Most listings match the BLPA21 battery model name to the Oppo A18, the 4G phone sold in India. Oppo lists BLPA21 as a 5000 mAh typical Li-polymer cell, in a BLP family that reaches Realme and OnePlus. Only the A18 is matched, and even that should be confirmed on the label. Close relatives of the A18 may or may not share the pack, so this page does not list them as fitting.
People search this code in several forms: "blp a21 battery model name", "oppo a18 battery model name" or just "a21 battery". Every spelling means the same small sticker on the cell. On the sealed A18 you cannot see it without opening the back, a job for a technician. Until then, use the phone name and model number to narrow things down, and let the sticker give the final word.
Quick facts
Step by step
Write down the exact phone name
Open Settings and tap About phone. Note the device name and the model number. If you cannot find it, type model in the Settings search bar.
Have the old label read by a technician
The code
BLPA21should be printed on the cell sticker along with a capacity and a voltage. Do not pry at the pack on your own.Put the old and new packs side by side
Compare the code letter by letter, then the outline of the pack and the position of the connector. A different outline means a different pack, whatever the mAh says.
Judge the new pack before it goes in
Feel its weight, read the print under good light and look for batch marks. Refuse a pack that is clearly lighter than the old one or that claims far more than 5000 mAh.
Which phone uses the BLPA21 battery model name
BLP at the start points to the Oppo group, and the letters after it separate one pack from another. Listings tie BLPA21 to the Oppo A18 4G. That is the only phone this page puts in the fits list. Several other budget Oppo phones look much like the A18, but a similar screen size or the same mAh figure does not prove a shared battery.
| Oppo A handset | Match status | Note |
|---|---|---|
| Oppo A18 (4G) | Listed for the A18 | 5000 mAh typical; check the BLPA21 sticker |
| Oppo A38 | Not confirmed | A near twin in looks and class, but read its label before ordering |
| Oppo A17k | Own page | See the Oppo A17k battery page |
| Oppo A16 | Own page | See our Oppo A16 battery page |
If your phone is not an A18, this table is no basis for ordering BLPA21. Find your own code from the label and look it up in the Oppo battery list.
Oppo A18 battery model name: what buyers really need
Most people who type this are standing at a counter with an A18 that no longer lasts the day. For them the answer is short: the pack to ask for is BLPA21, a 5000 mAh cell. The second half of the job is to be sure the phone is an A18 and not a neighbour in the same series.
The A-series has many phones with names that differ by a letter or a digit, such as A18, A38 and A17k. Each can carry its own pack. Look at the retail box or at About phone and read the full name, including any suffix. A short name said aloud over the counter is how wrong packs get ordered.
An owner asked for "the A1 something battery" and was shown two packs with near identical outlines. With the A18 open, the old label confirmed the phone was what its owner said. Only the pack printed BLPA21 went in, and the other was kept aside.
Capacity of the BLPA21: typical, rated and what it means in daily use
Oppo advertises the A18 at 5000 mAh typical, the BLPA21 figure. Oppo labels usually add a slightly lower rated minimum. No rated BLPA21 value is confirmed, so read the one on your A18 cell.
Work out BLPA21's watt hours by multiplying mAh and volts and dividing by a thousand. BLPA21's voltage is unconfirmed, but at about 3.87 V it would hold roughly 19 Wh. An A18 pack at a different voltage would store slightly different energy, so never judge BLPA21 by mAh alone.
How long an A18 runs depends on its chip, brightness, reception and apps. A fresh BLPA21 usually carries an A18 through a normal day, though results vary. A18 charge time depends on the adapter's wattage, which matters more than the cell code.
Check the label before you pay for a replacement
Let the printed cell code be your single source of truth. Websites, this page included, can be wrong for a regional version of a phone. The sticker cannot.
- Read all six characters.
BLPA21has the letter A before 21, and that letter matters. - Match the capacity line. It should be close to 5000 mAh, not a round number far above it.
- Match the connector. Pack outlines in this range are alike, but plug positions are not.
- Photograph the old BLPA21 sticker before the cell is binned, so a repeat visit has a starting point.
Keep the phone's box or a screenshot of the About phone page with you. The model number there helps a technician choose the right pack even when the old sticker is worn.
Look-alike Oppo codes that get swapped
At a counter the trouble is the pattern BLP plus a letter plus two digits. Several Oppo cells share that prefix, each with its own phones. Do not assume a neighbour fits just because the characters look close.
- BLPB21 and BLPC21 end in the same two digits but are separate packs with their own pages.
- BLPA19 and BLPA17 share the BLPA start with this code. Check their pages for the phones they serve.
- On a faint sticker, the digits 1 and 7 and the letters B and A are easy to misread. Tilt it under strong light.
A 5000 mAh pack under another code may not fit the A18 at all. Always match the code first and the mAh second.
Signs that the pack in the phone is wearing out
| A18 symptom | Likely reason | What to do |
|---|---|---|
| A18 percentage drops quickly | BLPA21 worn, or apps running in the background | Close extra apps, then follow the health check guide |
| Phone switches off with charge left | Tired BLPA21 sags under sudden load | Test BLPA21, then plan a new one |
| A18 back lifts or screen bulges | BLPA21 has swollen | Stop charging and go to a service centre today |
| Handset runs hot with no use | Faulty pack, bad charger or a stuck app | Remove the case, restart, get it tested |
Quick drain also has software causes, which are listed under causes of fast battery drain. Rule those out first.
If BLPA21 bulges, gets very warm, leaks or dents, treat it as a hazard. Take the A18 off charge at once, keep it flat and away from warmth. Have Oppo authorised service check it. Cheap BLPA21 copies often print invented capacities, so buy only when the code matches exactly.
Fitting a BLPA21 and caring for it
The A18 is glued shut, so let Oppo service or a repairer you trust open it. Give them the A18 model number and let them compare BLPA21 with the old sticker. General fitting advice for every phone has its own page, battery replacement.
A weak copy can often be caught with the eye: it is lighter, the print is smudged, there are no batch details, or the capacity claim is far beyond what a cell this size can hold.
With a new BLPA21 inside, charge the A18 somewhere firm and shaded, never on bedding, and remove a thick cover when it warms. Charge the A18 from its own brick or something rated no higher. Warmth and long hours full age BLPA21 more than almost anything.
Frequently asked questions
Which phone uses the BLPA21 battery model name?
Most listings tie BLPA21 to the Oppo A18 4G, a 5000 mAh typical Li-polymer cell. No other phone is confirmed, so read your old cell's sticker.
Is BLPA21 the Oppo A18 battery model?
Most listings say yes. Open the A18 and BLPA21 is printed on the cell.
What is BLPA21's capacity?
BLPA21 is listed at 5000 mAh typical. BLPA21 stickers may print a rated minimum a touch lower.
Is BLP A21 the same as BLPA21?
People type it both ways, and they mean the same code. The label prints it without a space.
Will a BLPB21 or BLPC21 work in place of BLPA21?
Do not take it for granted. BLPB21 and BLPC21 are listed for other Oppo models, and their shape or connector can differ. Match BLPA21 completely.
What reveals a fake BLPA21?
Fake BLPA21 packs are usually lighter, blurry, missing batch marks and overgenerous with capacity. Compare weight and BLPA21 code with the A18's old cell.