scalability of LifePO4, an insane battery pack.

brandnewb

Solar Enthusiast
I am not sure if I am going completely off the rails with what I would like to do and if at all possible or sane and what not.

But essentially I would like a battery pack that I can run heavy load appliances with like 11kw (3 phase) EV charging and 3KW electric cooking and 3KW (single phase) heatpump and what not.

I am not sure if I understood correctly but please consider a grade a, brand new and up to specs, 3.2v / 280 Ah cell.
Could the cells be configured as 128s2p to create a 384v / 560 Ah pack with a total 215 KWh WKw? (Edit)

Does that even make sense and is it possible?

Any advice would be much appreciated even if only to get me back to reality.

Further more is there any other configuration feasible that would total 384 volts but with less than 128 cells sacrificing the capacity of one or more of the other related units like Ah and KWh?
 
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Scph9002

Solar Enthusiast
You should not work with those high voltages if you are not 100% sure of what you are doing. You can easily kill yourself.

With that said...

Since most lifepo4 cells are rated for 1c discharge (I think?) which is a cells entire capacity discharged over 1 hour. You could get away with a 16s pack only made of 280Ah cells.
51.2v nominal 280A that is 14 Kw :p

But this is pushing it but still, you can make it 16s2p pack and that would be plenty of enough. Im not sure how available inverters are that can convert 48v to 400v 3 phase tho
 
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cosmicosmo4

Solar Enthusiast
It is possible to do what you're describing but I doubt 128 cells in series is something you want.

First, specify your loads in kWh (and kWh/day), not kW, and size your battery pack based on the kWh you need between recharges. For example, let's say you want to be able to charge your EV fully once and run the heat pump for 2 days on a single charge, figure out how many kWh that is, and remember to gross it up some for your planned depth of discharge and for capacity degradation over the life of the system.

Choose the voltage of your pack based on the things you need to attach to it. Usually people use 48V nominal packs. Going higher than this you are likely to have few devices available that can use it. Also, 300+ VDC can kill you instantly if you screw up, which is not an ideal thing to have around your house. You will also likely have issues with your local building codes if you handle voltages over 48v nominal. Why do you say you want such high voltage?

Determine how many Ah you need by dividing your kWh requirement from above by the voltage. Then figure out what size and how many cells in parallel it takes to reach that Ah target.
 

smoothJoey

Ooga Booga!
An 128s2p LFP battery would be...
dead empty at 320 volts
dead full at 467.2 volts
nominal voltage would be 409.6 volts
capacity would be 3.2 volts * 280 ah * 128 * 2 = 229376 watt hours
It would weigh ~12 pounds * 128 cells * 2 batteries = ~3072 pounds

Sourcing a bms, charger and "whatnot" would be a challenge
A sensible charge current would be 112 amps
Using the entire electrical capacity of a modern north American house(200 amps@240VAC service), you could charge the battery in ~6 hours
The heat by-product assuming 90% efficiency would be equivalent to 6.666666667 heat guns running full blast
 
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Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
LFP Battery Banks can certainly be scaled up in size (Bank Capacity) to huge, even 300kWh if you are obscenely wealthy. But then you have to charge that and manage it and that is yet another huge ball of wax. Again see Obscenely Wealthy and not necessarily smart enough to know better.

3-Phase appliances ? Really ?? North America 240VAC is Split-Phase and is common/typical in any North American Home but NOT 3-Phase which usually goes to commercial industrial. Please provide a Make Model of a 3-Phase appliance you have, I gotta see this.

You are looking at an EV Battery that may be 300-600 VDC and so your thinking that is apples to apples but it is not, quite another beast. Some EV's allow for DC Fast Charge but that is NOT residential and likely will never be (unless you are crazy rich). Level-2 Charging generally tops out at 240VAC/50A but most are throttled a tad lower, depending on brand & model and EV type of course.
50A@240VAC = 12,000 Watts
48VDC @ 12,000W = 250A (Uncorrected for inneficiencies)
- 1X 48VDC/280AH Battery Pack = 14.3kWh or 14,336 Watt Hours.
-- This consists of 16 LFP Cells in Series Only.

One company Example (I have no affiliation or anything with these folk) which is based in PA, USA builds these Battery Systems which you may wish to look at for a "Commercial" example https://www.fortresspower.com/products/evault-max-18-5kwh-lifepo-battery/

ClipperCreek EV Chargers (Made in USA) has their Big CS-100, 70/80 Amp (Selectable) EVSE, 240V, with 25 ft cable which pulls a MAX of 100A from 208-240VAC and only Split-Phase.

Grab your Power bills for the past 12 months. Take a look at the kWh consumed every month. Grab the two Highest & two Lowest bills (in kwh consumption) so now you will know what your "current" usage is in reality and when that occurs. Depending on your billing system, it may or may not show a "Daily Average" which you can figure out easily enough.
- Once you KNOW your Highest Use Time and the amount of kWh used during that period, THAT is your target for "Daily Storage - for use".
- Then figure out how many days of reserved/stored power you want for bad weather periods etc. Most folks use 3 Days for calculating their reserve.
- Next you can size the Battery Bank that would satisfy the requirements...
- Next you have to work out how much Solar Input will be required to charge that battery bank on the Lowest Sun Hour Days in your locale.
- Then at the same time, the sizing of the Inverter System(s) to support the household demands.

Please understand that Energy Conservation is FAR CHEAPER than Generation and storage !
Unload the Fridge you inherited from Grandma - It's a Power PIG like many older appliances & devices. Find where you can improve on energy efficiency for your home & the appliances/devices within. Old Hot Water Tanks (like leaving a gas car idling in the driveway all day long because "maybe" you may need to drive somewhere = very stupid indeed). Think, 3000W+ elements running 15 minutes of every hour just to keep it warm... On-Demand is good solid reliable tech and NOT NEW and not wasting power when not needed....

Bottom Line:
Figure out your Real & Actual Usage, consider what can be replaced (energy saving wise).
Then come up with a Plan to accommodate your "needs" NEXT add in your "wants" and then the "Would likes" and do the math to re-ground self. Make a Revised REALISTIC plan and then start the shopping process. DO NOT BUY ANYTHING UNTIL YOU HAVE A FIRM PLAN IN HAND ! Because without a Plan is a Plan to Fail and it can be very costly & quickly too.

FYI, unlike Lead Acid/AGM and such, with Lithium Batteries, you can ADD PACKS OVER TIME as money comes available. You do NOT have to buy the whole 12 course meal at once, like the old days. LFP does not age/degrade like Lead and each pack is its own entity. MANY have the idea / notion they have to buy everything at once which is Terribly Wrong. It just has to be incorporated into the plan and the system foundation built to support expansion.

Hope it helps, Good Luck
 

740GLE

Solar Addict
Also who said it was lvl2 charger? maybe he wants his own DC fast charger which run off 3phase, they are some serious hogs at peak draw. There’s a reason why Tesla has been installing batteries at super charging stations.

I saw the OP needs to buy a connex box, fill it with 280ah cells and power you’re neighborhood!!!
 

brandnewb

Solar Enthusiast
You should not work with those high voltages if you are not 100% sure of what you are doing. You can easily kill yourself.
good point, thanks for the warning

For example, let's say you want to be able to charge your EV fully once and run the heat pump for 2 days on a single charge, figure out how many kWh that is, and remember to gross it up some for your planned depth of discharge and for capacity degradation over the life of the system.
yes, I'll do more realistic planning then soon.

Also, 300+ VDC can kill you instantly if you screw up, which is not an ideal thing to have around your house.
Indeed, I have a 3 year old constantly touching anything she sees

An 128s2p LFP battery would be...
dead empty at 320 volts
dead full at 467.2 volts
nominal voltage would be 409.6 volts
capacity would be 3.2 volts * 280 ah * 128 * 2 = 229376 watt hours
It would weigh ~12 pounds * 128 cells * 2 batteries = ~3072 pounds
regarding weight.+- 1400kg would not be a problem though. I also have enough space to house such a monster

Again see Obscenely Wealthy and not necessarily smart enough to know better
Lol, I an neither wealthy and smart :( ;) But for power independence I am willing to find additional employment ;)
3-Phase appliances ? Really ?? North America 240VAC is Split-Phase and is common/typical in any North American Home but NOT 3-Phase which usually goes to commercial industrial. Please provide a Make Model of a 3-Phase appliance you have, I gotta see this.
I am in the Netherlands, near Amsterdam
You can find an image of my breaker panel in this thread as well as some others to give you and idea of what I'd like to power with the battery bank.

the ev charger is not (yet) in that thread so i'll add an image here
ev charger.jpeg

FYI, unlike Lead Acid/AGM and such, with Lithium Batteries, you can ADD PACKS OVER TIME as money comes available. You do NOT have to buy the whole 12 course meal at once, like the old days
sweet, good to know!
 

brandnewb

Solar Enthusiast
ahh ok, then the image here and in the other thread hopefully will give the requested info. if not please let me know and I'll try and see if I can get model numbers
 

toms

Solar Addict
Not sure why you are wanting 348V?

Other than that everything you are asking for is quite straightforward.
 

brandnewb

Solar Enthusiast
Not sure why you are wanting 348V?
I though needing that to run my 3 phase 380 volt appliances with. But I am no longer certain since you guys are warning about the safety issues and I have been reading a bit on step-up transformers which could perhaps do what I need
 

upnorthandpersonal

Administrator
I though needing that to run my 3 phase 380 volt appliances with. But I am no longer certain since you guys are warning about the safety issues and I have been reading a bit on step-up transformers which could perhaps do what I need

You don't have to have a 380V battery to run 3 phase AC - you need a 48V battery with a 3 phase inverter.
 

toms

Solar Addict
You can run your 3 phase 380V appliances from a 48V DC battery.

In your position i would use the following:

SMA Sunny Island (times 3) - for 3 phase power.
SMA Sunny boy (AC Coupled with PV as you require)
LiFePO4 packs in 16S (48V) strings.

Make up as many 16S packs as you require and connect to the Sunny Islands.

Use Batrium BMS for control of parallel packs and compatibility with SMA.
 

toms

Solar Addict
This is what you need, for the batteries make up as many 48V packs as you need and control them with the Batrium.

It is a very common way to set up large systems, nothing to be scared of (if you can afford it!)

In Australia, i could put that system together for approx $150k(aud)
 

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brandnewb

Solar Enthusiast
Ok, i'll start small then.
I am considering getting 16 of these

Can anyone please recommend an affordable yet reliable BMS, and battery charger to go with that?

If my test is positive I will see about scaling up if need be but I think I'd rather investigate this step-up transformer first if applicable

EDIT; @toms our posts crossed. I'll read up on what you wrote
 

brandnewb

Solar Enthusiast
SMA Sunny Island
wow, those are price over here. starting from +-2100 euro and going up fast with bigger models.

Is there no way around this hurdle? Something more DIY?
SMA Sunny boy (AC Coupled with PV as you require)
Currently I have
11 micro inverters
44 PV panels total
+- 12100 Wp

3 phase AC
Do I still need a sunny boy or similar?
Use Batrium BMS for control of parallel packs and compatibility with SMA.
I'll start with 1 x 16s and work my way up from there. I'd like to avoid vendor locking if possible. Does that influence my choice of BMS?
 

houseofancients

Solar Addict
I though needing that to run my 3 phase 380 volt appliances with. But I am no longer certain since you guys are warning about the safety issues and I have been reading a bit on step-up transformers which could perhaps do what I need
ik stap even over op nederlands.

384v is niet legaal in nederland, maar ik denk dat je het benodigde voltage wat overschat.

om je een voorbeeld te noemen :
16 cellen in serie is 48v ( het gangbare voltage voor thuis battarijen en inverters)
als je 280ah cellen in 1 serie zet, dan heb je effectief 14,4 kw.
dat betekend dat je 14,4 voor een uur kunt verbruiken.
zet je 32 cellen in 2 series, dan hou je nog steeds 48v , maar heb je de beschikking over 28,8 kw.
dit vermenigt dit zo verder

er is geen enkele (betaalbare en goed gekeurde voor residentieel gebruik zo ver ik weet) inverter beschikbaar die meer dan 48v nominaal ondersteund.

dat is dat ook niet nodig.
als je kijkt naar bijvoorbeeld de Deye 12kw 3 fase, of de mpp solar 10kw mpi 3 fase , die leveren op elke individuele fase 12 respectivelijk 10 kwh.

je kunt deze stacken, wat betekend verdubbellen, dus 2 inverters word dan 24 kw en 20 kw.

er zullen er weinig residentiele ev laders zijn die met meer vermogen overweg kunnen.

je verward KW (kilowat = vermogen ) en KWH ( vermogen over tijd)
 
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