Most listings tie the BN5J battery model name to the Redmi 12C and POCO C55, both Xiaomi group phones sold in India. The capacity given is 5000 mAh typical, and one listing quotes 3.85 V. That is normal for an entry level phone and equals about 19.3 Wh.
Here is the catch. Listings for this code do not all agree, and some sellers pair it with the Redmi Note 12 family instead. So treat the phone names on this page as a strong lead, not a final word. BN5J on the cell is the final proof, visible once a technician lifts the sealed back.
Quick facts
Step by step
Write down the exact phone name
Open Settings, then About phone, and note the device name. If you cannot find it, type about in the Settings search bar.
Note the model number as well
The same screen, or the retail box, shows the model number. Write it next to the phone name, because the name alone can point to a different version.
Let a technician read the old cell
A technician opens the back and reads
BN5Jfrom the sticker. On a sealed phone, do not try this at home.Compare the new pack before fitting
Put both packs side by side. The code, the size, the connector shape and the weight should all look the same.
Test the phone after fitting
Charge fully once, then watch the percentage for a day. A sudden drop or a hot back means the pack should go back for testing.
Which phones the BN5J battery model name is listed for
The letters BN tell you the maker group, which here is Xiaomi, covering Redmi and POCO. The BN letters do not identify the phone. Most BN5J listings name the Redmi 12C, with the POCO C55 alongside it, since the two are closely related 5000 mAh budget phones. Some seller listings also show the code beside the Redmi Note 12 phones, so that match stays open.
| Redmi or POCO handset | Status | Advice |
|---|---|---|
| Redmi 12C | Named by most listings | Check the BN5J sticker |
| POCO C55, sibling of the 12C | Named by most listings | Confirm on the cell sticker |
| Redmi Note 12 (4G or 5G) | Disputed between listings | Do not order on the name alone |
The Redmi 12C and POCO C55 are both budget phones with 5000 mAh class cells, consistent with a shared BN5J.
Redmi 12C or Redmi Note 12: two different phones
People often search by a short name such as "redmi 12 battery", and that is where wrong orders begin. The Redmi 12C is a budget phone. The Redmi Note 12 is a mid-range family with 4G and 5G versions. A 5000 mAh pack can still differ from BN5J in size, plug and code.
A Redmi 12C owner whose battery would not hold charge asked for "a Redmi 12 pack". The counter had two boxes with nearly the same mAh. Only once the back was off and the sticker read BN5J was the right box chosen. Close mAh figures had made the two boxes look the same.
Always give the full name, including the letter C, and say whether it is 4G or 5G where that applies.
Capacity of the BN5J pack: typical, rated and watt hours
Redmi 12C adverts quote 5000 mAh typical, the BN5J number. Xiaomi stickers usually add a slightly lower minimum. No rated BN5J figure is confirmed, so check the cell itself.
Turn BN5J's mAh into energy by applying the voltage and dividing by a thousand. At the listed 3.85 V, BN5J holds about 19.3 Wh. Another pack of the same mAh at a different voltage holds a different amount of energy, so compare watt hours when you can.
Redmi 12C endurance hinges on its large LCD, reception, brightness and apps. An entry-level phone with this pack usually gets through a day of light use, but a gaming or video-heavy day will be shorter.
Confirming BN5J before you pay for a replacement
Do this before buying anything. A wrong pack wastes a trip and may not fit at all.
- Carry the handset name plus its model number, not only a guess like "Redmi 12 battery".
- Have the technician read BN5J from the cell with the back open.
- Do not rely on a code typed from memory. B, 8 and 6 look alike in worn print.
- If the old sticker is missing or worn, have the technician match by the 12C model number and the plug.
Photograph the BN5J sticker before the old cell is thrown away. That photo ends any later dispute over what was fitted.
Our code finding guide has the full routine.
Signs the pack is wearing out
| What you see | Probable cause | Next move |
|---|---|---|
| Half a day of use empties it | Worn cell or heavy background apps | Check battery health, then decide |
| 12C goes dark at 15 to 25 percent | BN5J voltage dips when the 12C works hard | Xiaomi service can measure BN5J |
| C55 back or screen edge lifting | BN5J has swollen | Unplug the POCO C55 and go today |
| Warm back even when idle | Faulty pack, bad cable or runaway app | Remove the 12C cover, change the cable, then test |
Before replacing BN5J, look at our drain explainer and run the health test on the 12C.
A puffed, very warm, leaking or dented BN5J can ignite. Unplug the 12C, leave the cell unpressed and keep the phone cool. Take it to an authorised repair shop. Look-alike copies often print a made-up capacity, so insist on a pack showing exactly the code your phone needs.
Look-alike codes that are not BN5J
Xiaomi group codes differ by a single character, so a quick glance fools many people. BN5M, BN5H and BN5G each carry their own list of phones, and none of them should be assumed to share BN5J. The same goes for BN5R, which has a page of its own.
- Same mAh does not mean same pack. Size and connector can differ.
- One changed letter or digit can mean another phone, so read the whole code.
- A pack sold for the Note series may sit beside the C series on a shelf, but do not treat them as interchangeable.
The full Redmi code list shows every code in this family, each with a page of its own.
Fitting and daily care for a budget phone pack
The Redmi 12C and POCO C55 have sealed backs, so the swap belongs at Xiaomi authorised service or a shop you already trust. Request a check of BN5J against the old cell, and have it fitted with the correct adhesive and connector. The full job is described in our swap guide.
Put any new BN5J next to the old one to catch a weak copy. A much lighter body, smudged print, no batch details or a capacity far above 5000 mAh all point to a fake.
For daily care, avoid charging on a bed or in sun, take off a thick case when the phone runs warm, and use the charger from the box or a similar one. Nightly hours at 100 percent wear BN5J, so unplug the 12C when convenient.
Frequently asked questions
Which phone uses the BN5J battery model name?
Most listings match BN5J to the Redmi 12C and the POCO C55, at 5000 mAh typical. Some sellers also pair it with Redmi Note 12 phones, so read the cell sticker before you order.
Is BN5J the Redmi 12C battery model?
Most listings say yes. Some listings disagree, so have BN5J read off your old cell with the back open.
What capacity is BN5J?
Listings give 5000 mAh typical. Expect the BN5J label to print a rated floor just under the headline.
Can I use BN5M or BN5H in place of BN5J?
No, do not assume that. Changing one character can mean another phone, size or plug. Match the full code.
Is the Redmi Note 12 battery the same as BN5J?
Not confirmed. Listings disagree, and the Note 12 is a different phone. Confirm by the sticker and the model number, not by the name.
How can I tell a fake BN5J pack?
Counterfeit BN5J packs weigh less, look blurred, skip batch marks and overclaim capacity. Compare weight, BN5J print and plug against the 12C's old cell.