DIY BMS design and reflection

[Hedges]

Ok, thanks

So, apparently this implementation is not a clear way to display what I want to display.

But I think I solved the problem: I just write the range instead unique values. For example instead of "40" you'd have "40-49". I think that way it's super clear and everyone interprets it the same

You have 9 LED's in the bar graph. Why waste them on displaying with 10% resolution?
You could display 512 different values. And those don't even have to be linearly spaced, could be logarithmic.

There are only 10 kinds of people in the world.
Those who understand binary, and those who don't.

 

[BiduleOhm]

When I see a LIT RED 10-20-30- 40% i think 49% or lower ... If I see a lit 50 then I think 59% or lower .. I see the numbers as trip gates .. so at 49.9 the 50 is still not lit until it gets to 50. ...

That was my interpretation too

Is there a means to show a parallel sliding needle (like we use on our 100Kw Generator Power control board -- LOL) .. With LiFePO4 I sort of would like to know if I am at 29% or 20% ... when only the 20 number is lit ...

If you can do that with 9 LEDs then I take it ?

You have 9 LED's in the bar graph. Why waste them on displaying with 10% resolution?

So you want people to read binary? pretty sure 99 % of them will not like to do this ^^

And those don't even have to be linearly spaced, could be logarithmic.

Current will be on a pseudo-log scale: 2, 5, 10, 20, 50, 100, 200, 300 A


Also, keep in mind this is not the primary display, but just a summary display of the most important infos only.

 

[Hedges]

So you want people to read binary? pretty sure 99 % of them will not like to do this ^^

The MSB LED which is lit conveys the same information as your bar graph. Only the less significant bits of LED differ.
(of course their blinking will confuse the great unwashed, I mean the uninitiated)

 

[Cal]

84% could be 80 lit and 40 blinking.

 

[Aero]

So much I don't understand on the hardware side of things but looks very nice
Super boulot !

 

[DWrvsolar]

Ok, thanks

So, apparently this implementation is not a clear way to display what I want to display.

But I think I solved the problem: I just write the range instead unique values. For example instead of "40" you'd have "40-49". I think that way it's super clear and everyone interprets it the same

If this is just a quick SOC meter, I would not bother with the numeric labels, just have lighted bars. More bars = better. This is fine for battery and signal strength on a cell phone.

 

[BiduleOhm]

The MSB LED which is lit conveys the same information as your bar graph. Only the less significant bits of LED differ.
(of course their blinking will confuse the great unwashed, I mean the uninitiated)

84% could be 80 lit and 40 blinking.

I mean I can always add this mode if I have space left on the flash and RAM. But for the default mode I really need a clear and simple display that anyone can understand at first glance

So much I don't understand on the hardware side of things but looks very nice
Super boulot !

Thanks

If this is just a quick SOC meter, I would not bother with the numeric labels, just have lighted bars. More bars = better. This is fine for battery and signal strength on a cell phone.

Those labels are basically free as they're part of the same sheet for the front panel I need to print anyway, so I might as well put them so you have a more precise idea of the SoC

 

[Hedges]

84% could be 80 lit and 40 blinking.

OK, what is shown for 88%?

 

[Cal]

OK, what is shown for 88%?

It's OK to be off by 1 or 2%.

88% = 80 + 70 flash

 

[Hedges]

48%?

 

[Stevelk]

I mean I can always add this mode if I have space left on the flash and RAM. But for the default mode I really need a clear and simple display that anyone can understand at first glance




Thanks




Those labels are basically free as they're part of the same sheet for the front panel I need to print anyway, so I might as well put them so you have a more precise idea of the SoC

Hi. Not to be rude or nosy... may I ask if there is any word on your "state of reflection" WRT the BMS you have been discussing?

 

[toms]

The tricky part is finding the components to work with your BMS.

It’s all well and good to say it’s the SCC’s job to taper current at a given setpoint, disconnect PV when commanded etc. Where do you find a SCC that is able to be commanded in such a way.

 

[HaldorEE]

The tricky part is finding the components to work with your BMS.

It’s all well and good to say it’s the SCC’s job to taper current at a given setpoint, disconnect PV when commanded etc. Where do you find a SCC that is able to be commanded in such a way.

Victron Energy BPP900450100 Cerbo GX

And if that won't do what you want.

Home

Victron Energy Unix/Linux OS. Contribute to victronenergy/venus development by creating an account on GitHub.

github.com

 

[HaldorEE]

Actually I missed that you were talking about the SCC. Easy, get a Victron MPPT Smart Solar. Victron.Connect over BlueTooth. The BMV-712 battery monitor will do it without a Cerbo or a Raspberry Pi.

 

[toms]

Compared with the combination of REC BMS and SMA inverters, that seems an overly complex setup.

What are the advantages of using an extra interface module and bluetooth control over a system like REC where the BMS directly instructs the charge controller?

 

[BiduleOhm]

Hi. Not to be rude or nosy... may I ask if there is any word on your "state of reflection" WRT the BMS you have been discussing?

I was on holidays but will start to work again on the design in the next few days

I also planned to make a summary thread as this one is now very lengthy...

 

[ramiws]

Yes please. I just went through thousand pages. I was looking for how do you find out the state of charge (SOC) I had one idea in mind. But I am sure you have figured something better as you have been working on this for sometime already. If you just powered the BMS to a battery how can it tell the SOC? Is user input regarding the max capacity needed?

 

[BiduleOhm]

Battery needs to be brought to the high or low charge limit in order for the BMS to reset the SoC to 0 or 100 %. That's how every coulomb counting SoC meters work and that's pretty much the only solution so not much choice here.

If a full charge/discharge cycle is done then there's no need to input the capacity manually; but it will be one of the parameters the user can enter anyway (and there's actually multiple capacities at play here).

 

[BiduleOhm]

I also planned to make a summary thread as this one is now very lengthy...

As promised here's the summary thread: https://diysolarforum.com/threads/summary-of-diy-bms-design-and-reflection.17169/ ?

I still need to write a few things but 90 % is done

 

[BiduleOhm]

I added 95 % of the specs (and blown the 10 kchars limit per post so I had to split them between two posts):

Summary of DIY BMS design and reflection

This thread is a summary of all the infos related to the BMS I'm currently designing; you can read the full version on this other thread. If you want to ask some questions or make remarks please post on the other long and detailed thread instead of here to keep this thread as short and clean as...

diysolarforum.com

Summary of DIY BMS design and reflection

This thread is a summary of all the infos related to the BMS I'm currently designing; you can read the full version on this other thread. If you want to ask some questions or make remarks please post on the other long and detailed thread instead of here to keep this thread as short and clean as...

diysolarforum.com

I still need to add the DPB specs (the HMIB and the RBB specs are dependent on finishing their design first) and the general description.

I also added spoiler tags on a few things to reduce the page length and so the need to scroll too much.