run the air conditioning promotions.

You can run anything off their system, including AC if you want by idling the engine. It is up to you to decide if that is a good idea, or not, based on potential engine issues from idling.

As to the claim of not needing huge battery banks, I think they are right in most cases. You don't need 800/1600ah of battery if you don't want to run the AC of the batteries, in most cases. Davydd is the exception to this because he uses 300ah per day without the AC, but most of us would not have such an energy eating system, and 400ah a day is plenty. We never get close to 100ah. Add solar and you are good to go, as it will keep up well with 100-150ah per day, but not at 300-400 a day like Davydd uses.

I do think they are stretching a bit if they are basing all the capability on running AC of the van engine, as you can just run the dash AC, which is usually bigger than the coach unit. At that point you are getting a very good charging and short term power generator (microwave, hair dryer, coffee maker), which is just fine. You still save all the massive wiring needed for 12v, high watt systems.

 

[mlts22-ClassB]

This definitely makes the "engine generator" of the Roadtrek series pretty much obsolete, since the 120VAC coming from the MEPS device directly powers one rail, and the RV converter (which has to be there anyway for charging batteries from shore power) can easily turn 120 volts into 12 volts and feed it to the batteries at the best voltage/amperage.

The ironic thing is that the whole-van inverter system I drew out for the Transit upfit, going 120 volts for another input would be more of a liability than an asset. Skinnier wires are useful, but I would need two transfer switches, one to switch between MEPS and generator power, and one for the output of the first and shore power, as opposed to 12 volts coming from the alternator to the batteries.

To me, an onboard generator is still a must with of the setup I have, because it fires up the genset when the house batteries get to 60% SoC. I don't know of any vehicle engine autostart that would do that for house batteries, and wiring one up may void the van's warranty. It also would interfere with the vehicle's antitheft system, which isn't a good thing.

Of course, if someone lives in a northern climate and doesn't require A/C, has a good battery system, the MEPS system may be the ideal thing, although there is something about running a vehicle's engine and putting idle hours on that. Replacing an engine is expensive even compared to a $7000 PowerTech generator.

 

[Jostalli]

Cool but I'm more interested in all things 12V as that is what my batteries and solar panels provide. So far everything I am planning for my conversion is 12V except convection microwave and induction stove. 12V A/C, water heater, radiant floor heat, etc.

Engines are the worst.

 

[Boxster1971]

GW web page for specific Legend models lists the battery option:

"•Available 3000W Inverter with 4 6V AGM Batteries"

 

[Davydd]

GW web page for specific Legend models lists the battery option:

"•Available 3000W Inverter with 4 6V AGM Batteries"

Sterling does offer that but I was referring to the MEPS website statement about inverter/batteries. Also, options don't always work together as in if you if you pick one the other may not be available. I guess my question is how does it work? There is an implication it replaces an Onan. Does that mean the intent is only to operate it stationary at engine idle? Or does it charge batteries like a DC engine alternator while driving down the road? Also, is the intent to engine idle when you want to use 120v appliances? I can understand replacing the Onan directly with this but would never buy into having to use it like an Onan with campground engine idling just to use 120v systems. So, if you opt for a large battery bank with a large inverter does it make any difference to have MEPS or a second DC alternator under the hood?

 

[wincrasher]

I don't see that using this is precluding have a substantial battery pack. It just may be that you don't need a secondary inverter to power the battery charger. Or perhaps you'd have a second inverter to power devices from your battery pack.

I'd agree you could be saving alot of copper, but that may be offset by needing/wanting a second inverter.

 

[gerrym51]

does a 'true" engine generator that is producing 120 volt power then need a charger to put 12 volt into batteries.

that part of the cycle can't be as efficient as as direct 12 volt alternator creation?

As wincrasher said once -which got me to reconsider my original decision- there are TWO major functions of the roadtrek system.

1. creation of 120 volt power.
2. rapid and plenty of 12 volt charging.

i plan on using the inverter relativley rarely. its the high amp 12 volt charging that has come to the forfront for me artyman:

 

[booster]

We would have to assume that they generate the 3 phase AC power, which is unregulated so you can't use it for anything, and then convert it to 110v AC at 60hz, so it is just like shore or generator power. It would then run through the converter to charge the batteries.

What you lose is being able to put 200 amps directly into the batteries, unless you have a big converter. What you gain is the higher quality charging you get from having it go through the multistep charger, which IMO is a very big plus. I think that the trend toward more engine generating systems is going to make the already existing problem of coach battery overcharging worse because of the higher charge rates. The partial solution is to use a 12v to 12v battery charger, but nobody is doing that at this point, except a couple of DIY folks.

Personally, the AC generator and 150amp converter, with about 400ah of battery would be a very nice setup, I think.

 

[avanti]

does a 'true" engine generator that is producing 120 volt power then need a charger to put 12 volt into batteries.

that part of the cycle can't be as efficient as as direct 12 volt alternator creation?

As wincrasher said once -which got me to reconsider my original decision- there are TWO major functions of the roadtrek system.

1. creation of 120 volt power.
2. rapid and plenty of 12 volt charging.

i plan on using the inverter relativley rarely. its the high amp 12 volt charging that has come to the forfront for me artyman:

Yes, you do need some device to serve as a charger under this scenario. BUT, you need one anyway. Although it is common practice to feed the output of a 12VDC alternator directly to the coach battery while underway, this is a very suboptimal setup compared to a 3- or 4-stage temperature-compensated charger. We get away with it (more or less) by also having a charger that does a proper recharge while on shore power. The house batteries would not last long without this. If you want to optimize such a system, you need a DC-DC charger. Some people even run the charging current through a small inverter and then through an AC charger. Inefficient, but you have plenty of power so it doesn't matter much.

With an AC generator, you would simply use the same charger that is already there for shore-power purposes. My guess is that GWV's intent is to sell the MEPS system together with the listed 3000watt inverter/charger, the electric cooktop and an electric fridge. You could pick a large or small battery pack, depending on your need. No propane. In this regard, it is no different from RT and ARV. The innovation is strictly technical: no need for bulky, heavy, expensive DC cabling, and simpler relationships between the AC and DC systems.

Davydd: I think the comments you are seeing in the MEPS literature are generic--not RV specific. I agree that it doesn't make much sense to depend solely on engine idling for AC in an RV situation, but it may make sense for an ambulance or a military vehicle, which I infer is their main market.

 

[gerrym51]

i'm sorry i don't seem to understand this. isn't an alternator doing 12 volt to 12 volt charging?

 

[avanti]

i'm sorry i don't seem to understand this. isn't an alternator doing 12 volt to 12 volt charging?

Yes, but it is a very "dumb" charging profile. Battery health requires multi-stage charging where the charge voltage is modulated according to the instantaneous state-of-charge and also battery temperature. Also, the under-sized DC wires that many upfitters use between the alternator and the house tend to have enough voltage drop such that the house batteries never get fully charged at all, except when on shore power. This is a matter of voltage, not current capacity.

 

[booster]

i'm sorry i don't seem to understand this. isn't an alternator doing 12 volt to 12 volt charging?

Yes, but it is a very "dumb" charging profile. Battery health requires multi-stage charging where the charge voltage is modulated according to the instantaneous state-of-charge and also battery temperature. Also, the under-sized DC wires that many upfitters use between he alternator and the house tend to have enough voltage drop such that the house batteries never get fully charged at all, except when on shore power. This is a matter of voltage, not current capacity.

I totally agree, with one addition. In the past, the engine charging systems and the stock alternators were very prone to undercharging the coach batteries, primarily, as Avanti says, because of low voltage to the coach batteries. The low voltage was caused primarily by the fact that the systems used isolators, not separators like most do now (or nothing as in most engine generator setups), and secondarily by the small wiring and lower alternator voltages in some of the older vans. Many that I have seen numbers on would get only 13.2-13.7 volts to the coach batteries, which is definitely not enough to charge the batteries full and properly.

With the current setups of direct wiring and/or the use of separators, just the opposite happens much more often. Most of the vans are running alternator voltages in the 14.4 volts, or even higher. This is a good charging voltage for most battery types, and will get them full quite well under controlled conditions. No temp compensation can be an issue, though. Where you really run into a problem with the higher voltage systems is that once the batteries are full, the 14.4 volts is way to high to be putting on a full battery. If you come off shore power and drive all day, you can put 10+ hours of hefty overvoltage on the batteries, which is going to hurt them over time. Their are solutions, some better than others, for the issue. A shutoff switch for the coach charging is easy and cheap. If you control it by looking at the current going to the coach batteries (on a Trimetric shunt type monitor), you will be able to shut off the battery charging at exactly the correct time to have them full, but not overcharged. A 12v to 12v charger will also help the situation, but as of now, there don't seem to be any of them that monitor the battery current to determine full charge, which is the best way to do it, so they would be a bit less accurate. You could still do the manual monitoring of the current on a meter to get the higher accuracy, though.

We have had a lot of discussions of the overcharging issues here, which I think is really good because folks with Bs tend to drive a lot compared to other RVs. I hope that the B manufacturers get onboard with adding 12v-12v chargers with the engine generator systems, as I think they need them to keep the batteries happy. With battery banks often costing over $1000, keeping them in good condition is a very good thing. :mrgreen:

 

[Davydd]

Avanti, as you describe a setup it sounds ideal. I hope Sterling's approach is that way and not just an Onan direct substitute approach. The mention of idling control is what got me questioning the intent.

You need to eliminate the Onan in a B if you want to achieve serious battery power. They compete for the same practical space and weight.

That 4.0 AWG wire from second alternator to the battery bank I have is about $7 per foot. I don't think $140 or so is much of a premium per benefit gained. Charge control is not an issue for me.

Much has been discussed about second alternators and idling. I suppose the same will ensue with MEPS. I'm not too alarmed by either after talking to MB's RV rep despite the caveats.

Anyone have any idea how MEPS will stack up cost wise to a second alternator? I have to believe both will cost less than an Onan setup with less headaches and maintenance.

 

[avanti]

Charge control is not an issue for me.

Remind us again what ARV does for charge control from the second alternator? Do they use some kind of DC-DC charger? If so, do you happen to know which one?

Or, does the Li charging system do this regulation intrinsically--somehow accepting either AC or unregulated DC?

Or, is the Silverleaf system somehow involved?