Wakuu, kwema?
Leo tuongelee kidogo kuhusu
battery degradation za hybrids (
HEV na
PHEV) na magari ya umeme (
EV), especially used tunayonunua kutoka Japan.
View attachment 3597609
Ili kuelewa degradation ya hizi battery, tuanze na utangulizi basics wa EV, PHEV na HEV kwa kutumia mifano ya magari maarufu ya hapa Tanzania ambayo wengi tumeshakutana nayo na kuyaendesha/kuyapanda:
HEV – Hybrid Electric Vehicle
Hii ndio common electric vehicle form zilizopo Bongo, ambapo gari inapata nguvu kutoka kwa engine na hybrid battery, either kimoja kimoja au kwa kuchangia. Mfano wa gari ambalo leo nitalitumia ni
Toyota Prius ya mwaka 2010.
View attachment 3597610
Baadhi ya specifications za battery yetu hapa:
- Aina ya Battery: NiMH (Nickel Metal Hydride)
- Ukubwa/Size ya Battery: ~1.3 kWh (ndogo sana)
- Jinsi ya Kuchaji: Hai-charge kwenye socket, inachajiwa na engine + regenerative braking
- EV mode range: ~1–2 km tu, speed ndogo (chini ya 50 km/h) na barabara flat au mteremko.
- Fuel consumption: ~25–30 km/L average, ila inaweza kuzidi hadi 40 km/L na inaweza kushuka hadi 20 km/L, kwasababu mbalimbali.
- Bei yake ya CIF kutoka Japan: ~$4,000 – $7,000
- TRA + import: ~TZS 10M – 12M
Hybrid kama Prius inatumia battery kusaidia engine, si full EV.
Kwahiyo inakua na engine (mfano Prius 2010 ana engine ya cc 1,800) ambayo engine kuna muda inazima na kumuacha battery aendeshe gari. Energy ya battery ikiisha engine inawaka automatically.
EV – Full Electric Vehicle
Full EV yenyewe inakua na battery tu, haina kabisa engine, na battery linachajiwa kama unavyochaji simu nyumbani.
Battery inampa energy
motor [EV inaweza kua na motor moja imewekwa magurudumu ya mbele (FWD), au ya nyuma (RWD) au inaweza kua na motor mbili, moja mbele na nyingine nyuma (AWD) na wengine wana hadi motor tatu au nne]
Kwahiyo kazi kuu ya motor ni kuzungusha matairi. Hatuna gearbox hapa kama magari ya kawaida.
View attachment 3597611
Mfano tutakao utumia hapa ni
Nissan Leaf (2018). Tukigusia battery lake:
- Aina ya Battery: Lithium-ion (air-cooled).
- Ukubwa wa Battery: 40 kWh (2018 model) ila zipo za 62 kWh zinaitwa Leaf Plus.
- EV range ikiwa mpya: ~200–270 km
- Charging: Unachaji kwa socket (AC charging), na pia inajichaji kwa regenerative braking
- No fuel consumption kabisa
- CIF Japan: ~$6,000 – $12,000 (used 2018)
- TRA + import: ~TZS 13M - 15M.
Leaf ni EV safi ya kuanzia lakini ina weakness, kubwa kabisa ikiwa ni air-cooled battery.
Kwa lugha nyepesi, chukulia kama battery linavyofanya kazi linatakiwa liwe linapoozwa na system inaitwa TMS (thermal management system), sasa Leaf wanatumia hewa kupooza wakati EV za kisasa zinatumia liquid, ambayo imekua proved kua efficient zaidi.
Kumbuka, joto ndio adui namba moja wa
lifespan ya battery yoyote.
PHEV – Plug-in Hybrid Electric Vehicle
Hii ipo katikati ya Hybrid na EV, yaani ina battery na engine kama hybrid ila pia inachajiwa kama EV.
View attachment 3597612
Mfano wetu
Mitsubishi Outlander PHEV (2015), ambayo battery lake:
- Aina ya Battery: Lithium-ion (liquid-cooled)
- Battery size: ~12 kWh (ni kubwa kuliko Prius ila ndogo kwa Leaf)
- EV range: ~40–50 km
- Charging: Unachaji kwa socket + engine pia inaichaji battery + regen braking
- Fuel consumption: ~18–25 km/L (mixed use)
- CIF Japan: ~$7,000 – $11,000
- TRA + import: ~TZS 15M - 17M
Hii unaweza ukawa unachaji home kila jioni, na hauna haja ya kutumia mafuta kabisa kama home hadi kazini ni kilometa chini ya 50.
Okay, sasa atleast tumejua izo aina tatu za magari ya umeme, sana sana battery zake, sasa tujiulize swali: “
Kwa nini battery zinaharibika/zinapoteza uwezo wa kuhold nguvu?”
Kutoa jibu moja straight ni ngumu sana. Ila
kusummarize, ni mkusanyiko wa vijisababu vidogo vidogo ambavyo vipo kwenye makundi mawili:
1. Natural causes:
Ndani ya battery kuna electrolyte inayosaidia umeme kutembea kutoka kwenye cations (+ve ions) kwenda kwenye anions (-ve ions). Mfano, ukiangalia battery nilivokua nazitaja hapo juu nilikua nasema na battery type, kama vile Lithium ions kwenye Outlander.
Lithium ions hupoteza uwezo wa kuhifadhi charge kutokana na muda. Kwahiyo battery letu kwa ujumla litakua linapoteza sana nguvu.
Hii inatokana na kuchaji na kutumia gari. Nayo ngumu sana kuicontrol kwasababu ndio matumizi yenyewe.
Kila charge/discharge cycle inapunguza capacity kidogo kidogo. Kwahiyo muda unavyokwenda ndio battery inazidi kupoteza uwezo.
Hata kama huendeshi gari, battery inazeeka. Na ndio maana wanashauri unavyonunua EV na Hybrid used angalia sana kilometa iliyotembea. Gari ya 2010 yenye kilometa 30,000 iogope kuliko ya 2015 yenye 100,000.
Ev na hybrid hawapendi joto kali. Ndio maana wakawekewa
thermal management system kupunguza joto. EV nyingi zenye Lithium battery zinapenda joto la 20°C hadi 30°C na hybrids zenye NiMH zenyewe zinaweza kuvumilia zaidi kuanzia 10°C hadi 40°C
Sasa kwa mkoa kama Dar, joto kali kwa battery za Lithium litawahi kupoteza nguvu. Hii kwa sababu, joto kali lina ongeza:
- Electrolyte kuchoka mapema.
- Inapoteza hataraka uwezo wa kuhold energy.
- Uwezekano wa battery kuvimba, ambayo ni mbaya kiusalama pia.
Gari kama Nissan Leaf (air-cooled) uathirika zaidi kwa mikoa yenye joto ila litapenda mikoa yenye baridi kama Mbeya / Njombe.
2. Sababu kutokana na mtumiaji (hizi ndio kuu):
- Kutumia fast charging (DC fast charge) mara kwa mara. Hizo promo za “gari inachaji 0-80% kwa dakika 5” izo ni Fast Charging. Sio nzuri kwa battery health mara kwa mara.
- Kuchaji hadi 100% kila siku. Hii sana sana kwa Lithium-ion (Leaf, Outlander). Magari ya kisasa una option ya ku-limit charging level ikifika 80% let say, charging inastop. Unless una road trip ndio unaweka off. Mfano mwingine Tesla yeye amekuja na battery za Lithium Iron Phosphate (LPF) ambazo zenyewe kuchajiwa hadi 100% kila siku ndio zinapenda.
- Kutumia gari hadi (0%) mara kwa mara. Hii kama ambavyo ni hatari kwenye simu yako, basi ni mbaya kwa gari. Jitahidi gari iwe inachajiwa kila ikifika 30-35% na ikifika 75-80% unastop.
- Kupark gari mara kwa mara kwenye joto kali.
- Uendeshaji wako wa kila siku. Hapa wazee wa hard acceleration, hii inadraw high current, ndio maana EV nyingine zina button ya launch control ukitaka kufanya hard acceleration.
- Kutofanya maintenance ya cooling system. Mfano: Prius inatakiwa iwe inafunguliwa kwenye fan yake na kusafishwa mara kwa mara.View attachment 3597635
Sasa kwa ku-summarize, kucompare haya magari matatu battery zao:
Prius 2010 (NiMH)
- Inastahimili sana joto
- Inaweza kudumu miaka 15-25 kihurahisi tu
- Degradation yake ipo slow.
- Ni nzuri sana kwa mazingira yetu kama Tanzania.
Outlander 2015 PHEV (Li-ion)
- Hii mimi naona ipo katikati.
- Liquid cooling itailinda battery
- Used inaweza kudumu kwa miaka 10-15.
Nissan Leaf 2018 (Li-ion)
- Air-cooled battery hii ni disadvantage kuu.
- Iko very sensitive na joto. Kwahiyo kwa eneo kama Dar es Salaam sio rafiki.View attachment 3597632
- Itadegradate haraka kama utaishi nayo Dar/Dodoma
- Risk kua nayo Tanzania ila still unaweza ukasurvive. Ukipata 62 kWh itakua nzuri zaidi.
Tips za kupunguza degradation:
Ni ngumu kupunguza battery degradation kwa asilimia 100, ila unaweza kupunguza kiasi chake kwa kuzingatia baadhi ya tips hapa:
Wakati wa kuchaji:
- Jitahidi kuchaji kati ya 30% – 80% kwa matumizi ya kawaida. Labda ukiwa na safari ndefu.
- Kama sio lazima usichaji hadi 100%, labda battery za LFP kama za Tesla (2023+)
- Jitahidi gari lisiishe chaji hadi (0%)
kuhusu hali ya hewa:
- Usipark gari kwenye jua, tafuta kivuli au park ndani.
- Ukiwasha gari, na ulipark kwenye joto, iache ipoe kidogo kwa AC maana itasaidia na kupooza battery system.
Uendeshaji:
- Jitahidi uwe na mguu mwepesi (smooth acceleration).
- Tumia vizuri regenerative brakes
- Kwa hybrids ukiwa Eav mode, usiendeshe kwa speed kali
Aina ya Chaji:
- Pendelea Level 1 / AC charging za nyumbani.
- Kama sio lazima usitumie DC fast charging.
Gharama za kubadirisha Battery:
Tufanye umenunua gari battery likaja likazingua kabisa, halikai na chaji kabisa, je estimate za battery price zipoje (Note: Hizi gharama nimechukua kutoka Beforward spare parts website)
Toyota Prius 2010
View attachment 3597628
- Used battery (Japan): TZS 2M – 4M
- New OEM: TZS 5M – 8M
- Labour: TZS 200k – 500k
Hii system kuifanyia maintenance rahisi sana.
Nissan Leaf 2018
View attachment 3597629
- Battery pack: TZS 8M – 15M (used/import)
- New: can go > TZS 20M+
- Labour: TZS 500k – 1.5M
Leaf kubadirisha battery ni gharama zaidi kwasababu unavyochange unatoa battery pack yote, sio kama Prius.
Outlander PHEV 2015
View attachment 3597630
- Battery: TZS 6M – 12M
- Labour: TZS 500k – 1M
Nini kitatokea kama battery ikafa (0% / dead pack) na muda huo hauna pesa ya kubadirisha?
- Prius: inaweza still move using engine (limp mode possible). Ingawa haitakua nzuri kwenye mafuta.
- Leaf: haiwezi ku-move kabisa. Itabidi uipark.
- Outlander: inaweza kutumia engine but limited performance na bad consumption.
Next time Unaponunua Hybrid / EV / PHEV Tanzania, vitu vya kuzingatia:
- Battery cooling system type (liquid ni bora kuliko air)View attachment 3597631
- State of Health (SOH %) sema ni ngumu kujua maana katika website hawaandiki. Ila ukienda showroom rahisi, unaingiza OBDII na App (mfano Dr. Prius) inakupa majibu.
- Hali ya hewa gari ilipotoka (Mfano gari imetoka Japan sehemu gani?)
- Mileage vs battery degradation
- Angalia upatikanaji wa mafundi unapoishi.
Na vitu vya kuepuka:
- Cheap Nissan Leaf import bila SOH check, especially ukinunua Showroom.
- EV bila service history. Ila ukiagiza hii ni mtihani, kwasababu Auction Sheet haina msaada.
- High mileage EV in hot climate usage history.
Mi niishie hapa, jukwaa wazi kwa mawazo, maswali na michango zaidi.
Pamoja.