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Reviews > Lighting > Flashlights - Solar > GoSun SolarLight Flashlight > Test Report by joe schaffer

GoSun Solar Flashlight

Test Report by Joe Schaffer

INITIAL REPORT - May 19, 2021
FIELD REPORT - September 15, 2021

NAME: Joe Schaffer
EMAIL: never2muchstuff(at)yahoo(dot)com
AGE: 72
HOME: Bay Area, California USA

     I enjoy California's central Sierras, camping every month with a goal to match my age in nights out each year. For comfort I lug tent, mattress, chair and such. Typical summer trips run 5-8 days; 40 lb (18 kg), about half food and water related; about 5 miles (8 km) per hiking day in the bright and sunny granite in and around Yosemite. I winter base camp most often at 6,000 to 7,000 ft (1,800 to 2,000 m); 2 to 3 nights; 50 lb (23 kg); a mile or so (1.6 km) on snowshoes.

goSun pkg front

Product: GoSun Solar Flashlight

Manufacturer:  GoSun


Features and claims from mfr:    
    280 lumens/1000 ft (305 m) max with 3 settings
    20-hour battery life
    Integrated solar panel
    4-hour recharge with included USB cord
    24-hour recharge with solar panel
    Recharge quickly with 10 watt solar phone charger
    Solar lantern mode
    Spotlight ability
    Red strobe setting
    Magnetic back
    Weight: 0.4 lb (180 g) per website; 0.32 lb (145 g) per user manual
    Dimension: 6.69 in x 1.45 in (head) x 1.06 in (body) (17 x 3.7 x 2.7 cm)

Warranty: 1-year money-back satisfaction guarantee

Country of origin: China

pkg bkMSRP: US $29 (markdown from $39)

My Specs: 

        Weight: 5 1/2 oz (155 g)
         Dimension: 7 in x 1 3/8 - 1 1/32 in (17.8 x 3.5 - 2.6 cm)
         USB cord length: 20 in (51 cm)

Received:   May 17, 2021

My Description:
    This is a two-hand-length light most of which is about the diameter of a frankfurter. It's black, with a silver magnet in the back end strong enough to hold the light upside down or straight out. Charging port is on the bottom side of the barrel and has a rubber cover.

The particularly unique feature is the solar charging panel, which doubles as an area light with 10 white and 10 red LEDs embedded in it. The panel is actually two pieces each about 7/8 in x 3/4 in (22 x 19 mm). One bank of four LEDs separates the panels; and at each end are two more banks of four. The center LEDs appearing as white in the photo are red lights and the the outer ones appearing as yellow are white. The whites have two modes of brightness. The reds pulse either extremely quickly or strobe a bit more moderately.

One button on the barrel just behind the head controls all lighting features using either a press or a hold. The main light comes on with a single press. A second press dims the light. Third press switches to strobe. Fourth press turns it off. Pressing and holding the button for two seconds turns on the barrell's area light. Another press then dims the light. Pressing longer switches to the fast-strobe red light and then another press slows the pulse. A final press turns the area light off.

    I don't find any way to adjust the beam focus.
The light came as shown in the package photos. It was harder to get the plastic apart than to read the directions, which I find simple and informative. I appreciate that the vendor takes care to moderate user expectations regarding solar charging. My limited experience suggests the panels are going to require patience, and indeed the vendor website indicates what would be several days of sun to restore a full charge. The vendor suggests expecting the panels to add burn time rather than rely on restoring it. However, I do live in a sunny state and I'm delighted to learn how much practicality the solar aspect offers. The most critical part of this test for me will be remembering to grab the light off the granite on the way out of camp.

    First thing out of the package is to remove the cardboard insulator from under the battery cover, which I was able to do. Next is pawing the light to find how it turns on without blinding myself. I didn't accomplish that. I wasn't able to read directions to see if the battery should be drained before charging, so I just plugged it in. After less than an hour (could be any time less) the green light was on to indicate charging was complete. By then I could see again, and no, the directions don't reference battery management.

    Also of some interest is the option to charge other devices from the GoSun. Two issues I anticipate are that the i-Devices I might want to charge need more juice than the light can give up and still function; and more importantly, the provided cord's standard USB end does not fit any device in the household that might be tote-worthy. Unless I come across a suitable cord or adaptor I won't be able to test the cross-charging function.

    For as many settings as the light has, I find them easy to reach and not necessary to cycle through all of them each time to turn the light on and off. I don't find any setting that keeps both the main light and the area light on at the same time. The button operates very smoothly and I will be checking to see if it is prone to coming on by itself when crammed into the backpack. I don't find a lock-out mode. Ah, but there is a removable 'guard' that will prevent accidental activation. Inscribed on it are the words 'remove before use', which I did feeling very proud that I actually read and followed a direction, and assuming it was a factory-to-user type of packaging thing I put it with the rest of the packaging rubble. After being enlightened by a fellow tester's report I got on hands and knees to fnd it on the floor. Careful inspection reveals a witty-bitty icon indicating not to throw it away. Shouldn't take a genius to figure out the piece would be just as important in use as in packaging, and indeed such a descriptor has never fallen my way.

    Directions are simple enough I can understand them, which means since I tend to forget them I should still be able to use the light's features out in the woods. Though my garage is certainly way smaller than the advertised beam, it does a great job of filling the space while keeping a focused beam. The area light also fills the space without a beam.

    The light fits my hand nicely. I will have to carry it by hand as there's no way to attach it to me otherwise.

    The magnet is strong enough to hold the light firmly. I stuck it sideways on the washing machine and jolted the appliance, finding that the light did not shudder. Of course as a backpacker I'd remark that the magnet adds weight without function. I'd trade it or modify it for a dimple-bar to thread a lanyard.

Field Conditions:
  1. May 26-29, 2021: Yosemite Wilderness, California, USA. 3 nights, 8 mi (13 km); leave weight 35 lb (16 kg); 45-75 F (7-24 C), sunny & calm; 5,900-6,500 ft (1,800-2,000 m); 1 camp at 6,400 ft (1,900 m).
  2. June 4-11, 2021: Emigrant Wilderness, California, USA. 7 nights, 19 mi (30 km) mostly trail; leave weight 35 lb (16 kg); 32-75 F (0-24 C), hot and calm to freezing and gusty with even a spit of snow and hail; 7,200-9,000 ft (2,200-2,700 m); 6 camps.
3. June 23-28, 2021: Emigrant Wilderness, California, USA. 5 nights, 16 mi (25 km) mostly trail; leave weight 35 lb (16 kg); 45-80 F (7-27 C), sunny; 7,200-8,000 ft (2,200-2,400 m); 4 camps.
4. Jul 12-22, 2021: Emigrant Wilderness, California, USA. 10 nights, 24 mi (39 km)
mostly trail; leave weight 42 lb (19 kg); 40-90 F (4-32 C), mostly hot and calm with one showery day; 7,200-9,000 ft (2,200-2,700 m); 7 camps.
    5. Jul 28 & Sep 12, 2021: Home testing.


The fully charged GoSun occupies the realm of photon cannon. The first trip provided a clear opportunity to test the cast on thinly treed granite. During the day I set marked data points from 95 ft (30 m) to 1,000 ft (300 m) as measured by GPS. I did not expect the light to illuminate anything at that farthest distance as the night before I'd selected trees from dead-reckon and could not see anything beyond what I thought was much less. The vendor suggests that distance as the outer limit of the light's reach and
I felt compelled to test that claim.

    The light was fully charged at home a couple days before leaving for this trip. I had turned it on and off several times, perhaps using 2-3 minutes of battery service. I then set the light in full sun for six hours before the test. The test was conducted at 9:30 pm under clear skies with no moon. The test object was the trip's tent, which has a red tub, white sides and a reddish cap with eight small reflectorized guy loops.

          95 ft (29 m) Tent clearly and sharply visible.

        125 ft (38 m) Shape and colors of tent discernible.
        225 ft (70 m) Shape visible, but couldn't see color.

        275 ft (84 m) Shape slightly visible; reflectorized guys still shone.

        410 ft (125 m) Could see what I knew was the tent, but would not have otherwise been able to find it; guys slightly visible when knowing where to look.

        635 ft (194 m) Tent not at all visible, though knowing where and what I was looking at, guys slightly evident.

        740 ft (226 m) Nothing.

    Back at the tent I shone the light toward the 1,000-foot (305 m) object, which was a round boulder very roughly 10 feet (3 m) in diameter propped on the granite slope. The view to it was completely unobstructed, though of course there was essentially no background contrast. Bearing on trees that I could see, I would conclude the light fell 300 ft (100 m) short of being able to see the rock.

    Indeed the strength of this light does impress. I don't know how conditions could have been more favorable for this test, and I would conclude maximum reach to locate a tent-size object is around 400 ft (120 m), with a 'useable' cast about 300 ft (100 m). While that distance is way short of the claimed maximum, it is nevertheless remarkable.

    My main comment arising from the second trip is that the light is too bright in the tent. The area light does a decent job of illuminating the interior by laying it sideways in a corner pocket aimed up and slightly outside. I didn't have an attic on this trip, and I wouldn't have used it. One night the weather gods amused themselves with howling wind and freezing temps that made being outside so awful I spent from late afternoon until morning cowering in the tent. When I'm in a weather pout I find lighting can improve my spirit, but GoSun is so bright on any setting it seemed only to tease the nasty gods into sneezing their wrath ever more fiercely. The ideal light would have been a dim, steady red.

    The switch lock-out cover certainly works to prevent unintended activation. Other than that, it might benefit from some improvements. For example, if it would push forward or backward far enough to clear the switch but remain on the barrel, that would be better. I haven't lost it yet, but having to remove it to work the light is no good. I have to remember to find the cover and put it back on in the morning, as should the bogeyman wake me there's no way I'll be able to figure out in the dark how to make the light come on with the switch cover in place. More than once I also blinded myself
accidentally turning the light on trying to get the cover off or on.

    The charging port cover does not want to stay in place, especially when fiddling to get the switch cover on and off.

    I typically only spend a few hours a day hiking, so have ample time to put the light in sun. What I don't know is whether it is possible to over-charge system, thereby somehow diminishing its lifespan. As well, it seems silly to saturate GoSun in UV if the battery has ample reserve, but there's no way to know. I don't require Prozac to treat it, but anxiety builds at wondering whether the light needs charging to have enough juice to last the trip; or should I not use it in case an emergency requirement develops? This light is so bright it will easily orient me in the dark for a nighttime hike, but does it have enough reserve to complete the mission or will it burn out and strand me? (Spoiler alert: I would certainly trust the light for a hike of an hour or less on full charge.)

     CS was responsive to queries:
     a) "There are no downsides to excessive solar charging but, batteries do not like to be overheated. Overheating can affect the longevity of the battery, but does not pose any immediate threats." I'm not well understanding this as it should be fairly evident that something left in the sun for hours is going to get hot.
    b) "There is no indication of when the battery is running low other than the light will start to lose its brightness. The battery should last about 20 hours on a full charge." Vendor description says up to 20 hours on the low setting; up to 4 on high. (I think it might be good for about half that on high; not tested on low.)
    c) "This flashlight's power source cannot be replaced with anything other than this exact battery."
    The first three outings the light performed OK. On the fourth, I didn't switch it on until the 5th night and it lit up nearby trees. But thereafter it dimmed rather quickly to the point of essentially not being of any use. Extensive solar charging perked it up, but only momentarily.

    After having the light available for 25 nights of backpacking I've formed a few opinions. Let's start by noting that I wall-charged the light fully before the first outing and not again in the succeeding two months.
    1) I don't know how many hours I actually used the light--and certainly not how many on each setting--but my feeling is that it started going dim in way less than even 4 hours.
On the plus side, I would think the light held fairly well for the first 3/4 of the time I used it; then fell off a cliff. I didn't use it every night I had it; and when I did use it I'd be surprised if more than 5 total minutes a night. Even if I used it for 20 nights and 5 aggregate minutes a night, that would be less than two hours of use. During the last two outings I did not use any other light. It could be supposed that my estimations may be faulty, an argument that would not in my mind gain persuasive traction.
    2) I don't know how many hours I left the light in sun, but I can conservatively say a lot--dozens. My conclusion is that it doesn't solar charge very well; and that solar charging alone will not bring it to strength. Reading the vendor's description a few times causes me to think these observations likely correct.
    3) I don't know if the light dimmed from use or from time-drain. I will wall-charge the light fully, then wait a month before turning it on to see what happens.
    4) The light is way more powerful at full strength than any headlamp I've ever used.
    5) The light is too big and too heavy to carry as a backup or supplemental light.

I did not wall-charge the light before each outing and instead relied on solar charging to maintain service. The reason was wanting to see how much reliability should be accorded the solar function; and my conclusion is not much. I also wanted to observe the light's 'half-life', which required letting it burn down. I learned that it seemed OK after the 3rd outing and became useless during the 4th.

    The last trip did reveal to me that the switch guard can be installed from the bottom side, which serves the dual purpose of not losing it and keeping the charging port cover in place. Also, not to be accused of bending toward the intellectual elite, it came to be that standing the light on it's somewhat larger front end adds more stability for area light use than trying to balance it on the back end. (Why I thought the magnet end had to be on the ground is a point which continues to elude comprehension.)

     The light got wall-charged to full in more than 1 1/2 hours but less than 2 1/4. I turned it on and left it on high. While my experiment is far from standardized and free of error, I did try to make a go of it. I picked a target 12 ft (4 m) away in a dark room. The target was a heavy-block letter logo about 1/4 in (0.6 cm) high, white letters over red background.
       10 mins:
Letters clearly and crisply visible
       1 1/2 hr: Logo barely visible, could not read the letters
       2 hrs: Maybe 1/3 power; nothing visible in target
       2 1/2 hrs: Light minimally useful for immediate area, like 10 ft (3 m)
       3 hrs: Not much good beyond a yard (1 m)
       4 hrs: Barely makes a spot on the white ceiling
       4 1/2 hrs: Still emitting light, but of no practical use
       After letting it rest overnight, it was brighter again, but not for long and of minimal practical use.

    A second test six weeks after full charge yielded similar results. I noticed the barrel got warm for the first two hours, then cooled off. Full-recharge took 1 hr 45 mins.
      CONCLUSION: At full charge and for perhaps 1/2 an hour, this light will knock over a tree from across a football field. Useful light remains for maybe another hour. All testing was on the high setting only. I did not do any on-off-on-off interval testing to see if light-minutes would accrue more when not in continuous use.

    When I first started using the light the switch was remarkably sensitive. On/off now requires a firm press.

    This light is not expensive in the realm of camp lighting and to my thinking would be worth more with a couple of design changes; i.e., non-removable switch cover, better stay-in-place charging port guard, steady-red area light, some form of battery meter and a lanyard or other holding means.

SUMMARY: Very powerful, compact hand-held with multiple lighting features and supplemental solar charging capability that doesn't work very well.

Quick shots:
    a) light
    b) compact
    c) powerful
    d) solar recharging
    e) some design issues

Thank you GoSun and for the opportunity to test this product. Testing and reporting complete.

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