Battery Testing Fundamentals: Capacity, Voltage, and Internal Resistance — Three Numbers That Tell the Whole Story

Kumabolo

May 8, 2020

You cannot judge a battery by a single number. The most common mistake is believing that high voltage means a healthy battery — a battery sitting on the shelf for six months with heavy self-discharge can still show near-full open-circuit voltage while its usable capacity is down by half. Conversely, an old battery with thousands of cycles may show acceptable voltage but sag below the cutoff under load. These two examples demonstrate that single-parameter judgment inevitably leads to misdiagnosis: capacity, voltage, and internal resistance must all be evaluated together.

Capacity, Voltage, and Internal Resistance: Three Dimensions of Battery Health

Capacity tells you how much energy the battery can still store, typically expressed in ampere-hours (Ah) — the total charge deliverable under standard discharge conditions. Capacity fade is the most direct indicator of battery aging. Batiri min ka fanga ye 100Ah ye ani a be se ka 70Ah dɔrɔn di saan saba tɛmɛnin kɔ, a ka kɛnɛyako (SOH) ye 70% ye. Capacity testing requires full discharge to the cutoff voltage, which takes considerable time — typically not suitable for quick daily checks, but essential for acceptance testing, annual maintenance surveys, and end-of-life determination.

Kɔnɔna fanga be batiri kɔnɔna fanga yira, o min be suma ni miliyɔmu (mΩ) ye. It has three components: polarization resistance (from electrochemical reaction kinetics), ohmic resistance (from electrode material resistivity and contact interfaces), and electrolyte resistance. New batteries typically show internal resistance in the tens of milliohms or lower. Ni yɛlɛmani hakɛ be cayara ani elekitoroliti be dɔgɔyara, kɔnɔnafɛnw be yɛlɛma dɔɔni dɔɔni. The critical insight is that internal resistance and capacity fade are not linear — resistance changes very little in the first half of life, then accelerates in the latter half. Tuma min na setigiya dɔgɔyara cogo gwɛnin na, n’a sɔrɔ a ka fanga tun cayara siɲɛ fila wala ka tɛmɛ o kan ka ban. O b’a to kɔnɔnakow kɛlɛli ka ɲi ka lasɔmi joona sanni ka kiti laban tigɛ.

Voltage ye paramɛtiri ye min be se ka faamu ka ɲɛ nka a be se ka kalan cogo nɔgɔman na fana. Open-circuit voltage (OCV) reflects only the state of charge (SOC) — how much energy remains — not how much the battery can actually deliver. Batiri min be ni asidi 12V ye ani a be 12,6V la, o be charge ka ban; at 12.0V it is about 75% SOC; at 11.4V about 25% SOC; at 10.5V it is nearly depleted. But SOC and SOH are not the same thing — a battery at high SOC with high internal resistance will sag below operating voltage the moment load is applied, and the equipment will shut down regardless. Voltage ka kan ka kɔrɔfɔ tuma bɛɛ ɲɔgɔn fɛ ni doni ye, doni sɛgɛsɛgɛli fɛ walima seko sɛgɛsɛgɛli fɛ, abada voltage dayɛlɛnin kelen fɛ.

When to Use Capacity Testing vs. Internal Resistance Testing

Aplikasiyɔn sifa caaman be kɔrɔbɔli fɛɛrɛ sifa caaman lo ɲini ani n’an be fɛɛrɛ jugu sugandi, o be wagati tiɲɛ ani o be se ka gwɛlɛya sɔbɛw to yen. Seko sɛgɛsɛgɛli (full discharge) ye sanu sariya ye min be se ka batiri kɛnɛya lɔn, nka a ka ɲi ka kɛ cogo fila la: a be batiri bɔ ka ban, o kɔrɔ ko ka ɛntɛrɛnɛti ka sisitɛmu dɔ ta ka bɔ ɛntɛrɛnɛti kan; ani a be wagati jan ta — batiri 100Ah min be bɔ 5A la, o mako be lɛri 20 la. Seko sɛgɛsɛgɛri bɛnnin lo ni nin ye: batiri kuraw sɔnni, saan o saan sɛgɛsɛgɛri minw be kɛ u ladoncogo koo la, u ka ɲɛnamaya laban lɔnni sanni u ka batiri yɛlɛma ani sɛgɛsɛgɛri jugu minw be kɛ jurumuw sɛgɛsɛgɛri wagati la.

Kɔnɔna banakisɛ sɛgɛsɛgɛli be teli, a tɛ mɔgɔ tiɲɛ ani a be se ka kɛ ɛntɛrɛnɛti kan. Sumanni be sekɔndi damanin dɔrɔn lo ta, a t’a ɲini ka batiri bɔ baara la ani a t’a ɲini ka doni bɔ. O b’a to a ka ɲi ka sɛgɛsɛgɛri kɛ tuma o tuma: kalo o kalo ka batiriw sɛgɛsɛgɛ telefɔni yɔrɔw la, ka UPS ka batiriw marayɔrɔw kɔnɔnakow sɛgɛsɛgɛ kalo naani o kalo naani ani ka batiriw sɛgɛsɛgɛ tuma o tuma minw be sɔrɔ kunnafoni diyɔrɔw la. Ni an ye kɔnɔnafɛnw suma ni seliliw kelen kelen bɛɛ ye batiri juru kɔnɔ, an be se ka seliliw barikamanw lɔn — ni seliliw kelen be fanga yira min ka ca ni 30% ye ka tɛmɛ kulu hakɛ kan, o ka ɲi ka jateminɛ hali n’a ka nafa dafanin bele be spec kɔnɔ.

Cɛmancɛ fɛɛrɛ dɔ ye doni tansɔn sɛgɛsɛgɛli ye: ka doni surun dɔ don, min be yɛlɛma yɛlɛma (a ka ca a la, a be kɛ anpi tan ye sekɔndi damadɔw ka taga se sekɔndi tan ma) ani ka tansɔn yɛlɛmani suma. O be kunnafoni caaman di ka tɛmɛ tansɔn dayɛlɛnin kan nka a ka teli kosɔbɛ ka tɛmɛ setigiya dafalen sɛgɛsɛgɛri kan, o kama a be se ka kɛ foro kɔnɔ sɛgɛsɛgɛri ye ni batiri be se ka kisi wagati dɔɔni kɔnɔ yɛlɛmani ma ni minanw be baara daminɛna. PK59A marali batiri sɛgɛsɛgɛrikɛla be dɛmɛ don o doni sɛgɛsɛgɛri cogo la — batiri bɔli tɛ ani a be wagati jan kɛ ka bɔ.

PK59A: Ka paramɛtiri saba don bololafɛn kelen kɔnɔ.

Laada batiri sɛgɛsɛgɛri tun be kɛ ni minan saba ye minw tɛ kelen ye: vɔlimɛtiri min be fanga yira, bɔli minan min be fanga yira ani kɔnɔna fanga jateminɛnan min be fanga yira. Gwɛlɛyaw gwɛnin lo — minan caaman, nɛgɛjuru gɛlɛnw, kunnafoni minw tɛ taga ɲɔgɔn fɛ ani jaabi minw ka gwɛlɛ ka ɲɔgɔn sɔrɔ. Foro kɔnɔ baarakɛlaw tun ka ɲi ka kalan saba sɛbɛ ka bɔ ɲɔgɔn na, o kɔ, k’u don sisitɛmu dɔ kɔnɔ tugun biro la. Fili o fili tun be o cakɛda la — sɛbɛri, kunnafoniw doncogo wala u kɔrɔfɔli — o kɔrɔ ko kunnafoniw tun tɛ bɛn ɲɔgɔn ma.

PK59A be setigiya, tansɔn ani kɔnɔna fanga sumaninw don bolola minan kelen kɔnɔ. A ka sumanikɛcogo jɔnjɔn be baara kɛ ni nɛgɛjuru naani (Kelvin) ye walisa ka kɔnɔnafɛnw suma, o min be sɛgɛsɛgɛrikɛlanw ka fanga bɔ yen. Circuit de décharge standard intégré b’a to a be se ka decharge sɛgɛsɛgɛ wagati surun kɔnɔ n’a mako be o la. Voltage be sɛgɛsɛgɛ ADC dɔ sababu fɛ min be baara kɛ ni lɔnniyaba ye. O paramɛtiri saba bɛɛ be yira ekran kelen kan, jaabiw be taga ɲɔgɔn fɛ u yɛrɛ ma ani u mako t’a la ka sɛbɛri kɛ bolo la.

O la, PK59A be nafa dɔ fara a kan ni fɛɛn ɲumanw ye. A be batiriw ka kemikɛli caaman dɛmɛ — asidi-plɔn, litiyɔmu-iyɔn, nikɛli-nɛgɛ idɔrɔdi — o bɛɛ be se ka suman ni minan kelen ye, o min b’a to kemikɛli baarakɛminanw mako tɛ yen tugun. A be kɔrɔbɔli jaabiw mara walisa k’u suma ni tariki kunnafoniw ye. A ka yiracogo be kiti tigɛ cogo tilennin na — PASS / WARNING / FAIL — sanni a ka kɛ kalan gwansanw dɔrɔn ye, min b’a to foroba baarakɛlaw be se ka batiri cogoya sɛgɛsɛgɛ yɔrɔnin kelen. A be funteni yɛlɛmani kɛ a yɛrɛ ma fana, a be kalanw latilen yɔrɔ minw na funteni ka ca wala minw ka dɔgɔ walisa lamini cogoyaw kana jaabiw tiɲɛ.

Fili naani minw ka teli ka kɛ foro kɔrɔbɔli la

Batiri sɛgɛsɛgɛri kɛcogo la, fili caaman minw be kɛ siɲɛ caaman, o be na ni bɔnɛ gwansanw ye. N’an b’u faamu, o be gwɛlɛya sɔbɛw bali. Fili fɔlɔ ye ka tansɔn suma k’a sɔrɔ kɔnɔnafɛnw tɛ yen. I ko an y’a ye cogo min na, tansɔn be SOC dɔrɔn lo yira, batiri kɛnɛyako yɛrɛ yɛrɛ tɛ. Ladonbagaw minw delila ka la tansɔn na — u b’a miiri ko tansɔn ɲuman kɔrɔ ko batiri ɲuman — olu be to ka baara kɛ ni batiriw ye minw kɔnɔna fanga ka bon kosɔbɛ ka ban, fɔɔ ka taga se minanw ma wagati gwɛlɛ dɔ la.

Fili filanan ye ka ban batiri juru ka bɛnbaliya la. Batiri juru ka ɲi i n’a fɔ a ka seliliw barika ka dɔgɔ cogo min na. Ni kɔnɔna fanga be yɛlɛma yɛlɛma kosɔbɛ seliliw cɛma, juru bena yɛlɛma ka se tansɔn tigɛyɔrɔ ma yɛlɛmaniba wagati la barili nɔɔ kosɔn, hali ni selili kelen kelen bɛɛ be fanga dafanin kɔnɔ. N’i ​​be juru dɔ sɛgɛsɛgɛra, tuma bɛɛ, i ka seliliw bɛɛ lajɛnnin ni seliliw kelen kelen bɛɛ suma, ani i k’i janto kosɔbɛ seliliw la minw ka fanga be bɔ kulu ka hakɛ la ka tɛmɛ 30% kan.

Fili sabanan ye ka kunnafoniw sɛbɛ ani k’u sɛgɛsɛgɛ. Foro baarakɛla caaman be kɔrɔbɔli dɔ kɛ ka ban, ka jatidenw kalan ani ka taga — o kunnafoniw tɛ don abada ladonko la. Kɔrɔbɔli nata la, cogo si t’a la k’a lɔn fɛɛn min yɛlɛmana o wagati kɔnɔ. Fɛɛrɛ ɲuman ye ka kɔnɔna fanga ni tansɔn sɛbɛ kɔrɔbɔli kelen kelen bɛɛ kɔ, ka kɛnɛyako sɛbɛ dɔ sigi selili kelen kelen bɛɛ kan wagati la. Ni seliliw y’a yira ko a ka fanga be yɛlɛma joona joona, u ka ɲi k’a yɛlɛma sanni a ka tiɲɛ.

Fili naaninan ye ka lamini funteni kɔlɔlɔw to yen. Batiri kɔnɔna fanga n'a seko fila bɛɛ be bɔ funteni hakɛ la kosɔbɛ. Batiri minw be ni asidi pɔtɔni ye, 10°C o yɛlɛmani be kɔnɔna fanga dɔgɔya ni 30% ɲɔgɔn ye ani ka dɔ fara u ka setigiya kan ni 10% ɲɔgɔn ye; o kɔfɛko be kɛ ni funteni man bon. Ni funteni sara tɛ, rezistansi kalan minw be kɛ wagati wɛrɛw la, u tɛ se ka suma. PK59A ka funteni saracogo be yen kɛrɛnkɛrɛnnin na ka o gwɛlɛya ɲɛnabɔ.

Ladili nafaman minw be sɔrɔ ladonbagaw ni sannikɛlaw fɛ

Batiri ladonni dafanin tɛ tansɔn suma dɔrɔn ye. Sɛgɛsɛgɛli baarakɛcogo dafanin ka kan ka kɛ nin ye: batiri kuraw ka sɔnni sɛgɛsɛgɛli (min be SOH fɔlɔ sɛgɛsɛgɛ 100% la), kɔnɔna sɛgɛsɛgɛli minw be kɛ tuma o tuma baara wagati la (kalo naani ka baara kɛ ni bɛɛ ye, kalo o kalo telefɔni basigiyɔrɔw kama), saan kɔnɔ setigiya sɛgɛsɛgɛli (min be seliliw 20% bɔ ka ban), ani sɛgɛsɛgɛli minw be kɛ tuma o tuma ni fanga ye yɔrɔ minw na.

N’i ​​be kɔrɔbɔli minanw sugandi, u sɔngɔ dɔrɔn man kan ka kɛ sababu ye k’u latigɛ. Minɛn kelen min be se ka fanga, tansɔn ani kɔnɔnafɛnw suma, o sɔngɔ ka nɔgɔ, a be se ka la a la ani a tɛ wagati caaman ta ka tɛmɛ minɛn saba kan minw be baara kɛ cogo kelen na. Minɛn dɔ ka nafa jɔnjɔn i n’a fɔ PK59A, o tɛ sumali tiɲɛn dɔrɔn ye — o ye se min b’a la ka batiri dafalen sɛgɛsɛgɛ miniti duuru kɔnɔ sanni ka lɛri fila kɛ ka nɛgɛjuruw don, k’u bɔ ani ka kunnafoniw sɛbɛ.

Sannikɛlaw ka ɲi k’u janto fana koo misɛnninw na minw tɛ ye nɔgɔman na jagokɛminanw na: yala o minɛn be kunnafoniw bɔli dɛmɛ walisa ka don ɲɔgɔn na ni ladonko ɲɛnabɔcogo ye; ni batiri nɛgɛw be se ka terminal sifa caaman minɛ minw be sɔrɔ foro kɔnɔ; ni ɛntɛrinɛti kan (no-remove) kɔrɔbɔli be dɛmɛ; ani ni garanti ni kalibrasiyɔn baara be bɛn — kɔrɔbɔli minanw yɛrɛ be kalibrasiyɔn ɲini tuma o tuma. O kunnafoniw lo b’a yira n’o minan be baara kɛ tiɲɛn na wala n’a be laban ka ɲinɛ tiriwari dɔ kɔnɔ. View the Battery Test Instruments Collection