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Old 06-16-2015, 12:25 AM   #15
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Lots of questions there. We have a Sprinter-based Roadtrek with about 150 watts of solar panels, and an Airstream 310 with 400 watts. You have to be very careful about budgeting power and monitoring battery condition but it is possible to work out of a Sprinter running on solar. You may need to add more panels than come with the stock installation. It also depends on how big a battery you have onboard.

There are phantom loads typically of 10-40 watts for relays, status lights, and the fridge, which runs on propane but requires a very little bit of electricity for its brain. Your laptop computer will use 30-80 watts, a phone or Mifi very little if you have an efficient charger. Say you have an office load of about 100 watts. 8 hours times 100 watts is 800 watt-hours of energy.

Protagonist's comments are spot on. You will need to manage some combination of solar, plug-in, generator and batteries and you'll learn to cope, you'll probably do OK if you have all available roof space covered in high efficiency solar panels. We haven't tried full 8 hour days but 150 watts of solar panels have been enough nearly every time. 400 (and a big battery) means we can stay in the shade for a day or so.

If you get into the arithmetic of figuring out how much energy you can store with the power and time you have available, realize that you lose about 50% charging and discharging the battery. In direct sun in California you can plan on 5 hours of full power charging (so, if 100 watts of panels, 500 watt-hours per day, of which you will actually be able to use about 250 if you store it in batteries.) Likewise your batteries hold about half their rated capacity -- a 220 amp-hour 12 volt battery actually holds about 1300 watt-hours, not the 2640 you get by multiplying 12 x 220. This is because you don't want to discharge your battery more than about 50% if you want it to live.
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Old 06-16-2015, 09:34 AM   #16
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Hi all,



I'm thinking about getting a late model Interstate and using it to take my small family to places while I telecommute for work.

My question is: Is there enough solar panel to power my laptop (my 4g device can run from laptop tho it may be drawing more power) and possibly the lcd tv as a 2nd monitor? what else MUST need to use the battery.. refrigerator?



We've only rented a RV a couple of times for vacation... but I really don't know a lot about staying long term in RVs...especially working from a RV.



Thanks!

Unless you plan to add more solar to the Interstate you are considering it may not be the vehicle for your intended use. The late model Interstates only came with 50 or 100 watt solar panels depending on the year since about 2010. I upgraded to 400 watts of solar on mine so we could dry camp without much problem. If I were buying today I'd get a Roadtrek E-Trek or a unit from Advanced RV that are total electric without that noises propane generator.


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Old 06-17-2015, 01:31 AM   #17
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I was all set to be impressed by the E-Trek but its a cruel joke. It's really pretty and I really wanted to like it. You basically need to run the engine to cook breakfast. The optional fuel cell from Efoy is neat technology but the biggest one produces 90 watts and you have to buy the special methanol fuel from them at $193 for 31 kWh, or about 50x what power costs at home.

400 watts of solar and some large batteries go a long way toward making it practical, especially with newer solar panels that are getting more efficient. We carry an extra 100 watt one that we put out in the sun when we're parked in the shade, and that usually works for a long weekend if we are careful.
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Old 06-17-2015, 01:40 AM   #18
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Lots of questions there............


If you get into the arithmetic of figuring out how much energy you can store with the power and time you have available, realize that you lose about 50% charging and discharging the battery. In direct sun in California you can plan on 5 hours of full power charging (so, if 100 watts of panels, 500 watt-hours per day, of which you will actually be able to use about 250 if you store it in batteries.) Likewise your batteries hold about half their rated capacity -- a 220 amp-hour 12 volt battery actually holds about 1300 watt-hours, not the 2640 you get by multiplying 12 x 220. This is because you don't want to discharge your battery more than about 50% if you want it to live.
LiPo batteries are a very attractive energy storage alternative to lead acid based batteries.....even Lifelines!!!
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Old 06-17-2015, 02:11 AM   #19
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LiPo and batteries are indeed very interesting and can be used to about 80% of capacity without chewing into their service life, but they are very intolerant of misuse, unlike lead-acid or even AGMs. If Elon Musk can get enough people on his bandwagon for smart, processor-managed battery systems it could be a major shift. I have a 20 AH Li-ion pack for radios and stuff, it's about 1/4 the size and weight, and 4x the price of an equivalent AGM.
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Old 06-17-2015, 07:06 AM   #20
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Hi all,

I'm thinking about getting a late model Interstate and using it to take my small family to places while I telecommute for work.
How big is your small family and how comfortable can they be in an Interstate?
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Old 06-17-2015, 03:56 PM   #21
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I was all set to be impressed by the E-Trek but its a cruel joke. It's really pretty and I really wanted to like it. You basically need to run the engine to cook breakfast. The optional fuel cell from Efoy is neat technology but the biggest one produces 90 watts and you have to buy the special methanol fuel from them at $193 for 31 kWh, or about 50x what power costs at home.

400 watts of solar and some large batteries go a long way toward making it practical, especially with newer solar panels that are getting more efficient. We carry an extra 100 watt one that we put out in the sun when we're parked in the shade, and that usually works for a long weekend if we are careful.

AFAIK the fuel cell was only offered for one year and is no longer available. You can get an E-Trek with propane for cooking and heating. That makes a very useful B-van with big battery and solar capacity as you have pointed out. Of course you can also just add solar and more battery capacity to an Interstate. That's what I did. 😎


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Old 06-17-2015, 06:20 PM   #22
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How big is your small family and how comfortable can they be in an Interstate?
Baby and a dog..so I figure extended weekend or weeklong trips should be fine
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Old 06-17-2015, 11:26 PM   #23
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To get 12VDC and 600 amp hours from Lifeline 6ct batteries requires four of the 6Vdc 300 amp hour units at 92 pounds each for at total of 372 pounds. They will tolerate about a 50% power draw as compared to the 30% draw on the stock Interstate lead acid batteries.

Our 12Vdc 600 amp hour lithium iron phosphate battery weighs 168 pounds and we can us 80% of it's capacity. We have a 300 amp hour model on order that weighs about 84 pounds (the two stock Interstate SRM24 Airstream batteries weigh 90 pounds for the pair. The form factor in inches is about 11.25 by 14.5 by 9.5 tall. There is nearly 240 amp hours available.

There is still a significant cost penalty for the new technology.
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Old 06-18-2015, 10:38 AM   #24
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To get 12VDC and 600 amp hours from Lifeline 6ct batteries requires four of the 6Vdc 300 amp hour units at 92 pounds each for at total of 372 pounds. They will tolerate about a 50% power draw as compared to the 30% draw on the stock Interstate lead acid batteries.

Our 12Vdc 600 amp hour lithium iron phosphate battery weighs 168 pounds and we can us 80% of it's capacity. We have a 300 amp hour model on order that weighs about 84 pounds (the two stock Interstate SRM24 Airstream batteries weigh 90 pounds for the pair. The form factor in inches is about 11.25 by 14.5 by 9.5 tall. There is nearly 240 amp hours available.

There is still a significant cost penalty for the new technology.

The late model Interstates come with Lifeline AGM batteries so they can tolerate 50% draw down.

I did a lot of research on upgrading to LiFePO4 batteries. I like the power to weight they offer. But the issues of proper charging from Sprinter alternator and dealing with freezing temp issues made me stay with AGMs for now. Those issues can be solved, but it was too much work for me to take on right now.

To get a properly engineered lithium system means buying a new van for me.


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Old 06-18-2015, 11:48 AM   #25
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Mike,

No need to go out and spend $150K on a new AI. your existing rig can have LiPo batteries for a lot less than that! :-))


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Old 06-18-2015, 02:07 PM   #26
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Would it better to just buy an empty Sprinter (or more preferably, a more reliable cargo van.. maybe Nissan NV 3500? too bad the Toyota ones don't sell in USA) and find someone or company to convert it with all solar? Has anyone here seen a Nissan get converted?
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Old 06-18-2015, 02:39 PM   #27
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Would it better to just buy an empty Sprinter (or more preferably, a more reliable cargo van.. maybe Nissan NV 3500? too bad the Toyota ones don't sell in USA) and find someone or company to convert it with all solar? Has anyone here seen a Nissan get converted?
The NV3500 is basically a van body on a Nissan Titan pickup frame. You only have one wheelbase to choose from, 146½ inches, less than the Sprinter's 170 inches, and with the Nissan's long hood, actual living space inside isn't much— 323 cubic feet of cargo volume available for conversion, compared to the Sprinter's 428¾ cubic feet, or the Extended Sprinter's 467 cubic feet.

Sprinter cargo vans on the whole are very reliable. Automotive News still rates it best-in-class against other full-size cargo vans, though it is the most expensive of the current crop of cargo vans.

However, one area the NV3500 beats the competition hand-down is maximum towing capacity, 9500 pounds. It would make a much better tow vehicle for an Airstream trailer than it would as a base van for conversion to a Class B.
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Old 06-18-2015, 03:11 PM   #28
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Mike,

No need to go out and spend $150K on a new AI. your existing rig can have LiPo batteries for a lot less than that! :-))

...

Very true Lew. But how do you deal with freezing issue? Add a heater pad would probably work. It freezes often here in Maryland and I've been know to make trips to Minnesota in February - crazy but that's where I grew up.

I was all set to buy a 400 AH LiPO system from AM Solar, along with a new 2000 watt Magnum inverter. They were not yet ready to ship their LiPO systems when I called them a few months ago.

But when I discovered that my Interstate only has a 4 gauge wire from the chassis battery to the house battery. I didn't think that was adequate to handle the current that could flow from my Sprinters 220 amp alternator to the 400 AH LiPO batteries. The new Interstates have upgraded this wire to 1/0 gauge.

I know the Magnum and my Blue Sky solar controller could be programmed to properly charge the LiPOs.


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