The power adapter makes pulling power from a 4S pack's JST-HX balance port and converting to an XT30, easy.
This mates perfectly to a JST-brand XH connector (used for the balance connection of a battery pack). There are other types of balance connectors, battery folks use whatever flavor suits them. Thunder Power, for example uses one, Hyperion uses another, Traxxas uses another, etc. This one is for the JST XH connector.
They exist on batteries to make it easy to bleed off voltage from cells that are fully charged as the remainder of the pack continues charging, and as the connector for taking a pack to storage voltage. But it's a way to tap into the pack for another use (but not servos).
This one is for a 4S battery meaning 14.8V (because 3.7V/cell x 4-cells = 14.8V). And yes, you can trim this XH with an X-Acto and fit it up to a 6S pack - but - it's still only going to draw from 4 adjacent cells of the 6-cell pack (meaning 14.8V no matter what). We mention this in case you need 7.4V (2-cells) or 11.1V (3-cells) because we have 2S and 3S versions (ending in XH2 and XH3, respectively) instead of XH4 like this one, so heads up!
Problem
You want to power something using an XT30 and all you have available is an XH connector. These pins are larger than what's on a servo so guys ask for this thing. A buck's a buck and we're in business to make them so if enough folks ask, maybe we produce a solution. That's what this is.
Solution
This adapter lets you tap into the XH (usually the balance port of a battery pack) and convert to an XT30 expressly to draw off 4S-power from the pack, e.g. 14.8V. What's it really good for?
Downside - or be careful what you wish for!
Look, this may strike you as a strange way to sell something but there's this . . . just because we offer a way to do something doesn't mean you 'should' use this doohickey for what you want to do. Why not? Because everything has a downside.
Let's say you want this to power a winch for a 4WD rig, or maybe a fan, or LED lights, or an additional cooling fan then feel free to add this doohickey to your cart because it's perfect for this purpose. In short, you've found a great little accessory for your rig.
However, because our shtick are servos, maybe you've found this thing and hit up on the bright idea of using it to power the servo off the propulsion pack - like a poor man's BEC. Bad idea. We make servos and probably know more than you and our advice is . . . don't!
Put another way, if you want it to power a servo off the propulsion-pack, then watch out because there are significant downsides (more than one). Tapping into a propulsion pack to power your servo will, on the surface seems like a great way to power a 2S servo, but we think you should think twice. Why?
Obviously, because it's diverts battery life from propulsion to control. This costs you run time. So what? Doesn't the BEC also cost you run-time? Yes, it does, but this brings us to another downside (true for a BEC as well).
Exactly as with a BEC, the 'what's wrong with powering a servo from a propulsion pack is this; it exposes the control system (your servo) to the dips in voltage caused by the power system drawing down voltage. And it gets worse because it also lets ripple (bad news) get to your system. When does this happen? Every single time you accelerate and decelerate the rig!
For example, there you fat, dumb, and happy powering through a corner using throttle blips to balance the rig during a power-slide. Beautiful, life is good, right? Nope, because 'every' time you blip the throttle, the voltage of the propulsion pack goes down under the load. And because a servo (any servo, any brand) responds differently depending on voltage (look at the Specs TAB to see torque and speed varying with voltage input), then every time you blip the throttle, the servo responds differently.
So this begs the question; are you good enough to notice? Well, that we can't say because we don't know you (meaning how good a driver you actually are). However, many (most? all?) experienced drivers will definitely notice variable output based on variable input. Beginners? Not so much!
And yes, this also happens with a BEC (which is why they're given away with ESCs to beginners who can't yet tell the difference). But take note, a BEC is actually worse than a battery because the battery is analog voltage while the BEC is faking it digitally. Bad juju all around in our opinion but people are lazy.
Worse about a BEC, however, is it also gives you ripple (look it up, it's not the alcoholic beverage we're talking about). Ripple may actually cause damage. That's right, a BEC can kill the electronics of a receiver (or servo, which is all we care about), and this is due to voltage spikes - something manufacturers of those things are careful to not mention. Just saying.
Anyway, a servo responding to a variable input is exactly like carrying a heavy weight whilst walking on shifting sand - you can do it but it's not as easy as walking on solid ground. OK, so maybe you don't care. Then go ahead and buy this thing because as long as you're taking into account all we've said about (the mere fact we make something available, doesn't mean you should use it it for what you want), then we're good with taking your money. Just please don't come back later and say, 'Why didn't you warn me?!?'
And kindly take note, if you want this to power a servo instead of a winch or LED lights, there's a better way.
Dedicated pack
A better way to power the steering servo, THE BEST WAY, is an alternative we offer (along with everybody and their brother) is just buy a battery pack to power the servo. A battery is a perfectly clean analog source that can't be made better using digital electronics. Why? Simple, because now your control system (the receiver, servos, even the input of the ESC) sees a more steady voltage source. One without the dips and ripples associated with siphoning current off the the propulsion system.
Anyway, we offer dedicated 2S packs ranging from 850mAh to 6000mAh . . . with most pros opting for the 2000mAh packs as the best compromise between price, size, weight, and run time.