0
\$\begingroup\$

I would like to use a pre-assembled 12V-rated LiFePO4 battery pack such as the one advertised here. Due to nature of intended use I'm currently focusing on a charging setup where the load is connected to the battery while it is being charged. If I understand correctly in such a case a battery might consume most of the current from the energy source (e.g. solar panel via charger) while the remaining is consumed by the load.

enter image description here

The problem with the battery packs advertised is that a more detailed information, such as whether this configuration is allowed, isn't given. Therefore I'm wondering whether can I simply assume all such battery packs with internal BMS are capable of just that? Or is that likely not the case? Could it happen that battery internal electronics would recognize this situation as faulty and would disconnect the battery?

On the other hand, should I not find a pre-assembled battery pack that allows a load to be connected to it while the battery is being charged, I would aim for assembling individual cells on my own with either ready-to-go BMS board or designing my own. In either case this second option is more cumbersome and would prefer to go with a budget battery pack if it would allow such charging scheme.

\$\endgroup\$
3
  • 1
    \$\begingroup\$ you cannot charge a battery and discharge it at the same time ... current flows in only one direction ... the power supply powers the load, with excess being used to charge the battery \$\endgroup\$
    – jsotola
    Commented May 22 at 6:24
  • \$\begingroup\$ @jsotola I used bad wording but what I meant is that some portion of energy being consumed by the load and the rest is invested into battery charging (or discharging if load consumes more than the energy source provides). \$\endgroup\$
    – lucenzo97
    Commented May 22 at 16:27
  • \$\begingroup\$ @jsotola Just did. Please check if it needs further clarifications/corrections. \$\endgroup\$
    – lucenzo97
    Commented May 22 at 16:58

1 Answer 1

Reset to default
2
\$\begingroup\$

Passthrough mode

"Passthrough" mode is defined for battery power banks that are equipped with one charging port and one discharging port. This makes sense to indicate if both ports could be used at the same time.

Therefore I'm wondering whether can I simply assume all such battery packs with internal BMS are capable of just that? Or is that likely not the case?

Your battery

Regarding the battery mentioned above, there is no such thing as charging while discharging. The battery is either charging OR discharging, like any common Lead-acid battery with the same format. The internal BMS (which is more likely a cheap PCM rather than a true BMS that would give you the exact SoC for example) is only there to protect Lithium cells against overcharge/discharge and cell balancing and thus allows a similar use as any nimh or lead-acid battery.

Your use case

Regarding your solar panel use case there are some ways to design your system to make your battery charge from the panels and connect your charge/application to the battery at the same time. It will work this way:

  • Your load draws a power less than the one generated by your panels: the battery will be charged while your load will be power by panels.
  • Your load draws a power greater than the one generated by the panels: the battery will be discharged by the amount of power above the one generated by the panels.

More details regarding your use case should be asked in another post I guess.

Hope it helps.

\$\endgroup\$
1
  • \$\begingroup\$ The last section is what I had in mind. I messed up when I said charge and discharge simultaneously. What I meant is what you stated with the first bullet point. So the main point here is whether could I assume such charging scheme is doable with a battery that has internal BMS? I think in the worst case the internal electronics might recognize such situation as a faulty event and would disconnect the battery from externally accessible contacts. Hopefully this wouldn't happen. \$\endgroup\$
    – lucenzo97
    Commented May 22 at 16:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.