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How to design a batt pack
#1
Ok, stuggling where is the best place to learn how to design a battery pack,
thanks
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#2
(07-20-2019, 03:03 PM)jonisingt35r@gmail.com Wrote: Ok, stuggling where is the best place to learn how to design a battery pack,
thanks

Besides this forum, in no particular order - recommend @HBPowerwall,  @AveRage Joe,  @DIY Tech & Repairs, and @Jehugarcia youtubes containing a huge set of info on pack building. Do not mean to disparage or leave out others... it's just that these 4 were the major ones I enjoyed for my own journey.
100kwh-hunter and bogptrsn like this post
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#3
Thanks
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 23. 300 on their way ??
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
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#4
Ok i think i understand now,
Im planning to build a large 48v batt
My configurarion is this 13c 50p, 13cells in series, containing 50 cells in paralell? That ok ?
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 23. 300 on their way ??
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
Reply
#5
13s, not 13c. when referring to batteries, c is in reference to amps of charge/discharge.

48V with 13s is not very good for most chargers/inverters. 14s is a lot more in line with them.

Without knowing what your application is, we can't give recommendations on cells in parallel, or even in series as we don't know what your inverter/charger is.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
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#6
My mistake i ment to say s, not c. I havnt got an inverter yet, i thought it would be better to start with the storage,
I was going to set my min voltage on my bms to 3.4v to 4.1, thus giving 47.6v, which is close to 48vdc, iv3 learnt most inverters are 48v,
Would it be better to have a 15s configuration and achieve 51v.? Will a inverter trip out at 47.6v?
Im trying to make 230vac small ring main first.
Thanks
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 23. 300 on their way ??
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
Reply
#7
48VDC is somewhat nominal. Most inverters will go all the way up to 58VDC and shutdown around 42VDC. This is based off of lead acid which is a voltage range of 10.5V - 14.5V (*4 = 42V to 58V)

That's why the majority of builds here for a "48V" system is 14s, not 13s or even 15s. The exception is when using LiFePO4 cells which operate at a different voltage range than LiCo cells (standard 18650 cells used in laptops, etc)

And, you decide what inverter you want first to match your needs, then build your packs/banks accordingly. What you are doing is like buying all the building materials first, then building your house afterwards.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
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#8
Ok thanks very much.
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 23. 300 on their way ??
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
Reply
#9
A bit confused about protection of the battery does one use a dc trip switch like this
https://www.ebay.co.uk/itm/DC-400V-2P-Mi...2613468446
And limit the current to the inverter? Inverters have a high inrush current for a couple of seconds so the breaker would be ok to protect it?

Also im trying to build an electric skateboard, battery is 12s 4p, but a bit confused about the bms of it, i cant seem to find a bms that goes to 50amps
Do you just use the bms to charge it, and just use the battery with no protection on the output?

The way i understand bms,s is that they protect the charging, and discharging current from the pack ? Like this one
https://www.ebay.co.uk/itm/2S-7-4V-10A-B...2646703659
it has 10amp, proctection on the input so it doesnt draw too much current charging and discharging thus protecting the battery cells, im a bit stumped on how i am going to bukld my skateboard pack as the 2 motors draw up to 50 amps ?

Do i just use a 12s bms to balance charge the pack and just use the pack without overcurrent protecrion?

Thanks
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 23. 300 on their way ??
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
Reply


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