DIY 12V 7Ah 18650 UPS Replacement battery

1. Old electric bicycle battery
2. Battery batch charging
3. Battery batch capacity test
4. Battery capacity pairing
5. Battery spot welding
6. Connect to BMS
7. Assemble
Step: www.yousun.org/archives/660

[@OrlandoSiciliano]

I love your spot welder 👍

[@yousun2827]

Thanks!

[@yesican6851]

Good job. Cool to see how many people create content with lithium. Like!

[@powerlitech7365]

Well done! You are interested in making a battery pack, but I always feel that there is one important part missing (Battery Holders/Spacer Separator), I suggest you add it more safely.

[@yousun2827]

Which kind of gasket?

[@powerlitech7365]

I have previously purchased a similar product on this website litechpower.com suggest that you add this battery base will be more stable, and the disassembly is more convenient and quick.

[@yousun2827]

OK!

[@ashkananali8571]

جزاك الله خيرا. صديقي عندي ماتور بريشلس بيسحب تيار ٤٧ امبير ب full كيف اصنع له بطارية للعمل ساعتان

[@randyscorner9434]

The lack of any commentary or explanations on what the author is doing and, most importantly, WHY this is needed makes this mostly just an exercise in watching a technician work. A 5 minute video with excerpts and comments would be extremely useful and hopefully you can do that in the future.

[@szymon6650]

where you can get old bicycle batteries

[@osamaabdulsalam839]

Whats the charging voltage cut off of the bms?

[@jasperhart1188]

What spot welder do u use

[@akshayranjith623]

Hi, Is there any reason why companies are not producing UPS with Lithium Battery instead of lead acid battery? Is there any issues for building large number of units?

[@fixbuildmod]

Where did you find those 18650 discharge testers?

[@yousun2827]

I made it myself. www.yousun.org/product/18650-high-precision-capacity-tester

[@christianknapp1768]

what exactly is the glue you use for the LI-Po´s to stick together,i´ve got used to it in alot of common asian electrics but get never known to it.is it some sort of silolexan glue ? it seems to be rubbery but much more adhesive as it could be if I am using european silicon glue ....

[@yousun2827]

High temperature resistant silicone.

[@Kagomacha]

How that punching device is made??

[@srujanreddy6699]

The UPS transformer release high amps current while charging the battery. The BMS is for battery protection only. You need to have CC/CV regulation circuit added to it. Else batteries damage soon. Constant current/constant voltage board is must to charge these batteries.

[@yousun2827]

There is no problem with the pulse charger lithium battery.

[@Boboo5]

@@yousun2827 Hes referring to the UPS charging them up to 13.5V instead of 12.6V

[@c4pt1n54no]

Also, I see the BMSes you make go up to a 160A rating. I'm interested in some large BMSes but there only seems to be one stock image on the site. Is there someplace I could see images of all the models you offer? A little 2mm PCB is fine for 20 or 30A, but robustness has been an issue in the past for my project, I need something that can perform at it's limit indefinitely.

[@yousun2827]

OK! I will make a video when I have time.

[@sreekumarUSA]

Master YouSun thank you. Your meticulous performance is always appreciated and we learn many intricacies of careful handling of any Lithium Ion Cells; from your videos. I have learned. I am still intrigued at your SPOT WELDING unit ! I have SUNKKO 788H and it’s performance or the spot welded results are so poor. Would you, therefore, please recommend a better commercial spot welder unit? Thanks again for this video.

[@vextrek6036]

Sree Kumar K-weld Spot welder. Very consistent welds.

[@bobforte9343]

Rewrap the transformer

[@sergeykrukovski4011]

Hello! Which controller IC is used in your BMS?

[@yousun2827]

ricoh r5436t www.e-devices.ricoh.co.jp/en/products/lithium_ion/r5436/

[@abdulsamadmandli675]

3S 40A Li-ion Lithium Battery Charger Lipo Cell Module PCB BMS Protection Board For Drill Motor 12.6V with Balance www.aliexpress.com/item/4000129277612.html?spm=a2g0o.cart.0.0.62c43c00LOgxIM&mp=1

[@vsl5917]

Good Job, I subscribe to your channel

[@wesleytakano1]

Hello Friend! I mounted a battery similar to yours, but when the BMS cuts the voltage the APC nobreak is beeping accusing battery error. Is my bms the problem? because the equipment understands that this one with complete battery in 14 volts right?

[@yousun2827]

Hello! What is the battery voltage when the BMS is turned off?

[@islamragab8744]

Why didn't connect the red wire to the bms

[@seckinmenemenli3265]

Great job

[@teja9676]

Excellent videos bro

[@wesdogg7377]

What is the maximum charge and discharge rate of the wood with the removable holders, say if you put some good quality 2000 mah cells for a E bike

[@yousun2827]

?

[@atulbava7416]

Thanks, however u did not show how to connect the BMS at the different points for the different voltage requirements.

[@inovasitech8317]

Adaptorny pke brpa vol klo ngecas begitu banyak

[@user-mi2bf8ys7x]

Thank you very much for your efforts Question: Can I make a circuit turn 220 to 12 and 24 volts with a high amp 10 or 20 amp but without Trans.

[@yousun2827]

OK!

[@josephsvensson6637]

To turn 220v into a lower voltage (12v or 24v) you will need a transformer or switched mode power supply, there is really no alternative.

[@electronicshelpcare]

Excellent video.

[@jaredzayden4327]

Pro trick: watch series on Flixzone. I've been using it for watching loads of movies these days.

[@manuelsterling1193]

@Jared Zayden yea, I've been watching on Flixzone} for years myself =)

[@desmontech4x4pecas96]

friend , recently i buyed some 3s bms from your website, i see that bms you are using in this video is a bit diferent from , right? what its the main difference?!

[@yousun2827]

Yes! This is my own design, the parameters are more perfect.

[@desmontech4x4pecas96]

nice, it already for sale in your web site?!

[@yousun2827]

www.yousun.org/product/3s-4s-5s-6s-7s-8s-9s-10s-li-ionlifepo4-bms

[@pigeontransilvania4741]

Hello! .. tell me please for a 51.8v and 24ah battery which bms i need as many volts and as many amps i should have bms ?... thanks!

[@yousun2827]

This battery voltage, you need smart BMS to support.

[@juanmanuelnegreiroportas6569]

Hola, felicidades po tu trabajo, me podrías decir porque usas ese cartón verde oscuro para las pilas, también si puedes hacer un video de como hiciste ese soldador de puntos, un saludo

[@yousun2827]

Other videos have production information.

[@travisli-rufus1949]

Are we looking at about 2 days to fully charged all the cells?

[@yousun2827]

Yes!

[@DimitriPappas]

Very cool project! How does this BMS work? Supported input voltages, max input (charge) current, and max output (discharge) current? Seems like a perfect drop-in replacement for regular lead acid batteries (would it work on all UPS?) Tnx

[@yousun2827]

kzbin.info/www/bejne/iJfEd3mljbp9jLs

[@autoelectrician2009]

after AH?

[@firewallsistemas]

Very good 👍

[@abdullahbakhlulmeem7666]

What is the name of the BMS you used?

[@yousun2827]

www.yousun.org/product/3s-4s-5s-6s-7s-8s-9s-10s-li-ionlifepo4-bms

[@KaiserAhmed]

From where can I buy the "12V Box"?

[@yousun2827]

www.yousun.org/product/18650-battery-pack-empty-box

[@szymon6650]

@@yousun2827 where can you get bicycle batteries?

[@jperry3013]

Awesome!!!!! I just submitted my order!!

[@yousun2827]

I saw it, I will ship it as soon as possible.

[@jperry3013]

Can you wait....I want to order some battery boxes. Which one do I need to order for this project?

[@yousun2827]

OK! Box in the video L151mmW65mmH94mm.

[@yousun2827]

Waiting for payment after placing an order, I will remove the shipping cost.

[@jperry3013]

Ok, I submitted order for boxes and few other things. Thanx!

[@ianoiano3660]

Beautiful hands :)

[@akxtwire]

hello yousun, I am trying to convert a lead acid battery UPS to a Li-Ion Powered UPS. Should i install a BMS or just connect the terminals and call it a day.

[@yousun2827]

Each lithium battery pack must be used under BMS.

[@renatoalbuquerque7806]

Where did you buy this battery welder?

[@yousun2827]

expensive

[@maliktariq243]

Very nice 👌👍

[@9393dev]

what is the spot welder make you are using and can i buy it ? thanks a great viedo .

[@yousun2827]

It is expensive, around $200.

[@HillWillE]

@@yousun2827 I would like to buy one. $200 is ok.

[@hassangamal6531]

what is the maximum ampere can you take from the pack ?? because i think with low capacity cells ( 1100 mah ) it will be a high voltage drop when high current thanks

[@yousun2827]

Because it is an old battery, the pressure drop is large.

[@hassangamal6531]

@@yousun2827 any solution with this problem ?

[@mashedpotatoes5323]

That has to do with the resistance of the cell, some power tool batteries are 1500mah but can push out more than 10 amps

[@ranabarai1437]

what is the name of battery soldering iron?

[@yousun2827]

DIY kzbin.info/www/bejne/iqXHho2HoNKYkK8 www.yousun.org/product/digital-soldering-iron-24v-kits-for-hakko-t12

[@kennynvake4hve584]

I always leave a little tab so I can solder to them instead of pulling it off the battery.

[@yousun2827]

OK!

[@bharatpawar1708]

What is the backup time from this battery?

[@yousun2827]

Time is not tested.

[@maliktariq243]

Price 12 volt 7amp

[@jasonabygeorge]

Will the lead acid charging voltage and current be a problem for the Lithium ion cells ? Any issues yet ?

[@yousun2827]

If there is pulse charging, you need to add a capacitor to stabilize it.

[@georgef7754]

@@yousun2827 Hi, what value capacity should I use? Many thanks.

[@orlatris96]

Hello. Congratulations on your work. I was amazed by your video and very interested in learning how this work does. I am an old man, my name is Orlando Tristão, I am from Portugal, retired due to disability, I am in a wheelchair, but I would like to learn more about how to make these batteries. I have little knowledge of these things but I really like them, and after watching some videos, your video, fascinated me. if you can share something with me thank you. I would like to know how you made your board with the slots to load the cells? what are these slots and how are they made? what is the glue cartridge you use.? if you can and want to share your knowledge I will be grateful but I will also understand if I think otherwise. I wish you to continue with your projects. greetings

[@victorl2749]

Hey orlando , if it interests you, i just found 10old laptop batteries , all were supposed to be dead , but only 1 was really (8cells ) and one was bad cells (800mah ) all the other gave me 2000 to 2200mah !

[@bobforte9343]

He is using 18650 cell holders known as the SMD of surface mount kind. Then he is using a 4.2V charger that probably puts out 5 Amps to run along the connected cell holders. Positive to positive, negative to negative so they are in parallel and can be safely charged that way. Not sure what kind of glue he is using but due to the heat (45 degrees Celsius or more) you would need high temp glue. Using a hot glue gun is not advisable. I prefer to use cell holders (different from the previous ones) that lock into each other. They take up a little tiny bit more space but offer a more structurally sound pack. There is much more to know before even considering to put together a pack safely. If done incorrectly you will end up with an exploding pack that cannot be extinguished. Pouring water on burning lithium batteries only makes it worse.

[@desmontech4x4pecas96]

the BMS have normal behavior?! the bms not shut down the batery when it fully charged, and the ups thinks has no battery inside?!

[@yousun2827]

The BMS turns off the charge direction current at 12.60V, and the discharge direction current works normally. Does not affect the normal operation of UPS.

[@AtlaslcRU]

@@yousun2827 please give a link where to buy such bms like yours

[@user-jh7gz8gn7w]

Hello. What is the site where you picked up the capacity of batteries? Give me a link please.

[@yousun2827]

www.yousun.org/product/18650-high-precision-capacity-tester

[@user-jh7gz8gn7w]

@@yousun2827 You do not understand me. I need a website where you picked up the batteries for capacity.

[@user-jh7gz8gn7w]

@@yousun2827 Site on video 7minut13sekund

[@yousun2827]

repackr.com/

[@user-jh7gz8gn7w]

@@yousun2827 Thank you very much.

[@islamragab8744]

Couldn't understand the way you connected the bms . You show the welding in very detail but connection which much important missed

[@nicfpv9969]

what spot welser you using?

[@yousun2827]

Spot welder DIY

[@nicfpv9969]

@@yousun2827 what timer you using?

[@jessyterpoorten7197]

3 volt stop discharge if you test the cap is it not 2.55 volt stop discharge?

[@yousun2827]

3V stops discharging.

[@Shotiv889]

nice videos.. no talking

[@megaraitei]

Is that steam escaping from a steamer I hear ??

[@c4pt1n54no]

a full 6s lead battery should be 12.6v anyway, what does the APC usually charge to?

[@yousun2827]

I did not understand.

[@c4pt1n54no]

@@yousun2827 a 12v lead battery is 6s, they're 2.1v per cell fully charged. so 6X 2.1v cells is 12.6v. Thats the same as 3X 4.2v lithium batteries. Lead acid doesn't care as much about overvoltage though, that's why vehicle alternators can run at almost 15v. Does the example UPS have any BMS circuitry already or is it just float charging at up to .5a all the time? I'm trying to figure out the need, besides balancing for a BMS if the voltage is the same.

[@yousun2827]

Yes! Use BMS to protect the battery.

[@Sylvan_dB]

normally the 12v lead battery is float charge voltage about 13.5-13.8 volt.

[@yousun2827]

Lithium battery voltage 9.0 - 12.6V, The voltage reaches 12.6V to turn off the charging current. www.yousun.org/archives/1100

[@scootergem]

you can buy a 7ah 12volt battery from walmart for well under $20 - sometimes even $10

[@yousun2827]

Yes!

[@DELTASECComputer]

But not a lithium Battery...

[@ivanmr359]

excelent!

[@yousun2827]

Thanks!

[@amshamil1991]

Even though the video is unnecessarily long, Its really informative in my perspective. When the batteries are paired either in series or parallel, should all the batteries have equal voltage? I see you rebuilt them in discharged state and didn't check for the voltage of each battery.

[@yousun2827]

Yes! There was no balanced battery after pairing, and later relied on BMS balance.

[@amshamil1991]

@@yousun2827 Will the bms balance voltage of each battery?

[@yousun2827]

Yes! Use resistance discharge balance.

[@bobforte9343]

The series connections should be PERFECTLY equal down to 10 millivolts. Any difference larger than 100 millivolts is foolish. Most of his cells probably cut the discharge at 3.0 and bounced back up a bit to 3.1. Still should check the voltage and make minor adjustments

[@simpesfaip]

those cells take up to 4.2volt,3 in series is 12.6v . UPS will charge them up to 13.8 vwich is 4.6 v for a cell that will kill em slowly if ure lucky,or they will burst in fire...plus,UPS charges SLA batteries only,not lithium

[@DumahBrazorf]

The circuit protection board prevent overcharging the cells but I don't know how the ups circuit could react to this behaviour...

[@yousun2827]

Any battery that reaches 4.2V BMS will turn off charging.

[@EGspider]

Exactly what I was meaning to type here

[@sureshkumarm738]

Can we charge battery using discharge wire of bms

[@yousun2827]

Yes! This BMS discharge and charge is the same.

[@QUADBOYification]

There is of course a tiny issue with burst/float charging voltage. The UPS will put 14.4v on the BMS at first initial (Bulk) charge, but it will not get higher then 12.6v and therefore the UPS keeps charging with full force even if the current to the battery pack is stopped by the BMS protection. The actual voltage is only controlled by the BMS with a max of 12.6v. If the power fails, the BMS has to switch back quickly to discharge to enable uninterrupted power. I do not know if this has been fully tested with a BMS and a load (PC). In a practical application you would charge the battery with a solar panel and a solar charge controller. No power supply should be used. If full the solar charge controller disables charging and you can use the UPS as a Solar generator with 220v sine wave output. That is the main purpose of stored energy. Keeping a lithium ion battery pack full all the time for the purpose of uninterrupted power makes no sense, simple 12v lead acid battery will suffice completely for that. A dedicated charging power supply has logic that tests the current and if no longer current is going into the battery because the BMS blocks it, the power supply switches off and lights a green led to signal "Fully charged". No such thing inside a UPS unfortunately. So be ware of using a replacement pack with Lion cells.

[@yousun2827]

This problem does not exist. The current problem is that the voltage does not match and the battery capacity cannot be fully utilized. It is perfect to use LiFePO4.

[@Cpt_Adama]

The lead acid battery "wears" out quickly and your continuously replacing them every year to year and half. Lithium pack will be cheaper in the long run and extend the amount of time for the backup as well.

[@bobforte9343]

@@Cpt_Adama the lithium battery doesn’t work. Period. The lead acid charge protocol is incompatible. The voltage range is incompatible.

[@bobforte9343]

@@yousun2827 I guarantee that the charge profile of your UPS is incompatible with the BMS you have on the pack. Unless the UPS can lower the voltage down to 12.6 the BMS will block all current flow.

[@webmannycom]

I know this is an old video, but I am in need of a nice spot welder for these types of projects. I like the tips you have that are spring loaded instead of pedal. Could you share with me the welder and tip tool you have? Thank you for your help.

[@yousun2827]

www.yousun.org/shop

[@felipe.verasay]

How its called that tool for soldering those batteries?

[@johnbrewer9833]

Hi Felipe. It's called spot welder

[@felipe.verasay]

Thank you!

[@yousun2827]

kzbin.info/www/bejne/aomtnoSKnNCYfcU

[@idontwannalivebecauseimstupid]

So you build a 12V battery from a 12V battery? As I can see all cells were fine, why was it necessary to rebuild?

[@yousun2827]

36V Old bicycle battery pack, Rebuild 12V battery pack.

[@JAKOB1977]

these discharge tester that also give you native spec-information how do you connect with the PC software. is it all on the discharge tester chip.. just put power from a secondary cell and connect wirelessly with Maxim free software?? great video, btw

[@yousun2827]

Yes! 1-wire

[@JAKOB1977]

@@yousun2827 whats the softwares name.. do you ship that with the discharger??

[@yousun2827]

Yes!www.yousun.org/product/18650-high-precision-capacity-tester www.maximintegrated.com/en/design/software-description.html/swpart=SFW0004110A

[@muhammadnaveed6837]

I have same batteries. One is 1800mah and the other is 1300mah. Can i conect both in parallel??

[@yousun2827]

This doesn't work.

[@jesusortizcara9093]

Esa UPS solo está preparada para baterías de plomo ácido 12V ya que la carga en stand by de estas es de 13.5V-13.8V y las de ión litio su máximo voltaje de carga es 12.6V Sale más rentable comprar una batería de plomo correspondiente

[@Delorean29]

I like it!!! :D Where can I buy empty black battery box?

[@yousun2827]

Yes! L151mmW65mmH94mm www.yousun.org/product/18650-battery-pack-empty-box

[@tranat901]

Bạn là người VN đúng k. Bạn có thể cho mình xin thông tin về bộ đế sạc theo dõi dung lượng và tên app?

[@yousun2827]

www.yousun.org/archives/220

[@vtkboyfernandes4022]

aonde compro estes produtos? Obrigado

[@yousun2827]

www.yousun.org/shop Thanks!

[@jamalmustafa1810]

Hellow sir. Please show me how you connect the(B1 B2 B+B_) of BMS. To the cells of lithium battery and nice project. Bye

[@yousun2827]

?

[@LoganJarrell]

Can you explain please how you connected the BMS?

[@cahrlao]

where you buy the batery case box?? link?

[@yousun2827]

L151mmW65mmH94mm www.yousun.org/product/18650-battery-pack-empty-box

[@dilipraj-sy6bp]

May I know the voltage of each battery, mah of each battery and the details of that bms chip?

[@yousun2827]

BMS IC is Ricoh 5436.

[@dilipraj-sy6bp]

@@yousun2827 What's the voltage and current of each terminal battery? 3.7v or 4.3v?

[@yousun2827]

5A and 4.2V

[@dilipraj-sy6bp]

robu.in/product/3-series-40a-18650-lithium-battery-protection-board-11-1v-12-6v-with-balance-for-drill-motor-lipo-cell-module/?gclid=Cj0KCQiAh4j-BRCsARIsAGeV12CZewKAwma7Lp6WpaLwG9vVBVJACmXmU8qZ9te8de29HRpcFioqgNUaAiRaEALw_wcB

[@dilipraj-sy6bp]

@@yousun2827 Is this chip suitable for it?

[@videoalcion]

Hi serves for a motorcycle?

[@yousun2827]

Yes!

[@user-hc1jk5zp8g]

подскажите как спаять пластинами 12вольт 2*6 21700

[@yousun2827]

The anode material of the 21700 original battery is aluminum, and laser spot welding is recommended.

[@rubenhayastan4854]

А какой смысл всего этого ? Батареи разряжены были до 1,8 ,что является ниже кретического значения .А значит батареи пришли в негодность .И показательное красивое табло планшета ,не заменить ,обыкновенного прибора на замер сопротивления батарей . да возможно ,для UPS ,эти батареи ещё немного проработают ,но сколько выдадут при нагрузках и как долго вопрос открыт ?

[@abdulsamadmandli675]

i have ele bike inside 2 acid battery 12v 24ah i have SAMSUNG ICR 18650-26J 2600MAH LI-ION CELL (ORIGINAL), how many cell use plz tell me

[@yousun2827]

The ICR 18650-26J does not support UPS because the internal resistance is too large. Large current discharge is not supported.

[@abdulsamadmandli675]

@@yousun2827 plz suggest any cell ?

[@powwersupply]

Hi my Friend This is very dangerous! You will overcharge the Liion permanently because the APC will charge a pb- battery with approximately 13,8V. The maximum charge voltage for the 3S Li-battery is 12,6V. So, i think the bms will break the connection to the battery when the voltage increase aprox 12,8V. But then you will have a not connectet battery... Withot the bms you will have a very big risk of fire. The only thing you can do is a 4S battery. Then you will get only the half of batterycapacity...

[@yousun2827]

The latest version of BMS 12.3V turns off charging. The output is normal. BMS is mature and reliable. 4s LiFePO4 voltage is more perfect.

[@Roman-qp4bk]

ты куда электролит вылил?

[@themaniac5864]

i love this videos... a big part of them are all indian, you can tell that cuz of huge natural nails and recycling parts

[@elgato6763]

Can say my how make solder point

[@yousun2827]

I did not understand.

[@mwint1982]

Your spot welder shouldn't spark at all. Something is wrong. Check electrodes?

[@yousun2827]

There is not enough energy and it needs to be charged.

[@mwint1982]

@@yousun2827 OK be safe my friend

[@Drxxx]

not bad.

[@FARADISProduction]

Amazing... Nanya kangMas... Apa bisa UPS ke UPS ...? Maksudbya UPS mengisi ke UPS (2 UPS saling mengISI)

[@yousun2827]

I did not understand.

[@FARADISProduction]

@@yousun2827 Amazing ... Asking me ... Can UPS to UPS ...? Meaning that the UPS is charging to the UPS (2 UPS filling each other)

[@yousun2827]

Yes!

[@FARADISProduction]

@@yousun2827 please make a video about how 2 UPS charging the others...

[@anfik-blog831]

как у Вас?купить плату BMS

[@yousun2827]

www.yousun.org/product/3s-4s-5s-6s-7s-8s-9s-10s-li-ionlifepo4-bms

[@tatafatahillah]

How to buy battery capacity??

[@yousun2827]

?

[@NITINSHARMA-ho4nf]

Are bhai ye batteries kahan par milte h our kitne ki milte h

[@yousun2827]

Old electric bicycle battery.

[@syedrashid2247]

@Yousun, you took unnecessary much more time to spot welding, there was no need to stretch the video to show each battery be spot welded. Viewer will fade out with same but long process.

[@yousun2827]

OK!

[@sluge1]

Syed Rashid I watched with 2X speed)

[@t.h.o.r.]

Yes n- Im gone - how boring

[@markhinchcliffe5803]

Why watch the whole thing then idiot,i thought it was ok.....whingers...

[@AshkerTalks]

UPS is designed to charge lead acid batery 3 stage charging now its Li-ion battery complete change in chemistry

[@yousun2827]

Constant current charging - constant voltage charging - floating charge The latest BMS has been solved for pulse charging problems.

[@yousun2827]

Three-stage charging is also suitable for lithium batteries.

[@kotobukichannel4367]

Humming noises you should put a background music for this king of video!!!

[@yousun2827]

Music needs copyright.

[@bibulla88]

hello my name is habeeb, i have a requiremnet of 48 volt 12 ah battery for electric scooter , can you make it for me for reasonable price. thanks

[@yousun2827]

Sorry, the battery cannot be transported.

[@mdhrhelper4357]

Sir Aisha battery banaye jo ups on kar sale please

[@yousun2827]

I did not understand

[@adelkoo99]

3s 7p ?! How did you become a 7ah? 7 cell × 3000mah = 21000 mah = 21ah !! Please tell me how 7 ah

[@TheGrosos1]

he tested all and write a number on them, those numbers are the mah, i didnt see the entire video bot it loks like the batteries that he is using have arround 1000 mah each, srry for my english

[@yousun2827]

Yes! UPS needs to use a high rate battery , Support large current discharge.

[@adelkoo99]

@@yousun2827 Thank you I'm already wrong Because I did not watch the video well :( I was sure the battery was full capacity

[@adelkoo99]

@@TheGrosos1 you are right The measurement is different than I thought

[@hassanisswi5752]

the important thing in this assembly is how you connected the BMS card to the batteries and what you did not do show damage and not even a diagram. !!!!

[@helloworld6160]

Your BMS should come with a diagram

[@yousun2827]

OK!

[@sksbibi4895]

Pcb module to batteries are you keep secret?

[@yousun2827]

www.yousun.org/product/3s-4s-5s-6s-7s-8s-9s-10s-li-ionlifepo4-bms

[@MP-cko]

Battery capacity arround 1200mAh...this is not worth for this aplication by my opinion.UPS can draw lot of Amps if you have powerfull unit.Maybee check some old laptop batteries.I get from them 2000+mAh.And Cels bellow 2V is dead or low capacity.I toss them to recycling yard.Btw.nice spot welder I plan to get some too.

[@yousun2827]

Yes!

[@thebackyardjunkerscientist7732]

A 70 watt load would draw 7 amps out of the battery giving you one hour of run time . .

[@GamingAmbienceLive]

my PC had an internal UPS consisted of 3x18650 batteries, plugged directly into the mobo, it was a proprietary motherboard from asus server that asus sold as desktop... when my PSU died I was able to use the computer for about 15-20 minutes unknowingly, I didnt know why my computer wouldnt turn on anymore, im surprised that it ran at all, but those were brand new LG 1500mAh cells connected in series that could put out 30A each.

[@lazar2175]

Not a really good idea, these UPS will only run for couple of minutes before they overheat as they are designed that way. When you add a battery that lasts longer they really heat up, i melted quite a few, last one i connected to a car battery and it lasted around 17 minutes at 600w before it let out magic smoke. How long does your battery last? Make sure you don't melt yours, it'd be a really bad case with lithium batteries inside.

[@yousun2827]

You need a high rate discharge battery.

[@lazar2175]

@@yousun2827 The UPS melts, not the battery lol.

[@paulkline7831]

asmr