Creating My First Battery Pack

DarkRaven

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What is wrong with watts? :)
It's totally fine! Your result in watts * 0.85 is X, the power the inverter has to use. X divided by 51.8V is Y, the current the battery has to supply. Y divided by 40 is the current per cell. This is just an approximation, but it's fine.

With that you know the runtime, total current, current per cell. Wires, fuses and circuit breakers can be based on this. And you can scale if you want. This is valid for one battery pack, if you build more than one you can divide everything by the number of packs.
 
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hahaha nothing dude just wasnt 100% sure that was the best measure! I will point out this is a max watts with luxury living, reality this is about a 1/3 at the beginning stage of my build as I doubt any of the appliances that draw power will be onsite for the first year. :) So using the above:

52000w x .85 = 44200 (x)

44200 / 51.8v = 853 (y)

853 / 40 = 21.33

So seeing this figures what should I be planning for?
 

DarkRaven

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52kW? What are you powering with that amount? A blast furnace? :D

I made a mistake, it is not *0.85 but /0.85 obviously. Otherwise you need a magic inverter :)

52kW / 0.85 ~ 62.2kW
62.2kW / 51.8V ~ 1200A
120A / 40 ~ 30A

Seeing these figures, you should be planning to build your own nuclear reactor in your garage! Oh, and it would be helpful if you could find a copper vein in your garden!

Tons of issues here mate. I knew it from the start when I saw that you calculate with 52kW, but I went through it to give you the numbers and then tell you why this is difficult on almost every level. You must have realized this yourself while doing the maths? These are huge figures. Really HUGE.

Let's start with 1/3:

17.33kW / 0.85 ~ 20.38kW
20.38kW / 51.8V ~ 393.4A
393.4A / 40 ~ 9,835A

That tells you some things.
First, you need a big inverter or several smaller ones if you can't find a big one. I think this is already beyond household use and a single unit is probably industrial equipment if something like this at all exists in a purchasable form.
Second, main cables for 400A, even for short distances, have to be really thick. In the range of 100mm.
And third, you have to start with 10 of these 14S40P packs at least if using reclaimed cells. That means under 5600 usable and tested cells you have no chance. That's a long way.

Are you sure this is all correct? Seems very excessive to me! If this is all correct then you should probably start with 28S / 96V right from the beginning.
 
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To be honest I'm not 100% sure like you pointed out I did think that this was also excessive! But I included every hob on the induction hob like it was on max and there will be two, range oven, every cavity (oven) section on max, heating on max (gshp) electric water heaters (it will be gshp heated but back is electric) dish washer, tumble dryer, washing machine all on max heat.

Reality is I doubt I will see the this max figure and the things like the water heater will be scheduled during the day when solar is doing it's job if the gshp wasn't.

The wind turbine will run a almost every day although it's output will be extremely varied.

Maybe my packs aren't the right way to go and the conext xw+ isn't the right inverter. I'm still not set on doing things a way. Luckily I'm about 6 months away from starting the build but determined not to be on grid. It's probably also clear that I'm trying to stay away from burning fuels but I'm not ruling out wood as Its going to be a good way of boosting heat quickly. Also provides and outside oven.

I do completely understand it will be a very calculated way of living and for example my fiancee will have to change some of here wasteful habits!

So that all said and taking on board all the advice on the previous two pages I'm back to the beginning hahahhaha but massive thank you for all the help so far! I'll add my next thoughts on a pack later this morning at work :)


Forgot to add! Whilst I'm In traffic I can string conext xw+ together.
 
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OK amazing people of secondlifestorage.com

So done a little digging with tech sheets and this the spec of the Schneider Conext XW+

AC 240 output= continuous at 6800w or 30 mins at 12000w, max output 52A,
DC Input range 42-60v, 180A,
DC Output =40-64v, 140a, charge control (three stage, two stage, boost or Custom) Li-on charging, Battery Bank 440ah - 10000ah with battery temp sensor.

Claims it can support 7kw-76kw(30 Mins) in single or three phase. On a different page makes reference to clusters so stuggling to work out the max for this unit could I assume 60v*180a= 10800 = 10.8KW is the max for a single unit with the overload for 30 minutes at 12kw from the spec above? If so I think Im finally starting to get how to design my powerwall :)

1 potential issue I see is getting the battery bank min 440ah at the max dc input of 180a. My calculations of using 51.8v 14s40p packs give me 80a with an estimated 104ah per pack to reach 440ah I would need 5 packs 1s5p which then gives me 400a. By now you guys must have realised im far from knowledgeable. Am I reading this all wrong? Or is there a method in how you control the amps to the inverter or does the fact 400a is available actually make no odds to the inverter you simply need to protect the inverter with a 180a fuse?

Conext XW+ Spec Sheet

As always your patients with me is really appreciated and help is always welcome :)
 

Korishan

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could I assume 60v*180a= 10800 = 10.8KW is the max for a single unit with the overload for 30 minutes at 12kw from the spec above?
Yep, looks like it. That's about how much or a bit more than I use during peak operation at my house. I use about 14kWh/day max, during the summer months.

Battery Bank 440ah - 10000ah
1 potential issue I see is getting the battery bank min 440ah at the max dc input of 180a
That's not saying you "have" to have a battery of 440aH. That's just the minimum it recommends. You can have any size battery packs you want, with in reason, of course. I wouldn't put a single 10000aH pack in place. That'd be way over kill :p But you can break it up into smaller packs and connect them in parallel to achieve the 10000aH capacity.
 

DarkRaven

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The input can't be 10.8kW when the output is supposed to be 12kW. For 12kW output the input will be more like 13 or 13.5kW which means up to 260.62A at 51.8V.
 
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Korishan said:
could I assume 60v*180a= 10800 = 10.8KW is the max for a single unit with the overload for 30 minutes at 12kw from the spec above?
Yep, looks like it. That's about how much or a bit more than I use during peak operation at my house. I use about 14kWh/day max, during the summer months.

Battery Bank 440ah - 10000ah
1 potential issue I see is getting the battery bank min 440ah at the max dc input of 180a
That's not saying you "have" to have a battery of 440aH. That's just the minimum it recommends. You can have any size battery packs you want, with in reason, of course. I wouldn't put a single 10000aH pack in place. That'd be way over kill :p But you can break it up into smaller packs and connect them in parallel to achieve the 10000aH capacity.

Ok well glad Im getting things right hahhaa. So staying on the inverter then If I aim to have a house of electric consumers I would roughly need 4 to 5 inverters. I am not saying I am doing this, this is all in theory to achieve close to 50kw.

First question we take 1 inverter, we say 10kw at somewhere between 42-60v as recommended. What would anyone recommend as a design? Im thinkinging 14s80p still works well to the be placed in a 1sXXp battery bank arrangement and allows for a pack to be removed to check cells, replace dead cells or fuses etc and just effect the capacity and amps of the one 1 bank.

I think once I get just a little more advice from you guys the rest of my questions can go over to my off grid build you will be pleased to know! Promise in my upcoming youtube videos of all of this I will give all that helped massive credit for educated me! Plus this site! :)
 

daromer

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The configuration depends on the size of the battery bank. If you gonna run 50kW continously thats ALOT! That would potentially need more than 1000 cells in paralell. We are talking about 14 000 cells!

Imaging making 80p packs out of that. I would make 14s250p or something atleast. Just beware of the BMS so it can handle and can balance it withincertain time-frame.
 
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daromer said:
The configuration depends on the size of the battery bank. If you gonna run 50kW continously thats ALOT! That would potentially need more than 1000 cells in paralell. We are talking about 14 000 cells!

Imaging making 80p packs out of that. I would make 14s250p or something atleast. Just beware of the BMS so it can handle and can balance it withincertain time-frame.

Hi Daromer

Thats a lot of cells yes but actually my vision from the outset was to try and use a lot of recycled cellsBefore Looking to introduce new cells into my packs. Im a long way off! haha I have designed a fake wall 8m in length, 3m High, and 2m in width completely external to the house to house all the batteries, inverters, mppt units, etc so I have the space! haha

So Looking to deal with 50Kw in a way that makes sense. 50kw was a figure forecast by turning everything on this house I am building on to the max! Heating raging! Ovens, induction Hobs, Microwave, Toaster, Kettle, Coffee Machines, fridge and freezing running at max,Washing Machines, Tumble Dryers, Iron, Water Heating backup, towel radiators, Water Pumps,TVs, radio, interior and exterior lights, tool li-on batteries charging, laptops, nas, smart home bits, inverters, and 1 electric car charging in this scenariono wind or solar its christmas day and the demand for turkey on the table wins over common sense.

The likely chance of all these happening is unlikely. This would be a worse case scenario.

So Logically thinking using the inverter spec I foresee at the end 5 inverters, 5 Battery Banks, Banks will be min of 1s8p consisting of Packs of 14s80p taking your advice of increasing the capacity.

If for example I achieve this is over the next 2 years My Powerwall hopefully will be around 560Kwh on paper but usable around450kwh. I will be hoping to charge multiple electric vehicles and utilizing around 45000 used cells.

The crazy thing is this sounds a lot. I am looking to never pay an energy company again but instead invest in my own personal energy company. This is a house for life. Hence why my KW is so high. So Taking all of that in do you think Im now getting the right spec or does someone have a better plan? I am open to any suggestion if someone has it using this info?

Cheers :)
 

neurocis

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Methinks you'd be better off looking at home-automation with load-shedding rather than targeting the max load with everything on. In most cases your regular residential circuits trip breakers with EVERYTHING turned on. Do you have 200A 240VAC (48Kw) coming in from the street? Even with that supply you are short 2Kw ...

It's a grand target, I would love to see it built, but my gosh ... heh
 

Korishan

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I think you are calculating your loads in the wrong way. I know you want to work for worse case, or most load, but this is just not feasible.
You need to monitor your energy consumption throughout the day for several weeks, if not a few months. Then figure out when is the most power used in the day. Add about 20% to that total and you should be safe building a powerwall(s) based off those numbers. Not only will it save time, money, and space, it'll also save you a headache with all the wiring, building, and trying to keep everything in order.
However, with all that said. If you want to be able to run for a few days without any charging involved, then multiple the above by how many days you want to be able to run. If you have solar, wind, hydro to charge with, then you could definitely scale it back quite a bit.
 

DarkRaven

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And I think all the above :)
Plus: The main problem is actually just money. It can be done, but it will take ages to build or will be expensive. Or both. Imagine 45k cells above a certain threshold from used laptop batteries. Before we take building time into consideration, if your threshold isn't too low you will probably have to process around 150k cells. Or in other words, 25k 6-cell laptop batteries. Or you buy new ones which will cost you around 45k USD or EUR or whatever if you find cheap offers or more like 90k if you don't.
 
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Korishan said:
However, with all that said. If you want to be able to run for a few days without any charging involved, then multiple the above by how many days you want to be able to run. If you have solar, wind, hydro to charge with, then you could definitely scale it back quite a bit.

Sorry Dude I was trying to keep this just about the battery under this section but the build will consist of 120 Panasonic HIT 330N Solar Panels and potentially 2x 5KW R9000 Wind Turbines which roughly yield in my are at wind of 6m/s 13,500kwh annually. Geothermal Heating will have its own solar array and powerwall but I will wire in a maintenance route to bring it into the 240v circuit for the house.

I have mentioned this a couple of times. I have no way of monitoring my loads. I am currently doing house/pet sitting, so technically homeless family of 4 going from one house sit to the next where around where I live. I have no access to bills and I cant control everything that runs i.e. the massive fish ponds and swimming pool at this current sit. Simply looking at the meter is going to give me nothing valuable.

So if possible rather than worry about cost Im looking for advice and help stringing this complicated off grid living together.
 

DarkRaven

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Well, no offense, but it is very hard to almost impossible to do this. We can talk about some theory, as we have done, but when it comes to implement this for real there is just so many stuff that depends on real world circumstances. Money is usually one of these and you said no worries about cost. But does this mean that there is no budget limit? Usually there is and then this is important and limits the possible approaches to a solution. Decisions have to be made on the way, often there several ways to achieve the goal, some are ruled out for various reasons of which money could be one. And if it isn't, well, to be honest you could go out and just do it. Throw about 200k moneys on the table, buy batteries and large inverters and stuff, hire someone to wire it all up and you are ready to go.

Do you get the point? It is not that we don't want to help you but it is not very effective or plainly not possible to give you some sound advice based on this level of theory. It just doesn't work live that with so many variables left open.

At least these are my 2 cents, other peoples mileage may vary. This is how at least I proceed with things and not only with powerwall setups but on other topics as well.
 

Korishan

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Ok, I'm really confused here. How in the world are you going to build all this setup and move it around from house to house? Or is that not your plan? Where are these solar panels, wind turbines located at?
If you are planning for a future home that you are going to build yourself, you pretty much know the amount of electricity that will be used. I'm assuming you'd be using all new appliances, so they'd have all their consumptions listed. And, building your own home you'd be able to add in the needed insulation to help keep cooling/heating usages down as well.

I just dont see how you can live house sitting, and build the powerwalls for the houses you are sitting for. It's not feasible. Especially since you said the one you're in now has ponds and pool.
 

DarkRaven

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I don't think it is supposed to be portable, more like "If I settle down in the future...".
 
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The moving around is my current position. I am currently house sitting whilst I am saving for the first stage of my build dude. Once the first stage of 3 is complete I will be moving into my home. Currently I have a storage unit where I intend to store built battery packs boxed.

The first stage of my build will see the installation of 1 inverter and battery bank and I will not be using no more than 5kw. Stage 3 is actually when I intend to introduce a power plant into my property. Currently around 2 years away and I will be settling down as you will in 6-9months planning depending.

Used batteries. Through work I actually have access to at least 250 x9 battery cells a year plus currently ready for recycling I have shelved around 400 batteries which a mix of x6 or x9 cells in what appears to be mixed condition. first 600 cells have scored over 2600mah but the older cells have started coming around 2100-2300mah.

I am lucky I have this opportunity and looking to help out with effective recycling.

I've been house sitting for 6 months now, its not for the faint hearted as you live from suitcases. It has actually given me a huge amount of time though. Which is how I have changed my house design to a recycled project. The house itself is recycled shipping containers (9x 40ft at @1500 each +delivery fee for 50 miles of transportation @350) and recycled metal beams. I have a good roof footprint to rain harvest and also space for 90-100 solar panels. the plot of land has room to grow fruit and veg and sneak in around 2 Windturbines and lay a gshp. In the UK there is government incentives to do all of these including 100% payback on GSHP over 7 years and around 50% of wind turbine installation.

Talking budgets ground work is around 3k in materials to create 16 reinforced concrete piles around 3m deep, Containers rounded up 17k dived by 3 as there is 3 stages, Materials for each stage vary 1st stage is 9k. So around a year in if planning is excepted my cost is 21K including GSHP but not any Green Electric. At this stage I can get a mortgage upto 75% of the completed build which will be roughly 750k-1M sounds unlikely but actually UK housing market is weird, neighbouring properties are well over 1-2M the size in m2 is how I got this figure. I cant afford the mortgage at 75% of the value but I can afford a mortgage of 200k-300. Which then allows for completion of my build.

So im not just saying I dont care about price. I am doing around 85% of the build around work to minimise cost. Battery, inverter, mppt, etc costs are a concern. This is why over at least the next 6 months I am trying to work out a plan to stay off the grid.

I do think maybe I will get in touch with schneider and seek there advice. I simply thought you guys would not have the exact answer but now roughly a way of achieving this.
 

zag2me

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Very jealous James, I would love to have a plot of land to do this.

Just remember the UK is a nightmare when it comes to planning permission and house building bureaucracy :)

Good luck though, sounds like a great plan!
 
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Yep tell me about it, differs from district council but finally found one that is offering a lot of support with my application so fingers crossed ?!
 
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