I made this adapter to get 4 Quickcharge ports out of my Einhell battery. With this the battery is transformed to a very powerful powerbank. You could quickly charge 4 smartphones or use 4 TS80 (successor of the TS100, not tested).
Edit 2019-07-19: Tested it with the TS80, works like a charm at 12V with Ralims Firmware. :)

BOM:

• 4 (or 2) QC3.0 USB DC-DC Buck Converter https://www.aliexpress.com/item/QC3-0-QC2-0-USB-DC-DC-Buck-Converter-Charging-Step-Down-Module-6-32V-9V/32887717476.html
• Crimp male spade connectors https://www.aliexpress.com/item/100pcs-50pairs-6-3mm-16-14AWG-Female-Male-Electrical-Wiring-Connector-Insulated-Crimp-Terminal-Spade-Blue/32846771914.html
• 4 M3 screws, 6-12 mm length
• some hot glue

I printed it without support, but if your printer is not well tuned for bridging you might need support.

The top holds the USB modules in place without any screws. For the assembly i glued them down to get the top easily on.
You'll need to snip off the plastic things on the USB jack (see photo).

I've also attached a version with only 2 ports and the Fusion 360 project file.

PS: If i am not mistaken, it makes no sense to extra buy a Einhell battery just for this (maybe except if you need a lot QC jacks). A 20 Ah powerbank has 74 Wh (20Ah * 3.7V) and costs 20-30€, the battery in the picture has 54 Wh (3Ah * 18V) and costs 30-40€. I think this comes from the fact, that these tool batterys are made to deliver a huge amount of power in a short period of time. According to the support of Einhell, the battery can deliver 70A.