Just a few Quick Question's, regarding Capacity and Pack Protections

liskl

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Jul 27, 2018
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so Currently i've Built 7x 1s30p Packs Li-Ion packs,

Some Details:
Nominal Voltage per 18650: 3.7v
Nominal Capacity per 18650: 2000mAh
Max Capacity per 18650: 2400mAh

Nominal Voltage Per ParallelCell:3.7V
Nominal Capacity Per ParallelCell 60Ah


Current cable runs are 0.2-0.5meters max per cable in the pack using 12AWG which is just within the limits on 24V@60A = 12AWG or10mm (73A max) according to a DC Cable Sizing tool at solar-wind.co.uk

I'm Building a Batrium Protected pack of 7s30p currently and when I add to the pack i'll add more once I have enough for a 14s30p pack of quality cells.

Currently the system is not in use yet. awaiting Batrium Biggest Starter kit Delivery this week as well as Solar Charge Controller, (Victron BlueSolar75/15)

and a Basic Reliable 2000W Off GridInverter, and i'm trying to make sure i got the Safety Part Correct.

I'll be Limiting Total Battery Discharge to 1C, so with my current calulations i think is either

1s30p = 60000mAh = 1C = 60A
7s30p = 420000mAh = 1C = 420A

which of the Above Values are correct?

haven't done a initial Discharge test yet as i've not got the BMS yet, but once that shows up this upcoming week, i'll need to be able to setup the Circuit Breakers between Everything correctly.

I'll be putting in a 15A Circuit Breaker between Battery and Solar Charge Controller.
I'll be putting a (2000W/120V = 16.66A)~15A Circuit Breaker between Battery and Inverter
I'll be putting asmall 120V@10A CircuitBreaker on the Inverter Output, for now.
I'll be putting a 60A Circuit breaker between Each Batteryin the pack as they might be pushing power Large amounts of power between them for balancing (Guessing here),and 1C is 60A per Parallel Pack

i'll be using a 30v @ 30A DC Power Supply with a 12v relay attached to the Batrium Expansion Board to feed the Solar Charge Controller until i get Solar Panels in Play

I'm trying to be as safe as possible as well as feed my curiosity, currently i don't have fuses on individual 18650's as i'm using the ******* 2.0 battery connector kit for now,

will move to using glass fuses on the negative side once i upgrade to 48V.

any thoughts or opinions on this Idea / buildout would be useful to improve or fix any mistakes.... thanks in advance for anyone that shares there knowledge...

Current Build includes:
BMS: Batrium Watchmon4 with Shunt and Expansion board
Battery Bank: 24v=7s30p = Current Capacity between 1554Wh & 1722Wh
Charge Controller: Victron 75V/15A
Inverter: 24VDC -->= 120VAC@16.66A =2000W
 

Korishan

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1C = 2.2A per cell as they are 2200mAh in capacity

You don't multiply series connections to increase amps, that's only for parallel.
30 * 2.2 = 66A

If you are putting a 15A breaker between battery and inverter, then you will *not* be limited discharge based on C rating. You'll be limited to the breakers potential.
2000W / 120V does not equal 16A on the battery side. 2000W / 24V = 83.3A on the battery side
60A breaker between each pack?? You mean have 7 breakers for each 24V string? If so, no need. This is a waste of money. You only need "1" 60A breaker between the whole battery and the inverter

I believe you need to do more reading of the threads here to gain greater knowledge of the setup. You are lacking some basic knowledge that you should have before attempting such a task/project. Please read the FAQ and use the search feature on the threads if you want to find something more specific.
Watch HBPowerwalls, DIY Tech & Repairs (aka daromer here on the site) videos to get a more visual understanding of what's going on.


Now, questions for you:
Why 24V 7s setup? Do you already have the equipment for this, or still planning? How much storage do you plan on having? How much/many devices do you plan on running off the inverter(s). I know it's grid-tie, but how much are you going to expand on this, or are you only going to use the 1? What are future plans for the battery storage?
 

liskl

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Jul 27, 2018
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Thanks @Korishan

yeah 1C per 18650 is =2A

i was asking the questing just for clarity really and to assure myself.

30p * 2 = ~60A

the 15A CB betweenbattery and inverter is for initial Safety while i'm still learning to make sure noone overloads the Packs since the Off Grid 2000W Inverter is way to large at this time and not all that much quality,
i'll be adding more and more Parallel Packs over time current planned is the initial 7s30p for now as that is the battery pack's i've finished building,

i'll upgrade the Inverter and Charge Controller in the future to a INV: to a 48V 12kW with CANBus

Understood on the 7 CB's on the single 24V pack

I'll be putting a (2000W/120V = 16.66A)~15A Circuit Breaker between Battery and Inverter < yeah i wrote that wrong i was thinging in AC not in DC Fail on my part thinks for that.


Now, questions for you:

Why 24V 7s setup? Cause i've already built the 7x 1s30p packs. and need to get the wifey understanding that it's useful, by giving us useful power during hurricane season this year.

watched every video from HBPowerwall multiple times, also watched Average Joe and Jehu through and through,

but the only way to really learn is to work with it. and test and hypothesizeand test agian.


spent the better part of a year learning and thinking and play/testin small scale, i've done years of micro-electronic's in the past and have been working on electronic's in the DC world for +/- 10yr's, just never anything upwards of 24vdc and never more than 10A, but never to late to learn.

i've built a 1s80p pack before but decided to dismantle it for now to work on a smaller scale.

Do you already have the equipment for this, or still planning? Currently i've got the 7x1s30p packs, the Batrium Starter Kit isarriving this week, the Inverter and Charge Controller are also on there way.

How much storage do you plan on having? totally off grid in the Long term future 36kWh, with a 12Kw Inverterbut this is kinda an In Case of Emergency Lighting and Basic Small Electronic Use currently incase the hurricane kills grid power in september.

How much/many devices do you plan on running off the inverter(s). I know it's grid-tie, but how much are you going to expand on this, or are you only going to use the 1? What are future plans for the battery storage? it's not grid tie, i'll expand on this


Current Stage:
Assumptions: 210 18650's[size=small]made into (1s30p) parallelcells[/size]
[size=small]Voltage: 24V[/size]
[size=small]Stage 01: 7x 1s30p(60Ah) = (222Wh * 7) = 1.554Kwh
[/size]
[size=small][size=small]Next Stage:
[/size][/size]
Assumptions:420 18650'smade into (1s30p) parallelcells

Voltage:48V
[size=small][size=small]Stage 03:14 x 1s030p(060Ah) = (222Wh * 14) = 3.108kWh[/size][/size]

[size=small]There are 10[size=small]more stageswith each adding[/size][/size]420 18650's culminating in the Final stage below.

Final:
[size=small]Assumptions:4620 18650'smade into (1s30p) parallelcells
Voltage: 48V[/size]
[size=small]Stage 11: 14 x 1s330p(660Ah) = (2442Wh * 14) = 34.188kWh
[/size]
[size=small]i'm in it for the long haul. and it's kinda became a hobby working with the shucking and testing and soldering cleaning moving to more modular packing etc, etc.[/size]
[size=small]I had to go through to get these packs built.[/size]
 

daromer

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I would have gone to 48V directly. Going 24V first for learning is just wasting money unless you got the gear. Sad to say that but its true and we see people do it over and over :p

Beware of taking your current cells and just creating 14s15p system instead of 7s30p will give you the exact same max output at 1C! Yes it takes 7 more longmons but thats not much of a cust and you will be using it. But it saves you buying 2x inverters and 2x chargers...
Limiting current or such with a fuse is not really limiting but I understand your deal there and I would do the same thing at the inverter side.

Just beware of that a 15A breaker will easily hand out 20 or even 25A for pretty darn long time before it trips ;) Depends on the type of breaker you use.
 

Korishan

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Ahh, not sure why I thought "grid-tie". Brain must of been stuck on a previous thread :p Ok, that' clarifies a little.
 

liskl

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thanks to both of you and your help, i went with 24V cause that inverter / charger hardware will be moving to a portable system in a Large Pelican case later fro a family member. ::)here is method to my madness...
 

daromer

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Then I understand and approve your approach :D
 

Ebarnett

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I would like jump on this thread as I have changed my design idea to be similar to this one. After considering suggestions from korishan and daromer on my post. I plan on building a 7s20p setup with new 3000ma cells. Max load will be 30A, average load will be around 2-5 amps, I had planned to start out with 2 - 7s20p system packs first then expand later to provide additional amp/capacity.

Other than some efficiency and costs what are the additional benefits of going to 48v inverters over 24v ones. I havent purchased one yet but was looking at the Conext 4024, but they also make a 4048 model thats $300 more.

Also, you mentioned you were going to use 12ga wire for your internal bus bars were these going to be single or twisted?

What is your expected load and expected discharge rating per cell? How could you get that below C1?
 

liskl

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so i've got up and running with testing with the batrium watchmon4 using a system comprised of

Voltage: 24V
Stage 01: 7 x 1s30p(60Ah) = (222Wh * 7) = 1.554Kwh

got in setup at a basic level but still not trusting it yet as i don't have any automatic low Voltage shutoff functionality

I'm manually disconnecting and shutting everything down currently at the end of the day cause i can't figure this one out,

just a bit of help needed please?

i'm not 100% sure how to set that up, I've got the entire Batrium Watchmon 4 Starter kit with 14 cellmons and shuntmon

i purchased a 24V 200A Relay NO and just trying to figure out how to hook it up to the watchmon4 + expansion

Assuming it gets connected to Relay1 but if anyone has a bit of time and maybe a picture or explanation i'd be more than happy to dig into documentation just can't find any for my specific question easily, i know it's prolly super simple just can't find it.
 

Sean

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The first stage of low voltage disconnection should be provided by your inverter, based on overall pack voltage - cease inverting when pack voltage equals x

A second stage of LVD, or more accurately a cease inverting command, based on cell or overall pack voltage, can be provided by your WM and the toolkit logic - if you have a compatable inverter this can be done via CAN, if not you'll need to follow the documentation provided on Batriums site (which has been discussed at great length elsewhere on this forum) - generally this simply load sheds on the inverters output.

A third stage of more urgent LVD, may well require both DC and AC feeds to be immediately and permanently opened (until manually closed after fault clearance) via the WMs critical logic.

https://support.batrium.com/article/102-watchmon4-onboard-control-circuit-breaker
 

liskl

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so in my last test i lost 6 batteries cause the 24V inverter Alarms to late and a test pack 7s2p was drained below 3.0 on 3 of the 7 strings so had to throw out 6 batteries after the test cause they got triggered internally and popped something internally, not going to try to fix the cell,

would love for the watchmon when it senses a Cellmon with a Low Voltage level, trigger an External Relay to cut Voltage to the inverter.
 

Sean

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liskl said:
would love for the watchmon when it senses a Cellmon with a Low Voltage level, trigger an External Relay to cut Voltage to the inverter.

I guess the user cant alter the cease inverting voltage on those budget inverters ?

The link provided previously details how to configure the WM to open or close relays and breakers, based on cell or pack voltage.
 

liskl

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@sean

I'm not sure i understand how the link you shared shows how to do Low Voltage or Over Voltage Cutoff,

the link you shared showed how to hook a circuit trip to either the positive or negative sense. which would not that i know of help unless i'm more ignorant that i thought i was, but please if you can explain is a little more detail how those two concepts intertwine i'm sure i'll be able to figure it out...
 

Sean

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liskl said:
@sean

I'm not sure i understand how the link you shared shows how to do Low Voltage or Over Voltage Cutoff,

the link you shared showed how to hook a circuit trip to either the positive or negative sense. which would not that i know of help unless i'm more ignorant that i thought i was, but please if you can explain is a little more detail how those two concepts intertwine i'm sure i'll be able to figure it out...

If you read all of the "how to" documentation produced by Batrium it will become clear how you configure the WM logic, in association with a trip, to achieve low and /or over voltage cutoff.

I'm more than happy to point folks at the right documentation but I'm not going to be spoon feeding info on demand, certainly not when all of that info is so readily available via a few minutes of reading around a topic.
 

liskl

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Jul 27, 2018
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thanks then i'll work on trying to tie it together, thanks for the link at least. i might need to understand something i don't know yet.
 

OffGridInTheCity

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My Midnite Classic 150 controller has an external relay that you can set to turn things on/off at voltage set points of your choosing. I currently turn my inverter on at 52v and off at 48v to encourage charge/discharge in the middle range of the battery - in hopes of extending its life.

You can use the Batrium + expansion relay to do the same thing - e.g. explicitly control the inverter on/off by voltage settings of your choice thru Charging (ON) option or other.
 
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