If you like to carry a spare battery with you, then I can confidently say, that spare 18650 cells are lighter, smaller and cheaper than any other headlight battery on the planet (for the same amount of energy stored).
Better yet, you can buy them all over the world in a very competitive market. Other high-end headlight manufacturers force you to use their own special-shaped battery. This means you have no control over the quality or the price – and if they stop selling them oneday, then that’s just too bad!
I think Ay-Up make great bikelights and their batteries are some of the best. A ‘half-epic’ Ay-Up battery will cost you $66, has a volume of 52cc, a mass of 80 grams and holds 9.25Wh of energy. I can sell you an 18650 cell for $20, with a volume of 17.8cc, a mass of 45 grams and holding 11.47Wh of energy. That’s about 1/3 the cost, 1/3 the volume, half the mass and gives you 25% more juice!
Interested? Well, there are a few things you’ll need to learn first…
For the real geeks out there, (like me) you’ll want to do a lot of research and study all the different 18650 chemistries, capacities, brands, discharge curves and circuits. This article isn’t really for you, but I’m happy to answer any questions you might have. Then there will be people who don’t want to do any learning and are just happy to buy what we sell. That’s fine too. This article will be just a few quick pointers to help those who want to shop around and choose their own cells and chargers.
The name ’18650′ is actually a description of the size. It means 18mm diameter, 65mm long and the 0 means it’s a cylinder. The 65mm length is only approximate. Some can be up to 70mm (sometimes they get called 18700s) but they all fit in the V3.
This is the most important thing to look for. NEVER USE AN UNPROTECTED CELL! These cells store a lot of energy and if you abuse them, they can turn into a small bomb. The protection circuit watches what the battery is doing and shuts it down if you try to do something dangerous. All mobile phones and laptops have this kind of circuit. Otherwise you’d hear about phones and laptops blowing up all the time.
If you start searching on the internet, you’ll find a variety of 18650 cells and even more people willing to sell them to you. There are plenty of reviews out there but I’ll make it really simple for you. Go for something that says it has a Panasonic or Sanyo cell inside it. These guys make the best cells and then other retailers put their own badge on them and sell them to you. The Panasonics are the best. The best brands that use Panasonic or Sanyo cells are AW, Redilast, Callies Kustoms and Xtar. Stay away from anything with ‘Fire’ in the name eg, Trustfire, Ultrafire, Fandyfire and there are many others.
This is how much energy the cell can hold. More is better but don’t believe what the cheap suppliers claim. The Panasonics can reach 2900mAh or 3100mAh. The Sanyos only go up to 2600mAh but they are also a quality cell. Some of the cheaper brands have only half the rated capacity and lifetimes.
Button or Flat top?
You need a button top. The button tops work in all applications but the flat tops only work in some. You’ll need a button top for the V3.
A good charger is really important. There’s no point getting a good 18650 and then undefinedwasting it in a bad charger. Also, a good charger will stop a bad battery from becoming a bomb (it’s a second level of protection). There are only two chargers that I like. The ‘Pila’ and the ‘Xtar WP2 II’. Other chargers will still charge your cells up, but these two will really look after them. Spend a few extra dollars on these ones to get longer runtimes (more light each use) and longer lifetimes (more charges per cell).
The best Panasonic-based cells go for $16 to $20 + postage in many online shops. Don’t spend more than that on a single cell. The Ultrafires or Trustfires can be as cheap as $3 each but you get what you pay for. The Pila charger is US made and costs about $50 each. The Xtar is Chinese and goes for $15-20. In this case I think the Xtar is much better value for money. I’ve tested their products and am very impressed. The bad chargers can be as cheap as $5, but I think you’d be crazy to go past the Xtar.
I’ll have a variety of the better cells and chargers for sale when the V3 Spikelight is ready, but I’ll save the details for later. My prices are going to be very competitive amongst the quality products out there, but if you live closer to a different supplier then you may find you save on postage or time.
I hope this was useful. It was really hard to develop a headlight that could work with these cells and still be waterproof. Hopefully you’ll all see it my way and agree that it was worth it.