My Build

Rahtid27

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Sep 1, 2017
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Well I've been sitting back and taking in all the info available here and its time to introduce myself and share my progress.
My name is Garry. I am building a 48V system to eventually suppement the load on my house. I have 10k Solar Install to start in a week or so (awaiting final permits). Solar Edge with 37 280watt panels an no Storage. The cost was too much for my pocket. So I decided to add my own and that is how I found you guys.

Because my solar install is being professionally done there are some limitations on what type of Storage I can add to the system. I was told Solar edge will only permit Tesla or LG brand batteries to be hooked to it. So I am having them install 3 extra panels totally isolated from the main system. I will use this setup to perfect my Powerwall and satify my curiosity to Do It Myself. My hopes is that the restrictions will be lifted an I ca n add my batteries to the main system. Untill then I will be powering my Garage.

Although most of the Packs see here are all straight parallel I decided to do my packs as 14s11p or 14s 16p. This is proving to be very complicated and expensive but I am determined to overcome these challenges.

My Powerwall will be mounted inside Server Cabinets in my Garage
PCM60X Charge Controller
AIMS 2000W Inverter



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hbpowerwall

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Welcome, I fixed your post for you :)
 

Rahtid27

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Sep 1, 2017
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Thanks Joe!!!

Just curious, is anyone in the community building their packs to meet their actual end voltage? I would love to see how they addressed some of the issues I am facing. I initially modeled my pack from Daniels video.
1. BMS Issue - Mounting Longmons will now require 14 of them for 1 pack. :-( Is it possible or feasible to use only 7 longmons by attaching across series string?
2. Many of the strings are in the middle of the pack and longmons will not have physical contact for Thermal. I left the space around the edges to help affix Longmons. Remember my pack will be sitting on a shelf.

The picture below shows Daniels Pack (Pack1) and my alternative pack (Pack 2). Pack 2 has no strings internal to the pack. I can affix a longmon to every parallel cluster. I have other issues but lets chew on this one for a min. I would love to get some input.


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Korishan

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If you want full BMS control and monitoring, you'll need one for each series string. So for 48V pack, you'll need 14 of them per pack. However, depending on how you design your packs, you could only use 14 and each successive pack is just directly paralleled to the first pack. Each of the 14 strings are connected to the 14 strings of the next pack.

And for me, yes, I'll be designing my packs to meet voltage requirements. But I'm going to build my own BMS setup. Currently I'm thinking of basing it off of the BQ76940 by TI.

Curious, why did you put all that tape on the one pack?
 
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Rahtid27

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Korishan said:
If you want full BMS control and monitoring, you'll need one for each series string. So for 48V pack, you'll need 14 of them per pack. However, depending on how you design your packs, you could only use 14 and each successive pack is just directly paralleled to the first pack. Each of the 14 strings are connected to the 14 strings of the next pack.

And for me, yes, I'll be designing my packs to meet voltage requirements. But I'm going to build my own BMS setup. Currently I'm thinking of basing it off of the BQ76940 by TI.

Curious, why did you put all that tape on the one pack?
Ok I get it. This will require some custom wiring. As for the tape I did it just for safety as I move it around a bit and didn't want all those hot contacts exposed. I am building the packs in by trailer and it get quite hot during the day so I bring them in the house.

Thanks for the alternate hook up of the BMS.
 

Rahtid27

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Sep 1, 2017
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I can fit 4 - 48V Packs per shelf. 168 x 4 = 672 cells At 2000ah I calculate 5kw per shelf
My goal to start will be 10kw. So 2 shelves. (Lets see how that goes) :)
I am terminating each pack with an XT90 connector.
Each will plug into conduit running directly in front of the shelf.
Here is where things get fuzzy and need some expert advice/opinions.
How to combine all the connections from each pack so I end up with 1 pos 1 neg?
I came across an interesting Combiner box on ebay and curious to hear what you guys think.
I know its pricey but it has some kind of monitoring functions that might be nice to have.
Not sure how it works but at the very least it will keep things Nice and tidy. Right Pete :)
Is this feasible? If not how would you do it?

http://www.ebay.com/itm/Energy-Reco...636164?hash=item43b8775144:g:nWgAAMXQjq5Q~uxX
 

daromer

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You can run a 15wire interconnect between each pack and then just run 14 longmons on a board hooked up to them. You dont get any temperature monitoring of the packs as such but on other hand when the board balance they get hot anyways.

Its a little bit tricky to run it with long mons but it do work. You dont need very thick wires between the pack either since it only will hold balance current.
 

wim

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I like the idea of Daromer, maybe you could take a 16 pole connector of some kind ( like a old school parallel computer port connector ) for theballance wires.
Connectoronevery newpack and then makea kind of "hub" with4 or 5 (or 6,7,8....) connectors to plug the packs into.
Only the hub has the 14longmons connected.

Making sense ? :)
 

Rahtid27

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Daromer/Wim,

Here is what I am understanding so far. I will try to be very literal with my description.

Goal will be 3 shelves.
Each shelf will have 4 - 48v Packs. 14S 12P
Your advise is tie each of the 14 strings from each pack together to a cental hub of some kind.
From that hub I can tap the 14 Longmons. These longmons will Not be located physically with any specific pack.
As a mental visual I can line them all up just below the 3rd shelf with the Hub below them.
As I am a "Novice" please keep that in mind, where things get fuzzy is how to tap each string.
are these just sensing connections or will they transmit voltage?
 

wim

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You have got it... connect each string of each pack together... just to limit the amount of longmons needed.
The wires willcarry balancing currentsbetween strings, and between strings andlongmons when balancing, so a3A fusein the balancing wires is a good idea.
If you want full monitoring and bms controll youwillmost likely end up with Batrium, building something yourselve is maybe possible, but on a system as big as yours i strongly suggest to go for safety and do the right thing from the start.

Is it my advise... no, i would advise you to build parallel packs and put 14 of them in series.
This way you need less wiring, fusing, and it is easyer to manage.

If you want to stick to the 48v packs, you are better of with a (good)48v bms on each pack, and do some monitoring on the side.

Only my opinion of course :)
 

Rahtid27

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Sep 1, 2017
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Wim we think alike. I have a pretty interesting BMS board on order. If it performs well I will be adding one to each pack. Check out the link and let me know what u think. Maybe someone here has tried this one before. It appears to have functions that allow Bluetooth and Android Phone Monitoring.

https://www.aliexpress.com/item/14S...id=d30fdcf9-6795-4ed7-9f52-4197d58ac2bb&tpp=1

Also as you said I will continue to tinker on the side with Batrium. I dont want to go broke trying to purchase over $1500 of Longmons. It should get here in a week or so. The Kangaroo is swimming it across. I have a pack dedicated to be the guinea pig.

Description for BMS.
#3 below has an interesting statement. If I am able to limit the Max and Low charge this product would be nice!!!

1) Application :[size=small]This is The PCB for 14 series 48V(58.8v) lithium ionbattery pack with 30A constant[/size]
[size=small]discharge current[size=small]and charging current.the charge and dischargeport is same . Size :Max 108*65*8mm[/size][/size]
2) Protection functions :
This BMS has applied with high quality IC chip specially for lithium battery protection purpose .highly detection
precision degree on over-charge,over-discharge,voltage balancing ,and with detection on wires disconnection functions,
with three layers of over-discharge and over-current detections anddelay times in detecting process.( Over-current 1,
over current 2,short cicircuit protection ) . short-circuit of charging port ,with two layers protection against over-voltage
when charging :
3) With Mobile phone operation software systme to manage the detecting the battery working status and some parameters
setting . also this board can be available for the PC operation and Parameters setting on the computer .
4) This BMS will includes such list :
with one Bluetooth module for Android system only ,4.3Version Above . with wire and connector for the Battery and
Software system of mobile phone will be sent to the buyer .
 

daromer

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1500USD Batrium? How large system do you have?

14s system with shunt is around 600USD. And as explained you only need 14 of them if you tie them together for instance with paralellport contact as suggested :)

Above link need to log in to Aliexpress. Perhaps change that?
 

Rahtid27

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Sep 1, 2017
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I was just calculating how many longmons I would need If I used 14 longmons per pack that would be too expensive.
$14 for 1 Longmon
14 longmons per pack
12 packs total (Goal)
168 longmons x $14 = $2352 Even worse than I thought.
 

daromer

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Ah ok. But using 1 longmon per 12 cells is waste yes. Its not doable. Use atleast 80-150cells per longmon.

I got your message and it looks like interesting BMS as such but it cannot compete in any sense to batrium. And its not cheaper compare to functionality :)

I will order one for testing!
 

wim

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I do not have any experience with the bms in your link... looks good,if it does what is says .... connect and test it i woud say.
30A a pack,( Count on less, more like20A for the bms) with a good connectoron the packs to parallel themup should work just fine.
Do not forget to put fuses inline beside the bms.

Keep us in the loop, some pics, or a little video, we would like alot ;)
 

Rahtid27

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Sep 1, 2017
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daromer said:
Ah ok. But using 1 longmon per 12 cells is waste yes. Its not doable. Use atleast 80-150cells per longmon.

I got your message and it looks like interesting BMS as such but it cannot compete in any sense to batrium. And its not cheaper compare to functionality :)

I will order one for testing!

That sounds great. I ordered 2 of them 2 weeks ago and doesnt look like they left China yet. If I had them now I would send you one for the testing. Would love to see u put it through the paces.


wim said:
I do not have any experience with the bms in your link... looks good,if it does what is says .... connect and test it i woud say.
30A a pack,( Count on less, more like20A for the bms) with a good connectoron the packs to parallel themup should work just fine.
Do not forget to put fuses inline beside the bms.

Keep us in the loop, some pics, or a little video, we would like alot ;)

I agree on paper it looks promising. They are just not very clear as to what parameters are customizable. it is alot to pay for simple bluetooth viewing if you cannot control some key parameters. Daromer wants to do some testing but looks like I may get it first. I am not a Youtube video maker but I will try to get some footage. maybe an unboxing so everyone can get a good look.


daromer said:
Ah ok. But using 1 longmon per 12 cells is waste yes. Its not doable. Use atleast 80-150cells per longmon.

I got your message and it looks like interesting BMS as such but it cannot compete in any sense to batrium. And its not cheaper compare to functionality :)

I will order one for testing!

I am determined not to waste the $636 spent on this thing. I also dont want to blow it up trying to customize it to accommodate my setup. This could be another good test for you. Just a thought. :D


My initial thoughts for Customization is like this:
Mount all 14 longmons in a row beneath the packs. Mount 830 Tie point Breadboard close by.
Use a Breadboard to make the interconnects between the longmons and the corresponding parallel cells of each pack.
Use the Positive and Negative rails of the Breadboad for the Longmons positive and Negative leads
Maybe use Din Rail with Terminal blocks instead of Breadboard. http://www.ebay.com/itm/DIN-Rail-Te...836871&hash=item1c68bf1ce4:g:MTcAAOSwMNxXYV3p
The sense leads to the cells will need to be quick disconnects. (no solder) This will enable quick disconnects for maintenance of the pack.
This potentially would allow me to use 14 longmons for 14 packs.
Wire management would be a key concern.

Is this concept worth pursuing or am I missing something that would make this a pipe dream?
 

tbostjan

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May 26, 2017
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Excellent.....[emoji106]
I build something similar without Batrium it is a little to expensive for me.....
I use only balancers.... [emoji106]
In my case also use 2 xt60 conectors/pack.... And victron BMV 700 capacity monitor that is awesome device... [emoji106]
About your grid tie system you could add victron multiplus and your li ion battery bank I think it is possible to conect them together....
Frequency shifting .... [emoji106] try to research this possibility...

Poslano z mojega E6853 z uporabo Tapatalk
 
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