House electrical change to Tesla Battery modules

[freds]

The house side electrical heart has been upgraded with Tesla Power!!!




Tesla Battery modules are attractive for reuse in solar or RV installations due to their energy density and cost.

You can get a recycled Tesla module for a bit more than the cost of a single BattleBorn battery and have more than four times the storage capacity.

To safely use and protect Tesla battery modules you need a BMS setup/configuration.

In my application I make use of the SimpBMS open source product/project and other components that I purchased from the British firm “Second life EV Batteries”.

Tesla doesn’t put a fully functional BMS on each module like you get with a BattleBorn battery.

This is because a typical model S or X Tesla has 16 modules, they use the approach of slave BMS’s with a master controller for the entire battery pack.

So, in short, every Tesla Battery module already comes with an integrated BMS module that is offline as it is waiting for a master controller to wake it up!!!

As you can see from my posted picture of this bay I have the following:

1. Two Tesla battery modules cased up and mounted
2. SimpBMS controller with display
3. Two solar charge controllers
4. 70AMP 24V to 12V DC-DC converter

Here's a picture of the touch display:



In the next bay on the other side of the adjoining wall:



I have my 6KW inverter that can surge to 18KW and another solar charge controller.

Current storage is 10.4KW of power, that is reduced to 8KW in the interest of battery life and safety while charging while at the upper end of the charge zone. (Solar charge controllers will over charge two Tesla modules if permitted, restriction goes away with more modules).

I can post more details on this setup if people are interested.

[Gil_J]

Interesting. A single BMS for a fair sized battery bank would seem to be either extremly sensitive or not as reliable. It would seem like a single cell may have to degrade too far for the BMS to react.

Can the bank be split into multiple 24V banks so additional BMS units can be installed? A Tesla us operating at a voltage well above 24V. How was the 24V bank created? That looks like an AIM Power inverter. I've installed a few and discovered they, like most high frequency inverters, don't like surges. They also have very limited configuration options. At least that is the case with the blue ones.

It's good seeing some try out other options.

[freds]

The SimpBMS controller functions as the master BMS controller for your recycled Tesla battery modules and is based on open source projects that reverse engineered the protocol that Tesla uses to communicate with its battery modules. Each Tesla Battery module has a slave BMS that controls each module for balancing and reporting voltages and temperature for the module.

SimpBMS was initially developed for the hobbyist market of converting Gas Vehicles to Electric Vehicles using recycled parts from these vehicles.

However, the firmware does have a mode (ESS) for stationary use for Powerwall or in my case RV usage.

Also, note that the SimpBMS is heavily CAN based and can be used with other EV battery sources like LEV40 Modules, LEV50 Modules, BMW i3, E-Golf & GTE (slave PCB needed on all modules).

In the Tesla Battery modules every cell is individually fused which would blow if they got grossly out of sync with their compatriots. I am not really worried about the Tesla battery modules, as there are more than a million of them in use. Internally they are wired as 6 series of 74 parallel (6S74P) 444 cells.

My setup has the following following components:

• Victron 24V to 12V DC to DC converter
• Victron Color control head
• Victron Solar charge controllers (3 EA)
• 3.5 KW of solar panels divided up into three separate zones
• Singineer Inverter/Charger 6KW Tesla model APC6024DT 240/120V split phase power
• Two Tesla Model S modules connected in parallel for a 24V pack acquired off of EBay.
• SimpBMS for Tesla

I am using a fair amount of Victron hardware where it made sense to me; to go with SimpBMS approach as it supports a CAN interface to Victron control head and functions also as the battery monitor in this configuration.

So, no need to purchase a dedicated battery monitor as most people do.

I purchase the following SimpBMS related items from: https://www.secondlife-evbatteries.com/

• SimpBMS 2.3 board configured for Tesla model S/X battery modules
• NEXTION display pre-configured for SimpBMS
• Used/Recycled LEM CURRENT Sensor CAB300-C/SP2
• Used/Recycled OMRON CONTACTOR G9EA-3-CA-M2
• Connectors package for the SimpBMS

If I was to do this again I might have gone with a Victron Inverter though they are much more expensive as they support a wider variety of power input voltages for driveway surfing. The Singineer charger functionality is only for 240V input and is fairly wimpy at a 2KW charge level.

I have some hardware laying around from my e-bike days; before I got my Tesla, that I am looking at integrating to give more charging flexibility, but that portion would definitely be a one off that would be difficult to duplicate.

My next phase is installing internet in the bus and adding a Pi based controller running Home Assistant and NodeRed for my automation, reporting and control functions.

The next major phase after that will be a DIY hydronic system that I am working on.

[truxton]

Hi Fred

Im not much of an electric guy, understood about half of what you said but I know pretty soon the old way will be gone.

Looking at your pictures you have what looks like 2 water hoses running thru that bay with a whole lot of stuff under it. Are you concerned about that.

I was gonna be a smart ass and ask how many fire extinguisher's you had on board.

Later
bv

[Gil_J]

Fred, you are definitely a hands on guy. Curious if you have considered housing the batteries in a fire box?

The hydronic heating system should be a lot easier than what you've accomplished. Have you decided which brand burner you'll use?

[freds]

Hi Fred

Im not much of an electric guy, understood about half of what you said but I know pretty soon the old way will be gone.

Looking at your pictures you have what looks like 2 water hoses running thru that bay with a whole lot of stuff under it. Are you concerned about that.

I was gonna be a smart ass and ask how many fire extinguisher's you had on board.

Later
bv

Three fire extinguisher's and planning on lots of Internet of Things stuff on a standalone network, where there will be seperate fire alarms for all area's.

The inverter is purposely mounted about four inches off of the floor in case there is a leak in the shared bay.

The two hoses are to tap into the hot coolant feed from the engine to the drivers heater to warm the hydronic storage when driving.

When I get everything finished I will do more posts on the electrical and hydronic design on my update.

[freds]

Fred, you are definitely a hands on guy. Curious if you have considered housing the batteries in a fire box?

The hydronic heating system should be a lot easier than what you've accomplished. Have you decided which brand burner you'll use?

The Tesla modules are very well engineered and in my opinion just need to be protected from mechanical damage. So no not going to do a fire box.

As to the burner I got a military new surplus Espar Hydronic D10 unit ($800.00) that was part of a arctic winterization kit for a large diesel generator. It's a 24V unit so fits well into my house electrical system.

I tend to cuss at the previous owners saying "what the heck were they thinking on all their various make overs/modifications!!!". Found paper work where the bus previously had a Wabesto unit when I quizzed the PO, he removed it to fix it and found out that it needed a replacement motor that cost $400.00 so decided not to replace it... Crap you can't fix what is not there...

[freds]

Hey solar charging sort of goes live here in Soggy Seattle!!!





Not all of my static loads are running yet, but the Tesla battery pack gained a net charge while parked in the storage yard.

Next to be wired in and powered up is:

1. Cellular Data modem for always on Internet
2. Three POE data switches
3. Raspberry Pi 4 automation controller
4. Wify access point
5. Victron Color control display

Currently running is:

1. SimpBMS controller/battery monitor with:

a. Always on color display
b. LEM CURRENT Sensor CAB300-C/SP2
c. OMRON CONTACTOR RELAY G9EA-3-CA-M2
d. Two OEM slave BMS's on the Tesla Battery modules

2. Three Victron solar charge controllers
3. Victron 24V to 12V DC to DC converter driving the new 12V buss and float charging the 12V generator start battery.
4. Some minor 12V parasitic draw that I haven't tracked down yet, that totally drained the old house batteries.

PS. It's been raining all day....

[Ck2hans]

Hay Freds:
Does that solar panel double as a spray sheild for the wheels too? LOL
Chuck

[freds]

Hay Freds:
Does that solar panel double as a spray sheild for the wheels too? LOL
Chuck

Nope it's just temporary until I get it and it's brethren mounted on the roof. Though your question does spark an idea!

In looking at the placement of my windows, maybe I could make a an group of them that would pivot from vertical to horizontal to also function as a Sun Canopy? In that case it would be a spray shield for the right side drive axle when stowed.

In the meantime I am going to have to arrange to store it. I am thinking that I can simply mount a couple of 2x4's vertical to the bay wall orientation, on each side of one of the bays to make a slide in storage rack.