# Running a RV Trailer off LiPo Batteries, want to be able to charge my EV



## BikingBill (Jul 10, 2019)

I'm planning on converting a small used Airstream (still looking) to run on LiPo batteries (induction stove etc.)

What would I need in terms of components to build a "Level 2" charger to run off the LiPo batteries so I could charge my Kia EV?

Sources for the cables, parts etc?

Thanks.


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## john61ct (Feb 25, 2017)

BikingBill said:


> I'm planning on converting a small used Airstream (still looking) to run on LiPo batteries (induction stove etc.)
> 
> What would I need in terms of components to build a "Level 2" charger to run off the LiPo batteries so I could charge my Kia EV?
> 
> ...


No. 

Need a strong 240VAc genset in there and a decent sized fuel tank.

I mean it *could* be done, but likely cost close to USD $20K, and you still need to charge the source bank.

Which should be LFP certainly not LiPo. 

How many days do you plan to stay off grid? 

Charging the House bank off the EV would be more practical.


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## Electric Land Cruiser (Dec 30, 2020)

Don't listen to nay-sayers. Plenty of reasons why you would want this capability.

Check out this video for probably the easiest way to do mobile L2 charging; build a battery bank and use an off the shelf inverter. Doesn't get much more simple than that.


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## ITubego Youtube (Sep 21, 2021)

dear thanks


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## brian_ (Feb 7, 2017)

BikingBill said:


> I'm planning on converting a small used Airstream (still looking) to run on LiPo batteries (induction stove etc.)


Lithium-ion batteries for RVs are becoming popular... but why would you specifically want LiPo, and do you know what that means (lithium-polymer, meaning lithium-ion with polymer electrolyte)?

As john61ct implied, the normal lithium-ion choice for RV batteries is LFP (LiFePO4), especially if the trailer battery is to be at close to 12 volts (nominally).



BikingBill said:


> What would I need in terms of components to build a "Level 2" charger to run off the LiPo batteries so I could charge my Kia EV?


If for some reason you had a ton (literally) of battery in the trailer, and the trailer already had an inverter to supply AC power to the appliances, you would simply need the same EVSE (electric vehicle service equipment, or "charging station") that you would install at home.

"Level 2" implies 240 V AC, while most RV inverters provide only 120 V AC (which is "Level 1"), but you could just use the 120 V to charge the car.

But how much energy capacity would this trailer battery have? I don't understand why it would be so huge that it could ever have extra energy to charge a car, or the power capability to charge at anything beyond a trickle (less than 1 kW sustained). I don't even know why there would be a compact electric car wandering around with this travel trailer, while the trailer is being towed by another vehicle; the Kia can't tow the trailer. 

Why not charge the car from whatever power source charged the trailer?


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## Kato659 (Aug 5, 2019)

BikingBill said:


> I'm planning on converting a small used Airstream (still looking) to run on LiPo batteries (induction stove etc.)
> 
> What would I need in terms of components to build a "Level 2" charger to run off the LiPo batteries so I could charge my Kia EV?
> 
> ...


Is the Airstream going to be stationary and off grid? Or are you travelling in it? Got a big solar array in the works? Any reason you're not going with propane appliances?


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## BikingBill (Jul 10, 2019)

The idea is to have solar on the roof and yes, LFP (LiFePO4). The idea is to be able to do a Level 2 charge on occasion. The video was useful. Thanks.


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## BikingBill (Jul 10, 2019)

The other possibility is to get something like a Sprinter and buy a used Nissan Leah that gets towed. Either way, you may need to change the car from the trailer. I guess you'll need a 120/240v inverter. Saw this: 4000 WATT 48 VDC PURE SINE INVERTER CHARGER 120/240 VAC


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## BikingBill (Jul 10, 2019)

brian_ said:


> Lithium-ion batteries for RVs are becoming popular... but why would you specifically want LiPo, and do you know what that means (lithium-polymer, meaning lithium-ion with polymer electrolyte)?
> 
> As john61ct implied, the normal lithium-ion choice for RV batteries is LFP (LiFePO4), especially if the trailer battery is to be at close to 12 volts (nominally).
> 
> ...





Electric Land Cruiser said:


> Don't listen to nay-sayers. Plenty of reasons why you would want this capability.
> 
> Check out this video for probably the easiest way to do mobile L2 charging; build a battery bank and use an off the shelf inverter. Doesn't get much more simple than that.


That's a cool video. Even with GelCells and a pretty small amount of solar, he's getting some decent charged-miles on a daily basis.

Very helpful.


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## BikingBill (Jul 10, 2019)

Kato659 said:


> Is the Airstream going to be stationary and off grid? Or are you travelling in it? Got a big solar array in the works? Any reason you're not going with propane appliances?


The idea is for boondocking in a few years (work mobile, see the woods). By then maybe a Ford EV Pickup would make sense. If I'm sitting at a location for a week, it would be nice to be able to charge whatever EV I'm using.

And yes, I got the name of the battery type wrong.

Anyone try these packs?


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## brian_ (Feb 7, 2017)

BikingBill said:


> The idea is for boondocking in a few years (work mobile, see the woods). By then maybe a Ford EV Pickup would make sense. If I'm sitting at a location for a week, it would be nice to be able to charge whatever EV I'm using.


Realistically, the amount of energy which you collect per day from solar panels on the roof of a small Airstream will barely meet your energy requirements to live it the trailer (including cooking with electrical appliances), so charging an EV doesn't seem like a reasonable expectation.



BikingBill said:


> And yes, I got the name of the battery type wrong.


Okay, that makes sense, and that's why I asked if you really meant Li-Po.


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## brian_ (Feb 7, 2017)

BikingBill said:


> The idea is to have solar on the roof and yes, LFP (LiFePO4). The idea is to be able to do a Level 2 charge on occasion.


I don't think you're likely to need Level 2, and so you wouldn't need 240 V. Unless the battery is enormous, or you're using automotive-grade cells rather than what is commonly used in RVs, it won't safely withstand much more than the 1.44 kW possible at 120 V on a 15 amp circuit anyway. Check the specs, but if the charging station and charger will allow the 24 amps continuous allowed on a 30 amp circuit, that's 2.9 kW... still at 120 V. That would be a relatively common RV inverter, and 30 A 120 V is the normal service for a travel trailer.

If considering a huge battery, with most of the load being 120 V AC (not ~12 V DC), you might consider a higher-voltage battery to avoid huge currents and the corresponding heavy wiring and high resistive losses... but then you're not using common RV components (solar chargers, inverters, etc).


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## brian_ (Feb 7, 2017)

BikingBill said:


> The idea is for boondocking in a few years (work mobile, see the woods). By then maybe a Ford EV Pickup would make sense.


It only makes sense if someone is giving you free charging for the truck. A travel trailer's solar array will never make a useful dent in the energy demands of a EV pickup like that, expecting a place to plug in for cheap charging when you are in some on-grid place away from the trailer doesn't seem reasonable, and paying for fast charging is about as expensive as buying gasoline. The economic logic of EVs is generally based on cheap electrical energy, and by the time a charging system marks it up to fast-charging prices, it's not cheap.

In "a few years" there will be multiple EV pickups to choose from, but yes, a Ford F-150 Lightning will be one of the first available.


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## Electric Land Cruiser (Dec 30, 2020)

You are seriously underestimating the amount of power that solar will provide. Maybe in the frozen north it is not good, but here in the sunny US desert solar is awesome.

Just to make it easy I'll link to that solar LEAF again in his later iteration with more solar panels on a roof rack. He has roughly 4-5kw of solar on the car in direct sunlight. You can easily fit that onto a camper trailer like an airstream, probably more. Also you could make ground or roof arrays that can be angled when parked for better efficiency.

But just because the Solar LEAF actually works here's his latest video he shows that his current iteration gets him 22 usable miles of range per day in his LEAF. I'm guessing the Kia would have similar efficiency to a LEAF. Considering when traveling with a camper trailer or RV the whole point is to go some place and park for a few days and then move on to a new place, solar like this would give you real range over the course of a day or two.


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## BikingBill (Jul 10, 2019)

brian_ said:


> I don't think you're likely to need Level 2, and so you wouldn't need 240 V. Unless the battery is enormous, or you're using automotive-grade cells rather than what is commonly used in RVs, it won't safely withstand much more than the 1.44 kW possible at 120 V on a 15 amp circuit anyway. Check the specs, but if the charging station and charger will allow the 24 amps continuous allowed on a 30 amp circuit, that's 2.9 kW... still at 120 V. That would be a relatively common RV inverter, and 30 A 120 V is the normal service for a travel trailer.
> 
> If considering a huge battery, with most of the load being 120 V AC (not ~12 V DC), you might consider a higher-voltage battery to avoid huge currents and the corresponding heavy wiring and high resistive losses... but then you're not using common RV components (solar chargers, inverters, etc).


Yes, most of the larger 120/240 inverters want 48v.


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## BikingBill (Jul 10, 2019)

Electric Land Cruiser said:


> You are seriously underestimating the amount of power that solar will provide. Maybe in the frozen north it is not good, but here in the sunny US desert solar is awesome.
> 
> Just to make it easy I'll link to that solar LEAF again in his later iteration with more solar panels on a roof rack. He has roughly 4-5kw of solar on the car in direct sunlight. You can easily fit that onto a camper trailer like an airstream, probably more. Also you could make ground or roof arrays that can be angled when parked for better efficiency.
> 
> But just because the Solar LEAF actually works here's his latest video he shows that his current iteration gets him 22 usable miles of range per day in his LEAF. I'm guessing the Kia would have similar efficiency to a LEAF. Considering when traveling with a camper trailer or RV the whole point is to go some place and park for a few days and then move on to a new place, solar like this would give you real range over the course of a day or two.


My Kia Niro EV gets about the same miles/kwh as the Leaf. I was thinking the awning and roof of a trailer.


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## Kato659 (Aug 5, 2019)

You might run up against space for panels on the trailer. My father has a 40 foot motorhome that is just about full of solar panels, but it struggles to keep the batteries charged. In his case, he needs to leave space to walk but otherwise it's pretty full.

Part of the issue is the panels face straight up. You might also run into trouble with shade in the woods. Lots to consider, and I would have some kind of backup in case the output doesn't match the demand. Doesn't matter how much battery you have if you're using more than the panels are producing.

Edit: forgot to mention, the reason for my dad's issues is all the appliances, vents, and stacks on his rig. I have no idea how much square footage is available on top of an Airstream.


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## john61ct (Feb 25, 2017)

Solar limited by roof size does not begin to touch the Wh per day needed to charge an EV of any decent range.

Likely often not enough for an all-electric galley, better off using propane where you can. 

If you just drive the right EV to charge at a grid-fed station, then you can go back to the trailer and recharge your House bank off the car, and you won't be limited by your solar.

You need to get a handle on just the basic scale of consumption of these loads, most people camping off grid might only use half a kWh per day, a little compressor fridge using 10-30Ah is by far their biggest consumer.

Stuff you're talking about is like 60-100kWh.

You haven't floated aircon yet either 

If you need these huge inputs seriously off grid for days at a time, you need a FF genset, seriously. And high fuel bills, this is not even close to portable solar territory.


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## john61ct (Feb 25, 2017)

Electric Land Cruiser said:


> later iteration with more solar panels on a roof rack. He has roughly 4-5kw of solar on the car in direct sunlight.


Please stop "educating" yourself from watching YouTubers.


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## Electric Land Cruiser (Dec 30, 2020)

john61ct said:


> Please stop "educating" yourself from watching YouTubers.


Haha, no. This is just an argument from authority and it's a logical fallacy. Not an argument.

You are correct that if someone wants to have AC and a big fridge and bake bread every night they probably won't have much luck. But if they are efficiency-minded, like I dunno, an EV-enthusiast, then what's wrong with the concept?

5kw of solar is completely usable "bonus energy" for the average EV. End of story.


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## john61ct (Feb 25, 2017)

If you *really want* to spend $10K on a huge LFP House bank, plus as much again on support infrastructure to be safe, 

yes you can charge an EV off it.

But your kW of energy inputs to charge that source bank becomes the big challenge, and a huge additional expense, not just an investment in devices that last say 5-10 years, but ongoing daily/weekly fuel expenses. 

That source input might as well just charge the EV and your House bank at the same time, you're doubling up costs on extra storage

you lose a huge proportion of energy going from one bank to another, super inefficient at every voltage conversion, especially boost as opposed to buck.

And introducing inverters in there even more so!

Once you need high voltages and/or high currents, *each piece* of gear costs thousands, and needs professional systems design and installation to be done safely.

Not to mention weighing a lot and taking up a lot of space in your Airstream.


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## Electric Land Cruiser (Dec 30, 2020)

john61ct said:


> If you *really want* to spend $10K on a huge LFP House bank, plus as much again on support infrastructure to be safe,
> 
> yes you can charge an EV off it.
> 
> ...


Why? Why MUST one spend $10K?

Why not buy a 24kwh LEAF for $4-5k and strip the battery and use it? And why not sell the other parts like the motor to make back all the cost? Then buy some take-off solar panels from someone upgrading for 33 cents a watt? Who cares if you lose efficiency from conversions? It came from the sun!

Maybe expand your thinking?


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## john61ct (Feb 25, 2017)

No way any of the li-ion chemistries at 3.6-3.7V nominal are safe enough to use in a mobile use case, small enclosed living space. Way too much danger of thermal runaway, boom bad. 

LFP and LTO are the only way to go besides old-school lead. 

And even if they were, the risks, complexity and hassles involved in doing what you are talking about with scrapped packs are beyond the abilities of most.

Buy new Grade A cells from a trusted vendor with a warranty.


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## john61ct (Feb 25, 2017)

And no matter how cheap the panels, mobile solar will simply not power what OP is talking about, the wattage you can fit on an Airstream is simply not enough.

Paying for fuel for a genset will make you care about conversion efficiencies believe me.


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## Electric Land Cruiser (Dec 30, 2020)

john61ct said:


> And no matter how cheap the panels, mobile solar will simply not power what OP is talking about, the wattage you can fit on an Airstream is simply not enough.
> 
> Paying for fuel for a genset will make you care about conversion efficiencies believe me.


Use a real argument.

An airstream with 20 square meters of roof at 200 watts per square meter roof solar industry standard then the roof can hold 4kw of solar panels.

4kw is "simply enough."


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## BikingBill (Jul 10, 2019)

Kato659 said:


> You might run up against space for panels on the trailer. My father has a 40 foot motorhome that is just about full of solar panels, but it struggles to keep the batteries charged. In his case, he needs to leave space to walk but otherwise it's pretty full.
> 
> Part of the issue is the panels face straight up. You might also run into trouble with shade in the woods. Lots to consider, and I would have some kind of backup in case the output doesn't match the demand. Doesn't matter how much battery you have if you're using more than the panels are producing.
> 
> Edit: forgot to mention, the reason for my dad's issues is all the appliances, vents, and stacks on his rig. I have no idea how much square footage is available on top of an Airstream.


The good news here? My wife HATES Air Conditioning. She broke the AC on her car by simply by not using it for a few years. 85ºF? 90ºF? She loves it. 

I'm leaning for the Airstream (yeah, pricy even when used) because they have a lot of windows and are pretty reflective (of course the panels may mess that part up).

AC is a major power drain. A 15,000 BTU Air conditioner needs around 3200 to 3500 watts for start up and around 1200 to 1700 watts for running. I understand there's some clever power management systems that reduce the start-up requirements.

An induction stove? A portable induction cooktop with single burner has a wattage between 1200-1800 W. But I don't expect you'll need to run it for that long. I'm hopefully not to use propane at all and have that space for the batteries.

Anyway, typical Airstream has a lot of roof space and I hope to use the awning as well. 

So it looks like I'd need to have a 48v battery setup, battery management systems, inverter(s), and the level 2 charger (I have a portable one).


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## BikingBill (Jul 10, 2019)

Electric Land Cruiser said:


> Use a real argument.
> 
> An airstream with 20 square meters of roof at 200 watts per square meter roof solar industry standard then the roof can hold 4kw of solar panels.
> 
> 4kw is "simply enough."


4kw for the trailer is ok, if you're not running AC.

For any vehicle charging, I'll need the awning as well. 

Funny story. I got the Niro EV a year ago. My place had a dryer outlet in the garage (220v socket). After I got the car I found out that it was wired for 110v???

Turned out that charging at 1.4kw was good enough, even with a weekly 200+ mi. trip to Los Angeles.


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## Electric Land Cruiser (Dec 30, 2020)

BikingBill said:


> 4kw for the trailer is ok, if you're not running AC.
> 
> For any vehicle charging, I'll need the awning as well.
> 
> ...


Even for vehicle charging only you should consider a battery bank large enough to put a decent charge into your car. Solar + batteries is the only way to go. The peak output is only available during a few hours a day and if you are driving then you can't use it. If you have batteries in the trailer then they can always take on charge when the sun is up and you can top off if you stay somewhere with free hook ups or something.


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## john61ct (Feb 25, 2017)

Well no aircon is at least in the right direction toward realistic. 

Note that a large trailer with a flat roof will accommodate a lot more panelage than the curved roof of an Airstream

Forget about those "semi-flex" panels, very expensive to buy, even more so to mount properly, and even then, lifespan might average only 2-3 years rather than over a decade.

And large proper framed glass panel array suspended by heavy load bearing framework over the curve of an Airstream would have a huge wing-lift effect at highway speeds, probably way heavier than the trailer roof is designed to support, and would IMO completely ruin the intended aesthetics. 

IRL good insolation conditions, figure you might average 1 kWh per day actually charged per rated 300W panel output. Much less of course in foggy/rainy locations, and as you get away from the equator in winter. 

Note, the ability to tilt the panels in that case can double their output. 

If slow charging of the EV is OK, a smaller bank at higher SoC% just acting as a buffer will work fine, in effect most of the energy flow from the panels goes directly into the EV. But even then that means *lots* of panelage! 

The only reason to build a huge bank for that purpose, wasting energy going from bank to bank, is if you need to fast-charge the EV at a rate say 5x faster than the above approach, e.g. charging a car just visiting the campsite for a few hours, rather than the EV sitting there for days

but as discussed above, that approach has lots of downsides

Most of which a 240V inverter genset would help offset, supplement the solar in sub-optimal conditions, give a lot more flexibility.


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## Electric Land Cruiser (Dec 30, 2020)

I also want to add that in my opinion if you are serious about this then you should go for the renewable energy trifecta; Solar, Wind, and Hydro.

Wind is easy, you can buy off the shelf turbine generators. Something like this 3kw turbine could be mounted on the trailer itself on an extending pole or something you can set up with guy wires or lash to a tree. If it was attached to the trailer it might be annoying and shake it a lot: https://amzn.to/3u9VdzF

Hydro generators are not commercially available but I am very interested. They offer the most reliable of all 3 sources that will provide power 24/7. Of course you need to be near a flowing water source to even consider them, in the Rocky Mountains that is easy enough to find. I plan to build a floating hydro generator based on the "hydro-cat." I plan to use an e-scooter hub motor as the generator:


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## john61ct (Feb 25, 2017)

Those two options are easily available commercially, but are simply not practical for mobile use on land.

Even on yachts, barely. The cost of solar has dropped so low now, silent, little space, no setup, no moving parts to fail.

Unpacking more panels to spread out on the ground would be, not great, but lots better than hydro or erecting a wind tower and seeking out camping spots on mountaintops or the edge of a windy cliff


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## brian_ (Feb 7, 2017)

Electric Land Cruiser said:


> Just to make it easy I'll link to that solar LEAF again in his later iteration with more solar panels on a roof rack. He has roughly 4-5kw of solar on the car in direct sunlight.


That's complete nonsense. At the beginning of the video, he shows another car with what he claims is 2100 W of solar capacity. Since the silly panels pasted all over that other car don't even face the same way, the actual peak in ideal conditions is far lower. No, his Leaf doesn't have over double that area, and the sun doesn't wrap around the car to nicely expose all that crap stuck on the car. At around 6:00 in the video he's showing another Leaf with what he says are two 200 W panels - that's plausible, but note their size... his Leaf does not have 20 to 25 panels of that size on it, even with the extending brackets.

For a reality check, full sun means about 1 kW of light per square metre of area, and photovoltaic cells run at less than 25% efficiency (and in most cases much less). A large car and hood three metres long and two metres wide would have six square metres of area, capable of ideally producing about one kilowatt.

For a real-world comparison, 5 kW of peak capacity is a typical array for a house which is set up to produce as much electrical energy as it uses in a year, and that takes a substantial part of the roof.

I suggest when watching this video that viewers keep in mind that the creator's comments make it clear that he doesn't even understand the meaning of the word "efficiency", so anything he says is of little value.

Anyway, after the fourth set of ads in the first third of the video, I gave up on this garbage. About those ads... keep in mind that nothing in videos like this actually needs to work, or have any connection to reality - it only has to attract views to earn money from ads.



Electric Land Cruiser said:


> Considering when traveling with a camper trailer or RV the whole point is to go some place and park for a few days and then move on to a new place, solar like this would give you real range over the course of a day or two.


Reality in this case is very different. The trailer has to be towed to move, so staying for a few days in one place then moving requires collecting enough energy in those few days to

charge the car for its use during those days
meet all living needs for those days
charge the tow vehicle enough to drive it and the trailer to the next destination
charge the car enough to drive it to the next destination
Which of those are being done in the Leaf example? Oh, right, just the first one.

Yes, a large enough solar array in a fixed location can support living requirements and some vehicle use, in the right climate... but that's not what is being proposed. If what is desired is a small moveable home with a large solar array, perhaps moved occasionally by a contracted hauling company, that could certainly be built and it could certainly support some use of an EV.

By the way, solar conditions in Alberta in the summer are excellent. Even year-round, a fixed installation works well enough that "net zero" (total annual energy production from solar meets total annual electrical energy needs) homes work here.


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## brian_ (Feb 7, 2017)

BikingBill said:


> Yes, most of the larger 120/240 inverters want 48v.


That makes sense - they're probably mostly for the yacht market or perhaps stationary off-grid use.

If you run the battery at 48 V, and still have 12 V loads (as a travel trailer normally would), you'll need a DC-to-DC converter. Even with a 4S LFP lithium-ion battery, you might want a DC regulator because the battery needs charging voltage above what "12 V" stuff expects.


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## brian_ (Feb 7, 2017)

Electric Land Cruiser said:


> 5kw of solar is completely usable "bonus energy" for the average EV.


Sure, but 5 kW of solar doesn't fit on a small travel trailer, let alone a car.


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## brian_ (Feb 7, 2017)

Electric Land Cruiser said:


> An airstream with 20 square meters of roof at 200 watts per square meter roof solar industry standard then the roof can hold 4kw of solar panels.


BikingBill was talking about a small trailer, not the largest Airstream ever made. And the 200 W/m2 is optimally oriented to the sun.

But it's good to see, Electric Land Cruiser, that you have realized that a 4 kW array is far larger than what the YouTuber put on his Leaf.


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## brian_ (Feb 7, 2017)

BikingBill said:


> I'm leaning for the Airstream (yeah, pricy even when used) because they have a lot of windows and are pretty reflective (of course the panels may mess that part up).


Reflectivity of the surface doesn't make much difference to air conditioning energy requirement (which I assume is why you want the trailer to be reflective), and with the aluminum construction and thin low-effectiveness insulation (just fiberglass batting much thinner than in a house wall in traditional Airstream construction) Airstreams are not well insulated.



BikingBill said:


> An induction stove? A portable induction cooktop with single burner has a wattage between 1200-1800 W. But I don't expect you'll need to run it for that long. I'm hopefully not to use propane at all and have that space for the batteries.


I think it would be well worth the time and effort to seriously look at your energy requirements, adding up the daily energy consumption of the various systems and appliances. Many RV owners do this to determine their required battery capacity and generation (solar or otherwise) capability.

Space heating or cooling and water heating are two major energy consumers. If due to your location and the season you can live with essentially the outside temperature, as is common for people vacationing in RVs, that helps a lot. If you don't expect hot water for showers or washing dishes, that's another big help. If you are willing to use propane for water heating, or to set up a solar water heater (not electric), that would be significant.

Propane doesn't take much space compared to batteries. You can decide to minimize propane use, but saving space is not a significant benefit of that.



BikingBill said:


> Anyway, typical Airstream has a lot of roof space


There is no "typical" Airstream - they come in a wide range of sizes. Of course the roof area of a trailer doesn't depend on the brand, only the length and width. Even a small Airstream is still stupidly expensive, so I hope you have a lot of money for this project.



BikingBill said:


> I hope to use the awning as well.


You can't use the existing awning, because solar panels don't roll up like fabric. You could built an enormous flat array structure with one side hinged to the side of the trailer and struts to prop it up as a patio roof (instead of a fabric awning), which would be useful if you always camp with that side of the trailer facing south. The closest that I have seen to this is that some trailers have a rock-guard cover which hinges down over the front window - they put a panel on that and hinge it up when camped to expose the window and angle the panel somewhere near horizontal.


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## BikingBill (Jul 10, 2019)

john61ct said:


> Well no aircon is at least in the right direction toward realistic.
> 
> Note that a large trailer with a flat roof will accommodate a lot more panelage than the curved roof of an Airstream
> 
> ...


Ah, but I have a wife who can't stand the sound of a generator


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## BikingBill (Jul 10, 2019)

brian_ said:


> BikingBill was talking about a small trailer, not the largest Airstream ever made. And the 200 W/m2 is optimally oriented to the sun.
> 
> But it's good to see, Electric Land Cruiser, that you have realized that a 4 kW array is far larger than what the YouTuber put on his Leaf.


Well, not the really small ones. Maybe the 25' one.

Plan is to stay in various airstream AirBnB's and figure that out.

I do know one thing, 200 pairs of shoes is not coming along


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## BikingBill (Jul 10, 2019)

brian_ said:


> Reflectivity of the surface doesn't make much difference to air conditioning energy requirement (which I assume is why you want the trailer to be reflective), and with the aluminum construction and thin low-effectiveness insulation (just fiberglass batting much thinner than in a house wall in traditional Airstream construction) Airstreams are not well insulated.
> 
> 
> I think it would be well worth the time and effort to seriously look at your energy requirements, adding up the daily energy consumption of the various systems and appliances. Many RV owners do this to determine their required battery capacity and generation (solar or otherwise) capability.
> ...


Solar water heating makes a lot of sense. And at least that can be flexible. Sad to hear that the flexible solar photovoltaic panels aren't any good :-(


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## john61ct (Feb 25, 2017)

They aren't even flexible.

The idea is that they can be permanently mounted on a curved surface

They cannot flex at all once so mounted

so they must be mounted on a very stiff (thick) aluminum plate heatsink, with good airflow underneath

since all panels generate heaps of waste heat radiated from the bottom surface.

The PV cells are much less efficient in hot conditions

and they also cause the panel as a whole to break down more quickly.

Basically, they have been discontinued in the more civilized countries with strong consumer protections because warranty claims are much greater than profits.


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> But it's good to see, Electric Land Cruiser, that you have realized that a 4 kW array is far larger than what the YouTuber put on his Leaf.


He shows, right at the timestamp quoted, that he has 370 watts of solar. And gets 8.7 miles a day on them in October sun conditions. And then look at how ridiculous it looks to set up that much solar on a car, he's practically built a shed around it.

Naturally, a custom-shaped EV is is not going to scale with a giant trailer in terms of power usage per mile either. Not for weight, not for aero. Half if you're lucky, 1/3 more likely. 1/4 if it's a windpig.

He claims to use real-world measurements for "winter" light hours (in October, which is umm, about the solar average for the year, not the worst-case like he says, thinking he'll get "double" that in summer). But, probably isn't lying about his measurements.

Also, Brian, install the AdBlock Plus or UBlock Origin ad-ons for your desktop, I haven't seen ads in 20 years. There's even "sponsor block" addon, where popular videos (people who'd have sponsored ad-reads) have been crowd-sourced to timestamp sponsorship messages rolled into the content itself, which then automatically are purged for anyone watching the video afterwards.

Get VideoSpeedController too, mess with the settings so each click is 33% (default is 10%, too slow), and watch everything in 200-300% speed. Makes slow-talkers more tolerable.

And, give videos a chance. Unless you're looking at makeup tutorials or celebrity drama, especially project-based stuff, people are just there sharing what they've done same as they do in a forum. You can tell the time-padding vlogging "influencer" type soon as you watch, most content isn't that.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Also, Brian, install the AdBlock Plus or UBlock Origin ad-ons for your desktop, I haven't seen ads in 20 years.
> ...
> And, give videos a chance. Unless you're looking at makeup tutorials or celebrity drama, especially project-based stuff, people are just there sharing what they've done same as they do in a forum. You can tell the time-padding vlogging "influencer" type soon as you watch, most content isn't that.


Just before watching that video, AdBlock Plus had stopped blocking for me, because they have decided to start requiring payment for the "free" Chrome plug-in. I didn't realize at the time that ADP had been blocking YouTube ads, and after paying it's blocking them again; however, the point is still valid... that this crap is posted to get views, not because it necessarily has any value. No one selects content for value, or in currently fashionable terminology, it's not curated content.

Even if this particular YouTuber isn't deliberately padding out the length, there is clearly no content of value proportionate to the time. If he had posted the actual information as text in this forum it would have taken only seconds to skim over and dismiss.


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## john61ct (Feb 25, 2017)

And the overall quality of info just sucks.

If a trusted forum member recommended a short video that contained very valuable info not available elsewhere, then maybe

but otherwise not just waste of time but likely to lead you astray.

And that includes Will Prowse by the way, more of a "professional YouTuber" than a content matter expert.


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## BikingBill (Jul 10, 2019)

Funny enough, on a bike ride yesterday I spotted this Airstream.



















So it is possible, although I'm disappointed that flexible panels for the awning appears to be a non-starter.


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## brian_ (Feb 7, 2017)

BikingBill said:


> Funny enough, on a bike ride yesterday I spotted this Airstream.
> 
> 
> 
> ...


But what's possible? Yes rigid panels can be mounted on an Airstream (or anything else) with brackets. That trailer has only two panels on one side (and possibly another two similarly mounted on the other side), at less than 200 watts peak per panel (perhaps 150 W). It's a reasonable installation for camping, without enough energy available to electrically heat, cool, cooking significantly, or charge any vehicle.


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## BikingBill (Jul 10, 2019)

brian_ said:


> But what's possible? Yes rigid panels can be mounted on an Airstream (or anything else) with brackets. That trailer has only two panels on one side (and possibly another two similarly mounted on the other side), at less than 200 watts peak per panel (perhaps 150 W). It's a reasonable installation for camping, without enough energy available to electrically heat, cool, cooking significantly, or charge any vehicle.


Say we only get 600 W for some number of hours a day. Given my wife's no-AC lifestyle, it might be enough. I do know a boondock-er who has some sort of roll up panel on her trailer's awning. The other possibility is to have additional rigid panels you deploy at the campsite if you're staying there for a while.


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## john61ct (Feb 25, 2017)

So long as you also have an inverter genset along

for huge loads far beyond what a measly 600W would support. An all-electric galley wojld be marginal when the weather gets cloudy.

Even 1800W will not properly support a little aircon unit running off battery storage

much less charging a stock EV according to normal expectations.

The more panelage you need, the less a curved roof makes sense.


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## brian_ (Feb 7, 2017)

BikingBill said:


> Say we only get 600 W for some number of hours a day. Given my wife's no-AC lifestyle, it might be enough. I do know a boondock-er who has some sort of roll up panel on her trailer's awning. The other possibility is to have additional rigid panels you deploy at the campsite if you're staying there for a while.


If you assume 2400 watt-hours per day (from a 600 W peak panel array), is that enough? You could try at home: monitor how much electricity you are using (with the power company meter or your own added measurement) and see what you have to adjust in your lifestyle to live on 2.4 kWh per day. Then consider how much less you would need to leave any to charge an EV...



BikingBill said:


> The other possibility is to have additional rigid panels you deploy at the campsite if you're staying there for a while.


Yes, you can drag a portable solar power station around with you. Many campers actually do travel with a portable panel or two, for a couple hundred watts of peak output, usually so they can place them in direct sun when the RV is parked in the shade.


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## john61ct (Feb 25, 2017)

brian_ said:


> assume 2400 watt-hours per day (from a 600 W peak panel array)


That's about right, about 200Ah into a nominal 12V bank

but of course only in good insolation conditions.

A proper energy budget, in Ah per 24hrs is really the starting point.

Use a coulomb-counting wattmeter to measure the actual Ah used over time - duty cycling between peaks vs low continuous needs to be taken into account. 

And don't bother measuring grid power appliances at AC voltage, need to include the inverter overheads. 

So say your induction hot plate uses 35Ah over an hour of making soup or spaghetti sauce. 

You then guesstimate you'll be using it an average of 40min per day, so ballpark 25Ah/day is your budget for that load device. 

Do the same for screen device charging, lights, fans, your fridge etc. until you get a total Ah per 24hrs bottom line. 

And if you are trying to go solar-only, need to size components for worst case, figure a 3-4 day buffer with poor insolation conditions

but having a good inverter genset providing backup / supplementary power on demand (mostly-solar) allows for a much more manageable and affordable storage bank and panelage.


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## brian_ (Feb 7, 2017)

john61ct said:


> And don't bother measuring grid power appliances at AC voltage, need to include the inverter overheads.


Or measure grid power appliances at AC voltage, and add several percent for inverter overhead/inefficiency, at least as a first approximation. If the discovery is that the daily requirement is several times the energy which would be available, a more precise estimate isn't required.


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## john61ct (Feb 25, 2017)

it's a lot more than several percent


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## brian_ (Feb 7, 2017)

john61ct said:


> it's a lot more than several percent


Sure, it's a constant (idle power consumption) plus a percentage (a few percent, assuming a reasonable inverter). For a first approximation, it doesn't matter. If the only way to plan for demand is to build the whole system and measure its performance, that's not really planning.


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## john61ct (Feb 25, 2017)

Just talking the planned load devices.

Sure if you don't have it yet, then need to do some research, ask those who do, more guesstimation involved.

And this process really help people get more realistic, as they learn off grid solar requires prioritizing energy efficiency, compromising, not just taking every modcon for granted.


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## BikingBill (Jul 10, 2019)

We may want to use solar hot water heating as well.

I have these black croplast sheets we use as blackout curtains. They get very hot in sunlight. Running water thru them would work and they would be very light when empty.

Just looked and people have done this: Build a simple solar water heater - IWillTry.org


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## Electric Land Cruiser (Dec 30, 2020)

Check out what I saw when I was out driving around today!


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