Planned setup: 2 Tesla modules based housebank on a worldcruising yacht

[captainrivet]

Hi all,

I am planning to replace the small 12V AGM housebank with 2 Tesla modules and go 24V with the housebank.
The starter/bowtruster/windlass 12V batteries (2x140 AGM Fiam) will be kept completly seperatly, charged by the standard 60A/12V alternator and 2x75W solar panels to top up. A sterling 24V to 12V battery to battery charger is charging fallback in case 12V alternator and or solar fails.

Seeking for adivise/help regarding the setup of this modules tesla modules in a marine environment. Did I miss something,got something wrong....
Just find installations of this moduls in RV but didn't find a single one in a boat. So I take the two RV installation as base and work my way through to adapt to marine use.
frist one:

DIY Tesla Solar Battery

How to use a Tesla Model S for a DIY powerwall solar battery

www.mobile-solarpower.com

2nd Mortons on the moves setup


charger and inverter: Victron Quattro 24V/5000W/230 V with 120A/24V charge capabilities. The victron will take care about the specfic charge parameters Will suggests for the module on his page: https://www.mobile-solarpower.com/tesla-solar-battery-diy.html

I want to use 2 Tesla modules 5.3kw as my house bank which will never exceed 1C with 2 of them as a 5000W victron inverter is the biggest load. So in this case I don't need active cooling or heavy active cell balancing.

To marinize the modules I plan the following/What I figured so far:
1) To make them ready for marine environment you need to put the modules in an water tight box together with a BMS with low temp cutoff, so the agressive salt air is not penetrating into the battery.
2) even the victron Quattro takes care of the charge parameter for security reasons I want to add a smart BMS with low temp cut off to each module to manage the module: I plan to use one 320A 7s smart charger modules from Aliexpress (Will links the 100A smart modul from the same Aliexpress store) per modules

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The smart BMS will also be configured with the parameter Will suggests for the Tesla.
3) A 200A fuse at each module to ensure you don't run it constant above 1C and get thermal problems due to missing cooling
4) each module seperatly with its own smart BMS and 200 A T-fuse is in a watertight box. That "tesla" box is then wrapped in a Fire-Resistent blanket for welding with the ends working as handles. Due to a fire brigade captain this gives me approx 3 min time to toss it overboard (just cut the two cables that comes out of the box and rip it out) when a thermal runaway in the tesla module occures and it catches fire.

Amazon.com: Tillman Heavy Duty Welding Blanket 6' x 6': Home Improvement

Amazon.com: Tillman Heavy Duty Welding Blanket 6' x 6': Home Improvement

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That 3 min the module will need to burn through that blanket and gives me the thermal barrier to grab it and toss overboard. They tried that when they had to rescue someone out of a burning Tesla and it worked. Just as last borderline/plan D if everything else goes wrong.
All is overrated as marine environment is harsh and running everything far from the limit rises reliabilty and lifespan.
I will mount both modules easy accessible in the Pilot house in the well accessable lockers on top of the AGM batteries so I can really rip them out in worst case scenario.

What do you think so far about this approach?

 

[electric]

Seems pretty well thought out, but I could never sleep well near these modules on a yacht in the middle of an ocean, I'd be clutching those bolt cutters in my hands, ready to go. After you see a few videos of the fireworks these things can create...
Curious, why not go with much safer LFP chemistry?

 

[captainrivet]

Seems pretty well thought out, but I could never sleep well near these modules on a yacht in the middle of an ocean, I'd be clutching those bolt cutters in my hands, ready to go. After you see a few videos of the fireworks these things can create...
Curious, why not go with much safer LFP chemistry?

first all batteries are dangerous and I had much more incidents with LFA then any LFP I used in my race cars the last 15 years.

why not LFP,
1) they also catch fire and have the same over/undercharge problem as the Tesla, Tesla is just a bit more sensitive due to its energy density. So stay away from the limits which I do and you are safe.
2) space, 50% of my battery box is taken by 2x 140AH FIAMM AGM starter batteries, which leaves me with enough space just to fit 2x Tesla modules.
3) costs: I can get 2x modules for 2300Euros inkl. shipping to my boat (11kwh, 7,5kwh are useable with my high security parameters). Comparable Winston or Sinopoly LFP cells, only 8x400AH ( only 9.6kwh, same parameter give me 6-7kwh useable) will cost me 4000-4500Euro when shipped/taxed till they arrive at my boat.
Blanket and case for Tesla another 150Euro but everything else I need the same BMS, Battery protect....
4) longlivety: Tesla modules are fine even after 200000miles they have >80% capacity, so if all the fuses on the modul are fine you have a well working battery for next 10 years. The car I get mine out is a 2018 with 23000km, even driving but chassis is bent and they are in like new condition with warranty they have 95% capacity by the seller. Winston, Sinopoply: In which condition are these cells really, are the really new or grade B or.....never know where they come from, if they are mismatched and how long they really make it off their 2000-4000cycles. If I could get winston like in US very cheap ship to the boat I would consider them but here in europe superexpensive!

Well I had this week a AGM battery went off with thermal runaway in my BMW. Out of nowhere, all is absolutely fine with charging...checked everything and a new one in BMW is absolutly fine after 3 days. Never happened with normal FLA or LFP to me in 30 years.
It got dry due to whatever reason, assume a product defect and started to getting hotter and hotter. I needed to rip out as it got so hot that case deformed.

the tesla fireworks mainly happens because they are in series 700V plus each modul 2000+A creates a lightbow in case of a failure which bypasses every isolation and security mechanism. it starts with a failure when in heavy excelleration due to huge C rate discharge with 700V a lightbow bypasses all the security mechanisms, then it slowly works is way through till the runaway starts. cannot happen due to physics with 1 24V modul and how I use it. other they just didn't use a BMS and/or configured parameters wrongly, especially float voltages.

 

[Will Prowse]

Oh goodness, I hid that tesla battery page from the navigation menu on my website. I need to update it with a BMS. I loved running it without, but if you mess up the upper limit voltage, the whole thing will catch on fire and everything around it on fire.

I also took down my tesla battery videos. It works great for experts, but now I recommend everyone use lifepo4 instead. the charge cycle and safety benefits make it better than a tesla pack. Pros and cons. I prefer lifepo4 now

 

[Will Prowse]

The ANT BMS would work though. I just programmed one tonight for a system and I love that thing so much. I dont recommend it much because its a pain to setup, but once its set, its awesome.

 

[captainrivet]

Hi Will,
agree with the upper voltage, that's why I go 6 sigma like in airplanes and stick a BMS on each module, then the Quattro, then the BMV712 and a victron smart battery sensor on each poles of a module to make sure I don't get any overvoltage.
problem here in europe is to get the LifePo4 raw cells for a good price incl. shipping.
I need min 8kw so a 24V system is set. To make things simple, the 400AH sinopoly or winston cells would be an alternative but with shipping and tax its the double of the tesla modul.
On purpose I take more capacity then I need so on the boat if I have very sunny days the batteries are not full at noon, they are nearly fulll in the evening. 1 modul would be enough but the 2nd takes all the energy I would dump after noon as one module will be fully charged then. with 2 modules I can live 1 week without recharching. Tesla don't like when 100% full anyhow and they don't care if they cycle between 40 and 60% most of the time.

 

[Will Prowse]

Can LiFePO4 Batteries Combust in Thermal Runaway Event?

I would like to challenge anyone reading this to find a photo or video of a LiFePO4 creating internal combustion from thermal runaway event. I keep seeing people comment that LiFePO4 can combust, but UL listed companies and battery studies are telling me otherwise. Where are people coming up...

diysolarforum.com

LFP have flammable electrolyte, but they are considered non-combustible by most UL listed battery manufacturers and transportation studies. They are a million times safer than NMC/NCA variants.

Yes, the tesla is smaller. And much lighter. Very true.

Tesla is cheaper, but lifepo4 charge cycle life is out of this world for solar usage. They are getting impressive cycle life numbers, but I would still stick with lifepo4. Just look up the data sheet cycle degradation curves.

Yes I just had a lead acid fail and it almost melted. Shorted cell. Not fun. Did not explode luckily.

 

[strutzkoff]

i am doing similar witbut with 4 tesla modules in series parallel , and with twin electric motors in my sailing catamaran.
i am thinking about keeping the batteries on the outside of the boat in metal boxes, that could be dumped into the water.. but i feel decent charge controllers and such they are safe enough. and likely as safe as 40L of petrol

 

[captainrivet]

i am doing similar witbut with 4 tesla modules in series parallel , and with twin electric motors in my sailing catamaran.
i am thinking about keeping the batteries on the outside of the boat in metal boxes, that could be dumped into the water.. but i feel decent charge controllers and such they are safe enough. and likely as safe as 40L of petrol

Well did you calculate on how much C-rates you are using the tesla modules? Above 1C which is 220A per modul you need to cool the modules via the internal cooling pipes and all the gear that comes with that. And the risks are rising overproportinally.
Running the Tesla Modules on low C-rates around 0.5C like in housebanks then these modules are safe if you use a BMS and take really care about overvoltage/overcharge.
But on C-Rates above 1C constant like you will get with the use of twin electric motors for a cat thats a totally different animal and I would consider it not safe unless you get one of these hacked and completely reengineered Adapters that you can control the tesla OEM BMS so you can really monitor and use all security circuits. Even then its considered a high risk.

 

[captainrivet]

Can LiFePO4 Batteries Combust in Thermal Runaway Event?

I would like to challenge anyone reading this to find a photo or video of a LiFePO4 creating internal combustion from thermal runaway event. I keep seeing people comment that LiFePO4 can combust, but UL listed companies and battery studies are telling me otherwise. Where are people coming up...

diysolarforum.com

LFP have flammable electrolyte, but they are considered non-combustible by most UL listed battery manufacturers and transportation studies. They are a million times safer than NMC/NCA variants.

Yes, the tesla is smaller. And much lighter. Very true.

Tesla is cheaper, but lifepo4 charge cycle life is out of this world for solar usage. They are getting impressive cycle life numbers, but I would still stick with lifepo4. Just look up the data sheet cycle degradation curves.

Yes I just had a lead acid fail and it almost melted. Shorted cell. Not fun. Did not explode luckily.

Hi Will,

the Tesla's battery life and cylces are much higher then the ones of LifePo4 cells. with the strong cycling of the modules in the Tesla itself most have >90% after 150000miles. on a boat housebank like mine the 2 tesla modules will complete one full cycle maybe all 2 weeks.
2nd the capacity I can use is higher then your 2nd review feedback. The boat runs mainly on 12V so with 24V to 12V transformers I can adjust them that even 19V are transformed into 12V, so all gear still runs. But I don't need to upgrade the existing wires in the boat as the transformer will be placed at the end of the thick/long wire so I have the advantage of the 24V but still run all the 12V gear.
2nd main power usage is the Victron Quattro 3 or 5KW inverter which shuts down at only 19V (told by a victron dealer, true?), so I can use nearly all capacity of the tesla module.
But I don't expect to get even close to use 40% of the capacity of 2 moduls, more like 20% so each module 10%. But I wanna keep enough overhead to have reserve when eg all charging sources fail and the autopilot needs power to operate.

 

[strutzkoff]

Well did you calculate on how much C-rates you are using the tesla modules? Above 1C which is 220A per modul you need to cool the modules via the internal cooling pipes and all the gear that comes with that. And the risks are rising overproportinally.
Running the Tesla Modules on low C-rates around 0.5C like in housebanks then these modules are safe if you use a BMS and take really care about overvoltage/overcharge.
But on C-Rates above 1C constant like you will get with the use of twin electric motors for a cat thats a totally different animal and I would consider it not safe unless you get one of these hacked and completely reengineered Adapters that you can control the tesla OEM BMS so you can really monitor and use all security circuits. Even then its considered a high risk.

The motors will draw at .5c

 

[captainrivet]

The motors will draw at .5c

so 0.5C= 110A per modul so 440A x 23V = 10KW twin motor (so 5kw each), must be a small cat. A 5KW motor replaces a 10hp diesel.

 

[strutzkoff]

so 0.5C= 110A per modul so 440A x 23V = 10KW twin motor (so 5kw each), must be a small cat. A 5KW motor replaces a 10hp diesel.

Yes it had a 9.9 hp petrol outboard. It was able to reach 5 knots at half throttle