My Offgrid House & My Programable Solar BMS for any type of Lithium battery.

[electrodacus]

Electrodacus you are looking the wrong way at how a computer supply works.. It doesent have current sharing in the true sense.. In a computer it has many +12 and +5v output wires from the supply but at no stage do they reconnect again at their other ends. Each wire goes to a different device. ie hard drive,DVD player etc.. in yours they start from a common line and reconnect again to a common line.. The problem is if one wire now has poor connection at either end the other wires have to share its load. That doesn't happen in a computer. If a plug say to the DVD player becomes a bad connection that DVD player cant get additional load from another wire. It just stops working.

If you want to pursue that design. And it may basically be a good one. You just need to reconsider firstly the connections and always keep in mind it will mostly be used by "average" mechanically and electrically knowledgeable people.. You have to make it reasonably "idiot " proof.. .

Thanks for this replay.
Current is shared in an ATX power supply (I have extensive experience with those) All ground wires are connected together at both ends inside the ATX PSU and on the motherboard.
Same is valid for the 4 pin or more recently 8 pin connector providing power to CPU or those for GPU.
Also the 4 pin molex or SATA connector uses the ground as common for 5V and 12V even if in that case current is small enough that a single wire can safely transport that current.

But I think inside a case a different code apply. That leads me to the question what code apply to connections inside a panel where this BMS should me mounted.
I found the NEC 310.4 but that is not specific for this use inside a panel.
There are a few solution I think that can allow me to keep current power connector (changing is not an option).

One simple is to have 20A fuses on each parallel wire in that way if there is an imperfect connection the fuses will not allow current on a single wire to exceed the limit. This I think will prevent any possible problem related to safety but just got the idea I need to investigate more.

You can only have multiple parallel connections outside the BMS or inside there is no way around since I need a minimum of 4 MOSFET's even if they are not PCB mount and you use a large heatsink as a conductor there is still current sharing.
Target is to keep this device as small and light as possible.
In the installation instruction I can state that this is a component and not a device and that needs to be installed inside a fireproof cabinet where the parallel connections can be made. In that case even without fusses for each individual wire if any of the wires or more than one gets disconnected will be protected from fire since is inside the fireproof cabinet or box.

What do you think about this or are there any other solutions that allows me to keep the current design.

[Sunking]

NEC has no say what goes on inside a gizmo. That would be UL or other listing agency. NEC has everything to say about premises wiring system for power, lighting, and control.

Here is the deal. If your house or someone else house were to burn down, and your controller was found to be a part of the cause or even suspected, insurance company and fire marshal will be looking for you and holding you responsible for all damages and injuries. Part if the listing requirements is the manufacture has to have liability insurance. Do you have any of that? You have been told. I only hope you don't have to learn if you don't listen. Loosing all your money and property is a great teacher and motivator. It is the second best motivator and teacher after Fear and Intimidation.

[electrodacus]

NEC has no say what goes on inside a gizmo. That would be UL or other listing agency. NEC has everything to say about premises wiring system for power, lighting, and control.

Here is the deal. If your house or someone else house were to burn down, and your controller was found to be a part of the cause or even suspected, insurance company and fire marshal will be looking for you and holding you responsible for all damages and injuries. Part if the listing requirements is the manufacture has to have liability insurance. Do you have any of that? You have been told. I only hope you don't have to learn if you don't listen. Loosing all your money and property is a great teacher and motivator. It is the second best motivator and teacher after Fear and Intimidation.

What about individual fuse for each of the 10 connectors? Will that comply with the code. I do not see any possibility in this case to have a fire.
Having this BMS in a fireproof box where all parallel conductors will be and then outside the box single AWG 6 wire will make this a component inside a device.
There need to be a solution in order to keep current size and weight of the device so it can be used in other applications also where space is limited or weight is important.



As I mentioned before I can not take any responsibility for proper or improper use of this device even if I will try to make it as safe as possible to my knowledge.
For one this is a fully programmable BMS a single wrong parameter set out of the over 30 that can be modified can create a big problem.
This is not a general consumer device is for learning purposes should be supervised at all time when in operation and is not to be installed in a permanent installation since it dose not comply with any codes.
If that happens the person that installed this has the liability.

Since this will be an open source hardware and software anyone is allowed to make any modifications, improvements to this device.

[russ]

As I mentioned before I can not take any responsibility for proper or improper use of this device even if I will try to make it as safe as possible to my knowledge.
For one this is a fully programmable BMS a single wrong parameter set out of the over 30 that can be modified can create a big problem.
This is not a general consumer device is for learning purposes should be supervised at all time when in operation and is not to be installed in a permanent installation since it dose not comply with any codes.
If that happens the person that installed this has the liability.

Since this will be an open source hardware and software anyone is allowed to make any modifications, improvements to this device.

Sounds cute but ask a lawyer - not that easy to wash your hands of any and all responsibility - especially after this discussion where you are discussing tactics on a public forum which means a public record.

[mschulz]

Electrodacus,

I love that you are going out there trying new ideas and trying to make something really happen here, but unfortunately liability and litigation runs rampant in this country and you are going to have to have a lot of money to get to the point where you can even get insurance on this product - if it works and is safe.

Also many on here that are responding to you are in this business and have seen what works and what doesn't but then look at all the people who bought a 100w panel off e-bay, charge controller, and plan to hook it up to 10 car batteries. This person is where you are going to run into problems as they will hook it up themselves after watching a youtube video from a 150v -80AMP charge controller - nothing close to what you are selling. House burns down, kid is in the house when it does, you will never have another cent to your name at minimum and at worst you will see jail time (I am not in the industry or a lawyer no do I profess any knowledge of electronics).

My advice, work this out on your own and set it up in a storage shed first. From your video you spent a lot of hard work and sweat on your house so I would hate to see that go up in smoke.

My $0.02

[electrodacus]

Sounds cute but ask a lawyer - not that easy to wash your hands of any and all responsibility - especially after this discussion where you are discussing tactics on a public forum which means a public record.

I think if I make this as clear as possible it should not be any problem. Else how will anyone ever create something.
Anything can be dangerous.
Since this is not as of now a real product available for sale I can still make changes to my offering.
I hope to figure out all the aspects so that I can launch this on Monday. But I can delay that if I'm not sure.
Asking a lawyer will probably not protect me any better . The law is so wast and with so many interpretations that not one single layer has the answerer. (maybe I'm wrong here)

I will solve all the problems that I'm aware of (like the current sharing connectors) and hope that all my clients that did not got scared by my warnings know enough of what are they doing to stay safe.
Lithium batteries especially some chemistry can be quite dangerous and this dose not stop to many people to play with them.

[Sunny Solar]

Electrodacus. You seem obsessed with size and weight of the item. I think both are totally irrelevant . Its not like it needs to be installed inside some already made device.. It could be 3 times the size and still be compact.. This would allow you to make some great improvements to it. IE The use of single fully rated connectors.. Forget about the computer ATX and its multiple neg wires..Its done for different reason and purpose.

Personally my advice would be for you to seek some paid professional legal help before trying to sell it in any shape or form. Its not that easy just to put out a statement saying. its for fun use only not for real use.. I just cant see a judge accepting that if someone does use it for real and gets injured or suffers monetary damages in any way .

I know nothing about your laws there but im sure they are similar to Australia's. And I know how risky thing like this can be here. I was in audio manufacturing for many years.

[electrodacus]

Electrodacus,

I love that you are going out there trying new ideas and trying to make something really happen here, but unfortunately liability and litigation runs rampant in this country and you are going to have to have a lot of money to get to the point where you can even get insurance on this product - if it works and is safe.

Also many on here that are responding to you are in this business and have seen what works and what doesn't but then look at all the people who bought a 100w panel off e-bay, charge controller, and plan to hook it up to 10 car batteries. This person is where you are going to run into problems as they will hook it up themselves after watching a youtube video from a 150v -80AMP charge controller - nothing close to what you are selling. House burns down, kid is in the house when it does, you will never have another cent to your name at minimum and at worst you will see jail time (I am not in the industry or a lawyer no do I profess any knowledge of electronics).

My advice, work this out on your own and set it up in a storage shed first. From your video you spent a lot of hard work and sweat on your house so I would hate to see that go up in smoke.

My $0.02

Thanks for the feedback.
There is no way for me to make this product a fully compliant insured product for any user. There are many reasons for that.
One is that there is very little interest at the moment in a product like this and there will never be enough volume to make all this certifications and insurance at any sort of reasonable price.
As for my own house I take full responsibility for my actions. I know what I'm doing and if I'm wrong it will be my own problem.
All the electrical equipment including this BMS batteries, inverter will be housed in a fire proof box so if something go wrong the damage will be contained to the equipment.

[electrodacus]

Electrodacus. You seem obsessed with size and weight of the item. I think both are totally irrelevant . Its not like it needs to be installed inside some already made device.. It could be 3 times the size and still be compact.. This would allow you to make some great improvements to it. IE The use of single fully rated connectors.. Forget about the computer ATX and its multiple neg wires..Its done for different reason and purpose.

Personally my advice would be for you to seek some paid professional legal help before trying to sell it in any shape or form. Its not that easy just to put out a statement saying. its for fun use only not for real use.. I just cant see a judge accepting that if someone does use it for real and gets injured or suffers monetary damages in any way .

I know nothing about your laws there but im sure they are similar to Australia's. And I know how risky thing like this can be here. I was in audio manufacturing for many years.

Size and weight are important for many reasons here are few.

Weight especially will increase considerably the shipping cost every doubling in weight equates to an almost doubling in shipping price and especially for international shipping that can be significant even exceeding the price of the product.
This is not designed specifically for stationary applications in portable applications like electric bike or portable solar power pack both weight and size is important.
This is designed to be installed inside an electrical box and not outside as a self contained item.

This is not a business for me investing any money in this for insurance or layer will not be an option. I will sell this as a development platform and learning tools for those that want to design a product around this.
I guess in this case the responsibility is shifted to the user since is not meant for actual use in an installation.

[russ]

Well, your strategy to avoid responsibility is well documented on the net.

If one ever plans to do anything of questionable legality discussing it in detail on the net or with anyone is a real bad plan.

You seem to be hung up on a exceedingly small target market.

[Sunny Solar]

Electrodacus I think you are going to find less than 3people in the world wanting to pay money for that as a development platform... There are many designs for them.. You can Google some of them.

I can tell you this for sure I have seen many like yours in prototype form over the last 3 yrs. And still waiting to see any of them in commercial production... Some I have seen are really good and look like they would be good to produce. but it seems its not easy.. Some well lets say they not so good and we are lucky no one is making them.

We have a 100a 12,24, and 48v charger for LIFEPO4 batteries also in a prototype form that engineers have been working on for over 6 months. But it may also never be manufactured...(you would hate it .Its about 50 times the size of your device) As its main purpose is for us to test different batteries with the view of maximizing life from them... Even the slight differences between cell sizes make a big difference over a year.

The most promising cells were prismatic. But for now.?? no more.???

[electrodacus]

Electrodacus I think you are going to find less than 3people in the world wanting to pay money for that as a development platform... There are many designs for them.. You can Google some of them.

I can tell you this for sure I have seen many like yours in prototype form over the last 3 yrs. And still waiting to see any of them in commercial production... Some I have seen are really good and look like they would be good to produce. but it seems its not easy.. Some well lets say they not so good and we are lucky no one is making them.

We have a 100a 12,24, and 48v charger for LIFEPO4 batteries also in a prototype form that engineers have been working on for over 6 months. But it may also never be manufactured...(you would hate it .Its about 50 times the size of your device) As its main purpose is for us to test different batteries with the view of maximizing life from them... Even the slight differences between cell sizes make a big difference over a year.

The most promising cells were prismatic. But for now.?? no more.???

There is no design using this IC available. I was the first one to by samples directly from the manufacturer.
There are already at least 5 or 6 people that expressed interest out of my youtube subscribers and they know exactly what they are getting.
I will have lived for my use with a larger unit maybe not 50x bigger but the other problem is the power consumption.
There are some BMS units designed for electric cars usually with monitor boards on each cell that communicate using a serial protocol and are connected to a mini computer. The problem is power consumption quite high usually a few watts. This is not a problem when you have a huge battery bank 10 to 20kWh for EV and they are only active when the car is running.
In 24/7 applications and with smaller batteries that will be a real problem.
In contrast a simple PWM controller uses something like 10 to 20mA (they use inexpensive linear regulators to power the internal components) so power consumption is 120mW to 240mW at 12V and 240mV to 480mW at 24V this is more acceptable.
In contrast my device use a high efficiency DC-DC converter and carefully selected components so power consumption is the same at 12V or 24V and is just 25mW with LCD backlight off and no more than 65mW with backlight on highest level.
This makes it suitable for small battery banks even supercapacitors.
Most are concentrating attention on cost optimisation and not power consumption optimisation.
I can understand no one is making something like this. Low volume not much demand, high complexity and expensive regulations.

[electrodacus]

Well, your strategy to avoid responsibility is well documented on the net.

If one ever plans to do anything of questionable legality discussing it in detail on the net or with anyone is a real bad plan.

You seem to be hung up on a exceedingly small target market.

This is not a business is a hobby maybe I was not clear enough. I have no interest in high volume.
And have absolutely no intention in getting this in the hands of people that do not know how to use it and what are the risk involved.
I have no bad intention. I have no plans to do harm to anyone. If this is not clear is probably do to my bad English or the ability to express my self clearly.
If anyone will be afraid to express their opinion on a forum there will be no forums.

I have learned a lot in the last few days on the forum. A lot of valuable informations that I will not have had unless I had this discussions.

[inetdog]

I have learned a lot in the last few days on the forum. A lot of valuable informations that I will not have had unless I had this discussions.

We are very glad that you found the Forum useful and I have enjoyed following the discussion.

Just a warning to prevent future misunderstandings:
If and when you go live on Kickstarter on this project, please let us know, but do not include a clickable link to the Kickstarter page in your post.
Thanks!

[electrodacus]

We are very glad that you found the Forum useful and I have enjoyed following the discussion.

Just a warning to prevent future misunderstandings:
If and when you go live on Kickstarter on this project, please let us know, but do not include a clickable link to the Kickstarter page in your post.
Thanks!

Thanks for the warning. I was not aware of this so I will have posted a link probably. I will make sure not to do that.