I've had more than a few requests to talk through some of the pass-through charging configuration options open to kLite-ers when using the Voltaic battery line (e.g. V25, V50, V75) and thought I'd put up a shots of potential configurations.
This configuration depicts the elements of a kLite gravel kit --with the gravel ULTRA lamp, Dual USB charger, and a USB "always on" wire loom, along with a few extras to make the cockpit description fun. The gravel lamp and Wahoo GPS are connected to the BarYak Titanium aero bar with a specially modified Corki 22.2 Aluminum computer mount / GoPro lamp mount. The kLite Dual GPS is mounted to the inside rail of the BarYak XL with zip ties and a velcro strap--underneath the stem-mounted iPhone connected with a Quad Lock case and mount system.
For daytime riding, I generally keep a Voltaic Systems V25 or V50 plugged into my kLite dual USB charger and then tuck it into one of my waterproof handlebar bags. That way, it is out of the elements and is out of sight / out of mind. If I have a need for charging during the day, I'll use the in-line charging feature and run a line out of the handlebar bag to my iPhone or GPS.
At night, I stop charging the battery and run 100% lamp or if my GPS is low, will charge the relatively low draw GPS directly from the kLite Dual USB Charger while running the lamp. By nighttime, my batteries are generally charged up from the day's riding and I save them for direct-charging my iPhone or inReach, or for simply maintaining a margin of safety for my 100% electronic navigation lifestyle.
In the picture, I have the Voltaic Systems V50 in "exposed - bike path / beautiful day mode" with it securely Velcro-strapped to the BarYak crossbeams. Only really ride this way if you're pretty sure you're not going to experience a rain shower or a super bumpy descent. I've also used Voile Straps to secure the unit, but it's a little overkill in today's bike path mode! Before I stopped to take some pictures, the V50 was being charged by the kLite dual USB charger and providing in-line charging to my Wahoo unit, which was running a bit low from my weekend adventures.
The cool red "shorty" cable is one that comes with the V50 unit, and it's really useful for keeping the cockpit connections short and tangle free. The cable running into the Voltaic V50 unit from the kLite Dual USB Charger is a Titan Cable braided unit that has a LED enabled plug that glows green when it's charging. It's a nice late night companion that lets you know your dynamo hub is doing its business!
If you're going off the grid, you'll want to keep a duplicate of every type of cable that you run. Trail vibration, rain / mud, and good-old-fashioned friction has a funny way of killing just about any type of cord over time. One of the cool things about the Voltaic units is that they offer port redundancy. You can charge them with a micro-USB or USB-C cable, and you can draw current from either of the two USB-A ports. This gives you a lot of flexibility should cable gremlins start giving you trouble out in the wilderness!