【Update】 How does MX4 charger detect different battery types?
Smart chargers attempt to auto detect the battery type by the change of voltage. When you put the battery into the slots, the chargers will apply a small charging current (around 200mA) to the battery and observe the voltage. Due to different characteristics of the batteries, NiMH batteries will slightly boost the voltage under low current loading. As for healthy Li-ion batteries, the voltage will rise quickly. Then, the charger uses a short time to detect them again.
While, NiMH batteries and severely over-discharged Li-ion batteries may show overlapped voltage levels. It makes them challenging to be detected at first. Moreover, over-discharged high-capacity Li-ion batteries will require a longer time to be activated, around 5 to 10 minutes. To ensure accurate battery identification and avoid to identifying the over-discharged Li-ion batteries as NiMH ones, we set appropriate 10 minutes for detecting time on the MX4.
It’s important to share that the extended detection time won’t impede the charging process for NiMH batteries. Activation occurs together with charging, with a lower current. For those Li-ion batteries in good conditions, their internal cell voltages are between 2.5V and 4.2V. The charger will detect it and recognize it as Li-ion battery quickly.
There is the video by @Djani Again below. He used MX4 charger to revive some old over-discharged 18650 batteries and salvage them successfully. So how does xtar charger recover this kind of battery? Check more info here.
XTAR chargers use a specialized technique to detect and activate the over-discharged batteries. The process begins with the application of a small charging current (around 100mA). This gentle approach is crucial, to wake up and protect the battery. While, not all over-discharged batteries can be revived again. Batteries that have been deeply over-discharged to a point where their internal chemistry is significantly degraded cannot be recovered. This typically happens when a battery is left in a discharged state for a very long time or has been cycled far beyond its intended lifespan.
XTAR smart chargers can detect the over-discharged battery. It ensures the Activation process is initiated when necessary. Besides, the chargers are equipped with state-of-the-art circuitry and firmware that optimize the charging process for various battery conditions. All of these enhances the battery recovery rate.
To ensure your batteries’ performance and longevity, it’s always important to maintain them properly.
Fairly safe with modern cells. They just get some damage as in capacity loss, and may have higher self drain. Otherwise fine. Their recovery is the challenging part. Great that the MX4 has a smart mode for this. Less avoidable waste of good batteries.
Relatively safe, though there’s a higher probability for there being irreversible cell damage the deeper it is discharged, like capacity loss or a high self-discharge.
For example I had a 14500 (won’t name the brand as it’s not their fault) that got overdischarged and drained itself back to 1v only a week after recharging, while I’ve had some cells end up fine, with only some capacity loss.
The MX4 starts with a 200mA pulse current and continues to charge with a 500mA pulse current. After 5 hours 40 minutes, it appears to have 0dV or -dV detection to switch to a stage where it spends another 2 hours topping the cell off.
I’ll see if I can plot the average current. The top off current looks a bit high at first glance but the average could be 50mA instead of 500mA.
Bluetooth connectivity to one of my digital multimeters dropped out for a few minutes around 7 hours 40 minutes so there’s a small gap with the voltage measurements.
The eneloop pro AA cell is a bit older compared to the LADDA cell that I tested. The charging profile looks very similar.
Success! There was a 200mA trickle charge (TC) for the first 20 seconds where the voltage increased from 2.86V to 2.91V. The charging current then increased to 1A. This is the TC-CC-CV charging method in action.
