I have a powerbank, which can provide power on its single typeC port. Provided power is PD-capable: voltage and current can be negotiated by the standards.

The powerbank itself can only be charged up on the same typeC port.

Currently I have:

  • charger with 2 typeC output
  • powerbank with typeC in-out
  • a desire for a single typeC output ("GOAL") which works by my preferences below.

"GOAL" is a kind of multiplexed output from the charger and the powerbank:

  • in case charger doesn't provide power (because it is not connected to mains), route the power from the powerbank to "GOAL"
  • in case charger operates, route charger's typeC1 to powerbank AND route typeC2 to "GOAL"

This is a simple "routing" rule, but PD has many pins, and huge currents.

I am looking for the way to make this happen, and was pretty sure there are modules exist for this purpose, but I couldnt find any.

Any help would be appreciated, any module, any IC, and any circuit would be a great help if you have any.

Too much 'any' I know. I tried to search, but my Google is sticking to my earlier searches and giving me faulty results constantly.

  • \$\begingroup\$ I wonder if it is easier to make your own double-conversion power bank. \$\endgroup\$ Jun 29, 2022 at 16:40
  • \$\begingroup\$ Is there a device which has a PD input, and (i.e.) 4 PD outputs and a select button which can select the desired output direction from the 4 outputs? \$\endgroup\$
    – Daniel
    Jun 30, 2022 at 7:30

1 Answer 1


There are some battery banks with dual type-C PD ports but they recommend "Avoid charging and discharging at the same time. It could damage the battery and decrease lifespan."

This is what can happen when you want to multitask charge and load ports.

In order to protect the battery from extended time in CV mode, (the final stage of charging), the banks need to sense both charger current and battery current separately and make intelligent decisions during CV mode. Normally the cutoff for charging is 5% of the CC value but if an external load draws more than this, a single current sensor would never shut off. To do this intelligently requires some memory of battery history of how much of the 2nd layer* charge has been used and how much time has been spent during CV mode and how hot the battery is.

Since reliability is more important than this feature, not everyone might benefit from the added cost. But you may find what you are looking for by searching for other battery banks with dual type-C PD ports.

Many resources such as Battery University will support why this also significantly reduces the lifespan for the additional capacity.

This EDLC effect is primarily used to describe Supercaps but also exists in all secondary batteries including Lithium Ion. I also know that except for NPO, all ceramic caps have some memory effect and are rarely used for S&H apps.

  • \$\begingroup\$ "Avoid charging and discharging at the same time. It could damage the battery and decrease lifespan." - Why they allow it if it should be avoided? :) \$\endgroup\$
    – Daniel
    Jun 30, 2022 at 7:15
  • \$\begingroup\$ I have this one from Aukey: PB-XD26. It can provide power on its USBA output while it's being charged from its USBC. I think when it's being charged on USBC, it routes the power from the charger to its USBA output, and at the same time onto its charger circuit. This way battery is prevented from being concurrently charged and discharged. \$\endgroup\$
    – Daniel
    Jun 30, 2022 at 7:18
  • \$\begingroup\$ "battery banks with dual type-C PD ports": this search gives me all kind of banks with single typeC and dual A, single typeC, single A, and the only bank with dual typeC is the one you linked in the first line. It seems there are not too much options out there :) \$\endgroup\$
    – Daniel
    Jun 30, 2022 at 7:23
  • \$\begingroup\$ HINT: put quotes around the key 4 words, that's how to refine your search \$\endgroup\$ Jun 30, 2022 at 13:11

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