EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Nikolas on May 20, 2020, 03:47:17 pm
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Hey, so I am trying to design and build my own battery charger for 4 cell LiPos (including HV-LiPos with 4.35v/cell) but I don't have a lot of experience with circuit design.
I designed this circuit so that it can either supply a constant voltage or constant current to the battery with the other one being a backup.
I use OPAMP_current and OPAMP_voltage to control the corresponding mosfets, with the reference voltage being supplied by DACs which will be controlled by a microcontroller.
For measuring current I use a small resistor in series with the load and a current-sense-amplifier which amplifies the voltage drop across that resistor.
For measuring voltage I use a voltage divider.
Since both measurements are sensitive to loads being applied to them I use additional opamps as voltage followers and read their outputs with the microcontrollers ADCs.
The 100ohm resistors across the inputs of the control opamps are there to limit the overshoot for example when the battery suddenly gets disconnected. (found that idea on the internet and it works in simulation, not sure if it's a good way to do that though)
Regarding balancing of the cells, I will probably just copy one of those balancing boards that you can get for a few bucks on ebay.
My question is, would this circuit work the way it is and if it would, are there any things missing that would improve reliability or are just good practice?
Thank you,
Nikolas