$100/kwh used lion BMW car batteries for DIY back up, meeting code in Charlotte, NC?

[khanh dam]

I am researching what it would cost to add battery back up to a 10kw grid tie system I will be installing soon. I've been watching a lot of DavidPoz youtube videos he seems to really know his stuff
I've always read that using batteries for solar was not economically viable. But DavidPoz is using lion batteries which should last 3x times longer than lead acid and also are only $100/kwh

What are the basic code requirements for a DIY battery bank for a residential system? Do batteries need to be in metal box? Do those thick wires wires need to be in a raceway? Will most places even let you DIY a power wall or will they require you use a battery system that is pre manufactured and enclosed?

And last and most importantly can the 26% fed tax credit be applied for a back up battery system?

[Ampster]

You can not take the credit for a used battery system, or for a used solar system.

[khanh dam]

ok, lets say everything is new. what are the basic requirements for Lion In a home? I assume it should be in a metal box and have a fire protection system. Is it better to have it in external structure?

[Salts]

Lithium likes to stay cool.. heat kills them.. and you can't charge them when frozen. So with this in mind, your location is going to determine a lot about how you set up.

If you put them in your home, a steel box is an absolute must. Don't forget the BMS, that will be an additional $800, and don't even think about using a cheap BMS from China. You need a REC BMS or a Batrium or Orion unit.

Your BMS should be set up so that it can communicate with the charge controller to control all charging functions, this is usually done through something called a CAN BUS. It doesn't absolutely have to be set up this way, but its advantageous. You need to become intimately familiar with lithium batteries and you need to know their characteristics.

David Poz does not know what he's doing. His work is adequate but sloppy.. His video's used to be good and reliable, but when he became popular, and he is very popular, he's turned into a marketing outlet for the various battery sellers and inverter makers. Seems that they send him free stuff for a good video on it. But that said, his channel isn't a total scam either as he seems to point people in the general right direction.

Ampster is correct, if you buy a used battery, you CAN NOT take the tax credit.. BatteryHookup.com sells used and salvaged EV batteries, but sometimes they run across new cells and I'm pretty sure if the cell is new and unused, it CAN be claimed on the solar credit thing. I don't think that where you purchase it from is on the list of requirements for the credit.

I'm going to say this one more time to make a point... YOU MUST BECOME AN EXPERT with lithium batteries if you put these in your home. You need to be intimately familiar with charge and discharge curves, C-Rates, thermal management, circuit protection, etc.

Lithium Batteries are like firearms.. put one into the hands of an amateur without proper training and its an accident waiting to happen.

My system is a 10.7kw grid tied system that switches to Off-Grid mode when our power goes out every time an ugly cloud floats over. We use a technology called "AC Coupling" that tricks the solar array inverters into making power to run the house and charge the 24.5kw Lithium battery bank. You must make sure you're home is isolated from the grid when you do this.. some inverters can provide that functionality automatically with internal transfer switches.

Don't use anything made in China, especially if the batteries are in your home. I keep mine in a 14ga 3ft x 4ft steel Hoffman enclosure on a concrete floor.

[SunEagle]

ok, lets say everything is new. what are the basic requirements for Lion In a home? I assume it should be in a metal box and have a fire protection system. Is it better to have it in external structure?

I would contact an electrical solar expert in your area to find out what code rules must be followed for a battery system.
First and second rule is to stay safe and do it per code. The third step is to save money.

Next I would make sure I don't try to fool a Tax accountant into thinking the batteries are new and you want to get any FED tax rebate on it.

[Mike90250]

ok, lets say everything is new. what are the basic requirements for Lion In a home? I assume it should be in a metal box and have a fire protection system. Is it better to have it in external structure?

I'd never put them in a home. Always outside the living envelope . the fumes from burning Li batteries contain toxic Hydrofluoric acid fumes, which a whiff of, kills you slowly over several days.

https://www.emsworld.com/article/173379/hydrofluoric-acid-what-you-need-know

[Salts]

I'd never put them in a home. Always outside the living envelope . the fumes from burning Li batteries contain toxic Hydrofluoric acid fumes, which a whiff of, kills you slowly over several days.
https://www.emsworld.com/article/173...-you-need-know

The fumes from just about anything that burns inside a home are toxic. From the PVC and thermoplastics, to the hybrid pressed lumber composites. With the exception of maybe smoke from a camp fire burning dead wood or a beeswax candle, pretty much everything used in modern day conveniences is highly toxic when it burns.

[Ampster]

ok, lets say everything is new. what are the basic requirements for Lion In a home? I assume it should be in a metal box and have a fire protection system. Is it better to have it in external structure?

Different chemistries have different volatility. LFP are considered the safest but my building department still wants to see them in a metal cabinet. My BMS also has four temperature sensors that can be programmed to set off alarms. There are other forums where you can get some advice from more experienced posters. Not saying the advice so far isn't good but only a few have actually been using Lithium batteries and what you want is best practices.

[Mike90250]

The fumes from just about anything that burns inside a home are toxic. From the PVC and thermoplastics, to the hybrid pressed lumber composites. With the exception of maybe smoke from a camp fire burning dead wood or a beeswax candle, pretty much everything used in modern day conveniences is highly toxic when it burns.

Hydrofluoric acid is about as unique and deadly as it gets. just a bit of it, on skin or in the air, starts a reaction breaking the calcium apart in your tissues. Your nerves are affected quickly and die, so you feel no pain from the acid

excerpt:
THE DANGERS OF HYDROFLUORIC ACID

Although considered a weak acid, HF is one of the most dangerous inorganic acids known. Burns of as little as 1% body surface area (BSA), or approximately 25 sq in (about the size of the palm of your hand), have been known to be fatal due to the acid's unique properties.

HF penetrates tissue more quickly than typical acids. Because of this ability, systemic toxicity can occur by dermal, ocular, inhalation and oral routes. When human tissue is exposed to concentrated HF, the molecules disassociate into individual hydrogen and fluoride ions. The hydrogen ion burns like any other acid. The fluoride ion quickly penetrates dermal and muscle tissue and reacts with the calcium and magnesium found within the body, rendering these ions useless. Major organs or systems that are especially vulnerable to damage are the heart, liver, kidneys and nerves. Exposures of 6%-8% BSA burns of concentrations above 50% HF almost always prove fatal within hours.

At lower concentrations, death can still occur if definitive treatment is not sought quickly. HF interferes with nerve function, so burns from lower concentrations may not be initially painful. Accidental exposures can go unnoticed for hours or even days, delaying treatment and increasing the extent and seriousness of the injury. This is extremely dangerous, because victims may not recognize that they are injured. Death may result from the associated hypocalcemia or hypomagnesemia if too much damage is done before treatment is sought.

[Ampster]

Hydrofluoric acid is about as unique and deadly as it gets..........

I think everyone agrees about the dangers of Hydroflouric acid. The only case that i have heard of it coming from batteries was that garage fire in Faifield and those were Lithium Polymer otherwise known as Lipo.

[Salts]

Hydrofluoric acid is about as unique and deadly as it gets. just a bit of it, on skin or in the air, starts a reaction breaking the calcium apart in your tissues. Your nerves are affected quickly and die, so you feel no pain from the acid

excerpt:
THE DANGERS OF HYDROFLUORIC ACID

Although considered a weak acid, HF is one of the most dangerous inorganic acids known. Burns of as little as 1% body surface area (BSA), or approximately 25 sq in (about the size of the palm of your hand), have been known to be fatal due to the acid's unique properties.

HF penetrates tissue more quickly than typical acids. Because of this ability, systemic toxicity can occur by dermal, ocular, inhalation and oral routes. When human tissue is exposed to concentrated HF, the molecules disassociate into individual hydrogen and fluoride ions. The hydrogen ion burns like any other acid. The fluoride ion quickly penetrates dermal and muscle tissue and reacts with the calcium and magnesium found within the body, rendering these ions useless. Major organs or systems that are especially vulnerable to damage are the heart, liver, kidneys and nerves. Exposures of 6%-8% BSA burns of concentrations above 50% HF almost always prove fatal within hours.

At lower concentrations, death can still occur if definitive treatment is not sought quickly. HF interferes with nerve function, so burns from lower concentrations may not be initially painful. Accidental exposures can go unnoticed for hours or even days, delaying treatment and increasing the extent and seriousness of the injury. This is extremely dangerous, because victims may not recognize that they are injured. Death may result from the associated hypocalcemia or hypomagnesemia if too much damage is done before treatment is sought.

I understand the fumes from burning lithium batteries are uniquely dangerous.. Problem I'm having is that I can't find any info to put it into perspective. Lead in water is dangerous, but pretty much all water sources contain lead at some concentration.

Perspective is everything, and for perspective, we need a reference. So lithium battery fires emit Hydrofluoric acid fumes.. the questions are 1) how much 2) how much is dangerous 3) what is needed to be exposed to the dangerous levels. 4) what are the consequences of different levels of exposure.

Without all 4 questions being answered in full, the fact that burning lithium bats produce the acid is almost meaningless. This has become a common problem in our society with many subjects.. Content without context is about as useful as power without control.

I think its going to be some time before we have an adequate amount of research and experience to answer these questions.. I guess for now, if I see or smell a lithium battery burning, I'm going to get the hell away from it. We do have lots of instances of 18650's blowing up, and I have not heard any mention of remarkable consequences of these accidents other than the mayhem that results from the fires.. (IE: Burns, burning buildings, etc)