Replacing the old battery on rechargeable bike lights

robot_jesus•about 2 hours ago

Love this. I have a pile of nice Cygolites (both front and tail) that my whole family uses that are maybe 8 or 9 years old. Their capacities have largely dropped to the point that I need to charge them every ride or two. Maybe get about 90 minutes of use, down from 3-4 hours previously.

They're not user-serviceable by design but I've been pondering cracking them open and having a go at swapping the batteries. This post may inspire me.

I've got a pile of new 18650s lying around and hopefully the front lights use those!

mooshx•about 1 hour ago

Thanks for sharing this. It's nice to see something not immediately turned into landfill junk. I ran into a similar issue awhile ago, and was able to replace the battery too. Not trivial, but very satisfying. Here's that journey: https://www.mooshwerks.com/2024/11/09/bike-light-hack/

dragontamer•about 1 hour ago

I wouldn't worry about matching the exact model number of the battery. Instead, it's more important to get roughly the same chemistry and a capacity equal or maybe a touch greater (if technology improved in the last 10 years, capacity could be greater with modern parts).

Specific batteries go in and out of production. But as long as it's the same CHEMISTRY, voltage, and capacity, it's likely compatible. Chemistry tends to set the voltage, size sets the capacity.

Charge/discharge controllers and algorithms are based on these three bits of info.

In some cases, some chemistries are actually compatible with other chemistries. NiHM cells are largely backwards compatible with Ni-Cd chargers (but not vice versa). It's not good for the NiHM but they will actually take the charge.

bestham•39 minutes ago

The chemistry set the voltage and the voltage and the size set the capacity. Everything else equal, a larger capacity battery is often compatible with an original smaller capacity battery in a given device because the charge current will be lower in relation to the capacity.

esquire_900•about 2 hours ago

In the Netherlands many people use these kinds of detachable bike lights. I've never came across soldered batteries in the dozen or so I've replaced batteries for. Not always cheaper, but just tossing the whole thing seems like such a waste.

Well done!

cubefox•about 2 hours ago

There are also dynamo powered LED lights which only provide light while riding the bike, and about a minute afterwards (I assume from an internal capacitor). They are not detachable but why would that be necessary? From what I can tell they also don't require regular replacement.

kccqzy•about 2 hours ago

These are fine for bike commuters, and I’ve had them before. But they are in general not fine for recreational bicyclists; these people pay a hundred dollars for a new tire to shave off three watts and are not about to add any unnecessary human-powered accessories.

bootlooped•about 1 hour ago

An exception is bikepackers, who may prize reliability and runtime over brightness and weight. But then the dynamo we're talking about is $200-$400 and that's not including the light.

thirtygeo•about 1 hour ago

Love to see MEC gear - but I wish it were more repair friendly!

rollulus•about 1 hour ago

I don’t know what it is with Julia’s writing but it always makes me happy. It reminded me of replacing the soldered battery in Super Metroid so I could save my progress again. As a cheapskate I used a regular battery and connected the wires mechanically.

aenis•about 1 hour ago

I know it's slightly offtopic, but the brand I am using - ExposureLights - offers a battery diagnosis/replacement service for their bicycle lights.

Those are on the expensive side, but still, most brands would rather sell you a new one.

sandworm101•about 2 hours ago

Talk about burying the lead. This was a MEC bike light. It should have a replacable battery!

https://www.mec.ca/en/explore/sustainability-innovation

vohk•about 1 hour ago

Ah, memories. I miss the old MEC, before they overextended on real estate and had to sell the farm to private equity. I have a pile of MEC branded gear I'm still happily using 20 years on. I have some restrained hopes for the new ownership group to bring it back, but I'll always miss the co-op.

These lights would have predated the private equity era but I'm guessing sourcing options were somewhat more limited back in 2016.

Replacing the old battery on rechargeable bike lights

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