The main mobile battery types in phones today are lithium-ion and lithium polymer packs, and the choice that matters to you is whether yours is sealed or removable, plus its code, voltage and connector. Spec sheets use the words Li-ion and Li-Po loosely, so the label on the pack and the phone's model number tell you more than the marketing line.
This page helps you place your own battery: what kind it is, what its voltage means, why the connector and charger matter, and what a so-called power saver app can and cannot do. It does not list codes. To trace a code, follow the guide linked in the steps below.
Quick facts
Step by step
Find out if your battery is sealed or removable
If the back cover has no notch and no screws you can reach, the pack is sealed. Look at the box or the maker's spec page for words like non-removable battery.
Read the cell type and capacity on the spec page
The box or the maker's page gives Li-ion or Li-Po and the capacity in mAh. Treat that capacity as the typical figure. The rated figure is on the pack label.
Open the battery page in Settings
Type battery in the Settings search bar. Menu names differ by brand, so use the search bar instead of a fixed path.
Get the code from the label, not from guesswork
The code is printed on the pack. Sealed phones need a technician to open the back. The guide to tracing a battery code shows the safe routes.
Compare the connector side by side
Put the old and new packs next to each other. The flex cable, plug shape and pin count must look the same before anyone fits the new one.
Mobile battery types at a glance
Nearly every current phone battery is a rechargeable lithium cell. The differences are in how the cell is built, how the pack is fitted and how fast it can take charge.
| Type | Where you see it | Plain note |
|---|---|---|
| Lithium-ion (Li-ion) | Many phones, old and new | The family name. Spec sheets also use it for pouch cells. |
| Lithium polymer (Li-Po) | Most slim phones | A soft, flat pouch cell. It is still a lithium-ion cell inside. |
| Sealed pack | Most phones sold today | Fixed under the back or frame. Fitting is for a technician. |
| Removable pack | Older basic phones and some older budget phones | Back cover comes off and the pack slides out. |
| Dual-cell pack | Some phones with very fast charging | Two cells in one pack share the charging current. The phone still shows one battery. |
| Silicon-carbon cell | Some newer phones with a very large capacity | Packs more energy into the same space. The maker's spec page says if it is used. |
| Nickel based cell | Very old handsets only | Not used in current phones. |
Li-ion or Li-Po: does the name change what you buy
For a buyer, not much. Both are lithium-ion technology. Li-Po usually means a pouch cell without a hard metal case, which suits thin phones. A phone sold with a Li-ion label may still carry a pouch cell, because makers are not strict about the term.
So do not choose a replacement by the words Li-ion or Li-Po. Choose by the battery code, the handset's model number and the plug type. A pack of the right type but the wrong code can have a different size, a different plug or a different protection board.
When a seller says a battery is better because it is Li-Po, ask for the code on the label instead. The code is what proves the pack belongs to your phone.
Sealed or removable: how to tell and what it means for repair
A removable battery is easy to swap, but very few phones sold now allow it. The slim body, the water seal and the larger cells of current phones all push makers towards sealed packs. An iPhone is sealed, and so are most Redmi, Realme, Oppo, Vivo and Samsung phones in the current range.
A sealed pack is held by adhesive and a flex cable on the board. Pulling it out the wrong way can bend the cell, and a bent cell can heat up later. That is why the work belongs with the brand's service point or a trusted repair shop. The page on mobile battery replacement covers what to ask and what to avoid.
Mobile battery voltage and watt hours
Capacity in mAh tells you how much charge a cell holds. Voltage tells you how hard that charge is pushed. Many phone packs are listed at a nominal 3.7 V to about 3.9 V, and they charge up to a higher figure, which is why a full pack reads above its nominal voltage. Your own label gives the exact numbers.
Two packs can be compared fairly only when both are in Wh, a unit of energy. Start with the mAh number and multiply it by the pack's nominal voltage. Then divide what you get by 1000. A 4000 mAh pack rated 3.85 V, for instance, comes to roughly 15.4 Wh. Apple's own documentation states iPhone battery size in watt hours. Any mAh value you find for an iPhone comes from regulatory filings and teardowns.
A dual-cell pack may be listed at a different voltage or mAh figure from a single cell, depending on how its two cells are joined. Do not read that as a bigger or smaller battery. Compare watt hours instead.
Mobile battery charger and cable: what the battery needs
The charger does not push power by force. The phone and the charger agree on a speed, and a small protection board on the pack stops overcharge and short circuit. The watts printed on a charger are its top output, not what every phone will draw.
- A charger with a higher watt rating than your phone is usually fine, because the phone asks only for what it supports.
- A weak cable limits speed and can heat up at the plug. Replace a cable that feels hot.
- Cheap unbranded chargers may lack proper protection. Prefer the accessory packed with the phone, or one that follows the same standard.
The time to fill the pack depends on the watts, the cable and the phone, not on the battery type alone. Long hours at 100 percent and heat age any lithium pack faster. For daily habits that drain a pack, see why a phone loses charge quickly.
Mobile battery connector: why a same-mAh pack can still not fit
Every pack comes with its own connector or flex cable. The number of pins, their position and the cable length are all fixed for that pack. Brands often alter these from one model to the next, even if the capacity stays the same. If a pack has the same mAh rating but a different code, it may fall short of the socket. It may also reach the socket and still fail to work.
A customer brought a pack that read the same capacity as the old one. The technician saw that its flex cable came out on the opposite side. It would not reach the socket, and forcing it could have damaged the board. The right code was ordered instead.
Never bend a flex cable to make it reach. Match the code first. The code lists for each maker, for example the Redmi battery model list, tell you which phones share a pack.
Power saver apps and other myths
An app that promises to boost a battery cannot add capacity to a cell. Chemistry sets the capacity, and no app changes it. Such apps may close background apps for a short while, which Android already does by itself. Some add adverts or drain more power than they save, so skip them.
- Do not open a sealed pack or try to repair the cell.
- Do not chill a battery in a cold box or heat it in an oven.
- Do not trust a pack that claims double the capacity of the original. The size of the cell sets a hard limit.
If the battery seems weak, read the real health figures first. The battery health check page explains the method for your phone. Samsung owners can also use the maker's support page for service options.
Watch for a back cover lifting at the edge, a screen that bulges, a pack that gets very hot, or a smell that is sweet or burnt. Each of these signals danger. Stop charging and pull out the charger. Place the phone on bare tile or concrete, well away from anything that can catch fire, and never press or squeeze it. After that, take it to the closest authorised service point. Cheap copy packs that print a very high capacity often cause such problems, so use only a pack that has your exact code.
Which type to look for when you need a new battery
You do not pick a type. You match the one your phone was built for. Take the full handset name with its model number, the code from the old label and the capacity. Then check that the new pack has the same code, similar weight and a plug that looks like the old one.
If you want a phone with a bigger pack, the big battery phones page lists the high capacity range. Remember that a larger mAh helps only if the chip, screen and software use power sensibly, so screen-on time does not rise in a straight line.
Frequently asked questions
Which battery is used in mobile phones?
Almost all current phones use a rechargeable lithium-ion or lithium polymer pack. Most are sealed inside the phone, and some basic phones still have a removable pack.
Is a Li-Po battery better than Li-ion for a mobile?
Not in a way that changes your buying decision. Li-Po is a lithium-ion pouch cell. Choose by the exact battery code and connector for your phone.
What is the voltage of a mobile battery?
Many single-cell phone packs are listed at about 3.7 V to 3.9 V. Some dual-cell packs are listed differently, depending on how the cells are joined. The exact figure is on your label.
Does a mobile battery power saver app really work?
No. An app cannot raise the capacity of the cell. It may close background apps for a short time and add its own load. Check battery health and apps instead.
Can I use any charger on my phone?
Prefer the charger packed with the phone or one with a matching standard. A higher watt charger is usually accepted because the phone draws what it supports. A cheap charger without protection is a risk.
Will a battery with the same mAh fit my phone?
Not always. The code, size and connector must also match. A pack with equal capacity under another code could be the wrong shape or have the wrong plug.