The BN66 battery model name is matched by most spare part listings to two phones, the POCO C40 and the Redmi 10 Power. The POCO C40 and Redmi 10 Power each hold a 6000 mAh Xiaomi cell. Check the POCO C40 or Redmi 10 Power model number on its box before ordering.
Buyers usually type this as "poco c40 battery" or "redmi 10 power battery". The phone list here comes from parts listings, not from a maker document, so treat it as strong but not final. Neither phone opens without tools, so BN66 stays hidden until a technician lifts the back.
Quick facts
Step by step
Write down the phone name and model number
Open Settings, tap About phone and note the device name and model number. If you cannot find it, type model in the Settings search bar.
Match the name against the box
The retail box carries the same model number. Make sure the box says Redmi 10 Power or POCO C40, and not Redmi 10 or Redmi 10 Prime.
Have the back opened by a technician
Ask the technician to show you the sticker on the old cell. The text
BN66should appear beside the capacity and voltage marks.Compare the new pack before it is fitted
Put the two packs on the counter together. The code, the plug shape, the size and the weight should all look the same.
Which phones use the BN66 battery model name
BN points to the Xiaomi group, but does not name the POCO C40. Most BN66 listings give two phones, the POCO C40 and Redmi 10 Power. Both are budget phones with a 6000 mAh pack, which is why they often show up together.
| POCO or Redmi model | Status | Note |
|---|---|---|
| POCO C40 | Matched by listings | Shown with a 6000 mAh pack |
| Redmi 10 Power | Matched by listings | Shown with a 6000 mAh pack |
| Redmi 10 Prime | Unconfirmed for BN66 | Different phone, read its own sticker |
| Redmi 10 and other Redmi 10 versions | Not confirmed | Not assumed to share BN66 |
If your handset is not a POCO C40 or Redmi 10 Power, a similar name is no reason to buy BN66. Start from the full set of Xiaomi, Redmi and POCO codes and find the page for your exact phone.
What 6000 mAh means for BN66
BN66's 6000 mAh is the typical figure in POCO C40 and Redmi 10 Power adverts. Xiaomi stickers often add a rated value slightly under that. No rated BN66 number is confirmed, so trust the label in your C40 over the round 6000.
BN66 watt hours equal 6000 mAh times the cell voltage, divided by a thousand. Voltage is not confirmed for BN66, so use the figure on your sticker. As a worked example only, 6000 mAh at 3.8 V would be 22.8 Wh. A 6000 mAh pack at another voltage would hold a different amount of energy than BN66.
A pack this large gives a long day on light use, and often more. The real result still depends on brightness, signal, the apps you run and how old the cell is. Charging speed depends on the charger in the box and the cable, not on the mAh figure.
Confirming BN66 before you pay
A listing can name the right phone and still ship the wrong pack, so check three things in order.
- The POCO C40 or Redmi 10 Power model number from About phone and the box.
- The code
BN66on the old sticker, read by the technician with the back open. - The plug and the size of the new pack, placed beside the old one.
Request a photo of the old BN66 label before it is thrown away. If the repair needs a second visit, you will already hold the exact code and capacity.
Print on the cell can be faint, and N and M look alike under poor light. Tilt the sticker towards a lamp, or use the phone torch at a low angle, before you decide.
Redmi 10 Power, Redmi 10 Prime and Redmi 10: three different names
Xiaomi sold several phones with Redmi 10 in the name, and shoppers mix them up often. The Redmi 10 Power is the one that listings tie to BN66. For the Redmi 10 Prime, see its own battery page, since its cell code is read separately. A plain Redmi 10 may use something else again.
An owner brought in a phone labelled Redmi 10 and asked for a 6000 mAh pack by the code BN66, because a friend had one. The technician read the box first, saw it was not a Redmi 10 Power, and opened the back to read the actual label. The code was different, and the friend's pack would not have been right.
The lesson is simple. A shared capacity and a shared "Redmi 10" name say nothing about the code.
Neighbouring codes that get confused with BN66
Xiaomi codes run in a long series, and BN66 sits close to others in spelling. Two to watch are BN62 and BN63. Each neighbouring BN code has its own phones, so a one digit difference is never a reason to swap.
- A one digit difference can mean a different phone, a different size or a different plug.
- Same mAh on the label does not make two packs interchangeable.
- Any pack sold as "compatible" still needs the code BN66 printed on it for these phones.
The page for BN5X shows the same kind of look-alike problem in the BN5 range, which helps if you are comparing several codes at once.
Signs the pack is wearing out
A big 6000 mAh pack on an entry phone is used hard, and the first sign of ageing is usually a sudden fall, not a slow one.
| C40 symptom | Likely reason | Next step |
|---|---|---|
| Charge drops fast even on light use | Worn BN66 or a heavy app | Restart, check app usage, then test battery health |
| POCO C40 dies at 15 to 30 percent | BN66 cannot supply peak current | Have BN66 tested at a service counter |
| Redmi 10 Power back or screen edge lifts | Swollen cell | Unplug the POCO C40 and go today |
| Phone warm while idle | Worn BN66, poor cable or a misbehaving app | Remove the cover, change cable, have it checked |
Rule out software first. Our drain page covers app and signal causes, and the health check shows what to read on a POCO C40.
Swelling, overheating, leaking or a dent turn a BN66 into a fire risk. Unplug the Redmi 10 Power, avoid pressing the cell and keep it cool. Take it to Xiaomi service. Copies sold with an inflated mAh print are common, so accept a pack only when it shows the exact code BN66.
Fitting a new BN66 pack and spotting weak copies
The POCO C40 and Redmi 10 Power are both sealed, so let a technician open them. Prying the back off yourself risks the BN66. Quote the C40 or 10 Power model number and have them confirm BN66 before anything is fitted. For the general routine, see mobile battery replacement.
Look closely at the pack you are handed:
- It weighs clearly less than the BN66 that came out.
- BN66 print is smudged with no batch line.
- It claims a figure well above 6000 mAh in the same size of cell, which no honest pack of that size can reach.
After fitting a BN66, run the POCO C40 through one full charge and note how long it lasts the next day. A new pack that falls fast within a week should go back.
Everyday care for a large budget pack
Phones in this class often charge overnight on a bed or a sofa. Sitting warm and full shortens BN66's life, so charge the C40 on a firm table and take off a heavy cover once it heats.
Charge with the POCO C40's 10 W adapter or the Redmi 10 Power's 18 W one, or something rated no higher. Swap a cable that warms at the plug. Avoid using the phone for long gaming sessions while it charges, since that adds heat on top of charging.
Frequently asked questions
Which phone uses the BN66 battery?
Most parts listings match BN66 to the POCO C40 and the Redmi 10 Power, both given as 6000 mAh packs. The BN66 print on your old cell confirms it.
Is BN66 the Redmi 10 Power battery model?
Most listings name it for the Redmi 10 Power. With the back open, a technician reads BN66 directly off the cell.
How many mAh is a BN66 battery?
It is shown as 6000 mAh typical. The BN66 in your C40 may print a marginally lower rated figure.
Does the Redmi 10 Prime use BN66 too?
Do not assume so. The Redmi 10 Prime is a separate handset covered on its own page. Read its sticker before ordering.
Can I fit a BN62 or BN63 pack in place of BN66?
No, not on the strength of a similar code. Each code has its own phones, size and plug, so ask for the exact code.
How can I tell if a BN66 pack is a copy?
BN66 copies are often light, blurred, missing batch marks and claim far beyond 6000 mAh. Compare weight and code against the old pack.