Switch for providing continuous battery or external power supply

Hello Digi-Key,

I have a mobile PC mounted onto a user mobile backpack. I currently have a set of charged lithium-ion batteries that supply power to the PC (20V / 100W) when in mobile mode. They last around 2.5 hours on continuous runtime. However, if I want longer runtime without shutting down the PC, especially when I’m continuously processing data overnight, I’d typically run on external power supply. 120V DC converted power supply that the PC generally runs off of.

What components can digi-key recommend so I can 1) charge the 100W USB-C batteries 2) run off the battery 3) switch to external supply without shutting down PC 4) charge battery while on switched external supply? Small form factor is preferred as everything is on a mobile user unit intended for moving around the lab or office.

Link for the batteries: https://www.amazon.com/gp/product/B094V37MQ5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Digi-Key User


The listing for the battery pack appears to indicate that it supports pass-through charging:


It is not especially clear what the capabilities of the device in this mode are, or if the constraints of USB-C power delivery would permit a recharge time for both devices which would be found acceptable.

Presumably however, the PC mentioned has a battery of its own which would be capable of supplying power for at least the few seconds required to disconnect the external battery pack and replace it with a standard power supply, which I infer to be using a USB-C interface. A second such supply could then be connected to the battery pack to recharge it.

Thanks, Rick. What is the device of the 2nd option you’re referring to? Can you point a link to something off the shelf that I can easily purchase to perform the quick switch-a-bility between battery & external supply?

This would be a thing that seems quite doable by hand, again with the presumption that the “mobile PC” mentioned is a device with an internal battery and power management facilities in the pattern of a common laptop computer or similar device.

HI @cedricwu You could most likely triple, or quadruple your battry packs and plug them all into eachother if they do allow pass through charging. IF you do not need your laptop screen on overnight, make sure this is off to save power by adjusting “when lid closed” settings.

IF this is too much battries, weight, expense etc, I would recommend going over to a LiPo chemistry, these are much more power dense than Li-on. using a 4S LiPo battry pack (14.8v nominal), ran through a power supply of some kind to regulate to a 20v output. You would have to make a connector adapter to align the plugs. Although most intelligent LiPo chargers have a “power supply” feature, some don’t so it is best to know if they do list this feature before purchase.

1568-PRT-16793-ND from Digi-Key would be a great option in conjunction with a 4S battry, but is only rated for 60W instead of 100W. This one specifies in the datasheet: “B6 V2 charger is integrated with DC power input, pumping max power of 60W with the voltage output ranging of 5-26V and 1-6A current. With this charger, RC drivers have a convenient gadget to power their DC devices in the field, such as tire warmer, PIT light, etc.”
-This one accepts 11-18v DC input (3-4S LiPo battry), can output a value between 5-26v (set to 20v in your case) up to 3A. (Power= voltage x current) = (3A x 20v = 60W)

Tenergy T180 100W Balance Charger Discharger, Touch Screen RC Battery Charger for NiMH/NiCd/Li-Po/Li-Fe Packs from amazon is rated at 100W, and “most likely” has a power supply feature, but it does not specify for sure.

I wasn’t able to locate a valid DC/DC Converter in our system, and the switching portion between outlet/battries would most likely involve jerry-rigging of some kind and most likely not something off the shelf.