Adjusting voltage on charger

HrKlev

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Dec 6, 2019
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Hi

I have a YZPower 10A 20S charger Im using to charge a 20S battery made up from LEV40 cells. I want to cut charging at 4.1V per cell, so about 82V. I opened it up, and found 4 different pots. I found instructions somewhere on the web for which one I should adjust, but I can not get it lower than 83V. So far I have used the BMS to cut the charge at 4.12V (I think, cant remember exactly right now), and the cells settles for just under 4.1V. I works OK I guess, but the charger never gets into CV state. Is there any way to fix this issue? Can I change the potmeter to so I can get a wider adjustment range? What are the other 3 pots for?
 
1V difference over 80V is hardly worth worrying about

Especially with the risk of messing up your charger.

If you are staying lower intentionally for longevity then there is no reason to hold CV.

In fact going a little higher on CC-only HVC based charging is a normal strategy to get to a target "Full" SoC without holding any CV.

Just make sure you can take care of balancing within the charge profile you want.
 
Alright, thanks for the input. I'll just keep using it as is, then. I have set the BMS to start balancing from 3.8V, but these cells are so well balanced from factory (they all come from the same low mileage phev battery pack) that I have never seen BMS doing any balancing at all. Hopefully they keep decent capacity for some years :)
 
HrKlev said:
I opened it up, and found 4 different pots.....What are the other 3 pots for?

I have a similar situation with a similar charger (4A version).

Like you said, one of the trim pots can adjust the voltage limit, within about +/-1V, but not enough to get down to 80-82V. Changing the pot probably won't help. There are other resistors in the voltage reference side that would need to be changed to lower the output further. But it's not obvious after a brief look at the circuit board unfortunately.

It looks like there are 2 channels in parallel. The little vertical PCBs and SMD components make it difficult to trace the circuits, and I haven't had time to spend on it.

If anyone else has experience adjusting these types of charger, please let us know. Thanks.

HTB10wSNbqSs3KVjSZPiq6AsiVXaV.jpg_640x640q90.jpg
 
Hello, I've also got a similar situation with a similar charger. It is marked "YZPOWER-600" on the case and "YZ300" on the PCB. I would like to decrease the charger output voltage from 87.6V to 86V. The lowest I can get it to go by adjusting the trim pot is 86.8V.

Back side of the board showing where I added a white wire
IMG_20210327_122430.jpg
IMG_20210327_122324.jpg
IMG_20210327_122259.jpg
IMG_20210327_122352.jpg
3.3k ohm resistor near each trim pot (photo taken before adding white wire)
IMG_20210327_082942.jpg
IMG_20210327_083047.jpg

You can see where I added a white wire to make it easier to add more resistors in etc... I tried adding a resistor in line with the white wire but it seems to have no effect on output voltage. Any ideas how I can lower the output voltage?
 
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