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Power supply won't go into CC mode when charging li-ion cells with series diode.
tylerssims:
Hi all,
I have a Kikusui PMC 18-5A power supply. I am trying to charge an individual li-ion cell with it. I've watched this video by Dave (https://youtu.be/jNmlxBXEqW0) where he sets the current limit to 1.7A and voltage limit to 4.2V and the supply works in CC mode until the cell reaches 4.2V and switches into CV mode. My cell has the same charging parameters.
When I connect my cell to my supply I can get the supply to work fine in CC mode like described above. However, in the Kikusui manual, it recommends using a diode in series with the load to protect the power supply. They recommend for the diode to have a reverse voltage withstand capacity at least twice
the rated output voltage of the power supply, and the forward current capacity to be three to ten times the rated output current of the power supply, I am using this diode: https://www.mouser.com/ProductDetail/821-SRAF1640HC0.
However, when I put the diode in series with the battery cell, the load will remain in CV mode and wont draw more than an amp.
How can I use a diode to protect my power supply while still operating in CC mode? Can I use the remote sensing feature of my power supply to fix this? Or can I choose a diode that has less resistance?
Seekonk:
You will have constant current, but not constant voltage. The added forward voltage drop of the diode will not be constant and will vary with current and temperature. When charging just one cell that is significant.
bdunham7:
You can just turn the voltage up to 4.4V and you might get your CC operation. The voltage drop across the diode should be more than 0.2V down to 100mA or so. Remote sensing should also work, but be careful to make sure the wiring is solid otherwise you might fry your battery--losing the remote signal may cause the power supply to go to full output.
BeBuLamar:
The voltage drops across the diode is more than 0.5V so you will have to increase the voltage by that much.
Fungus:
What do you get if you measure the voltage on the battery?
--- Quote from: tylerssims on December 29, 2022, 07:33:21 pm ---Can I use the remote sensing feature of my power supply to fix this?
--- End quote ---
Answer the question above and you'll find out...
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