The Ajazz AK820 shows a solid blue light when the battery is completely full

The Ajazz AK820 is a wireless mechanical keyboard that uses a rechargeable lithium battery. When you plug it in to charge, a light on the keyboard tells you what is happening. A blinking blue light means it is charging. When the light turns solid blue and stops blinking, the battery is full and you can unplug it.

The keyboard will not overcharge if you leave it plugged in after it reaches full capacity — modern lithium batteries have built-in protection that stops charging once the battery hits 100 percent. That said, unplugging it once the light goes solid is the gentler choice for long-term battery health, since keeping a lithium battery at 100 percent all the time can shorten its lifespan over months and years.

Charging time is typically two to three hours from empty to full, depending on how much power was left when you started. The keyboard uses a standard USB-C cable, which you can plug into any USB power adapter, computer, or power bank.

Key Takeaways

  • A blinking blue light means the Ajazz AK820 is actively charging; a solid blue light means it has reached full capacity.
  • Charging from empty to full usually takes two to three hours with a standard USB power adapter.
  • The keyboard will not overcharge if left plugged in, but unplugging once the light goes solid extends battery lifespan.
  • You can use any USB-C cable and any standard USB power source — computer, wall adapter, or power bank all work.

What the light colors actually mean

The Ajazz AK820 uses a single LED indicator to communicate battery status. Blinking blue is the active charging state — this is what you will see the moment you plug in the cable. The blink rate does not change based on how full the battery is; it just blinks steadily while power is flowing in.

When the battery reaches 100 percent, the light switches to solid blue — no blinking, just a steady glow. This is your signal that charging is complete. Some users find the solid light easier to spot than waiting to see if the blinking has stopped, so glancing at the keyboard every 30 minutes or so during a charging session will tell you when you are done.

If the light is off entirely and the keyboard is not responding to key presses, the battery is completely dead. Plug it in and wait for the blinking to start. It may take a few seconds for the light to appear if the battery was fully drained.

How to charge without damaging the battery

Lithium batteries — the kind in the Ajazz AK820 — last longest when they spend most of their time between 20 and 80 percent charged. If you use the keyboard daily, you do not need to think about this. Charge it when it gets low, unplug it when it is full, and the battery will hold up well for years.

If you plan to store the keyboard for weeks or months without using it, charge it to about 50 percent and then put it away. This middle-ground charge is easier on the battery than storing it completely empty or completely full. When you take it out again, top it up before use.

Avoid leaving the keyboard plugged in 24/7 for months at a time. If you have a desk setup where the keyboard lives and you charge it daily, that is fine — just unplug it once the light goes solid. Heat also degrades lithium batteries, so keep the keyboard away from direct sunlight and warm spots like radiators or vents.

Charging speed and what affects it

The Ajazz AK820 charges fastest with a standard 5-volt USB power adapter — the kind that comes with most phones and tablets. Charging from completely empty to full typically takes two to three hours. If you use a lower-power source, like a computer's USB port, charging will be slower, sometimes taking four to five hours.

The battery charges more slowly as it gets fuller. The last 10 to 20 percent of the charge takes noticeably longer than the first 50 percent. This is normal and is built into the keyboard's charging circuit to protect the battery. It means the blinking light may seem to go on forever near the end — this is not a sign anything is wrong.

Temperature also affects charging speed. A cold keyboard (below 50 degrees Fahrenheit) will charge more slowly. If you bring a keyboard in from outside on a winter day, let it warm up to room temperature before plugging it in.

What to do if the light does not change

If you plug in the keyboard and the light does not blink after 10 seconds, the battery may be completely dead. Leave it plugged in for a full minute — sometimes a fully drained battery takes a moment to wake up and start accepting power. Then check again.

If the light still does not appear, try a different USB cable. The cable you are using may be damaged or may not support data and power transfer (some cables are power-only or data-only). A cable from a phone charger or another keyboard will work fine for testing.

If a different cable makes the light blink, your original cable is the problem. If the light still does not appear with a known-good cable, the keyboard's charging port or battery may have failed. At that point, contact Ajazz support with the keyboard's model number and serial number, which are usually printed on the bottom.

Using the keyboard while it charges

You can use the Ajazz AK820 while it is plugged in and charging. The keyboard will work normally — the light will keep blinking, and the battery will keep filling. There is no performance penalty or safety issue with typing while the cable is connected.

Some people prefer to charge overnight or during a break so they do not have to think about it. Others charge while working and unplug once the light goes solid. Both approaches are fine. The only thing that matters for battery health is not leaving it at 100 percent charge for weeks on end.

Frequently Asked Questions

Can I use any USB-C cable to charge the Ajazz AK820?

Yes. Any USB-C cable will work, including cables from phones, tablets, and other keyboards. The keyboard does not need a special cable. If charging is not working, the cable itself may be damaged — try a different one before assuming the keyboard is broken.

How often should I charge the keyboard?

Charge it when the battery gets low — most people charge every few days to a week depending on how much they type. You do not need to wait until it is completely dead. Charging from 20 percent to 100 percent is fine and is actually gentler on the battery than draining it all the way.

Is it bad to leave the keyboard plugged in overnight?

It is not dangerous — the keyboard will not catch fire or explode. However, the battery will last longer if you unplug it once the light goes solid. If you regularly leave it plugged in for 12+ hours after it is fully charged, the battery may lose capacity slightly faster over a year or two.

What does it mean if the light blinks red?

The Ajazz AK820 does not have a red light indicator. If you see red, you may be looking at a different keyboard or the light may be reflecting off something nearby. The keyboard only uses blue — blinking for charging, solid for full.

How long does the battery last on a full charge?

Battery life depends on how much you use the keyboard and whether the backlight is on. Most users get three to seven days of typing between charges. Heavy use with the backlight on may require charging every two to three days.