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The Jackery Explorer 100 Plus Garmin Fenix 7X ultra marathon pacer setup is the small-battery, crew-bag charging combo that keeps a Fenix 7X Solar (or Sapphire Solar) alive through a 100-mile finish without forcing the runner to stop, fumble cables, or rely on an aid-station outlet that may or may not exist. The Explorer 100 Plus is a 99Wh LiFePO4 brick (about 2.1 lb) that ducks under TSA crew-flight limits and refills a Fenix 7X roughly six to eight times from empty - enough headroom for a pacer to top up the watch at every crew exchange and still have juice left for a headlamp, a phone, and a backup GPS. In 2026 it remains the default pick for buckle-chasing pacers who want one device that handles the watch, the lamp, and the runner's phone without bringing a generator-class unit into a dusty pacer drop bag.
Why ultra pacers care about a 99Wh power station
The Fenix 7X Sapphire Solar holds roughly 89 hours in GPS-only mode and around 37 hours in all-systems GNSS + music mode. The reality at a Western States, Cocodona, Tor des Geants, or UTMB pace is uglier: backlight on at night, multi-band GPS engaged in canyons, Pulse Ox sampling, and ConnectIQ data fields all chew battery faster than the spec sheet suggests. Most pacers see real-world battery drain of 4-6% per hour, which puts a fully charged Fenix 7X at the edge of failure between hours 22 and 28. That is exactly when a runner needs the watch most - splits get hazy, drop bags get missed, and the pacer becomes the navigation backstop.
A 99Wh class unit like the Explorer 100 Plus solves this with two USB-C PD ports. You clip the watch onto the Garmin charging cradle, drop it into a chest pocket on the pacer's vest, and the Fenix 7X jumps from 18% to 90% in about 75-90 minutes of trail time. The runner never stops. That is the entire value proposition.
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If the Jackery Explorer 100 Plus is out of stock: the EcoFlow RIVER family
In 2026 the Explorer 100 Plus sells out repeatedly during ultra season (April through October), and the closest functional substitutes are the EcoFlow RIVER 3 and RIVER 3 Plus - both LiFePO4, both with USB-C PD fast charging, both small enough to live in a crew tote. The two larger RIVER units (RIVER 2 Max and RIVER 2 Pro) belong in the crew vehicle, not the pacer's pack, but they earn a place at the aid station for charging Stryd pods, Suunto Race S backups, drone batteries, and the inevitable dead phone the runner hands you at mile 78.
| Model | Capacity | Weight | USB-C PD | Best role at the race |
|---|---|---|---|---|
| Jackery Explorer 100 Plus | 99Wh | 2.1 lb | 100W | In the pacer's vest or chest pocket |
| EcoFlow RIVER 3 | 245Wh | 7.8 lb | 100W | Crew bin, aid-station tote |
| EcoFlow RIVER 3 Plus | 286Wh | 9.9 lb | 100W | Multi-runner crew, 1200W X-Boost |
| EcoFlow RIVER 2 Max | 512Wh | 13.4 lb | 100W | Crew SUV, overnight aid station |
| EcoFlow RIVER 2 Pro | 768Wh | 17 lb | 100W | Mountain ultras with no grid |
EcoFlow RIVER 3 - the closest 1-to-1 swap for pacer carry
At 245Wh and roughly 7.8 lb, the RIVER 3 is heavier than the Jackery 100 Plus but offers more than twice the energy and the same 100W USB-C PD output. For a Western States or Cocodona pacer working two 20-mile legs, this is the unit to throw in the crew bin at the start line, then transfer a charged Fenix 7X and a backup Anker nano cube into your vest at the handoff. Charge time from empty is about 60 minutes from a wall outlet, which matters if your runner is moving fast and crew prep slips. It handles a Garmin watch, a Petzl IKO Core headlamp, a Stryd footpod, and a pacer phone simultaneously without throttling. Check the EcoFlow RIVER 3 on Amazon.
EcoFlow RIVER 3 Plus - when one crew supports two runners
The RIVER 3 Plus jumps to 286Wh and adds the X-Boost mode that pushes AC output to 1200W. For ultra pacing the AC matters less than the four extra USB ports and the slightly larger battery, but the X-Boost is the reason crews running coffee makers and an electric griddle at the Foresthill aid station choose this one. If you are pacing a partner and crewing a teammate in the same weekend - very common at Cocodona 250 in 2026 - the RIVER 3 Plus gives you enough headroom to charge two Fenix 7X units, a Garmin inReach Mini 2, two phones, and a tablet running LiveTrack without juggling the queue. See the EcoFlow RIVER 3 Plus on Amazon.
EcoFlow RIVER 2 Max - the crew vehicle anchor
Once your needs cross the 300Wh line, you are out of pacer-carry territory and into crew-vehicle anchor territory. The 512Wh RIVER 2 Max sits in the back of the SUV and runs lights, a small electric kettle, and a phone-charging hub at remote aid stations like Hope Pass at Leadville or Cougar at Tahoe 200. The 1-hour wall recharge means a crew chief can top it up during the 90-minute drive between exchanges. It will refill a Fenix 7X roughly 28-30 times from full. View the EcoFlow RIVER 2 Max on Amazon.
EcoFlow RIVER 2 Pro - for true off-grid mountain ultras
Hardrock, Tor des Geants, and the more remote stretches of the Cocodona 250 course put crews in trailheads with zero power infrastructure. The 768Wh RIVER 2 Pro pairs with a 110W solar panel to recover during daylight handoff windows, which is the only way to run a 60-hour crew operation without a generator. For a Fenix 7X-only mission this is overkill - but if you are also running a Starlink Mini, a DJI Mini 4 Pro for course documentation, and a portable fridge for runner nutrition, the Pro is the only RIVER unit that actually finishes the weekend with charge left. Check the EcoFlow RIVER 2 Pro on Amazon.
How a pacer actually uses the Jackery Explorer 100 Plus Garmin Fenix 7X ultra marathon kit
The mistake first-time pacers make is leaving the watch on the runner's wrist and trying to charge it mid-stride with a clamshell cradle. It works for a Garmin Instinct, not for a Fenix 7X - the cradle pops off on technical terrain and the runner ends up with a dead watch and a missing cable. The proven workflow is the swap method: the pacer carries a fully charged backup Fenix (or a Forerunner 965 in some crews) on a wristband in their vest. At a quiet runnable section, the runner hands over their Fenix 7X, takes the backup, and keeps moving. The pacer cradles the depleted Fenix 7X to the Explorer 100 Plus inside their pack, charges it for 60-75 minutes, then swaps back. The activity stays continuous because the runner never powered down - Garmin's Power Manager handles the gap as a brief disconnect and the FIT file merges cleanly in Garmin Connect.
If you do not have a backup watch, the inline approach still works on Fenix 7X with a long magnetic charging cable threaded up through the runner's vest sleeve. Set the watch to GPS-only (not multi-band) during the charge window to reduce thermal load - charging a Fenix 7X at full multi-band GNSS draw in a hot pocket will trigger the thermal cutoff and stall the charge at 60%.
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Battery math for a 100-mile finish
A Fenix 7X in multi-band + Pulse Ox + ConnectIQ mode draws about 1.2Wh per hour. A 24-hour finish needs roughly 29Wh of total watch energy; a 32-hour finish needs about 38Wh. The Explorer 100 Plus delivers around 80Wh of usable energy after USB-C conversion losses, so a single charge cycle covers the watch with a comfortable buffer plus a headlamp top-up and a phone recharge. For 200-milers (Cocodona, Tahoe 200, Bigfoot 200) the math gets tight - you want a RIVER 3 in the crew bin and the Explorer 100 Plus on the pacer.
For related gear breakdowns see our Garmin Fenix 7X ultra-running battery life guide, the best portable power stations for pacers roundup, and the ultramarathon crew bag checklist for 2026.
Frequently Asked Questions
How many times can the Jackery Explorer 100 Plus charge a Garmin Fenix 7X?
A fully charged Explorer 100 Plus delivers roughly 80Wh of usable energy. The Fenix 7X battery is about 5.2Wh, so you get six to eight full charges from 0 to 100% in real-world conditions, depending on cable losses, temperature, and whether you also top up a phone or headlamp on the same cycle.
Can I bring the Jackery Explorer 100 Plus on a flight to a destination ultra like UTMB or Cocodona?
Yes. The Explorer 100 Plus is 99Wh, which sits just under the FAA and EASA 100Wh carry-on limit for lithium batteries. You must carry it in the cabin, never in checked luggage, and you cannot use it during the flight. Crews flying to Chamonix, Flagstaff, or Auburn in 2026 routinely carry one per person.
What is the best USB-C cable to use between the Jackery 100 Plus and a Garmin Fenix 7X?
Use the official Garmin charging cradle or a known-good third-party clip with a USB-C end. Pair it with a short braided USB-C-to-USB-C cable rated for at least 60W PD. Long, no-name cables drop voltage and trigger trickle-charge mode, which doubles the time to fill the watch from 20 to 100%.
Will the Garmin Fenix 7X charge in the rain during a pacer leg?
The Fenix 7X is 10ATM rated, but the contact pins on the charging cradle are not. If you must charge in rain or mist, keep the watch and cradle inside a sealed dry bag in your pacer vest, run the cable out through a sleeve, and avoid letting water bridge the contacts. Damp pins will cause Garmin's safety circuit to refuse the charge and may corrode the contacts over time.
Does charging a Fenix 7X mid-activity break the FIT file?
No. Garmin Power Manager treats an active charge as a normal charging event, and the activity continues recording. If you swap to a backup watch and back, Garmin Connect will show two separate activities that most pacers merge with a free tool like FIT File Tools or Combine FIT Files - this is standard practice at Western States, Hardrock, and Cocodona.
Is the EcoFlow RIVER 3 a real substitute for the Jackery Explorer 100 Plus on a pacer leg?
Functionally yes for the electrical role, but it is heavier (7.8 lb vs 2.1 lb) and larger, so it lives in your crew bin rather than your vest. Most pacers in 2026 carry the smaller Jackery 100 Plus in the vest and stage a RIVER 3 at the next aid station to refill the Jackery between legs. That two-stage approach gives you the lightweight carry and the deep capacity reserve at the same time.
What other devices should I plan to charge from the same power station during a 100-mile pace?
A typical pacer load is the runner's Fenix 7X, a backup watch or Garmin inReach Mini 2, a Petzl IKO Core or NAO RL headlamp battery, a pacer phone running LiveTrack, and occasionally a Stryd or COROS POD 2. Budget about 35-45Wh for all of that beyond the watch itself, which still fits comfortably inside the Explorer 100 Plus envelope for a single pacer leg.
Key Takeaways
- Choosing the right Jackery Explorer 100 Plus Garmin Fenix 7X ultra marathon means matching capacity and output ports to your actual devices
- Always check actual watt-hours (Wh), not just watts — runtime depends on Wh, not peak output
- Also covers: Jackery 100 Plus ultra runner power
- Also covers: Fenix 7X pacer charging kit
- Also covers: 100 mile race crew power station
- Compare price-per-Wh across models to find the best value for your budget