Tesla power wall?

[Cottontop]

I called Tesla a couple of months ago (when they announced Powerwall 2.0). The guy I talked to checked with somebody and reported that Tesla did not intend to sell the Powerwall to a boat, but he didn't know why.

The Powerwall is not LiFePO4, but it is not the same chemistry as the Boeing batteries, either, I don't think. I suppose Tesla is aware of their exposure if Powerwalls burn houses down.

[u4ea32]

Its hard to beat 6v trojans in real life.

[wannago]

Originally Posted by concretejungle

In the RC world, LiPo batteries have become very popular. I don't think they would have much use in the marine world as they are designed mostly to dump large amounts of power at a time. They are super light weight and carry large charges and can handle vibrations and movement very easy. But, i'm not sure about how they will handle heat. I could see you getting large amounts of amp hours out of them, but don't know they are a good choice.

And in the RC "world", using those LiPo batteries, it's often recommended to use a "liposack" when charging, a fireproof bag.

Dealing with a 1/2 pound overheated battery in my house is a risk I'm willing to deal with for me RC car to go fast (having played with these cars for over 20 years on and off, I was stunned how much faster a newish, kinda low end brushless motor and lipo battery is, peeled the tires off the rims of my 20 year old racer).

But, a lipo battery larger enough for even just the electronic on a boat, overheating in my boat? not interested.

[RaymondR]

Originally Posted by u4ea32

Its hard to beat 6v trojans in real life.

[a64pilot]

If the Powerwall is the same as their car battery pack, then it is nothing more than a whole bunch of 18650 cells. If that is the case, then there is nothing new here at all.
I have not disassembled a Tesla battery pack, so I may be wrong

[Adelie]

Originally Posted by concretejungle

. . . .
It's crazy to see how many people eventually fall back to the lead acid batteries. They just work great if you take care of them. Check to see they are full of water and keep going. But, they are heavy and large.

My observation is not that FLAs work great if you take care of them but that they work OK even if you abuse them. Other types don't recover nearly as well from abuse or neglect.
I think that's why FLAs remain a good choice for a lot of cruisers.

[exMaggieDrum]

I have 400Ah of LiFePO4 cells/battery precharged and conditioned ready to go in to my 44' boat very soon when I finish a couple of other DC projects. They will replace my three 8D Lifeline AGM batteries. The LiFePO4 cells are approximately the same size as one 8D and the 400Ah provide much more usable and sustainable power for marine use on my boat then the three 8D's rated at much higher 20hr Ah's. They are also significantly lighter. My 400Ah are about 120lbs compared to the 460+ lbs of my AGM's.

They do require a different charging regimen than AGM's or FLA's. This is critical to their longevity. They are not the same chemistry as that Boeing used (lithium titanium phosphate) or in cellphones/toys/etc. They are for all intents and purposes no more dangerous than FLA/AGM's. You do not need to put them in a fireproof compartment (like Boeing has done). In the case of FLA's they are less of a hassle because of they don't have corrosive acid to deal with nor do they need to be watered. They are much more expensive right now per Ah for sure but the number of cycles they provide over their useful life makes them cost about the same.

They charge super fast provided you have robust charging available. In fact one issue with them is that they can burn out alternators easily so you have to carefully limit the output of alternators and size them to the battery bank. When I say fast, it is very, very fast. They are not harmed by drawing them down far more than you can for the same Ah FLA or AGM and the voltage does not vary much (relatively) from full charge to the point you should recharge them.

They do NOT like to be overcharged or allowed to discharge below a certain level. They do not "push back" on charging the way FLA's and AGM's do as they approach full charge. You can charge them to 100% at the same rate as you can at 50% state of charge. Since they can be severely damaged (but not catch on fire) by overcharging, you have to carefully monitor the charge process which can be automatically dealt with by smart charging systems properly set up. A disconnect switch should be installed at a minimum to prevent them from over discharging.

FLA's and AGM's are not as sensitive to charging. AGM's can be damaged by over discharged but FLA's are more able to come back (to some level) is severely discharged. But doing this can dramatically lower their lifecycles so you still have to be careful to save money and labor replacing them often. (And 6V Trojans are very good FLA's and what I would use if I put those in, but some people are entirely happy with Costco batteries.)

There are extensive discussion (and I mean extensive) about using LiFePO4 batteries in cruising boats on this forum and in the excellent site provided by one of the best contributors to the forum concerning electrical issues.

http://www.cruisersforum.com/forums/...nks-65069.html

www.marinehowto.com

You have to navigate down through the marinehow to site to get to the discussion on LFP batteries. Note: they are several contributors on here who have been using LFP batteries for several years without some of the complex control systems that you will see on these sites. It is a bit like which anchor or type of sailboat is best. RV's are also putting on similar size LFP batteries that are used much like on boats when they are off the grid. If they are mostly just plugged in, like boats kept at docks most of the time, the advantages you get from LFPs are not as great except for the huge weight savings.

They are "new" to the marine market but are now in many more boats then you would think, and many of the installations are many years old now. Converts say they will not go back, although the ones who did not take the proper care of their LFP's have regretted that. Some users have just gone back and replaced their damaged LFP's any way and will take more care of them. They are NOT "drop in" replacements for FLA's or AGM's as you have to understand how to set up your system for them despite what you might see in marketing literature. And you have to be careful which particular brands you get as some have not held up. There are several brands which have proven themselves though.

There are other lithium battery chemistries that are being developed that may prove better. And there are completely different chemistries coming out (like carbon foam) which may well be the "best" in class in the future although I suspect that will not get to the marine market for 10 years or more.

I am not an "expert" on LFP's but have done a lot of research on them and convinced myself that I can DIY and be happy with them. You will have to see all the ones who are currently using them to double check whether they work for years now.