Full-time planning

[Ned5555]

100sqft, I also went with the 400 AH batteries just to get more running time on the fridge and lights between charges at campgrounds. Sportsmobile Texas did suggest adding the second alternator, but it does get pricey. As the above image shows, you have to get the second bracket from the factory for $405 or SMB will install one for $680. Then the actual alternator would be about $2,600 installed.

Since it's belted into the drive train, the second alternator is always turning whether you need the extra amps or not. SMB estimated there would be a small drag on fuel economy (up to 5%) because of the added pull on the engine. I didn't see any options for a more powerful main alternator when ordering my Sprinter (V6 engine). It comes with a 14 Volt/200 amp alternator. Like Chance posted, looks like you can order up to 250 amps on the 7 speed with no extra cost.

Extra power wasn't essential for me, and I figure it would be cheaper to buy a small Honda generator if I need more off-the-grid power down the road. In the meantime, the plan is to use high idle to help charge the batteries, and supply hot water with the flat plate heater.

[100sqft]

Ned5555: Great information. I'll be interested to hear about your experiences with 400A-Hr and the standard alternator - that's the configuration I'll have to begin with. I'm still not clear on the real reason for a 2nd alternator. Is it that a single alternator will be overloaded and have a shortened life, or is it simply to recharge the higher capacity batteries more quickly? Did SMB offer any rationale for their recommendation? Could they point to any specific prior experience?

[Ned5555]

I don't know too many specifics on the second alternator vs. extra load on the single. My goal from the start was to make the van "all electric" without the complexity of a propane system or diesel generator. But I wanted the ability to use the van off-the-grid for a few days. So the SMB rep basically put all other options out on the table, including the extra house battery, second alternator and roof solar panels.

But with all SMB options, you have to do a reality check or the price just keeps climbing. My power demands weren't going to be that high (No TV or A/C) and the two batteries seemed to be enough. I will just make a habit of plugging in shore power whenever possible. Other limiting factors like fresh water will mean trips back to civilization after a couple of days anyway.

[Chance]

Reported benefits of two alternators usually include:

Leaving van's electrical system intact
System voltage not limited to 12V
Greater total power

Roadtrek seems to be moving in all-electric direction as an option. It's kind of expensive though.

[k9sprinter]

Originally Posted by Ned5555

. My goal from the start was to make the van "all electric" without the complexity of a propane system or diesel generator.

.

You alternator(s) IS a generator and it runs on diesel. It would take much , much, much, more fuel to run the sprinter at the, proper, higher rmps, (so not to foul up the DPF) then running the powertec generator.

I have 3 8D batteries,(1 alternator) never had a problem recharging while driving. And I draw a lot more power while driving than most sprinters due to all the aftermarket bells and whistles, and bells and whistles, and bells and whistles. . Lol lol lol

12v fridge, in motion satellite tv dish, cable box, 5 monitors, 10 video cameras, 16 channel video recorder,gps, laptop, amplifier, cb, ipod, phone, 12v rear ac.... plus what the sprinter normally draws(including daytime running lights,

[Ned5555]

Originally Posted by k9sprinter

I have 3 8D batteries,(1 alternator) never had a problem recharging while driving. And I draw a lot more power while driving than most sprinters due to all the aftermarket bells and whistles, and bells and whistles, and bells and whistles. . Lol lol lol

That's good to hear the alternator is able to keep up with the electrical demand in your van. I understand the Power Tech generator would be more efficient long term. But as a $7,130 option and diesel running $3.80 in my area, I would have to burn 1,876 gallons of fuel while idling before we're at the cost of the generator.

Admittedly there are some other factors like wear and tear, but I think relying on the stock alternator makes sense in vans with low power demand. Even high-idling an hour for power and hot water at the campsite each night seems well within the capabilities of the engine.

[Chance]

Originally Posted by k9sprinter

You alternator(s) IS a generator and it runs on diesel. It would take much , much, much, more fuel to run the sprinter at the, proper, higher rmps, (so not to foul up the DEF) then running the powertec generator.
.....cut.....

Do you have data to quantify how "much" more fuel an idling Sprinter uses compared to a generator?

When I researched this a while back (in order to run van's air conditioner off engine), the data I found was that there is little difference in fuel consumption. It's a little different application but should be similar comparison.

[k9sprinter]

Originally Posted by Chance

Do you have data to quantify how "much" more fuel an idling Sprinter uses compared to a generator?

When I researched this a while back (in order to run van's air conditioner off engine), the data I found was that there is little difference in fuel consumption. It's a little different application but should be similar comparison.

Sure... start up the sprinter , idle it up to about 1800rpms, leave it running..... see how long till you run out of fuel

[100sqft]

Here's a quote right off the SMB website:
"The diesel engine will use about 1.25 gallons per hour idling at 1500 RPMs."
This is given in the context of running the engine to prolong A/C use off of batteries. You can find it on this page:
http://sportsmobile.com/2_sr_heatingcooling.html
Here's another interesting/useful quote:
"The Sprinter’s engine is actually a little quieter than a diesel generator."

[SteveTOaks]

Originally Posted by Chance

Do you have data to quantify how "much" more fuel an idling Sprinter uses compared to a generator?

You can find out exactly how much fuel your engine uses if you get an ODB2 scanner and an app for your smart phone to mate with it. I got this Bluetooth ODB2 scanner and the TouchScan app for Android, both for less than $20. There are lots of apps to choose from, and lots of scanners, too. I got them to measure the fuel mileage on my 2012 Sprinter RB with pop-top. My calculations based on gallons filled and miles driven was only 17-19 MPG, which was confirmed with the ODB scanner on a trip of a few hundred miles, mostly on the freeway or highway, mostly 55 - 65 MPH. Disappointing. I know people with older Sprinters who get over 25 MPG.