Lithium Ion Battery Charging / Discharging Currents

I bought an XTAR Dragon VP4 Plus charger and various 21700, 18650 and 16340 batteries.

I'm wondering what the correct charging and discharging currents I should use? For NiMH in my Maha MH-C9000 I use 0.5C charging and 0.25C discharging.
Also is it advisable to discharge lithium ion batteries before charging?

Many thanks!

Depends on type of liion battery. For lower load cells, charging at 0.5A is better, prolonging life of the cell. Also, you don't get a big improvement on higher currents. From battery university "Increasing the charge current does not hasten the full-charge state by much. Although the battery reaches the voltage peak quicker, the saturation charge will take longer accordingly. With higher current, Stage 1 is shorter but the saturation during Stage 2 will take longer. A high current charge will, however, quickly fill the battery to about 70 percent."

Not necessary to discharge before charging. Best to think in terms of optimum voltage. You don't want voltage to go too low or too high, both of which stress battery. If you can afford loss in capacity, don't charge all the way to 4.2V. If you can stop around 4-4.05V.

Read this article for much more info: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Distorted Vision said:

I bought an XTAR Dragon VP4 Plus charger and various 21700, 18650 and 16340 batteries.

I'm wondering what the correct charging and discharging currents I should use? For NiMH in my Maha MH-C9000 I use 0.5C charging and 0.25C discharging.
Also is it advisable to discharge lithium ion batteries before charging?

Many thanks!

Click to expand...

I can only discharge at 1A for my li-ions and NiMH, so that's what I use. I want to try and mimic the load of my lights, as closely as possible.

Chris

Distorted Vision said:

I bought an XTAR Dragon VP4 Plus charger and various 21700, 18650 and 16340 batteries.

I'm wondering what the correct charging and discharging currents I should use? For NiMH in my Maha MH-C9000 I use 0.5C charging and 0.25C discharging.
Also is it advisable to discharge lithium ion batteries before charging?

Many thanks!

Click to expand...

I would say you have this slightly backwards. I would reverse those numbers. Lower charge current, higher discharge current. I would not discharge Li-ions before charging. Deep discharge is not good for Li-ions especially every time. If it happens in use because you needed the light, that's one thing. But I would not do it intentionally every time.

XTAR chargers can autoatically choose the best charging current according to detect the batteries' type, internal resistance, capacity and voltage, and also the inserted quantity of the batteries.

The battery is typically charged at a constant current of 0.5 C or less until the battery voltage reaches 4.1 or 4.2 V (depending on the exact electrochemistry). When the battery voltage reaches 4.1 or 4.2 V, the charger switches to a "constant voltage" phase to eliminate overcharging. The constant voltage gradually reduces the current until it reaches around 0.1 C, at which point charging is terminated.

As the li-ion battery has no memory effect, you don't need to discharge it before charging. The VP4 PLUS has max 2.4A output current. Just do not exceed it and do not over-discharge your batteries.

InvisibleFrodo said:

I would say you have this slightly backwards. I would reverse those numbers. Lower charge current, higher discharge current. I would not discharge Li-ions before charging. Deep discharge is not good for Li-ions especially every time. If it happens in use because you needed the light, that's one thing. But I would not do it intentionally every time.

Click to expand...

I simply followed the manufacturer's recommendations:

https://www.mahaenergy.com/faq-c9000/

I have the following lithium ion batteries:

KeepPower 18650 3500mAh 10A
KeepPower 16340 700mAh 10A
Samsung 50E 21700 5000mAh 10A
Sony VTC6 18650 3500mAh 30A

As a general rule use 1A for charging 18650 LiIon batteries, if you know the specification you may be able to go higher.
For AA cells 1A is usually also fine.

Distorted Vision said:

I have the following lithium ion batteries:

KeepPower 18650 3500mAh 10A
KeepPower 16340 700mAh 10A
Samsung 50E 21700 5000mAh 10A
Sony VTC6 18650 3500mAh 30A

Click to expand...

If Keeppower is telling the truth (they probably are), then it's likely using a Sanyo GA cell. That's fine to charge up to 1.5 amps. You could push it to 2 amps if you want, though it's a bit harder on the cell.

The Sony VTC6 is a 3000mAh cell, and only 15A (or 20A if you monitor the cell temp and keep it under something like 75C). If the seller is telling you different, then I'm not sure I'd trust them. But if it's a genuine Sony VTC6, then 2 amps is fine, or 3 amps if you want to push it a bit.