After my Wahoo TRACKR RADAR post/video a few weeks ago, where I noted that Garmin’s RTL-515 is the very last micro-USB device in my house, a bunch of you jested: “What about SRAM AXS batteries?!?!”.
That’s because, indeed, SRAM does still distribute a micro-USB charger with all AXS-equipped bikes. That’s the same battery type as eTAP, they are fully interchangeable. While I will continue to give SRAM a hard time for still distributing a micro-USB charger with $15,000 bikes, I will give them credit in that the eTAP/AXS batteries haven’t changed in like a decade. Seriously, what other company has kept the same proprietary battery for that long? Even most legacy camera companies slowly shift/tweak their batteries over time. So, kudos there.
Still, it’s ridiculous to have micro-USB for the charger in 2025.
Thankfully, there are some 3rd party USB-C options for charging that are great. I’ve been using one of them for a few years now, this dual-battery USB-C charger:
Simply slot in two batteries, plug a USB-C cable in the back, and come back whenever, and it’s charged. Donezo.
On the unit there are three status lights: Green, Yellow, and Red. As you might guess from your extensive experience with such primary colors, red means something’s bad-bad, yellow means charging, and green means go. Complex, this is not.
On the back, it notes this is a 5V-2A charger. While charging a single battery, it seems to float between 1-1.5W, and while charging 2 batteries, it floats around 2.5-3W (according to my Anker PowerBank I bought a year ago, also a favorite cause it can charge everything from my laptop, to drone batteries on a multi-day hike…all at 100w):
(At left, the USB-C variant. At right, the official SRAM micro-USB charger.)
Officially, the manufacturer claims it charges the batteries via USB-C some 30% faster, though practically it’s really hard for me to validate that, since I virtually never get my AXS batteries down to dead-dead status (let alone two of them to test side-by-side). And even if I did, I have no idea which ones are 3-5 years old, and which ones are 3-5 months old.
Wattage-wise, I’d see the USB-C version pulling about 4.0w for one battery, whereas the micro-USB one was pulling about 3.0w. But that’s, of course, only a piece of the amp/watts/volts story, and both units fluctuated a bit.
Either way, charging speed has never really mattered to me here…cause…uhh…below. If my math is right, I think I currently have five SRAM AXS battery-equipped bikes active in our fleet, between my wife’s bikes and mine. Additionally, we have three Shimano Di2-equipped bikes.
Now, while there are 3rd party batteries for SRAM AXS, I don’t use them. In general, my jam is that I try to use company-specific batteries as much as possible, to reduce any unexpected problems. Especially when that might result in me being gazillions of miles away from a solution (such as in the mountains on a multi-day trip). So I keep to the official SRAM AXS batteries, but use the third-party chargers. Likewise, I used to use third-party GoPro batteries, but eventually the GoPro ones became reasonable enough, price-wise with certain bundles/discounts, that I didn’t bother with third-party ones. However, for my main mirrorless cameras, I do use a third-party battery because those have USB-C charging ports directly in them (making it so I don’t have to carry any extra chargers):
At this point, we’ve totally gotten sidetracked on this review. But frankly, there isn’t much more to say. It just works, and I don’t think about it. As for the older micro-USB charging blocks? I actually stick them in my bike case in one of the secret compartments, just in case I somehow forgot the real USB-C charger, I’ve at least got something (and someone can always find an older micro-USB cable in a hotel from a desk drawer somewhere).
Now, I will leave you with this: You can also buy an 8-port AXS battery charger. While the inner-charging-geek in me could easily find a justification for this (at least, to justify it to my wife), it’s pretty hard for me to realistically justify it:
Still…I want it.
With that, thanks for reading!
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Sticking to its battery (connector, the chemistry changed):
Lupine is building premium bike lights since the 90s and the batteries are fully compatible. Yes, the old ones don’t deliver enough umph for all lights to shine at highest setting, but the other way around will work.
Since Lupine was sold to an investor lately… I fear that might change in the future.
Ray,
This appears to be a first world or should I say five bike problem. I ONLY have one SRAM AXS Red XPLR bike, so only one battery. It lasts, according to SRAM, somewhere between 25 and 60 hours. Even at 25 hours at an almost leisurely 15 mph gravel ride that’s 375 miles. I carry a spare aftermarket battery in my seatbag that costs about $15 off of Amazon. I’ve never had to use it. I top off my battery before any rides longer than 100 miles with the standard charger. I’ve never urn out of power nor ever seen anyone in a race run out of power on an SRAM battery. So, the SRAM being micro usb is hardly an issue. Garmin, however, with their varia devices and slightly older computers that have to be charged, in my case twice a week, that gets annoying.
I’d be mildly interested in whether or not that 3rd party battery in your seatbag actually works (if you haven’t charged it in a long time).
I’ve noticed that SRAM batteries left on bikes, but not used actively, quickly die. James Huang also noted the same thing in some of his reporting over the years as well. I haven’t honestly paid enough attention to whether or not off-bike charged batteries hold well though, since my general ‘policy’ is to try and grab ones direct from a charger to avoid such situations.
I’ve got to get in some lengthy rides for Unbound training this weekend. Tonight I’m on the trainer due to weather. I’ll pull it out and give it a whirl and let you know. I think it may have been charged about six weeks ago in anticipation of the cancelled Midsouth gravel race. I think I used it for one short approx. 20 mile ride right after I bought it about 15 months ago. Since then, I’ve just charged it a few of times to top it off in case. I agree it probably needs to be tested. I’ll report back
Initial report is that the 3rd party battery in the seat was fine this last weekend. As I mentioned it may have been charged around March 15. I’ve topped it off a few times since I purchased it on 2/5/24. I only got a 40 mile ride on it over the weekend but the SRAM app is showing it has a “Good” battery level. Of course, good, according to SRAM literature, only means it has more than 25%. Nonetheless, it made it the 40 miles and I have a 70 mile ride coming up Saturday
to test it more if I don’t get more in before that. I’ll try to see just how many miles I can get out of it over the coming weeks. We are having several straight days of rain so I’ll be on the trainer most of this week plus I’m trying to STTFP on my training and that’s much easier hitting power numbers on the trainer. Still, if a person had this 3rd party battery and charged it a few times a year and left it in the seatbag, if it will get you 40 miles and still show over 25%, you should be good to go on most races or rides. This is the one I purchased from Amazon for $19.95 link to amazon.com. For less than half the OEM, and it’s lasted over a year, I’m happy with it. It’ll get me out of a jam and that’s all that’s necessary. I’ll report more as I use it.
I had a SRAM battery, connected to the derailleur, and the bike ridden intermittently on fairly flat pavement and gravel roads, last me close to 6 months and 1500 miles.
Then took the same battery on a very hilly 135 mile gravel road course, and it died about 100 miles in.
I’ve also had a not-quite fully charged battery, on the derailleur, go dead while the bike was being carried in a rear rack on a vehicle.
I think in this case, either the road bumps, or possibly some jostling with another bike on the rack (possibly pushing the derailleur or shift buttons?), was causing the shifter to be activated while in transit.
I think shift frequency is the largest contributor.
If a battery is going dead on the bike sitting at home in the garage, or a spare in the bike bag (with the contacts protected), then I think that’s a defective battery.
I always take my battery off when transporting the bike any substantial distance. The races I attend are usually a 2 to 6 hour drive. I have been warned that batteries experience a huge drain being transported on a car carrier for whatever reason. I certainly don’t want to start a race with a drained battery because I left it on the bike transporting it.
Ports lament. My Assioma Duo pedals use micro-USB cables that plug into the adapters. Don’t yours? My Polar Verity Sense HRM cradle plugs directly into a USB A charger port!!! My new Sigeyi spider PM uses a propriety cable that plugs into a USB A charger port. My Samsung laptop uses a small coaxial power plug, not USB at all. I’ve still have mini and micro USB bike lights. Wife’s Edge is micro-USB. My car’s active USB port is A. It does have B charging though. Dashcam is micro. And it goes on. I’ve got way more non C devices than C devices.
I don’t mind USB-A as much, since most of my battery banks/etc still have USB-A ports. It’s not awesome, but not a huge deal.
I agree that I wish things like the Shimano Di2/PM cable were USB-C on both sides. All my other bike lights are actually USB-C, somehow most companies were ahead of the game there for the ones I have.
I picked up a tiny USB-C to Di2 charging adapter on Aliexpress for 20€. It’s worked seamlessly in testing. I have seen some mixed results from other people but I’m very happy to have it in a travel kit (along with similar for my Shokz and Garmin watch).
Hey Ray,
SRAM has manufactured a four slot USB-C charger for several years now. Need us to send you one?
Best,
-Troy
Only if you put one in the box of all new SRAM AXS-equipped bikes too! 😂
While I agree with the sentiment it’s possible SRAM have a huge stock from a manufacturing run. I wouldn’t want to see that stock binned just to satisfy a port fetish.
If they make more though, that needs to change.
Regarding your comment about USBA at the charger end above, I actually prefer the more robust ports at that end and out of 6 laptops we have only two have USBC ports so modern cables are a hassle for us.
When I bought my Moots RCS with SRAM Red my dealer gave me a full price credit for the included battery charger and substituted the SRAM USB-C four-port charger, for about $50 IIRC. I think the one-port charger is silly anyway. SRAM should have provided a two-port charger all along. I rarely charge four batteries at a time but I do charge two.
I’d be curious to hear about others experiences (and specifically data geeks) with 3rd party batteries.
I generally love all things SRAM, but the price of their batteries and USB-C charger, leave a lot to be desired.
There appears to be a massive mark-up on these.
And like Garmin’s taillights, it’s pretty obnoxious to ship premium devices with micro-USB these days.
I have two non-SRAM batteries that I have in rotation with 2 SRAM branded batteries. I can not tell any difference in use nor in hours per charge.
I have one off-branded one in my rotation, and generally haven’t noticed a difference.
But, I haven’t tracked longevity (difficult in varied conditions).
Was looking for someone who might have evaluated electronically.
Hey one more thing about that dual port charger… I have a battery that was totally bad bad red dead, the official SRAM charger just would not charge it. Tried putting it in and out like 50 times as they say to do.
This charger charged it right away. This thing can bring back dead batteries that the official Saran one can’t.
I can tell my older SRAM batteries from the newer ones because the engagement tab on my 2 original SRAM batteries cracked and I had to super glue them back on.
it is worth noting that Sram has a 4 port usb-c charger, not sure when it launched but i’ve had it on my wishlist for some time expecting it to drop down in price because…. IT’S $120 DOLLARS.
link to shop.sram.com
i’ll stick with having a bunch of single ports on a multi USB-A port charger
So…you’re telling me I can justify 2×8-port ones + another dual porter?
That’s 18 ports worth of charging goodness!!!!
You’ll need more bikes with more batteries to charge though…:-D
Thanks for sharing, this is great!
Been a longer time reader, 10+ yrs, and I love these posts that you have before the pending big ones :)
Small nit: The link to the 8-port charger leads to a page for a 3rd-party 2-port charger.
Unfortunately Favero also refuses to move to USB-C for their power meters, too bad.
“…red means something’s bad-bad, yellow means charging, and green means go. Complex, this is not.”
About 8% of males are colorblind.
Why does anyone make a product that a significant part of their user base will have trouble using when there are easy and just as cheap alternatives?
Red, yellow and green are not great charging color choices.
I’m glad someone else understands my pain! I have protanopia (a form of red/green colorblind-ness), and I literally can’t see the difference between the yellow and green lights on some of my chargers. How it became a standard color scheme for cheap battery chargers is beyond me.
The AXS charger is one of the implementations where I can’t see a difference. I either have to ask my SO if it’s green, or I just wait for a few hours and hope it’s done.
There are so many better paradigms out there — separate LEDs to indicate the status would be my preference, but blinking light patterns are OK too if well done/documented — especially at SRAM’s price points.
I’m half interested in picking up one of these for a teardown and test. Even though I don’t have a SRAM axs.
Why?
Several 3rd party chargers based on tp4065 (single cell) don’t properly disconnect upon charge and then hold voltage at battery charge level. But the light changes to charged. Where this gets dangerous is long term holding the voltage can cause gas generation, swelling, fire, and dead battery.
I’ve seen it happen to many 3rd party gopro chargers. The GoPro ones market as storage too but if you don’t unplug it your cells will eventually over time be destroyed if you leave them in it.
The SRAM batteries are 2s but there are still bad charge IC’s or misconfigured.
Some also don’t use the ntc so they don’t respect overtemp or reduce current for cold temp.
Edit. Not real GoPro chargers. 3rd party. My last statement I missed the qualifier.
I suppose this cheap chinese USB-C charger has not been CE certified? If so, I will pass.
I show the photo of the back of it including the CE markings…
I totally missed that. Sorry.
No worries!
Now…admittedly, I have no idea if they actually have CE certification, or, just printed it. I suppose, no different than probably 99% of other electronics out there.
SRAM makes a 4 battery factory charger that’s USB C part number 00.3018.359.000 I coulda sworn I learned about it here on the site.
Hey Rainmaker, you can totally justify the 8-port (off brand) charger for travel. My friend snagged one and when we go on a mountain bike trip, he will plug his gigantic 8-port in to a kitchen outlet and everyone can just charge their batteries off his charger without having to deal with multiple individual chargers. I have done the same thing with a 10-port USB hub for a travel charging station in the past as well, and everyone will appreciate it. Of course, if you always travel alone then it’s likely not worth it… but you should get some friends if that’s the case. :D
Thanks, Ray!
As was already mentioned…very first-world problem….I have 25 bikes, 22 of which have electronic drivetrains. Half Shimano and half SRAM. On top of the SRAM batteries there are power meters, lights, and various Garmin head units. So I am constantly rotating through the fleet charging things. Both to keep bikes ready to ride and also to keep batteries healthy. For example, I have had to send two separate pairs of SRM power meter pedals back to the factory for new batteries…presumably from not keeping them charged.
I also keep a spare generic/Amazon SRAM in the seat packs of various bikes. I get the ones that are like half the size of a SRAM battery, so they are small enough the stash anywhere.
One thing I found useful is a SRAM battery meter which displays the current percent capacity of a battery. Purchased on Amazon, and it works great. Very useful if you’ve got, say, 30 SRAM batteries and you have no idea when some of them were last charged….
Woah, I didn’t even know that thing existed!?!? Super cool.
I assume this is the one? link to amzn.to
Yes! That’s the one! Very useful indeed. Of course one can check the status of your SRAM battery when installed on a bike by using, say, your Garmin head unit…but if you’ve got a bunch of batteries in your hand and you quickly need to know how much charge they have this little thing is just great.
SB
Hi DC Rainmaker, I think I bought this same two-battery charger off Amazon a year, two years ago now. It did not last me long. Worked for a while then one side stopped charging and then the other stopped charging. It lasted about a year.