Power pack connections

[Mathieu]

Hello!

I want to make a little power pack for camping, and I don't know how I should connect the power distribution modules.

When I connect the power supply, I want it to charge the batteries automatically if needed and I want the PD modules to use the current from the power supply.

And when the power supply is disconnected, I would like to use the current from the batteries.

Is my schema correct? Is there a better way to do it?

And can I use MOSFETs (with a microcontroller) to alternate the connections?

Thanks!!

---

 

[Harald Kapp]

Always use power from the battery. No switching of connections required. When connected to primary power, the power supply will keep the battery charged and, if required and sufficient power is available, will supply the load, too. IF maikn powre is insufficient, the battery will supply the rest.

 

[Mathieu]

Always use power from the battery. No switching of connections required. When connected to primary power, the power supply will keep the battery charged and, if required and sufficient power is available, will supply the load, too. IF maikn powre is insufficient, the battery will supply the rest.

Danke!

Is it possible because of the BMS?

And it shouldn't be bad for the batteries if enough current is always available from the power supply when connected to AC?

It would make everything much easier if I don't need to add switching components "everywhere".

 

[Harald Kapp]

This should be entirely possible. The BMS has to handle this situation anyway when no external power is applied.
And it is not bad for the batteries because as long as external power is available it will be used.

 

[Mathieu]

This should be entirely possible. The BMS has to handle this situation anyway when no external power is applied.
And it is not bad for the batteries because as long as external power is available it will be used.
View attachment 58136

I just realized, the PD modules cannot be connected to the buck converter, they would be limited to 4A during charging?

And I guess the charge would be impacted too?

So they have to bypass the buck converter when the batteries are charging?

 

[Harald Kapp]

I beg to excuse my oversight of the 4 A limit.
Assuming, as is usually the case, all your modules have a common ground ("-", you can use 2 diodes:

If there is power from the power supply, the lower diode will provide power to the PD module. No current can flow back intoi the BMS or Buck converter becaus the upper diode is non-conducting.
If there is no power from the power supply, current will flow through the uppe diode into the PD module. No current can flow back into the Buck converter or the power supply because the lower diode is non-conducting.
The diodes need to be rated for the max. expected current into the PD module - a tad higher won't hurt and you'll be on the safe side.

 

[Mathieu]

I beg to excuse my oversight of the 4 A limit.
Assuming, as is usually the case, all your modules have a common ground ("-", you can use 2 diodes:
View attachment 58179
If there is power from the power supply, the lower diode will provide power to the PD module. No current can flow back intoi the BMS or Buck converter becaus the upper diode is non-conducting.
If there is no power from the power supply, current will flow through the uppe diode into the PD module. No current can flow back into the Buck converter or the power supply because the lower diode is non-conducting.
The diodes need to be rated for the max. expected current into the PD module - a tad higher won't hurt and you'll be on the safe side.

Excellent

Thank you very much, it's better than using relays!

I will maybe use some MUR6060BS-BP (600V 60A), it's surely a crazy choice but it should easily last forever

 

[Mathieu]

If I understood well, it's very not sure, this should be good?!