TP4056-based modules are the cheapest single-cell lithium battery charger available on the market. Commonly sold in packs of 10 on Amazon, e-Bay, AliExpress and other online retailers, they are a classic buy for most DIY electronics hobbyists when first trying to work with a lithium-battery in their project.
But they’re just that: chargers. In most cases, hobbyists drastically overestimate their utility and then end up in a potentially dangerous situation, and lithium batteries can easily catch fire if abused.
At PN Labs, we have extensive experience working with lithium batteries and care about people using them correctly, so we’ve written this article to discuss how you can use one safely, and where most people get it wrong.
If you’re looking for an all-in-one charger/protection/voltage regulator board for a single-cell lithium battery, check out the Battery Pal!
TP4056 Module Breakdown
Your standard TP4056 Module looks like this:
What these parts do:
- TP4056 Charger IC: Implements a CC/CV (constant current / constant voltage) charging profile suited for single lithium-ion cell. During bulk charging, it drives a regulated current set by the programming resistor (labelled R3 above). As the cell voltage approaches 4.2 V, the charger holds the voltage constant until the current decays to 1/10 of the programmed charge current. The IC also includes thermal regulation: automatically lowering the charge current if the die temperature exceeds roughly 120 C to protect itself.
- DW01-EV Protection IC: drives the MOSFETs and cuts off if the cell is above 4.30 +/- 0.05 V or below 2.4 +/- 0.1 V. It also features overcurrent shutdown by sensing the voltage drop across the MOSFETs with a dedicated pin.
- FS8205A Dual n-channel MOSFETs: Routed on the PCB in a back-to-back (common-drain) configuration for bidirectional current control.
Overall TP4056 Performance
The TP4056 module can be expected to:
- Provide a safe CC-CV charge (although without temperature feedback) over USB for a single cell up to 4.2 V when no external load is connected, although often it will be less than 1 A because of thermal constraints.
CC/CV Charging profile of a lithium cell from a TP4056 datasheet - Get a little hot due to the linear regulation of the charge current, which is not a problem if it is not touching the battery or anything temperature-sensitive.
Incorrect Uses of the TP4056 Module
Here are the most common incorrect uses of the TP4056 module that we see online and through people we talk to:
- Simultaneous Charge and Use applications. There is no separation between the charge current and the load current on the TP4056 (no power-path management). This means that loads placed on the cell output will confuse the charger, because the termination current on the CV hold step of the charge is never reached. This results in a trickle-charge scenario which greatly reduces battery lifetime.
- Relying on the DW01 protection IC as over-discharge protection for your battery. 2.4 V is far too low for protecting lithium cells designed to operate from 3.0-4.2 V. The designers of the IC likely intended it to be used as a last resort, or with cells that have long leads and thus a lot of voltage drop. It could be okay if 2.4 V is briefly reached under high load conditions where the true equilibrium voltage is closer to 3.0 V, but a slow discharge will certainly kill the cell if it was gradually brought to 2.4 V.
- Putting the charging board in close proximity to the cell: The heat generated from the linear regulator can start a fire if directly in contact.
All these problems make you question why even design a board like this in the first place. The TP4056 modules are intended to be used as charging modules, and they do an adequate job at that.
I actively use them when needing to charge a cell to 4.2 V all the time. The problems appear when people extend the intended use case. The worst part about all this is that battery cells fail slowly, meaning that you probably can get away with doing things wrong for a while, until the battery fails prematurely or something goes very sideways.
As an Alternative:
Our Battery Pal module is an all-in-one battery charger, protection board, and voltage regulator capable of 3.3 or 5 V outputs up to 1.5 A continuous, perfect for embedded applications.
Take a look at our pre-launch page here!
