I am trying to build a circuit to emulate a lipo battery. Basically the circuit consists in a power supply to emulate the discharge behaviour and a variable load to eulate the charge behaviour. This is the circuit in a simplified way























This basically generates 2 circuits, one to emulate discharge behaviour (with which I don't have any problem) and one to emulate charge behaviour:



















The issue that I'm having with this circuit is that, when I am emulating the charging behaviour the voltage generated by the power supply (which I use in the charging stage to emulate the battery voltage when charging) some of it's current is leaking through the variable load as shown in the picture by "Unwanted current". This is making the sensing of the current to be off and obviously to wasted a los of power because of that unwanted current.






























Is there a way to "block" the current from going to the load? I thought of a diode in the load entrance but that will make the charging current to be blocked as well. Maybe some way to make the voltage coming out of the power supply to be only use as reference to maintain a battery charging voltage and not having that much current going through the load but how can I do that? Any suggestions?

Thank you in advance

 

Your circuit has a number of problems.

Lipo battery chargers are complex beasts, If you emulate the battery with a crude circuit, the results will be very inconclusive.

Have a peek at this TI application note.

https://www.ti.com/lit/an/slua999/s...41360&ref_url=https%3A%2F%2Fwww.google.com%2F