Overvoltage tih hi eng nge ni?
Nikum Thawhlehni khan Ohio-ah pack integrator aṭangin call a dawng. Anni hian 14S LFP pack an nei a, chu chu solar install atanga rawn haw a ni a, cell pahnih 3.91V a chhiar a ni. LFP a ni. A hman dan pangngaiah chuan 3.65V aia sang engmah hmuh ngai lo tur a ni. Cell te chu pawn lam atang chuan a tha hmel hle a mahse pakhat kan crack chuan cathode foil chu a sir lamah a rawn sen vek tawh. Classic overcharge a tichhia.
a rawn chhuak a, lead-acid charger an hmang a. Customer chuan original a thih avangin a thlak lut a. Lead-ACID 48V Charger chuan 58.4V float a tichhuak. 14S LFP pack ah chuan cell khatah 4.17V thleng a thawk thei. Lead-acid tan harsatna a ni lo. LFP tan harsatna lian tak a ni.
Hetiang thil hi miten an pawm aia tam a thleng thin.
Overvoltage tih awmzia chu cell pakhatin a charge voltage rate sang ber a paltlang tihna a ni. Number hi chemistry ah a innghat a ni. NMC leh NCA te chu 4.20V ah an top out. High-energy NMC variant thenkhat chu 4.35V ah an rate a mahse chu chu specialty cells a ni a, anmahni nena i tih tur i hriat a ngai a ni. LFP chemistry hian 3.65V ceiling a nei a, a ceiling pawh a sang hle. LTO hi 2.85V vel a ni. Heng number te hi cell vendor datasheet atanga lo chhuak a ni. Ngaihsak lo la, harsatna i nei ang.
A chhunga cell a chhiat dan .
Overvoltage-a cell chhunga thil thleng hi a buaithlak lo. Cathode material hian lithium tam lutuk i force chhuah chuan oxygen chu bansan a duh a ni. chu oxygen chu electrolyte nen a inrem a ni. Chutih laiin lithium metal chuan anode surface-ah plating out a tan a, a chhan chu graphite hian ion a absorb rang thei lo a ni. Plating hi chhan pahnih vangin a chhe hle. A irreversible capacity loss a ni a, dendrites a siam a, chu chuan a tawpah chuan a chhungril lamah cell a ti tawi thei a ni.
Mi tam tak chuan 4.20V spec-ah hian margin built a awm niin an ngai. A awm lo.
Cell siamtute chuan chu limit chu degradation chu pawm theih loh a nih theihna hmunah an dah a. Vawikhat 4.25V-a kal chu a tha mai thei. Going there every cycle chuan cycle za engemaw zat chhungin cell chu sang tlemte chhungin a that ang. 4.30V aia sang a kal chuan cycle za tlemte i hmu lo mai thei. Charge pakhat hnuah 4.35V-ah cells a lo hring chhuak tih ka hmu tawh. cell-ah a innghat.
BMS-a chanvo .
BMS hian hei hi an man tur a ni. Pack chhunga cell tin hian an sense wire an nei vek a. AFE chip hian cell voltage zawng zawng a chhiar vek a, threshold nen a khaikhin a ni. Cell eng pawh a kal chuan charging a tawp thin. A awlsam khawp mai.
BMS a hlawhchham thei tih loh chu. Sense wire connector-a cold solder joint nei BMS board ka hmu tawh a. Cell pakhat chuan report a titawp a, firmware chu fault flag ai chuan zero ah a default a. Afe chips chu cal calft out of cal over temperature ka hmu tawh. TI’s BQ76940 hi a tlangpuiin a solid a mahse BQ76925 hlui zawk hian internal reference shifting ah issue a nei a. Chinese AFE chip man tlawm zawk chu hmun tinah a awm thei.
Mite ngaihdan aiin balancing hi a pawimawh zawk. Pack pakhat cell sawm series-a awm chuan a capacity-ah spread engemaw zat a nei ang. Cell pakhat chuan a dang hmaah full charge a hit a. Balancing a slow lutuk chuan high cell chu 4.20V ah a thu a, current erawh pack chhungah a luang lut zel thung. Chu cell-a voltage chu a rawn inher chhuak a. Passive balancing hmang hian bleed resistors hmangin heat engzat nge i dump theih tih hian a limited che a ni. Design tam zawk hi 50mA atanga 100mA balance current a ni. I cells te chu za zela tlemte aia tamin an inmil lo a nih chuan a tawk lo mai thei.
Active balancing hian cell sang atanga cell hniam atanga charge a kal a, a halral ai chuan a kal tir zawk thin. A man a to zawk. a complex zawk. Makes sense to large packs where the wasted energy adds up emaw, capacity spread eng pawh i tuar thei lo application-ah emaw.
Charger design hi equation chanve dang a ni. Switching converter chu feedback regulation sloppy tak nei chuan light load-ah a overshoot dawn a ni. Pack-in charge tawp dawn hnaihah 100mA aia tlem lo a draw chuan 42.5V a chhuah tir thei charger ka teh tawh a ni. Chu extra half volt chu cell sawma sem darh chu 50mV ve ve a ni. Chhiatna a ni lo va, tolerance dangte nen a inzawm tlat a ni.
Charger-a temperature compensation pawh a pawimawh hle. Lithium cells te chu a lum laiin voltage hniam zawkah charge tur a ni. Charger thenkhat chuan CV setpoint chu thermistor hmangin an siam rem thin. A man tlawm zawk chuan an ti lo. 45C-a ni chhuahna hmuna thu pack pakhat chu cell khata 4.20V normal-a charge a nih chuan effective takin overcharged a ni.
Protection layer pahnih chu pakhat aiin a tha zawk. BMS hian cell voltage an en thin. Secondary protection IC hian pack voltage a en thei a, thil dik lo a awm chuan FET a cut thei bawk. He sawihona zawng zawng bul tanna Ohio Pack tan chuan, an pahnih hian an awm lo. Dumb BMS an nei a, chu chu balancing chauh a ni. venhimna a awm lo. Customer chuan charger hian a handle ang tih a ngaihtuah a. Ngaihtuahna tha lo.
Design Checklist 1000 a ni.
Pack design i nih chuan checklist hi a tawi hle.
- Cell tak tak nei BMS hmang rawh-level OVP.
- Threshold chu margin engemaw zat hmangin set la, NMC tan 4.18V a ni mai thei.
- Balancing hian i cell spread nen a inmil thei tih hria ang che.
- A operating envelope atanga charger chu bench-a room temp-ah chauh ni lovin qualify rawh.
- Application-in a dik chuan secondary protection path add bawk ang che.
Ohio Pack hi BMS dik tak leh LFP tan charger spec'd nen an siam thar leh mek a ni. Zirna man to tak a ni. A chhe zawk pawh a ni thei. Tuman hliam an tuar lo va, engmah a kang lo. Chu chu heng thawnthute hi a tawp dan a ni ngai lo.
