MI BMS

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miwall

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Right over the last Month or so i have been working on a BMS using Arduino, Inspired by BMS Tesla Power Wall Many thanks to him i have had to get up to speed with Arduino and C++ also thanks tohttp://www.toptechboy.com what great Tutorials finished most of them.

I have Built a board for Prototyping using 7 Cells, but in principle if it works for 7 individual cells it will work for cell packs, I am about half way through!!!.......after managing to destroy 9 High level trigger 2 channel relays and i Arduino Megga some nice fireworks though.

The system is configureable and should be able to work on 3, 7,14,28 Pack power walls, I have got the output voltages displaying on a 20,4 LCD screen.

OK with that would be good to get some feed back on what the system should include!!
Cheers Simon Miwall.
 

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Inter cell sharing of balance current, rather than dissapative
Per pack over/under discharge protection
Per pack over/under discharge alarms
Per pack over/under discharge alerts SMS/SMTP
Per pack charge/discharge reporting to ThingSpeak

That should keep you busy for a few days :)
 
You may also want to think of the amps being passed through on a 140ah battery. Sounds like you have your consumption well underhand, but solar charging can put quite a few amps through at a time. May need to beef up some of those wires?
 
Dantheman said:
You may also want to think of the amps being passed through on a 140ah battery. Sounds like you have your consumption well underhand, but solar charging can put quite a few amps through at a time. May need to beef up some of those wires?
Click to expand...

Ok when you say beef up the wires they are just sampling the voltage so there will be no heavy current passing through the monitoring wires!! ......................Please explain further if i am wrong;)
 
No, Maybe I'm misunderstanding. A BMS is a Battery Maintenance System. So either passive, or active. Charges or discharges. I'd imagine you'd want active, or charging. To use some of the solar energy. Am I on the right path here? If it works good on a 7s1p system, won't it take forever on a 7s100p system?
 
A bms can be everything from just monitoring to actively doing something with it.

When it comes to balancing. Doesnt matter if its passive or active:
The current for balancing a pack does not have to be large. When it comes to that stage that you constantly have to balance 1 pack with 1A 24/7. (100p for instance)
You have started to have big issues to that pack. There are systems that do up to 10A of balance current and higher but thats something capable of 1000Ah or even larger banks.

Fot initial balance you might want higher current but its always recommended to do that before its put into use.

Hope that clears some questions slightly.

Nice project btw!
 
looks nice for a prototype :) . But as far as could see, this is not a MBS but just a voltmeter...

At first, I'd like to have a graphical screen showing the voltages, maybe a nice OLED (i.e. SSD1306) screen or even touch (Nextion have nice ones, easy to handlewith Arduino).

Then you'll need to add more features like charge/discharge control. This is the key feature of a BMS, to protect teh cells from ocercharging/overdischarging.

And balancing would also be nice. I mean real balancing, not only transferring a few mA between the cells.

But I'm sure, if you seriously want to make a BMS, the Arduino will not be suitable...

Anyway, keep up the good work :)
 
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