Pete's BMS Story - Regular updates with issues or excitement I find along the way.

hbpowerwall

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Ths thread shall serve as the new home for my BMS journey.


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I must start by saying that I've not only tried to talk myself out of a BMS but also many on the interwebs have also been anti-BMS also. I don't know if I was just taking more notice of their side of the story or it was just what I wanted to hear.

Recently in the past few months, I've been thinking more and more about a BMS during one of the MANY trips back and forth to the battery shed to manually check the voltage several times a day that there really needs to be a better way. At first very happy to do it but now it seems more of a chore - Guess that also where complacencysneaks in and issues might start to occur.

I have ventured into playing with BMS's when I had the PIP2424MSX unit (24V system) from memory I purchased 4-5 different BMS all from ALI or eBay. The Large 200amp unit I bought was a 200a unit (well on the sticker) but was so poorly put together just turned me off. I mean it worked kinda - if you call 40mv balance working. And would have been safer than not running one at all. But the question in my head was what if the BMS fails and I'm not going down there all the time to check it?

So moving through several different ones either through my own fault for letting the pixies out or just plain DOA I gave up on BMS.

Ones I've looked into since have been the REC BMS unit looked fantastic but considering I have so many packs/banks of batteries it would have got quite expensive fast. Asked for a price & let's just say the wife was around... Wasn't horrible but by the time I was done I would have needed five or more. Wasn't happening

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So then to the 1S units, some are using with success others aren't. They seem to work but given a hand full of people that have contacted me directly saying they have had the odd one or two failed either DOA or after a few weeks kinda turned me off. Price per Unit is $39au each with no temp control or data loggingby the time I got to 50kWh hours it would have cost $2730au :huh:So that was a deal breaker also.

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So it brings us to Damian's post on FB DIYPowerwalls group. I'm a visual person and seeing his post

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I needed more, instantly started googlin' like mad, as time passed a few more comments come up in the post and I was in full creepy stalk mode trying to get info without looking... well creapy/desperate/ or overly interested. Few more minutes passed and the old FB message notification popped up. Checked as I do and it was Jaron from Batriummessing me hoping he hadn'tbreached our 'rules' when it comes to commercial advertising. "Not a problem buddy, I know the boss" lol

Lots of questions & a few quick skype calls later I received a package.


Please note this is not a "Paid" gig Can't buy bread and milk with a demo model to test and evaluate

Some things so far that impress me -
  • It's logging function 10 yrs!
  • The number of batteries that can be hooked up to one device!
And there is probably a bunch more, now I've turned it on once or three times already and hooked it up to the computer to take a quick look and after installing Watchmon ToolKit it was plug and play to get the computer/software to see the unit. I thought to myself, I have two Watchmon so plugged the other in with the same instant results. That's a win for me in my books - anyone plugged in a pip then had to spend quite some time to get the computer to see the com port?

I'm going to be installing a test rig within my workshop for now just to learn it and begin the process of trusting what is on the screen. I plan on putting it through its paces by maybe building a really bad pack out of really bad cells and hooking it with a pack full of gray LG's or something and see how it handles the balancing of such an indifferent pack. I'll have the thermal camera on hand to really keep an eye on it.


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This little project can move in may directions - if you would like certain tests done or have ideas on how it should be done let me know I'm keen to accommodate where possible.
 

Korishan

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Waaaay to many words and too many pictures. You're going to have to cut back on your wordage and picture quota. :p
 

hbpowerwall

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k
 

hbpowerwall

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any better :)
 

Korishan

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:heart: :heart: :heart: LOL Perfect! :heart: :heart: :heart:

*was looking for a little smiley with a thumbs up, but didn't find one. perhaps u can add it
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;)*
 

hbpowerwall

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Done :)
 

hbpowerwall

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A few hours later and one coat of primer poorly applied & two coats of some type of white paint I scraped from the bottom of a paint tin later we have some sexy!


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Looks so good against the white!
 

Korishan

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Looking good. Funny how small your packs will look against that wall though. When in your other shed they look huge! :p
 

hbpowerwall

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There is not way known to man I'll outgrow the ability of this BMS. Spent all day reading and setting it up as a test rig. I'm gobsmacked and now wondering how I translate whats in my brain into a youtube movie. There isn't a question I've asked so far that hasn't been greeted with a Sure - it does that! Perhaps I'm not asking the right questions tho :) Ask away!!




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daromer

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Paulkennet. There is no such limit. Atleast not on proper BMS systems like this one :) It can handle up to 249 packs. And since it can discharge up to 2A (With fan) But its recomended to not go higher than 1A you could have several 100kWh in total connected on same Master. Since this system is a modular slave-master approach.

They have most functions anyone ever would need and some more ) I have though found a few that they didnt have but as said.. All the others covers most whats needed.
 

hbpowerwall

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error found in boobs - can't complete request, Google I.T. Crowd and follow their advice :)
 

hbpowerwall

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Got it up and running with issues naturally, grateful I didn't blow the thing up from stupidity. Moving on

 

Rerouter

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I would assume they did an OK job on the thing, and included a diode or mosfet based polarity protection,

what i dont fully understand is the red flash code, this may hint that they are using a little bridge rectifier to power there microcontroller, but that would seem odd to me.
 

Korishan

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Yeah, I agree with Rerouter. Seems they put a few extra protections in their unit. Would be the smart thing to do since you don't want your customers constantly blowing up the hardware and giving a bad rap to the company. This definitely adds cred to the companies building style and hardiness.

Love to see what other "mistakes" you make, Mike :p
 

hbpowerwall

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Might do it to a few more volts see how it holds up, this time deliberate as I'm told it can handle it. :) one thing to be told another to see it..
 

Rerouter

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Read through there brochure, and its indeed a N type mosfet acting as a reverse polarity protection circuit, which explains the +-20V rating, (what the gate of the mosfet is rated for)

Something like this http://electronicdesign.com/site-fi.../uploads/2015/02/0216_TI_RevPolarity_F4_0.gif

The other thing i can tell is the units are quite low power, and have a sufficient amount of local capacitance to keep the module on for quite a while, the communications looked to work for about 3 seconds after removing a cell, (still curious why it was still broadcasting its last known value) and the unit itself looked like it took a full 12 seconds or so to shut down (low voltage cut out)

Now its the +20V spec i would be more cautious on, as in the negative protected state, the circuit cannot complete a loop, its isolated, but in the positive, i would imagine they are using the internal protection diodes in there processor to shunt the voltage from the ADC sense, which being as crazy low power as it is, could be a problem.
 
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