tmxkn1

Has anyone found any 2x18650 battery waterproof case with DC output? I searched everywhere, the closest ones I have found on Aliexpress are either designed for 4x18650 or 2x26650; the sizes are too big.

I plan to use this battery pack to power a ebike light (Busch + Müller Lumotec IQ Avy E Front Light). I only use my bike for commuting and it is usually a 15-minute ride. I think 5000mhA battery will be good enough to run 15 minutes a day for a week.

I have also considered to design a simple one by myself because I have a 3D printer, but I find it difficult to make a mini waterproof button... I might be able to rip one off from either A and B though. However, before I go down this route, I need to make sure I do not have a better option.

VegasTriker

See the private message I sent you for one possibility.

tmxkn1

Thanks, but I can't see private message yet because: "The administrator has restricted use of the private message system to members with less than 10 posts."

Would you mind posting the contents as a reply please?

VegasTriker

I sent you the PM because I think this will be of little interest to nearly all who read this section.

If you can find a case to fit it, the simplest way is to buy a two cell battery holder from overseas. Then find or make a case to go around it. If you put the batteries and case in a plastic bag, the camera bag which I use and which attaches directly to a bike frame should be the simplest way to go.
2 cell battery holder for 18650 batteries – 89 cents postpaid from Hong Kong https://www.ebay.com/itm/ABS-

A pair of the 3,400 mAh genuine NCR/Panasonic batteries costs around $12 on eBay. They work far better than the Chinese batteries with the fictitious mAh capacities that don't really exist for this size battery.

Here is a picture of the small camera case that I use to carry the battery case. See the two types of holders – pre-wired with spiral clips to hold the batteries. Do not buy that type as they do not hold the batteries secure enough to keep your light lit. The flat clips work far better.

01 CAt Man Do

There are many options and some that may be very simple. The simplest option is to just use a small ( battery / self-contained lamp. In the U.K. you have Merlin Cycles and they sell a variety of self contained bike lights. I'll highly recommend the Raveman CR series of lamps, either the CR-700 or the CR-900. I own both and both provide a wide beam pattern with a cut-off type lens. If you are only riding 15 minutes you may only need to charge them every 3-4 days depending on what output mode you choose and how cold the weather ( cold weather can effect how long a Li-ion battery will run ).

On the other hand if you are dead set on using the lamp you mentioned everything that Vegas T. said should work. Two cell 18650 holders are very common on e-bay ( although I don't know how common on E-bay U.K ). If you buy the one I linked to you have to wire up the way you want ( depending on the voltage requirement of the lamp ). I'm sure somewhere in the U.K. you can find an in-line on/off switch that should work for you. Then all you need is some basic soldering skill, some good wire and enough electronic knowledge to know what you are doing.

On a side note some e-bike batteries have output ports that may be used to power a bike light. You may want to check with your local bike shop and see if this is possible with your e-bike battery. ( edit; sorry, if you aren't using an e-bike I misunderstood but otherwise everything else should work )

VegasTriker

Why not do what this light was designed for? It is advertised as using the power supply for your e-bike. Depending on the system, all you might need is a separate switch.
The new Lumotec Avy E-Bike light from Busch & Muller incorporates all of the best features of the dynamo model but is designed to work with most E-Bike systems currently on the market. It can be connected to all DC power sources supplying between 6 and 42V DC. The 40 lux output with Close Range Light creates a far reaching, wide and evenly lit beam pattern ideal for faster moving E-Bikes. The Avy is switchless. This means that it is always turned on or is switchable via E-Bike console. source: https://www.sjscycles.co.uk/lighting...light/?geoc=US

tmxkn1

Thank you very much! I appreciate your simple and low cost solution. I use my bike every day and would prefer a more sophisticated solution. If I were to make my own battery case, I would definitely make it waterproof, but the problem is a small-size waterproof push button. Thanks for the tip about the battery clips. I haven't thought about that at all.

2_i 

Finding waterproof boxes that meet one's space constraints is tough. Cheaper cases on AliExpress may be of such quality that one fears that opening them would break them. One way going about this is to look into headlamps meant for outdoors. Many of them will have waterproof 2-cell cases for the rear of the headband, even with charging electronics there. As the market for headlamps is wider than for separate cases, it may be easier to find a usable case there without paying much.