Reservist: Battery Pack :battery: ======================= 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. :::warning :eyeglasses: [How To Build Your Own Lithium Battery]( ::: # 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: ## Samsung INR18650-29E E7 2750mAh - 8.25A :::warning 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: :::info 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** :battery: 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 :::warning Estimated using ::: ### Physicall connections: TBC ![]( :::warning :warning:**Bus bars current limitations** _"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 ## 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 ![image alt]( ![]( 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. ![](,c_pad,dpr_1.0,f_auto,q_auto,w_700/c_pad,w_700/F3254840-01) 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 0. 1. 3. 2. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.