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

[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]

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.

[Sunny Solar]

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.. .

[electrodacus]

eLECTRODACUS. It seems its hard to get you to understand than multiple small cables used trying to share current is VERY BAD DESIGN.. There is no one on this forum that will ever agree with you...Its an instant red flag to everyone. I showed the photo today to 3 engineers .ALL instantly said whats with the "silly" screw connectors??.I said he wants to current share.. ..REALLY. ? .Their advice rate the thing at 15a and use one connector for each in and out..and remove the other screws.

Sorry cant give brand names of items we test as items we test may or may not be exactly the same as the ones you would purchase commercially..

I will give example.. .Manufacturer x1 sends a inverter to evaluate .I test and find it great and really good features.. I really like it can handle input v dc up to 16.5v. I tell people this is great device wait for it to be on sale.. It comes on sale but can only accept up to 14.8v. Friends buy it and tell me I gave bad info.. Now don't trust me.. I contact manufacturer. They just reply it was "to expensive to make like that" ..Also some items we test never even get to production.

Current sharing is what I want to do and how I want to use the device. Anyone can remove the screws and limit the current from software to 16A (there is no 15A option) Next is 24A for charging that is more than 20A so it can not be used with one single screw and 32A for discharging so 16A will work for both.
Why is an ATX power supply connector different and allowed to share current usually 20 or 24pin with 5A max per pin and AWG 18 copper conductor? Some ATX power supply can deliver power in excess of 1000W with smaller voltage most power on the 12V rail.
I think you think this parallel connections are for power transmission and they are not.
There is no way to insert more than 20A in a single point on a PCB so you need power sharing for PCB mount connectors where more than 20A is required.

I decided I will make this open source HW and SW so people can use the design and modify to met their needs.
Maybe even some small companies will take this and make a product now that most of the design is done and since will be open source many will contribute and improve the design.

[electrodacus]

That may scare away a lot of kickstarter responses....

I agree with you but if that protects me is OK.
I will attract them in a different way like making the software and hardware open source that way also the responsibility gets shared since they can modify the hardware and software.

[Sunny Solar]

eLECTRODACUS. It seems its hard to get you to understand than multiple small cables used trying to share current is VERY BAD DESIGN.. There is no one on this forum that will ever agree with you...Its an instant red flag to everyone. I showed the photo today to 3 engineers .ALL instantly said whats with the "silly" screw connectors??.I said he wants to current share.. ..REALLY. ? .Their advice rate the thing at 15a and use one connector for each in and out..and remove the other screws.

Sorry cant give brand names of items we test as items we test may or may not be exactly the same as the ones you would purchase commercially..

I will give example.. .Manufacturer x1 sends a inverter to evaluate .I test and find it great and really good features.. I really like it can handle input v dc up to 16.5v. I tell people this is great device wait for it to be on sale.. It comes on sale but can only accept up to 14.8v. Friends buy it and tell me I gave bad info.. Now don't trust me.. I contact manufacturer. They just reply it was "to expensive to make like that" ..Also some items we test never even get to production.

[inetdog]

That may scare away a lot of kickstarter responses....

[electrodacus]

What do you think about this disclaimer added to the Kickstarter page will it be enough?
Maybe I will even print a sticker and apply this to each individual product.


Important Disclaimer:

I will not assume any responsibility for injuries lose of life or property do to proper or improper use of this product.
The product is intended for educational purposes only there will be a series of videos on my youtube channel describing in details the functionality of the hardware and software used and both will be open sourced so you can do your own modifications.

[electrodacus]

every one in my family is a lawyer Brother, Sister (former compliance officer for Johnson and Johnson) and wife who does safety law.
You are treading on very thin ice with your family and personal assets going down the path you have chosen from a liability standpoint. you have no corporate veil to protect you from a product liability case.

There must be a way I will not be legally liable.
Even if I need to sell this as a display only with a warning do not connect to any power source this is just for display
I hope I do not need to go that far. It seems Europe is extremely different in this respect for low volume production.
Can you ask anyone in your family what is the best option for me. Else I will just not sell this product. At least not in US and Canada.
As for my own use I take full responsibility for using this. For my personal use is the safest product I can use(designed and tested by me what can be better than that ).
If my house burns down it will not affect anyone but me since is offgriid far from any other construction. At least is what I think maybe I will be sued because the smoke will pollute the atmosphere .

I promise I do not enjoy my self this can ruin what i worked on at lest in the last few weeks preparing this for Kickstarter.
The other product that I produced and sold was in Europe and was also a micro-controller development board not sure how anyone can burn down the house with that but everything is possible.

[Sunking]

I'm not familiar with any of them I only worked in the electronic industry low voltage, low current DC
Do they cover low voltage battery powered systems <32Vdc?

CSA and NEC cover all electrical premises wiring and does not differentiate between AC DC high or low voltage with the exception of article 700 applications of limited power Class 1 and Class 2 which covers things like AV, data, sensors door bells etc...

[Sunking]

The Canadian standards are similar to the US
It would be against the NEC to parallel #12 conductors to acheive an 80 amp capacity.
This is only legal here for over 1/0 conductors. I am sure Sunking will correct me if I am wrong.

You are spot on correct and same for CSA which is a mirror image of NEC - 1 cycle.

[Naptown]

Some of you mentioned the legal ramification in selling an unlisted product (thanks for that)
Is there any way around?
I need to know before my project go live on Monday so I can make the necessary changes or even take it out if necessary.
UL certification will probably not be possible for a product in such a low volume the cost will kill the project.
One more thing I'm not a company but an individual person if that makes any difference.

Your help with this is highly appreciated.

every one in my family is a lawyer Brother, Sister (former compliance officer for Johnson and Johnson) and wife who does safety law.
You are treading on very thin ice with your family and personal assets going down the path you have chosen from a liability standpoint. you have no corporate veil to protect you from a product liability case.

[electrodacus]

Some of you mentioned the legal ramification in selling an unlisted product (thanks for that)
Is there any way around?
I need to know before my project go live on Monday so I can make the necessary changes or even take it out if necessary.
UL certification will probably not be possible for a product in such a low volume the cost will kill the project.
One more thing I'm not a company but an individual person if that makes any difference.

Your help with this is highly appreciated.

[electrodacus]

Then look at the CSA standards which is the Canadian equal to the NEC.
Yes you could probably do what you want to with CSA llisting (basically the same as a UL listing) BUT GENERALLY MORE STRINGENT.
You are opening yourself up to a major liability if something goes wrong with one of your systems and it is not a listed product.
Good luck and I hope nothing goes wrong.

I'm not familiar with any of them I only worked in the electronic industry low voltage, low current DC
Do they cover low voltage battery powered systems <32Vdc?
I will like to know if there are specifics in this codes referring to that. I will need to find the code and see I I can get the parts that apply to my product.
Not that this product will be UL listed as I mentioned before it will be probably to expensive for a low volume product like this.
One of the reason I used 24V DC as max was the safety reason.

Anyone that installs an unlisted product must take full responsibility for that. There must be a category where I can sell my product as an unlisted product for DIY users that want to have this for their electric bike or small offgrid cabin.
The legal part is an unknown to me so if someone can help me here I will be grateful.
I'm sure making this a listed product is not possible do to costs involved. Or I'm wrong?

One thing that I can allays do is limit the overcurrent protection in software at any level for both charge and discharge paths.
Overcurrent is done in hardware but with possibility to set that from software.

[Naptown]

Then look at the CSA standards which is the Canadian equal to the NEC.
Yes you could probably do what you want to with CSA llisting (basically the same as a UL listing) BUT GENERALLY MORE STRINGENT.
You are opening yourself up to a major liability if something goes wrong with one of your systems and it is not a listed product.
Good luck and I hope nothing goes wrong.