Connect PowerSupply+Inverter at the same time (ground loop)

[ProfLinux]

Hi again,

I would like to charge a LiFePO4 battery using a switching power supply and use a SoyoSource inverter to get the stored energy back into the grid later - both controlled via a raspberry pi. So both the power supply as well as the inverter are physically (galvanic) connected through the battery poles.

So while the inverter is working the power supply will be set to 0Amps and vice versa, but they will still be connected all the time.

Could this be a problem in regard to ground loops?
Or should the inverter in theory even work when it is fed by the switching power supply (of course does not make sence except generating 25% heat).

Thanks & best regards

 

[sunshine_eggo]

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...

diysolarforum.com

When using a power supply, there may be a concern with backflow of current from the battery to the power supply if it doesn't have diode protection. Some sources are not intended to be connected to other sources and may be damaged.

Ground loops should not be a problem provided the switching power supply has the correct input type and are wired correctly. Many power supplies like Meanwell can accept 120 or 240V input; however, that's always SINGLE PHASE where the G is expected to be bonded to the N. If you power a single phase 240V switching power supply with L1/L2 on split phase, you must NOT connect the ground.

 

[ProfLinux]

When using a power supply, there may be a concern with backflow of current from the battery to the power supply if it doesn't have diode protection. Some sources are not intended to be connected to other sources and may be damaged.

Good to know, I have to admit I haven't thought about that. What is a good solition to solve this - is a shotky diode like MBR60200PT the best solution? Are there better types where I loose less voltage?

The switching power supply as well as the inverter are both single phase would be connected to the same phase / neutral / ground.

 

[sunshine_eggo]

Schottky diodes work, and the voltage drop isn't an issue provided you have the surplus voltage.

MBR60200PT in particularly looks like the specs check out, but it needs to be mounted to a heat sink.

Some PSU are fine with being connected to a battery. You don't know how it will fair until 1) you try it or 2) confirm it has reverse polarity protection or reverse current protection by spec or via wiring diagram.

Lastly, if you always energize the PS before you connect to the battery and after you disconnect from the battery, the likelihood of reverse current is reduced.

 

[ProfLinux]

Schottky diodes work, and the voltage drop isn't an issue provided you have the surplus voltage.
MBR60200PT in particularly looks like the specs check out, but it needs to be mounted to a heat sink.

I've a bit headroom regarding the voltage, but every V means lost efficiency .
The switching supply only has 85%, the inverter is spec'ed at 90% ... losses with my cheap components seem to accumulate quickly

Some PSU are fine with being connected to a battery. You don't know how it will fair until 1) you try it or 2) confirm it has reverse polarity protection or reverse current protection by spec or via wiring diagram.
Lastly, if you always energize the PS before you connect to the battery and after you disconnect from the battery, the likelihood of reverse current is reduced.

I just contacted the seller and he mentioned no reverse current protection is built in and I need a diode.
Thanks for the hint, I would have never thought about this and probably cause a PSU to go up in smoke...