The BP9 battery model name is really vivo B-P9, written without the hyphen. Sellers list it for the vivo S9 (V2072A) at 3900 mAh and 3.89 V, and for the vivo V21 5G at about 3905 to 4000 mAh. vivo sold the V21 5G in India with 4000 mAh, so that is the figure most Indian readers need.
Because Xiaomi uses BP codes too, BP9 searches sometimes surface Xiaomi packs such as BP41. Those are unrelated; B-P9 is a vivo part.
Quick facts
Phones listed with the BP9 battery model name
| Phone | Listed capacity | Support |
|---|---|---|
| vivo V21 5G | 3905 to 4000 mAh | Several listings |
| vivo S9 (V2072A) | 3900 mAh | Several listings, China model |
Our vivo V21 battery page covers the phone side, including the 4G V21.
BP9 battery model name and the V21 selfie phone
The V21 5G was marketed for its 44 MP front camera with autofocus and a front flash, packed into a slim 7.29 mm body. That thinness is why the battery stops at 4000 mAh: vivo chose a slimmer phone over a bigger cell. When the B-P9 ages, the thin body also shows swelling sooner than a thicker phone would, usually as a gap along the back edge. Owners who use the front camera heavily for video calls tend to wear the pack faster because the screen and camera run together for long periods.
B-P9 among vivo's short codes
vivo's short labels share one shape, a B followed by a hyphenated pair such as P9. B-P9 sits near B-O5 for the Y20 family, B-S1 and B-R5 for the V23e. Slim phones like the V21 5G and V23e have smaller packs than the 5000 mAh Y series, which is why their codes come with 4000 mAh class figures.
Confirming B-P9 on a V21 5G
Heat and a suction cup are needed to free the V21 5G's glued rear. Underneath, the pack should name B-P9 and list its voltages and mAh. Check the phone name first under About phone; the V21 5G and the 4G V21 may not share a pack.
The V21 5G is a slim phone, and a swelling B-P9 shows first as a back lifting near the camera. Unplug the phone and get the cell out before it damages the screen.
Battery life on the V21 5G
The V21 5G pairs its 4000 mAh pack with a 90 Hz AMOLED screen and 33 W charging. Most users get a full day; heavy camera and video use shortens it. A fresh B-P9 restores that, and a full charge takes about an hour with vivo's adapter.
Ordering a replacement
vivo service centres fit genuine packs by model. If you buy elsewhere, choose a listing that names the V21 5G and prints B-P9 with 3.89 V. More vivo packs appear on the vivo listing page.
Signs your B-P9 is worn
Watch for a V21 5G that no longer lasts until evening, that shuts down around 20 percent, or that takes much longer to charge with the original 33 W adapter. Check the battery usage list in Settings first; if nothing unusual shows, a new B-P9 is the likely fix.
Frequently asked questions
Is BP9 a vivo battery?
Yes. BP9 is how people type vivo B-P9.
Which phone uses the B-P9 battery?
The vivo V21 5G and the China-market vivo S9, according to listings.
What is the B-P9 battery capacity?
About 4000 mAh for the V21 5G, with an S9 listing at 3900 mAh.
Is B-P9 the same as Xiaomi BP41?
No. BP41 is a Xiaomi pack for the Mi 9T; it has no link to vivo B-P9.
How long does the V21 5G take to charge?
Close to sixty minutes from nearly empty when you use vivo's 33 W brick.
Can a B-R5 battery fit the V21 5G?
No. B-R5 belongs to the V23e and is shaped for that body. Match B-P9 for a V21 5G.