Hello: I built a circuit with MP2659 to build a small 4s battery charger. The schematic diagram is as follows:
Now the problem is: I use a 4s2p battery for testing, when the battery voltage is relatively high (tested 16.1V and 16.3V), when the circuit board is powered on and then connected to the battery, it cannot be charged, and the cable connected battery can be charged when it is powered on again. A 12V battery was tested, and it can be charged by connecting the battery after powering it on. Excuse me, is it normal for the above to happen?If so, what could be the reason? How do I debug? In addition, I found a EV2759A-Q-00A that I bought before, tested it and the phenomenon was the same. Could it be that this is how your chip is designed? Is it problematic that the battery cannot be recharged if it is not fully charged? Thank you
Hello,
Since you are using 4 series cells (4.2 approximately x 4) and you mention that your battery network is 16.1V - 16.3V, then your battery is already about 96% - 97% charged. Charge current tends to slow down or limits all together depending on what your full charge threshold is.
Since the 12V battery was charging, (12V / 4 series cells = 3V per cell) which is below the full-charge threshold makes sense. For your original 4 series cells, have you tried charging when these cells are deeply discharged?
Here is the typical application schematic for your reference. The only differences that I see would be the extra 47uF for Cin and Cbatt, which I don’t think should cause any issues. I would suggest testing with the deeply discharged battery. Let me know if this works.
Best,
Krishan
Hi，
Thanks for your reply。
I just tested that I connected a battery pack that was discharged to protect to the test board and it charged normally.
I also tested two battery charges, and the aforementioned phenomenon occurs when the battery voltage is around 15.8V.My battery pack voltage is 15.75V, the circuit board has been powered, and there is a probability that the battery will not charge when I connect the battery to the battery port of the charger. In this state, keep the battery connected, the circuit board can charge the battery by powering it back on
Interesting. Seems as if the battery charge regulation per cell is set lower than you think.
What is the lowest voltage this phenomenon occurs at for your battery voltage?
It sounds like you are hitting Phase 3 charging as described below at (15.8V or 15.75V / 4 cells = 3.95VV or 3.94V cell threshold for charging to either limit or stop.
See charging phases below:
Let me know if there are any updates from this information.
Hi,
I tried my MP2659 board and EV-2759A-Q demo board,it seems the voltage threshold is about 15.8V.I use TI BQ24610 before,and i have never met this phenomenon.
In addition, the following figure shows the discharge curve of our 4S2P battery. The approximate capacity of 15.8V should be about 80%. So it doesn’t exist because the battery voltage reaches the threshold (VBAT_REG) where the charge current decreases. Even if this were the case, the battery would be charged at a low current instead of stopping when it is connected to the charger, and there would be no situation where the battery can be charged or not depends on the sequence in which the battery is connected and the charger circuit board is powered on, right?
I have a video that I recorded at that time, and I can see this phenomenon in the video, and I don’t know how to send it to you? Can you provide an email address?
Thank you
