Tesla DIY Powerwall with Model S Modules

DudeBro

DudeBro

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I am planning on building an off grid home this coming June and have been looking in to solar power recently. I am not incredibly knowledgeable so when I watch videos from evtv (or anywhere for that matter) I am lost after about 10 seconds. I understand basics, I just dont know what is needed to interface everything together. Is there a laymans guide somewhere you can point me to? One without a guy saying You need to remember the EVS and the BBAMT and the whatever other acronym exists that I have no idea what it means.

Basically I want to build a powerwall using the Tesla modules out of a Model S such as this
https://www.ebay.com/itm/Tesla-Mode...m2ac6e33656:g:1~sAAOSwFAtcQm0g&frcectupt=true

I am confused about a few things.


1) The controller I need to buy must be able to interface with the Tesla built in BMS right? The only ones I could find
http://store.evtv.me/proddetail.php?prod=esp32bms $2495
or
http://store.evtv.me/proddetail.php?prod=basicsmodulecontroller $1295

Whats the difference between these? They seem kind of pricey just for a controller but I could be wrong. Also, does DC from the solar panels enter through the controller? If not, how do you connect the panels to the batteries?


2) Coolant. I don't see any type of coolant system available for these modules. Any recommendations? Does the coolant systems (IE Chiller) connect to a controller so it knows when to turn on and off?

3) Inverter. Again from evtv I can find this
http://store.evtv.me/proddetail.php?prod=12kw $2195
Do I really need to buy an inverter specifically made for these Tesla modules?


Maybe I am mistaken but I thought it would be price beneficial to DIY vs buying a Tesla Powerwall (even though you have to wait forever to get one).

From what I can see an absolute minimum ill need

1) Module - $1300 Each for 5Kwh
2) Controller - $2495
3) Coolant System - $?
4) Inverter - $2195

Total: $5990 plus coolant
$1198 per KWH

Maybe the price per Kwh becomes cheaper for bigger systems? IE, using 10 Modules instead of 1?

Any help would be greatly appreciated.
 
Hello "Dudebro"
Have a look at this thread:
https://secondlifestorage.com/t-rev...ased-working-with-Tesla-module-oem-slaveboard

So with Tesla modules it works out of the box with Victron and SMA Sunny Island range,
Myself most happy to use it on Victron kit, from single Tesla module + 24V/3000W MultiplusII,to big build with 8 Tesla modules modules 920Ah/42Kwh in a 2S4P set-up and a 48/10Kva Quattro.
It just works with this SIMPbms

If your building a small system with just 1 module 5.3Kw, I don't think one is in need for using the fluid system used for heating and cooling,
only needed if you go over 1C, or in extreme condition climate zone's,
more info needed contact me using mail

best Carel Hassink

image_elozgg.jpg

image_lztgzo.jpg
 
"Idle Consumption: 145 Watts" - factor this in if your planning on 24 x 7 use. This can be one of the main criterias to consider...
Above low voltage trip of 39V try pulling 36kW and the unit will fail.... 150A per FET, pop...
Charger Specifications : Output voltage: Up to 50.5vdc ?????

If your going to pull 12kW from a 5kWh pack cooling may be just fan/airflow based, nissan leaf style. The battery would be empty in around 20 minutes anyway. You don't really want to run the cells that hard if you want them to last.....

BMS, bypass the Tesla modules and hook up something cheaper...
 
Late reply.

So basically I don't need to cool the batteries so that simplifies it. It does get quite hot here though. What is considered a normal operating temp? If I find that they are getting too hot could I just add more batteries to the system to reduce the discharge or charge rate? Does the battery monitor do this already? Can the battery monitor turn off the system to protect it?

New home builds cant do grid tie systems where I am or at least you need approval and its a whole lot of hoop jumping. I also like the idea of self sustaining. After all, Zombies might happen one day :). I would like to log the build on this site if that section exists (im new).

So if I decided to go with the Tesla modules I can get a setup like this?

1) Solar Panels - (Do they direct connect to the Batteries since they are already DC? Do they hook into the battery management system so the batteries are protected in case they are overcharging?

2) Victron Color Control GX Monitor - Honestly not even sure what the role is with this
https://www.amazon.com/Victron-Colo...or+control+gx&qid=1553551445&s=gateway&sr=8-1

3) VICTRON ENERGY QUATTRO 48/5000 Inverter - Connect directly to batteries or through BMS?
https://www.invertersupply.com/inde...tBSxeGjdPH_Bj-szd7Ufc8lFtOR45LxBoCkzoQAvD_BwE

Batteries - Model S Modules

Custom Board in that thread that is linked here? Is what he is talking about a custom board that was made to interface with the Model S modules so that they can talk to the BMS? This is a wild guess.


I apologize for, what im sure, everybody knows are super noob questions. I am just trying to become somewhat knowledgable and there are so many things to know. I am reading as much as I can but a lot of it is foreign to me lol. I actually want to build this system to be powerful enough to fully charge my Tesla daily so i'm expecting it to be a very large investment. (At least 100-150KWH of storage and production daily.) I could have just bought a few deep cycle batteries but they are inferior to lithium ion and would actually be more expensive than just building the system with the Model S modules. Cheapest deep cycles would cost 30K+ for 100KWH storage. $ - KWH seems to favor these builds handsomely.


Any advice on anything is greatly appreciated.
 
If built correctly with enough batteries to obtain reasonable C rates, cooling is just not needed. These are not high drain applications like cars.


At the bare minimum you need the following items to make this setup work

  • Batteries
  • Solar Panels
  • Solar Charge Controller
  • Battery Management System (Batrium over whatever you linked us to)
  • Wiring/fusing/incidentals
Now that you have the ability to make the power, store the power, and manage the DC side of the system. You need to convert the power into something that is usable for your application. If that is charging the Tesla, you need the following items at a minimum:

  • DC to AC inverter (most likely split phase capable)
  • Car Charger
This would be about all you really need for an off-grid car charger some of the above items should be separate pieces of equipment, sometimes you can get items that take care of multiple functions like an inverter/charger.


Keep in mind that a REAL Tesla Powerwall is AC coupled, end users have very little to do with the DC side of the componentry. If you want to make something like that, but you would be using something like a nice Grid Tie inverter charger like some of those Victron units which are great. This often becomes the heart of the system and the function will largely depend on the type of equipment you select as they are generally sold with different features and capability.

As for your choice of batteries personally I think there are better things to consider other than Tesla modules for stationary storage if you dont need the power density. You pay a premium for it, but they are great cells if you get good batteries. If you end up with abuse Tesla modules, then you would be better off looking for something else.

Lastly, you are going to need to select a battery voltage which is going to be compatible with your choice of inverter/equipment. Tesla modules being 6s start to present some challenges as you would either be 6s, 12s, or 18s. Most 48v inverters are going to be better suited with a 14s to 15s input voltage. Anything beyond 48v is also considered high voltage DC which enters an area where safety is a larger concerns, and there could be permit/code requirements around that too.

Personally I am using 3 x 5s modules, to make a 15s setup my battery costs are about half of what it would cost to build using Tesla modules, and I get a better final voltage, and more efficiency from the inverter since I am running towards the top end of the input voltage range.

All thing to consider when designing a system...
 
Awesome. Thank you so much for taking the time to give me all that information. I think I have a pretty good handle on it now.

Only question would be, Do you have any other battery recommendations?
 
DudeBro said:
Awesome. Thank you so much for taking the time to give me all that information. I think I have a pretty good handle on it now.

Only question would be, Do you have any other battery recommendations?
Click to expand...

Really any EV car battery would be more than adequate for an application like this... searching for deals or sourcing from an auto salvagewould be my suggestion.

I am using modules from a Fiat 500e, here is a thread I made about mine but I haven't updated it in a while. I need tostart putting together more media and do that when I get more time.

https://secondlifestorage.com/t-Fiat-EV-Module-Powerwall

These have been awesome batteries... but I am sure than can be said about Chevy volt, leaf, and many other EV car batteries. Its a substantial step up in quality and consistencythan sourcing random miss-matched 18650 laptop packs. Everything I have pretty much still exhibits full capacity.

Tesla packs are cool because they are Tesla packs, they have some of the best density if you NEED density, but you pay a premium for it. The 6s just does notwork out as good as some of the other configurations, but it does work with the right equipment.
 
CrimpDaddy said:
DudeBro said:
Awesome. Thank you so much for taking the time to give me all that information. I think I have a pretty good handle on it now.

Only question would be, Do you have any other battery recommendations?
Click to expand...

Really any EV car battery would be more than adequate for an application like this... searching for deals or sourcing from an auto salvagewould be my suggestion.

I am using modules from a Fiat 500e, here is a thread I made about mine but I haven't updated it in a while. I need tostart putting together more media and do that when I get more time.

https://secondlifestorage.com/t-Fiat-EV-Module-Powerwall

These have been awesome batteries... but I am sure than can be said about Chevy volt, leaf, and many other EV car batteries. Its a substantial step up in quality and consistencythan sourcing random miss-matched 18650 laptop packs. Everything I have pretty much still exhibits full capacity.

Tesla packs are cool because they are Tesla packs, they have some of the best density if you NEED density, but you pay a premium for it. The 6s just does notwork out as good as some of the other configurations, but it does work with the right equipment.
Click to expand...

Interesting. I just checked out Ebay listings to make a KWH cost comparison

Fiat 500 Pack
https://www.ebay.com/itm/2013-17-FI...868486&hash=item3b24920d68:g:8PkAAOSwusdcCu7O
$522.50 - 6.6kw = $80 per KW


Tesla Module
https://www.ebay.com/itm/1x-Tesla-M...027276&hash=item2873f7f060:g:kCcAAOSwHlRbNp-b
$1,150 - 5.3kw = $216 per KW



Tesla battery modules looks to be a lot smaller so it would be easier to store them vs the Fiat pack.

How would you go about hooking up the Fiat battery instead of the Tesla one? I am looking for a relatively easy solutions. I would do Lead Acid if it made sense from a cost per kwh perspective.
 
That's overpriced... I don't buy anything off e-bay and shipping batteries is expensive. I find deals locally...auto salvage.

The guy selling it probably paid that much, maybe even less, and is trying to flip it.

Where are you located?
I got more than I need... id sell you some for about that much if I don't have to ship it.


image_uchsrt.jpg
 
Hawaii lol

Probably dont have all that many options for salvage here.

I actually just called the only Salvage place on the Island and was told that they sell them so fast they never have them. I am sure there is much higher demand here because of how many people are doing solar.
 
Considering shipping to Hawaii cost even more than the mainland, you might actually be better off buying those Tesla cells at least the density works in your favor with shipping.

Either way, you have to spend the time seeking it out, being patient, or throw money at the problem.

The only thing I dont like about Tesla modules is that its 6s, other than that, its made from excellent quality cells. Personally I would have a solid design / engineering before buying a single component.
 
It means 6 cells in series you have a nominal pack voltage of 22.2vdc

It limits your choice in equipment options, and on 24v equipment, it may run on the lower end of the efficiency curve.
 
Ah I see. Can packs also run parallel and series? IE can we increase voltage that way with whole packs?

What are the options? 12v Vs 24v? Do you have to hit exact voltage numbers or does equipment range for what it can handle?

Obviosuly I dont know very much. Lead acid seems like it would be easier but I love DIY.
 
Batteries are batteries ... you can wire then just like any other battery. Parallel to increase capacity and series to increase voltage. That said, lithium cells have their own working voltage ranges and nuances just like lead acid. Learn the characteristics of these cells before you proceed.

With your level of experience, I wouldn't even start to consider building a powerwall unless you fully understand what you are working with. No offence but with some of the questions you are asking, you should not move forward just yet. There is plenty of reading to be done to brush up on your fundamentals first... go make a small system using some 18650 cells until you understand what you are doing.

You pretty much need to design it yourself and work within the parameters of both the battery setup and equipment selections.
 
CrimpDaddy said:
Batteries are batteries ... you can wire then just like any other battery. Parallel to increase capacity and series to increase voltage. That said, lithium cells have their own working voltage ranges and nuances just like lead acid. Learn the characteristics of these cells before you proceed.

With your level of experience, I wouldn't even start to consider building a powerwall unless you fully understand what you are working with. No offence but with some of the questions you are asking, you should not move forward just yet. There is plenty of reading to be done to brush up on your fundamentals first... go make a small system using some 18650 cells until you understand what you are doing.

You pretty much need to design it yourself and work within the parameters of both the battery setup and equipment selections.
Click to expand...

Yes I agree completely with you. My level of Experience is a big Zero which is why i'm asking these questions.

I stumbled across this video which seems to be exactly what I am looking for. I don't see why I couldn't do the same exact thing with putting multiple modules in parallel. I may just need a bigger inverter. I guess I could set up more than one inverter also right?

 
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