Tesla Powerwall instead of lead-acid battery bank

[mod45]

I'm working with a friend currently to utilize this system in a boat he is building. It's really quite interesting because pretty much everything you ever learned about batteries, charging, operation, and how to build a good DC power system no longer applies, and is probably the wrong thing to do.

Would *love* for you to expound on this. Either here or a meaty blog post works I've really enjoyed going through your archives and have learned a lot. Thank you.

 

[twistedtree]

Would *love* for you to expound on this. Either here or a meaty blog post works I've really enjoyed going through your archives and have learned a lot. Thank you.

I will. I've just not had much blogging energy lately.

 

[Jazmin 1]

The tesla powerwall is 72 volts, I believe.

 

[dhmeissner]

Specs for power wall 2

Spec sheet.

 

[twistedtree]

The tesla powerwall is 72 volts, I believe.

It's 50VDC, but it's completely internal to the unit so it really doesn't matter.

 

[bowball]

Updated 4 years later…

https://www.tesla.com/powerwall

Compact (at least thin) . With a solar input.

 

[stubones99]

There are better battery packs with more storage and less money... Check out Big Battery dot com...

 

[BandB]

Updated 4 years later…

https://www.tesla.com/powerwall

Compact (at least thin) . With a solar input.

We've been studying and evaluating Tesla Powerwalls and other similar systems for quite a few years, thinking of using at our home and for use at businesses. We're still waiting for a solution that shows a good payback. It started with 10-12 year paybacks, then 7-8 years. I can't bring myself to invest in such long paybacks plus keep believing that before today's units will ever pay for themselves, a better technology will be out.

Those pushing these units remind me way too much of snake oil salesmen. I would never place a future Tesla order. Did so once for a car that never materialized as sold and the Powerwall sales people have regularly made promises they couldn't fulfill. Others have presented similarly flawed stories. They'll show up with comparisons to electric rates far higher than where we are. They assume we use far more electricity than we do. Then the real creative ones put together packages with all sorts of energy improvements, the other things being actions we've already taken. They toss in improving insulation-done. Then, LED lighting-Done. Energy efficient appliances-Done. Managing peak usage-Done. We would love to remove generators for potential hurricanes and replace with battery banks, but every proposal we've seen has been absurd and the battery banks far more costly. I burned out from their pitches, but have staff that does still entertain their pitches.

I want solar and battery banks to be far more practical and I'd love to have such at my home. I've tried. I'm sure there will be more pitches this year. If any are credible, then they'll be brought to me.

 

[Simi 60]

No
There was a boat fire with one recenly here, boat copped green, batts got wet

Lifepo4 far safer and more suitable

 

[JLD]

We are finishing the build of our new home, and I looked into a Telsa Powerwall. My understanding is that Tesla will no longer sell just the Powerwall, you need to buy an entire system from them. So, I also looked at the Generac PWRcell.

In the end, we decided against a large battery system for the house and we will just use a backup propane generator as we have installed a large underground propane tank.

Jim

 

[socalrider]

No
There was a boat fire with one recenly here, boat copped green, batts got wet

Lifepo4 far safer and more suitable

This. Tesla uses NMC chemistry for their Powerwall cells last I heard - LFP is better for boats due to inherent safety.

They seem to be switching to LFP for a lot of applications, including their utility-scale PowerPack units and standard range cars (my Model 3 SR+ actually uses LFP), so it may be more viable in the near future.

That said, I'd be nervous about using a battery designed for residential stationary use in a marine environment. I do love the integration though - with the new version you could plug your solar straight into it, then wire your boat in AC. You'd still need a separate start battery & DC converter for electronics, etc though, so I'm not sure you'd be better off in the end versus a bespoke system.

 

[twistedtree]

I also believe the power wall is strictly a grid-tied device. In other words, it expects to be connected to an active grid, and augments it with solar and/or stored energy. But without a grid, it won't produce AC. It can't be it's own grid.


So to make it work in a boat you would need to have a battery powered inverter to create the "grid", and it would have to be an inverter that supports so-called "AC coupling", and most don't. The whole arrangement and power flows are quite different than the original intent of both products.

 

[socalrider]

I also believe the power wall is strictly a grid-tied device. In other words, it expects to be connected to an active grid, and augments it with solar and/or stored energy. But without a grid, it won't produce AC. It can't be it's own grid.

So to make it work in a boat you would need to have a battery powered inverter to create the "grid", and it would have to be an inverter that supports so-called "AC coupling", and most don't. The whole arrangement and power flows are quite different than the original intent of both products.

Good point - the PowerWall is configured to provide emergency backup power, so it does have a grid-forming inverter. However last I checked (a couple of years ago) you're correct in that it wasn't configured to be permanently off-grid. You might be able to work around this with marina power and/or some sort of grid forming inverter, but the solution would likely be a kluge, and needing another inverter sort of defeats the purpose of the integrated unit.

It's frustrating as my understanding is that the engineering required to make it fully off-grid capable is pretty minor, it's just not worth it for the tiny market size of boats, RVs & off-grid cabins. Maybe something's changed since I last checked.

 

[dannc]

I looked at the PowerWall and some of the other brands years ago to use for our house.

Bottom line, pun intended, is I would not use them ON my house as they are intended.

1. Cost.
2. They are Lithium chemistry not LiFePo. If the PowerWall catches fire it will burn down my house. No ifs, no ands, no butts. The fire department will not be able to put out a Lithium battery fire before my house is toast. Not as bad as having to abandon a boat but I still loose my house.
3. You cannot hook a generator up to the PowerWall to recharge.
4. Memory is fuzzy on this one, but I seem to remember there being an issue with charging from PV when the PowerWall was disconnected from the grid.

I think I could get a better value for money installing LiFePo or even lead acid traction batteries with Victron or Mastervolt inverters. We want the system as a backup for power outages.

No way in heck would I put a PowerWall, or any other Lithium chemistry battery, as a house bank on a boat.

Later,
Dan

 

[nwboater]

Could anyone explain why someone with a large battery bank and occasional large loads (a/c, washer/dryer, water maker, fridge) couldn't replace it with a 24kwh Powerwall?

I have installed a 4.5kw “All-In-One” lithium battery pack on my tug to run the electric stove, coffee maker etc. Package includes 3kw inverter, AC fast charger and solar MPPT controller. Works great!