alo

In recent years, solar bicycle lights have come out. I think, in the future they will become much more widely used. You just put them on your bike, and don't need to recharge them, or replace batteries.

Following are pictures of the brightest solar bicycle headlight that I have seen. This model also has the largest battery, and a built in horn.

At the time of writing, you can buy these on ebay for less than US$15.






Following is a picture of the only solar tail light I have seen.

At the time of writing, you can buy these on ebay for less than US$3.




If I am likely to spend a significant time riding at night, I normally use two headlights. If the battery goes flat on one, the other can be used.

In the future there may be new models. Some may not be as good. Some may be even better.

fooferdoggie 

I doubt you will ever get enough light for one. Plus is your bike always left out in the sun?

VegasTriker

Be the first one of the owners to sacrifice your tail light and find out what battery is inside the light. When I looked up the light on eBay the third choice that popped up was this exact light offered for $2.55 postage included. https://www.ebay.com/itm/Solar-Energ...0AAOSwmZFdW5-D There is zero information on the battery inside the light. I'm betting it has one or two CR2032R button cells as the rechargeable power source. Those have a capacity of 40 mAh. That's not much so you can't have a very bright LED and still get a long run time.

I bought twp very cheap "USB rechargeable rhombic tail lights" for under $3 each when they first showed up on eBay. They were interesting and definitely better than no tail light at all but because the button cell battery capacity was so small I didn't end up using them. Compare that to the Raypal 2266 light (500 mAh Li-polymer battery) or a Lezyne Drive 100 clone (650 mAh Li-polymer battery) available from China for around $5 and you can see why I do use both of these lights. Solar is more a gimmick than a practical design.
Raypal 2266 - under $4 COB 29 LED light 500 mAh https://www.ebay.com/itm/USB-Rechargeable-LED-Bike-Cycling-Front-Rear-Tail-Light-Lamp-6-Modes-Waterproof/372276967310?var=641112347075&hash=item56ad6fb78e:g:LbkAAOSwjS9a0Hjf

There is a lot more information on the front light. It shows up for $13.39 https://www.ebay.com/itm/Solar-Charg...EAAOSwi7Rd~GOg
It says it has a 2000 mAh internal battery and uses an T6 LED with a rated output of 350 lumens. The CREE version of the XML-T6 bin is used in a lot of LED flashlights. It can put out nearly 1000 lumens if properly heat-sinked to keep from frying the LED. The reason this light maker is not running it at full ~1000 lumen output is to increase the run time and to keep from destroying the LED. I often use a CREE XML-T6 flashlight powered by a Panasonic 3,400 mAh 18650 battery as my front light. It costs under $10 without the battery and is way brighter than the 350 lumen bike light. The fact that the manufacturer included a USB charging port may give you a hint that sunlight is not enough to keep the battery fully charged if you use it frequently. I don't leave my lights on my trike when I'm not using them so solar charging is not going to work for me.

alo

You don't need to sacrifice a light. You can take the screws out, have a look inside, then put it back together, and continue using it. There is another solar headlight, not shown, which appears to be a sealed unit. The light is not as bright as this model.

The headlight shown here uses an 18650 battery. This is the largest battery in any of the solar headlights I have seen. Other solar headlights, not shown, use a battery similar to a small phone battery.

The tail light shown here uses two button batteries, approximately 10 mm in diameter.

alo

I have just recently bought the headlight shown in the first post. In the past, I have used different model solar headlights. I found the model I used was not rain proof, would get water in it and fail.

In the past, I have used the tail light shown in the first post.

I had two solar headlights on my bike, so if the battery would get low in one, I could use the other. I had one solar tail light. I did most of my riding during the day. There were some days when I did not spend much time cycling, and the bike was normally inside. There were times when I would be out after dark. When I turned the lights on, they always worked. I never used the USB charger.

If someone was to do most of their riding after dark, they would need to leave the lights exposed to sunlight during the day, or use the USB charger.

I have actually put one of these tail lights in the window of the house, where it is exposed to light, but never exposed to direct sunlight. It charges the battery, no doubt more slowly.

znomit

18650? I think the self discharge would likely be more than the real world power available from a small solar panel like that. Yes, it relies mostly on the usb charger.

We have a few solar garden lights that do just fine for a couple of hours every evening, so I think the concept is fine.

VegasTriker

If the button cell is about 10 mm in diameter it is not the LIR2032 40 mAh lithium battery. The number means the 2032 battery is 20mm in diameter and 3.2mm thick so you have some other battery. I couldn't find one with a 10 mm diameter but there are rechargeable button cells that are 12.5 mm in diameter (1220).
Some manufacturers do not make it easy to access the battery in a bike light. I was given a Blitzu Gator 320 bike headlight two Christmases ago. When I tried to look up the specs on the light, there was no information on the battery capacity so I opened the case. It wasn't hard to get it apart but far more difficult to reassemble the light. I found two pieces of information - the battery was labeled Raypal and it was 1200 mAh. Raypal is a major Chinese bike light manufacturer and obviously labels the lights for American companies. When I looked at eBay sellers I saw that I could buy the same light with the Raypal name on it instead of Blitzu at much lower cost. I wasn't really worried about breaking the light because it was far dimmer than the flashlight I use and that one allows me to switch out the battery in seconds. The thought was nice.

alo

Why would you want to replace a battery in a light that costs less than $3 to replace?

Koyote

Quite aside from the impracticality of a solar-powered bike headlight, I don't want a 120db horn blaring three feet from my ears. OSHA would not approve, and for good reason.

alo

You don't need to use the horn. The horn button cable plugs in to something like an earphone jack. Just don't connect the horn button.

In Australia, I like to have a bell and a horn. When I am going slow and up close, I use the bell. When I am going fast, and want to warn people from some distance, I use the horn.

I live near a cycling track where I can go 20 km, and it is 90% uphill. I can go home fast, as it is 90% down hill. It is popular for cyclists, and many cyclists go down that track fast. Occasionally when you are flying down the track, you want to warn people ahead. A loud horn is very useful. I don't use it very often, but it is good to have it when needed.

A loud horn is beneficial for safety, for people cycling fast.

I also use those old style squeeze the rubber bulb air horns. They are slightly louder than the horn on this light.

Koyote

You’re free to damage your hearing, if you wish. But you should at least be aware that 120db will damage it.

Others have already explained why the light is inadequate, so I won’t get into that.

alo

The horn is not as loud as a car horn. Do car horns damage people's hearing?

alo

I also spend time in Cambodia. In Cambodia, people normally don't obey road rules. There are a lot of accidents, and a lot of people killed. I ride a bicycle, as anything faster is too dangerous. I am normally going slow enough, so I can stop when I need to. There is still a big risk of getting hit from behind. I normally avoid narrow busy roads.

In Cambodia, I use a horn, and don't use a bell. There are times when one needs to use the horn.

If you spend time in countries where people don't normally obey road rules, things will become clearer.

A bicycle also has the advantage of normally being able to get through traffic jams.

Koyote

If you get out of the sound-insulated passenger compartment of your car, open the hood, and put your ears 2-3 feet from the horn… Yes, it will damage your hearing.

alo

It is not as loud as a motor bike horn. Do motor bike horns damage people's hearing?

Seattle Forrest

We just went through 33 consecutive days of rain.

mtbtrlrguy

My bike trailer battery is solar-recharged since 2016. A single 3W panel recharges the battery based on length of time, amount of sunlight, and battery quality. A fully-charged battery gives me three days of use on the roads.

bobwysiwyg

Yipes! You still sane?

Seattle Forrest

I don't know that I was sane to begin with, but the sun came out, it's 35 degrees now that sunset is over, and I'm sitting outdoors looking at the cloudless night sky. That's probably a no.