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Comment by burnt-resistor | Hacker News Reader

Rechargeable safe(r) chemistries. Alkaline batteries are insta-e-waste. Like the common form-factors of AA/AAA Ni-MH that are acquirable locally.

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Conference badges are basically insta-e-waste too.

Not the ones from these events they are really well designed (welll... Feature wise) and offer great learning and usage opportunities.

This one has a big colour screen and a full qwerty keyboard. It's not really to be used as a badge. More as a way to get people interested in making something cool with it.

After all, hacker conferences these days are about 50% traditional security and 50% makers.

citation needed. From mining over production to recycling, NiMH batteries are ecologically inferior to alkaline batteries. A breakeven and superior performance may only set in after many recharge uses which NiMHs may never reach (ageing, rare usage)

It's a bit odd to declare "citation needed" and then claim things like "rare usage" which just so happen to suit your argument, while ignoring things like, say, the fact that NiMH batteries mean batteries are only shipped to the end-user once.

I use NiMH batteries in all my thermostats, two scales, etc. Bought them 10 years ago or so. The thermostats get charged every few months and the scales every few weeks.

I think ~12 or so NiMH batteries have replaced, by this point, by rough back-of-envelope-math, thousands of of alkaline batteries.

Did it occur to you that probably one of the most energy-intensive parts of a AA battery's life is its transportation from factory to user? Which NiMH batteries only have...once? And most of that transportation is powered by non-renewable fuels, etc.

A quick check on GPT suggests that shipping the thing via ocean freight is going to be comfortably less than 1% of the carbon emissions of manufacturing. Batteries are really tiny, so they ship well, and they are really complex, so they are more difficult to manufacture than say a simple plastic toy.

I'm glad you are making use of your li-ion batteries, I'd love to see aggregate data on that. I know in my own personal life, rechargeable AA batteries usually get lost or forgotten before their third recharge for me. Climate wise, I'm probably net negative overall on my rechargeables.

But it's also kinda not the right thing to focus on for climate. Driving 50 miles in a gas car will cause a greater climate delta than manufacturing a battery. Eating 12 ounces of beef (300g) causes more emissions than manufacturing and shipping a battery. One international flight can be equivalent to several hundred batteries, etc

Mercury free alkaline batteries are not e-waste, even if they are often handled as such for simplicity (battery bad mmmkey?).

AA/AAA won't fit in a flat conference badge. I've wanted to get coin cell format NiMH, but they only seem to be the more thicker button type (or I don't know the magical term to search for), and I can't seem to find cheap options either. The 40 maH ones seem to be 5mm tall and I can't seem to find many smaller capacity ones that are thinner.

In the badge from the article they're using 18650s, so AA batteries would actually have slimmed it down by 3.5mm.

Lower voltage, of course.

OK, but my point is more general than reproducing the badge from the article. I was rather pointing out the lack of easily-purchasable NiMH (or other "rechargeable safe(r) chemistries") batteries that could serve as a replacement for a very flat coin cell. For instance, CR2032 (3.2 mm tall), CR2025 (2.5mm tall), and CR1616 (1.6mm tall) lithiums are easily-purchasable, and it would be nice if NiMH batteries were purchasable with those heights.

The fact that NiMH is 1.2V is another thing to consider cause their heights would add stacked, though it isn't too much of an issue cause they can be placed flat side-by-side, or could use one of those ultra-low voltage MSP430s that can run off 0.9 V to 1.5 V.

Is a lithium ion button cell (LiR) big enough to pose a danger? I can't really find any tests.

Wikipedia claims several rechargeable chemistries for button cells including NiMH but most of the seem to barely exist.

Do you need more current than ML can provide?

For the type of applications I imagine, I wouldn't need more than 1mA of current...just enough to run an attiny-like microcontroller and blink a LED on occasion before going back to lowpower mode. It seems NiMH just doesn't come in those small sizes. I don't know much about ML, I'll have to look into if ML and LiR in the smallest coin size are safe enough. Actually now that I've thought about it more I might be able to just use a small supercapacitor for around an hour if I'm really careful with energy consumption.

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