Power Supply Switching & charging battery

[EEngineer93]

So my aim is create/find a circuit that will switch between 2 power supplies as follows:

1- When generator is [OFF] - The battery will power the load

2- When generator is [ON] - The generator will power the load and supply power to the charger in order to charge the battery.

Note: Switching between both supplies must be done simultaneously to ensure no interruption of power.

Thank you!

 

[betwixt]

This is a DC circuit - just use a diode (or MOSFET equivalent) to combine to the load.

Note that your charger needs a source of power exceeding the generator voltage and of course can't work off its own battery.

Brian.

 

[EEngineer93]

This is a DC circuit - just use a diode (or MOSFET equivalent) to combine to the load.

Note that your charger needs a source of power exceeding the generator voltage and of course can't work off its own battery.

Brian.

Why is more voltage needed from gen?

 

[KlausST]

Hi,

Again here I see no need for "no interruption". This just causes trouble .. at least in finding suitable solutions.
A simple capacitor will provide enough energy to cleanly switch from one source to the other.
"No time" is not a useful requirement. Consider a useful timing specification.

Diodes will work when generator voltage is higher than battery_charging_end voltage. This will be much higher than 24V.
Otherwise the charger may not be able to fully charge the batteries.

Usually charger_input comes directly from generator, not via the load_switching_circuit.

Klaus

 

[treez]

You just need high side FET switchs.
If its high current , then NFETs are better.
You may need some charge pump high side fet driver...or else just use a DCDC isolated module to provide the high side fet drive voltage.
Beware the diode in the fet. If necessary, use back-to-back fets so the diode in the fet cant conduct when you dont want it to.

Analog.com do some high side fet drivers...i think they call them "load switchs" or something

 

[betwixt]

Why is more voltage needed from gen?

Simply that you can't fully charge a 24V battery from a 24V source. It needs more voltage to allow current (charge) to flow in to the battery. You may also need some extra 'overhead' if a charge regulating circuit is used.

Brian.

 

[FvM]

For clarity, the charger supply connection should go directly to the generator.

By using a buck-boost converter for the charger you get rid of prerequisites for the generator voltage.