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Reservist: Battery Pack
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Design a battery pack system to power a NARDI SANY+AIR Compressor (24V version) for at least 1h based on 18650 lithium-ion cellsthat could be charged using standard 220V AC mains power.
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Compressor Motor Specs
Battery pack design proposal
Cell type
18650 Lithium-ion Cells
Nominal Voltage: 3.6 V
Capacity: 1.500–3.500 mAh
Examples:
https://www.nkon.nl/es/rechargeable/li-ion/18650-size/sort-by/price/sort-direction/asc.html
Samsung INR18650-29E E7 2750mAh - 8.25A
Only a proposal
Model: INR18650
Nominal Voltage: 3.6 V
Capacity: 2750 mAh
C-Rate: 0.5
Discharge Current: 1.45 A (or 1.25 A?)
Cost aprox: 3.92€ at 100 units
Distributor:
https://www.nkon.nl/es/samsung-inr18650-29e.html
UN3480 is the model we finally bought (2.9Ah, 0.5C-rate)
Cells Configuration: 7S 12P
The most commonly accepted lithium-ion battery for 24 V ebike systems is 7 cells in series, which creates a 25.9 V nominal battery that actually ranges from approximately 21 V - 29 V during use. From DIY Lithium Batteries
Series: 7 cells
Parallel: 12 cells
Total: 84 cells
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Number of cells in the pack: 84 cells
Nominal voltage of pack: 25.34V
Minimum pack voltage: 17.50V
Maximum pack voltage: 29.40V
Max discharge current: 17.40A
Estimated capacity of pack (Ah): 34.80 Ah
Estimated capacity of pack (Wh): 881.83 Wh
Estimated capacity of pack (kWh): 0.88 kWh
Configuration diagram
Estimated duration
Watts drawn from pack: 400W
Estimated run time: 2 hours and 12 minutes
Pack discharge rate: 15.79A
Cells cost and weight
Cell cost of pack: 336 €
Weight of pack: 3.6 Kg
Estimated using https://cellsaviors.com/pack-planner
Physicall connections: TBC
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"We recommend that for best results, you limit the current draw of the battery pack you build with Vruzend battery caps to approximately 3.5 A continuous per cell. Current bursts of up to 7 A are acceptable, but for periods not exceeding 10-15 seconds. Higher current results in more waste heat being generated which can rob your pack of performance."
Sounds ok, we should be drawing less than 1.5A continuous per cell.
"That means that if you build a battery with six cells in parallel, you should try not to exceed about 20 A continuously with that pack, though bursts of higher current are ok. We’ve had some people do tests with higher current, but it usually isn’t worth the extra waste heat. Extremely high current can even be dangerous. Please be safe and don’t try to pull too much current from your battery cells – this is true with any battery building project, not just with Vruzend kits."
Sounds ok, we should be drawing less than 18A continuous per pack.
Distributor
Manufacturer
https://vruzend.com/product/vruzend_basic_kit/
BMS: Daly 7S 24V 40A
DALY 7S 24V BMS
Cells: 18650 Lithium-ion
Discharge current: 40A
Charge Current: 30A
With Balance and Common Port (single ground)
- Over charge protection
- Over discharge protection
- Over current protection
- Short-circuit protection
- Temperature protection
Distributor
Configuration
Charger
Standard li-ion cells charging voltage is 4.2V, that equals 4.2V x 7 cells = 29.4 V
Nominal charge voltage: 24 V (7S)
Full charge voltage: 29.4 V
Charging current: 3 A
Distributor
Building process
Series connecton of 7 cellsprepered to be conecctrd with a total of 12 series connections in paralel.
It's important to keep track of each group to ckeck all the batteries are in the correct position.
To connect the BMS be sure that you follow the right wiring diagram, connecting the cables wrong may cause damage to the system.
In orther to protect the battery and the load that is going to be connected it's highly recomended to use an In-line fuse holder. For this configuration the fuse that is been used is a 25A fuse to be able to withstand the peak power consumption during engine startup (20A).
To add an extra layer of security addind a battery isolation switch to be able to open the circuit when is need it.
The battery shoud be able to be working with the NARDI SANY+AIR Compressor during 2 hours and 30 minutes aproximately.
To charge the battery using the charger from VRUZEND it would take between 10 and 12 hours to charge completely the battery.
Having the design already done gives us the chance to make a new enclosure using recycled plastic.
Links and references
- https://nvhrbiblio.nl/biblio/boek/Toll - DIY Lithium Batteries.pdf
- https://cellsaviors.com/pack-planner
- https://cellsaviors.com/pack-builder
- https://calc.esk8.news/#/0
- https://www.electricbike.com/introduction-battery-design-1/
- https://hackaday.com/2022/10/10/lithium-ion-battery-circuitry-is-simple/#more-555591
- https://hackaday.io/project/170192-backup-battery-pack
- https://www.cetronic.es/sqlcommerce/disenos/plantilla1/seccion/producto/DetalleProducto.jsp?idIdioma=&idTienda=93&codProducto=111051070&cPath=407
- https://cellsaviors.com/blog/building-a-battery-pack-from-18650-cells
- https://vruzend.ie/collections/6s/products/li-ion-bms-pcb-6s-24v-40a-daly-waterproof-balanced-battery-management-system-uk
- https://cellsaviors.com/blog/building-a-battery-pack-from-18650-cells
- https://www.youtube.com/watch?v=_WI9Nwqvplo&list=WL&index=21
- https://www.youtube.com/watch?v=PVnQ87Fvsk4
- https://hackaday.com/2019/12/13/a-modular-system-for-building-heavy-duty-18650-battery-packs/
- https://emusbms.com/products-catalogue
- http://liionbms.com/php/bms_options.php
- https://electrodacus.com/
- https://jag35.com/products/7s-24v-battery-modules-new-lgm36-cells
- https://www.wesellcells.eu/18650/en/
- https://www.youtube.com/watch?v=9Kb0Nmv3Wfg
- https://www.youtube.com/watch?v=dQ4zqkezMs0
- https://batterysecondlife.com/baterias/
- https://www.apexboards.co.uk/collections/bms
- https://enepaq.com/
- https://www.youtube.com/watch?v=adY-S8AH_Jc
- https://www.reguerobaterias.es/p90040912_bateria-litio-12-voltios-20-amperios-lifepo4-fpli12-20ah.html
- https://es.aliexpress.com/item/4000648390976.html?spm=a2g0o.ppclist.product.2.3b24E7ZrE7ZrIv&pdp_npi=2%40dis!USD!US %2412.78!US %2410.88!!!!!%40211b440316629721372285094e69ce!10000005180815173!btf&_t=pvid%3A995cdb88-2bcc-46b7-aae2-049ec2e7cd44&afTraceInfo=4000648390976__pc__pcBridgePPC__xxxxxx__1662972137&gatewayAdapt=glo2esp4itemAdapt
- https://es.aliexpress.com/item/1005002006800802.html?_randl_currency=EUR&_randl_shipto=ES&src=google&src=google&albch=shopping&acnt=439-079-4345&slnk=&plac=&mtctp=&albbt=Google_7_shopping&albagn=888888&isSmbAutoCall=false&needSmbHouyi=false&albcp=11758679187&albag=116841987329&trgt=295204014427&crea=es1005002006800802&netw=u&device=c&albpg=295204014427&albpd=es1005002006800802&gclid=Cj0KCQjw-fmZBhDtARIsAH6H8qh_0CPhsVivDo4e1tvmqRVloC7w5KQvnsnYEhOJKneoZY4s2YJ4wE8aApKQEALw_wcB&gclsrc=aw.ds&aff_fcid=5b8cd0aac2f64615ba1329a8857683f4-1665051123633-01820-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=5b8cd0aac2f64615ba1329a8857683f4-1665051123633-01820-UneMJZVf&terminal_id=9889c2e7dbb349d3bd63d1948f5f879d&afSmartRedirect=y
- https://www.youtube.com/watch?v=9Pxq4Au5iuc
