I’ll share my experience from today as well
screen brightness set at 50%
Ride time was 5:00
Idle time was approx 15 minutes - loading route, calibrating pedals, one gas station stop
Bontrager Blaze front light set to slow blink
Garmin Varia radar and light set to slow blink
Polar H10 heart-rate monitor
Assomia power pedals
Karoo 2 was navigating the route
had 49% battery remaining
Counterpoint….long gravel ride (120 miles). Screen at 65% (I think), Quarq PM, Varia radar, HR and running nav. Screen was on the map page.
By mile ~80 / 5 hours, I was down to 35% battery. I had a large capacity power block in my HB bag, plugged it in and by the time I was home (40 miles later) it was at 100%.
I have zero confidence it will get me through SBT GRVL……if anyone has a suggestion for a smaller battery charger, lemme know. The one I have is powerful, but I don’t need 10 hours of charge time for a bike ride! 
@power13 I’ve used a small charger taped to my stem for an 140+ mile gran fondo w my K1. No particular brand, just something I found on Amazon, like this one. It’s about the size of a pack of Lifesavers. I take advantage of their “special needs bag” option, so at the 80-mile rest stop I have a ride-bag waiting for me that I’ve loaded up with items I’ll want (sun screen, water bottles loaded up w powdered fuel, etc…) and drop-off items I no longer want (vest, arm warmers, etc…). I drop off my charger too in my bag so I don’t have to carry it the whole way. I get to mile 80 @ 100% and then have plenty of battery to finish the next 60+. I forget the timing, but I recall finishing w my battery around 65-70%.
Thanks…I have one about that size, but it doesn’t seem to do anything on the Karoo.
I’ll give that one a shot maybe. Appreciate it.
That particular power bank is huge compared to lipstick-sized ones you can find on Amazon.
If you have a top tube bag and don’t care about form factor, there are a number of credit card sized models of various capacity. Make sure the USB-C cable is long enough and whether a 90-degree tip is required.
If you are willing to scale back what you enable during the event and how often you refer to your head unit, battery life can be extended by a substantial margin.
Karoo 2 Battery Life Expectations – Hammerhead
Yeah, I just have never had any luck with the lipstick style ones….I have a couple of them now and they don’t seem to do anything for Karoo.
I already have my cables sorted, just trying to find the right battery pack. I may just stick with this one because I can also use it for my GoPro if I want.
I can’t really park anything back…I want nav up, especially for the descents, need power and at altitude, having HR up is also a good idea. I suppose I could skimp on the Varia, but hate riding without it and SBT GRVL is on open. (If secluded) roads.
Just wondering, have you experimented with display brightness? It’s probably the biggest driver of battery draw, especially because it’s a bright, smartphone screen.
On the batteries, it may be more a question of max amps supported rather than capacity. In other words, the Karoo might need to draw power from the battery faster than the battery can support.
I have an Anker brand lipstick battery - I’ll test it with my Karoo this afternoon to see if it charges it…
So I just tested this Anker lipstick battery (I bought it on eBay last year). Initial results look like it might work well for you - I charged it 6% in 13 minutes. See below how it worked…
Test conditions:
In 13 minutes, the battery went from 41% to 47%. HTH…
Oh yeah….but at 56, dim screens don’t really work for me anymore. I don’t know how my daughters can even see what is on their phones most of the time. 
Thanks, I’ll check it out.
slightly off topic, but does anyone think Garmin will bring a similar route-less climber functionality to the 1040? That is about the only thing that intrigues me about the Karoo since I rarely know what route we’ll be doing ahead of time.
i almost bought one of these with the trade in program and and with an industry discount but the battery and needing wifi to upload were turnoffs. Just bought another 530 (my previous died with a cracked screen and water).
The climber options look great though and will do another serious look when they announce the Karoo 3.
I got a data-only sim (at no cost, the data just goes against my existing plan)
Issue is that in a lot of countries, they will still charge for the extra SIM, even if its only data. Here in Sweden its around 10 euro for en extra SIM, even if it goes towards your current plan.
So in 2 years time, it would cost me as much as a brand new Wahoo BOLT does, just to have my rides upload when I don’t have Wi-Fi.
Thats almost as bad as charging a monthly subscription for heated seats in the car…
What about the hotspot built into the cellphone? I’ve used that when standard WiFi wasn’t available…
This might make me sound lazy, but I honestly expect a bike computer, built for recording and uploading workouts, to not force me to faff around with mobile hotspot for every ride when I am abroad.
Of course it’s possible to do it like that, but that shouldn’t be the norm when somewhere without Wi-Fi.
Yeah, I had a similar conversation with HH re: having reminders on the Karoo for things like eating / drinking.
They suggested I could use phone apps and then just enable notifications so it popped up on my Karoo.
I shouldn’t have to jump through hoops to get a workaround for a pretty basic function.
There was enough about the UX and battery alone that have relegated it to a paperweight in my shop. I don’t care for it at all TBH.
Same reasons why I had to sell my 1040 (wanted to try it for the larger screen) before I headed back to Wahoo.
I rather have Tetris graphics on the computer as long as the thing does what its meant to do, allow me to ride my bike!
I don’t need Spotify controls or other stuff that distracts me from traffic.
Once the hotspot is setup as a recognized network in your HH, it’s super easy. Either…
a. Leave joining the hotspot enabled all the time, in which case your HH will find it and join it automatically once your ride is ended. Or…
b. Enable the hotspot after your ride. And then the HH will join.
I do “b” and it takes all of 5 seconds for me to pick up my phone, unlock the screen, open settings, and slide Personal Hotspot to ON.
Sure, I wish my HH would just sync w my phone over bluetooth, but I’ve grown accustomed to the WiFi sync, with the occasional hotspot solution, and it works just fine.