LOSSLESS SOLAR PANEL / LEAD ACID BATTERY ISOLATION

NachoSC said:

As far as I read the LTC4376 data sheet and with the application circuit shown on its page 10 data sheet "Lossless Solar Panel Isolation" -see picture- I could do it with the LTC4376 for the batteries isolation (12V), but in case of the solar panels due LTC's voltage range is up to 40V and the solar panels Voc is higher (almost 45V) I wonder if I if the LTC4376 will be damaged in that case and if there is another integrated ideal diode with a higher voltage range.

Operating range is 40V, but abs max is 80V. The LTC4376 should survive.

NachoSC said:

By the way, is there any way to "sense" (read) the Vout from Vin in the circuit shown? I mean is there any way for the solar panel charger/regulator (shunt regulator in the picture) to read the battery voltage when the LTC4376 is connected as shown? As far as I understand the circuit and in my experience, the solar panel charger/regulator needs to sense (read) the battery voltage and if the ideal diode is connected as shown the solar panel charger/regulator will not know the battery voltaget.

Can't you just take the solar panel regulator's sense pin and wire it to Vout (battery anode)?

Thanks so much!

Great news for me. I can use the LTC4376 to isolate all components I wanted.

I plan to quote some units with Seeedstudio.

Regarding the "sense" issue I think I didn't express it in the right way.

The inexpensive solar panel regulators I use (either PWM or MPPT) has the following I/O:

- 12/24 V Solar Panel Input

- 12 V Battery Output (Battery Charge)

- 12 V Load Output (Bulbs, ..)

If I connect the ideal diode between the 12 V Battery Charge Output in the solar panel and the 12 V battery, the regulator can't read the battery voltage ("sense" as I expressed it) then it is not switched on (must read 10V at lesst) and does not how to follow the charging cicle.

How to solve it? (in case)

Hope that helps.

In the first post, you say that you have successfully used the circuit with regular Silicon diodes.
The solar panel must have sensed the battery voltage through the diode, so it read ~0.4V high.
It should be the same if you replace the Silicon diode with an ideal diode.

Notice the direction of the body diode in the MOSFET of the LTC4376; even if the controller doesn't enhance the FET, the body diode can still conduct current from IN to OUT, so at worst you are back to your original situation.
When controller is off, the forward voltage is 700mV.
At low current, the controller regulates a forward voltage of 30mV.
At high current, the forward voltage is I_LOAD x 15mΩ (typ).