The ThinkPad Power Bridge is dead (and why that’s a good thing) — Part 2
If you haven’t read Part 1, I encourage you to do so here and get a primer on ThinkPad history and how “Power Bridge” came about.
In Part 1, we left off lamenting the loss of Power Bridge in all but the T480 and T580/P52s models in the latest line of ThinkPads. Now, we’ll talk about why the loss of Power Bridge is inconsequential when we have USB-C. The addition is a loss for Lenovo’s profit margins, because instead of being forced to buy their proprietary rear battery, we get the choice of “race to the bottom” manufacturers building great power banks that can output far above the full system TDP of ThinkPads supporting USB-C. We’ll take a look at why that last bit is important in a second.
There are a few primary arguments I see against the replacement of Power Bridge with battery banks. The main ones can be summed up by the following three points:
- Banks are big, heavy, and bulky
- Frequent wear of internal batteries degrades them
- Banks have to charge the ThinkPad
In reality, none of these are objectively true, with the last one being categorically false (more on this later).
Banks are big, heavy, and bulky
With the removal of Power Bridge, you now need to carry additional accessories in order to make up for the battery deficit. This is completely true, but what is often overlooked by rear battery proponents is the fact that removal of said battery actually causes the base footprint of the device to shrink considerably. It’s about choice. You can choose to opt out of accessories and miss out on the additional run time, instead having a smaller device. You can choose to get higher capacity by bringing accessories with you. Power Bridge also gave you choice, but it pigeon holed you into a proprietary battery, and with just the rear 3-cell, most devices had 48Wh. While the X280 still has just 48Wh, the other USB-C supporting devices have gotten a modest bump up to 57Wh. In the case of the X280, its footprint was significantly reduced with the change, much like the T460s was when it ditched Power Bridge. The bottom line here is that instead of being forced into expensive proprietary accessories, you are now able to bring your own brand to serve as an external battery.
Frequent wear of internal batteries degrades them
Using the same battery more often causes it to wear down and degrade. One of the larger issues with internal batteries is that replacing them is simply harder, and in UltraBooks it has to be done more often over the lifespan of the laptop because of how much smaller the battery capacity is in the first place. Because of the removal of the rear battery, you’ll end up with more charge cycles, faster, compared to the Power Bridge system. Lenovo luckily makes it quite easy to replace its internal batteries, as for the last few years it has become as simple as unscrewing the back panel, a few screws holding the battery itself in place, then disconnecting the battery and connecting a new one; but this doesn’t excuse having to more frequently replace batteries that you otherwise wouldn’t have to — replacing a rear battery is much simpler. Luckily, you don’t have to wear your internal battery more often, because power banks don’t have to charge your internal battery.
Banks have to charge the ThinkPad
What has essentially become the crux of the argument against removing the Power Bridge feature is the fact that it takes time to charge your internal battery with a bank. This causes you to put more wear on your battery because it leads to more cycles — as mentioned above, it simply leads to trashing your battery significantly faster if you have to use it more often, and you generally want to replace your internal battery as little as possible.
But what if I told you that your Power Bank can be functionally identical to a rear battery? Well, it can. As far as I’m aware, Lenovo is the only mainstream laptop manufacturer that allows you to set battery charging thresholds for their battery, after which point the internal battery will no longer charge. What happens instead, is that the laptop will run purely off A/C power. With USB-C, power banks can output higher wattage than the laptop is capable of (even when fully unlocked, the newest Kaby Lake-R chips don’t go over 44W) , and this leads to only the power bank being discharged and the laptop has no hiccups in performance and never has to temporarily switch to internal power, reducing wear. The result is that the power bank performs identical functions to that of a rear battery, with the added benefit that you don’t have to use Lenovo only options for capacity, size, output, and the bank can power more than just your ThinkPad. You also get the added benefit of charging your ThinkPad if you are going to be without the power bank later on, or simply don’t want to leave it hanging around when using your machine later on.
My preferred battery bank is the Jackery Titan X — a 45W USB-C charger with a whopping 77Wh of capacity — leaping my X1 Carbon from 57Wh to 134Wh, beating out any possible Power Bridge combination on the market, and it has roughly the same volume as a 72Wh rear battery. You will want a bank like this, because it supports Power Delivery and goes as high as 45W, which is above the maximum you would expect to draw from a USB-C supporting ThinkPad, though on average even as little as 25W will do.
EDIT: Since first writing this article the Jackery Titan X has been superceded by an even more impressive 99Wh upgrade called the SuperCharge 26800 in an identical form factor (in fact nothing else about the bank has changed), bringing my capacity up to 156Wh without taking up any additional space.
Introducing FakeSlice — Instant Slice Battery!
The final caveat of using your power bank as a slice battery is that you need to use Lenovo Vantage and constantly set your battery thresholds based on what your current internal battery is at to make sure when you plug it in your internal battery doesn’t start charging instead. This can get annoying rather quick, and there’s no easy way to automate this — so I decided to take matters into my own hands. With the help of Ciastix, I monitored the Lenovo Vantage application to see what changes and calls it makes, and I isolated the plugin manager Vantage uses to figure out how the thresholds are set. With Ciastix’s sharp C# and .NET assembly reversing skills, he was able to whip up and expose the proprietary Windows interface used by Vantage to set battery thresholds. With that, I bring you FakeSlice — Instant Slice Battery!
By binding FakeSlice to a hotkey, you simply toggle whether or not you want to run off A/C power. If you’re plugged into an actual A/C outlet, you’ll presumably want to charge your internal battery. If you’re using your power bank, you would want to discharge it first, so a quick toggle using FakeSlice instantly switches you to your power bank for discharging. FakeSlice also accepts simple on and off command line arguments, in case you want to use the application in some sort of script or automation. I personally have it bound to Fn + F12 with Lenovo Vantage’s custom hotkey, so it’s easily within reach when I need it.
Thanks to Lenovo including this feature and leaving their interface easy to expose, we can choose where we want to discharge from at any time, allowing us to hot-swap power banks instead of slowly charging and discharging our internal batteries, leaving little to no reason to want rear batteries. At first I was a skeptic and thought the death of Power Bridge would bring the death of ThinkPads, but thanks to USB-C and Power Delivery I am now a believer. All hail the power of choice, something Power Bridge did not give us!
