Tesla Powerwall for RV use?

[chaseav]

When I first heard about the Tesla car, I knew it was a game changer. I'm less convinced the Powerwall is quite so ground breaking (yet) but I've got to think that it has an application for solar powered RV use. We're all limited by our batteries and if, for $3500, it enabled us to go almost completely off-grid for extended periods of time, sign me up!

So, I was hoping to start a discussion here with the spark chaser types that may have an opinion on this.

If you haven't seen it yet, full details on the Powerwall are here: Powerwall | Tesla Home Battery

[lewster]

Originally Posted by chaseav

When I first heard about the Tesla car, I knew it was a game changer. I'm less convinced the Powerwall is quite so ground breaking (yet) but I've got to think that it has an application for solar powered RV use. We're all limited by our batteries and if, for $3500, it enabled us to go almost completely off-grid for extended periods of time, sign me up!

So, I was hoping to start a discussion here with the spark chaser types that may have an opinion on this.

If you haven't seen it yet, full details on the Powerwall are here: Powerwall | Tesla Home Battery

It's a very nicely designed package, but is similar in capacity to the lithium batteries that AM Solar is already producing specifically for RV use. I calculated the Tesla battery capacity at around 345 amp/hours. AM SOlar makes a 400 amp/hour pack for $3300. They are also configurable to fit differing available spaces.

We are installing them as fast as we can get folks in the door. I have 6 people headed to Oregon for these, with 3 more installations in the next few weeks. With a potential lifespan of up to 15 years and a 5 year warranty, they don't look so bad when you factor in all of the benefits related to the price.

Check them out here: 400 Amp-Hour Lithium Battery | Lithium Batteries

[The Ice Man]

Hmmm. Little over 4 feet tall and under a yard wide, so it would fit in the bed of your TV. Run your umbilical from the inverter to your TT. Wonder how large a solar array is needed to support it? Probably more acreage than you can provide. You need to get Lewster's take on this.

[The Ice Man]

Looks like Lewster was posting while I was typing....

[DKB_SATX]

I don't doubt that the AM Solar batteries have significant advantages for Rv applications based on their form factor alone, plus the fact that the native voltage of the AM Solar setup can be nominally 12v (depending on how the modules are interconnected) and the Tesla's native voltage is 350-450v. The Tesla has a 10-year warranty (though that might not apply in an RV installation) and is liquid-cooled, so it has some nice features as well.

[kscherzi]

If I'm reading correctly, that's $3,300 for 112 lbs of lithium's. Two golf cart batteries weigh about the same and have about 55% of the power for 10% the cost. I assume the charging electronics, power converter, so forth also have to be changed out at additional cost. The early adopters pay a premium.

[chaseav]

Great input so far. I was definitely thinking an install under the bed area which would probably take some cabinetry modifications. The umbilical connection to it is a great idea, whomever wrote it. (I can't see that once I start typing on the mobile app) If the AM Solar numbers are correct, a 400amphr setup weight is surprisingly less. Weight is my biggest concern and I'd love to have more weight off my A frame if possible. I'd definitely like to see a capability of more than 1000watts too for the coffee maker and hair dryer.

[Aviator]

This may be somewhat of a moot exercise in a year or two. I just finished reading an article on Aluminum Ion batteries.

Aluminum-Ion Batteries Are Flexible, Fast-Charging, And Won't Catch On Fire | Popular Science

According to the article, they are faster charging than Lithium and do not pose the thermal runaway issues which Lithium batteries suffer from. If this comes to market, it looks to be an ideal solution for our Airstreams.

[chaseav]

How long before Aluminum Ion gets FAA Approval do you think?

[lewster]

Aluminum batteries show great promise, but I don't think you will see them much before 5 years.

Also, the article was quite inaccurate in their description of lithium batteries. The newer LiFePO-4 formulation shows more like 5000 charge cycles. You can easily get 1000 cycles from a quality AGM now, and far more if they are kept at around a 25% discharge level.

Plus, lab findings are great, but it's usually a long way to the production level at an acceptable price.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[switz]

We have just installed an AM Solar 12Vdc @ 600 amp-hours Lithium Iron Phosphate battery under the front sofa of our Classic. It weighs just over 168 pounds and one can use up to 90% of the available power (540 amp hours) and it will take a charge rate up to 125 amps.

The custom stainless steel battery box and the four Lifeline 6ct batteries that were removed from the A frame behind the ProPride jacks weighed over 520 pounds. So we took about 350 pounds off the tongue weight.

The Magnum MS-2812 is to the left of the battery. Positioning was critical for everything to fit properly. We moved the sofa rearward about an inch so the sofa drawer would close properly. The battery safety circuit is to the left of the large red disconnect switch and is covered by a hickory cover we fabricated. The solar system circuit breaker is to the left of the safety circuit box. A sheet of plexiglas covers the battery to prevent accidental shorts if something were dropped onto the battery.

[lewster]

Originally Posted by switz

We have just installed an AM Solar 12Vdc @ 600 amp-hours Lithium Iron Phosphate battery under the front sofa of our Classic. It weighs just over 168 pounds and one can use up to 90% of the available power (540 amp hours) and it will take a charge rate up to 125 amps.

The custom stainless steel battery box and the four Lifeline 6ct batteries that were removed from the A frame behind the ProPride jacks weighed over 520 pounds. So we took about 350 pounds off the tongue weight.

The Magnum MS-2812 is to the left of the battery. Positioning was critical for everything to fit properly. We moved the sofa rearward about an inch so the sofa drawer would close properly. The battery safety circuit is to the left of the large red disconnect switch and is covered by a hickory cover we fabricated. The solar system circuit breaker is to the left of the safety circuit box. A sheet of plexiglas covers the battery to prevent accidental shorts if something were dropped onto the battery.

Lou,

Where did they locate your inverter fuse? Battery looks great!

[chaseav]

How much re-wiring was involved with the battery relocation? Getting weight off the tongue is almost as important to me as gaining solar capabilities.

[AWCHIEF]

Originally Posted by switz

We have just installed an AM Solar 12Vdc @ 600 amp-hours Lithium Iron Phosphate battery under the front sofa of our Classic. It weighs just over 168 pounds and one can use up to 90% of the available power (540 amp hours) and it will take a charge rate up to 125 amps.

The custom stainless steel battery box and the four Lifeline 6ct batteries that were removed from the A frame behind the ProPride jacks weighed over 520 pounds. So we took about 350 pounds off the tongue weight.

The Magnum MS-2812 is to the left of the battery. Positioning was critical for everything to fit properly. We moved the sofa rearward about an inch so the sofa drawer would close properly. The battery safety circuit is to the left of the large red disconnect switch and is covered by a hickory cover we fabricated. The solar system circuit breaker is to the left of the safety circuit box. A sheet of plexiglas covers the battery to prevent accidental shorts if something were dropped onto the battery.

What did all that cost?

[lewster]

Originally Posted by AWCHIEF

What did all that cost?

A lot?

[ghaynes755]

Ballpark on the batteries only from AMSolar would be $4699 for 600ah. Basically after you get the initial 100ah at $1199 each additional 100ah is $700. At least that is my understanding of the pricing model. Rest of system would be the same for panels, controller and inverter/charger. But the weight difference is huge and at the end of the day the cost of AGM vs Lithiums should end up the same or favoring the lithiums based on the lifespan/charge cycles of the two types of batteries. Larger investment up front for lithium but weight and space savings swayed me to do lithiums in my new Classic.

Switz just a suggestion. Don't run them down past 80%. I've had a lot of experience with lithiums for UAV systems. They are LiPo's so different chemistry but in the UAV world running below 20% is often a death sentence for the battery. The usage curve is different since in flight we are pulling a fairly high number of amp hours continuously but I can't begin to tell you the number of folks that killed their batteries with over discharge. Normally they would find it out while on the ground or the charging station but every once in awhile the battery would allow a takeoff and then once in flight abruptly drop voltage and capacity leading to the only part of a flight that is not optional, a landing, sometimes with unhappy endings.

[lewster]

Thank you Gary!

I don't post pricing details on the open Forums due to commercial vendor status, but you are perfectly free to do so and you hit the nail on the head!

I just picked up a pair of 400 A/H lithium packs along with a 300 A/H unit and a bunch of other solar stuff for my initial stock as I re-open my installation center in Hood River, OR.

Many folks are adding lithiums to their larger solar packages......especially on Airstreams. I also have 6 other Airstream owners who have recently completed solar installations that I did while in FL stopping by during their summer travels to install their lithiums that will complete their projects.

Expensive.....yes! Worth it? Considering the huge weight saving and potential 15 year life span.........Definitely!!

[switz]

The solar circuit breaker and fuse were left where they were installed above the board on the first go around. We blanked out the two holes for the wires through the wall going to the battery box on the tongue and reskinned that area on the outside and installed an external power outlet. We put a 4"x4" electrical junction box extension on the inside to protect the wiring of the outlet. It was then plugged into a GFI duplex outlet that replaced the existing airstream single outlet inverter outlet.

Since a 30 amp outlet was the only choice with the twist cover design, I made a 30 amp twist lock male to 20 amp standard female extension cord about three feet long.

We were unable to put the existing sub woofer back due to it's size and will look for a more petite shape.

Since we had already installed the Magnum MS-2812 along with the 800 watts of solar panels on the first modification, the rewiring was basically pulling the 4-0 black and red wires back inside along with the TriStar and Magnum sensors wires and reconnecting. Some were made a little shorter as there was less distance between connections for the intended results.

Another bonus was the original battery cover that had been cut down to a 4" wide opening was replaced with a full sized cover allowing freer access to the disc brake pump and controller that reside in the box after the disc brake conversion.

During the original conversion, there was an extensive rewiring of the trailer with a new main box installed in the street side locker. A breaker was changed from two circuits to a single circuit breaker to drop the water heater AC power (installed a Truma AquaGo Custom propane instant on water heater that only needs 12Vdv for control circuit) this trip so we have only a two pole 30 amp breaker with #6 wires going to the Magnum in front, a breaker for the front air conditioner and a breaker for the refrigerator.

Then #6 wires returned from the Magnum to the existing Classic power panel in the rear curb side roof locker. All breakers there are now single circuit. All AC outlets were converted to 20 amp GFI commercial grade outlets.