I’m trying to figure out the most efficient path to get to a 12…15V variable voltage output from my new (not even arrived yet) EB3A. The product specs list an AC output, 12V-10A DC from a couple of different plugs, 5V-3A from USB-A and a slightly mysterious USB-C option that is supposed to provide up to 100W of power and be able to charge a laptop, which I interpret as 20V-5A.
Now, since the underlying batteries are nominally 22.4V, it would seem best to go from that straight to USB-C and, through the modern wonder that is Power Delivery, request whatever voltage I need between 12V and 15V from there. Or, if granular voltage control is not supported in the PD implementation inside the power bank, get 20V and step down to what I need (assuming that stepping down is more efficient than boosting up – I’m not an electrical engineer, by the way, so correct me where I go astray). But if the whole DC portion of EB3A, including PD, is wired through 12V, then going through PD wouldn’t provide any efficiency benefit. Hence the question in the title: How is the USB-C output wired inside EB3A, and what PD protocols does it support?
If we get to the bottom of this, I think the information gleaned would be a great fit in the specifications documentation of the device.
Inside the EB3A the USB-C DC/DC is supposedly a buck step-down non-isolated converter. The 12/13 V cigarette plug supply and PD supply are located into 2 separate rails on the battery bus.
The USB-C being advertised as 100 W is at least PD so you should select its 5/9/12/15/20 V output voltage by using an adapter that supports the protocol.
Therefore, since you need a 12-15 volt variable voltage your best option will be to use an USB-C to DC adapter, to directly use the internal USB-C converter to get the voltage you need, that is to avoid to use a boost converter on the cigarette plug to elevate the voltage from 13 to 15 since it would result in more inefficient losses through unnecessary conversions.
You can search for “usb-c pd module” or “usb-c pd trigger” on eBay or Aliexpress to find something that could suit your needs.
The PD fast charging protocol of EB3A supports PPS/PD3.0/PD2.0/QC4+/QC4/QC3.0/QC2.0.
The battery voltage will be passed through a voltage reduction circuit for output, and the output voltage depends on the voltage requirement of the load.
Thank you both very much for your answers! The fact that it supports PPS is very good news, and since it’s a separate rail from the 12V DC output, it should be reasonably efficient as well.
May I recommend again that these facts would be a good addition to the spec sheet / user manual of the product?
Suggestion received, I’ll forward it to the relevant department. :)