My PicoCalc has been dispatched but I’m a complete amateur when it comes to 18650 batteries and am looking for some advice. I’ve seen other battery threads here but they mostly relate to other ClockworkPi products so I want to make sure my understanding is correct for the PicoCalc.
From what I can see, 18650 batteries come in unprotected and protected form, with the protected units having some overcharge protection circuitry embedded in the cell. Other threads suggest the protected cells are slightly larger and a tight fit (sometimes requiring a pry tool to remove them from devices). The PicoCalc page suggests the device itself have battery charge management built in, so does this mean I can/should opt for an unprotected 18650 battery?
I’ve also seen vendors list the cells as flat or button top - which would be most appropriate for the PicoCalc?
Bonus points if anyone can recommend a trustworthy vendor and brand in the UK!
That’s how I interpreted it. For the uConsole – if I remember correctly – they had recommended protected batteries for lack of that circuitery. For the PicoCalc, I believe they integrated the protection circuit onto the product so it isn’t required that the batteries have it. As for the form factor (flat or button top), both will fit, just be extra careful with the polarity with a flat top battery.
If you go to a vape or flashlight shop, they will have some. There are usually a few models, with varying capacity and max discharge rate. For our application, we don’t care about the max discharge rate. Capacity will be around 3000mAH to 3500mAH, but not much above that. Be wary of anyone promising 4000 or more: these batteries don’t exist.
While the Samsung batteries mentioned here (unprotected flat top, or protected button top) might be overkill for the PicoCalc since its power requirements will be more modest than a uConsole, they’d still be excellent choices. It seems like most 18650s seem to fall into a few categories:
fake batteries that claim to have impossibly high mAH – not only will these not last long, they are likely to damage your hardwares since they might be so poorly made they could explode or catch fire.
cheaper batteries that either don’t have very high mAH (and don’t claim to), which seem to be common at vape shops. These don’t work well (or at all) with the uConsole or Devterm since those devices require higher (and sometimes sustained) power draw which these sorts of batteries tend to struggle with. Something like this might work ok for the PicoCalc, and would probably be safe. They may need to be replaced sooner though.
more expensive batteries that can supply higher power draw for longer periods of time, from trusted sources. One example is at the link below, but there are others. Generally speaking, Samsung and Panasonic seem to make quality batteries, but in all cases you should carefully look at the specs: not just the mAH, but also continuous discharge rate, protected (or not), discharge cutoff voltage, and physical length. For PicoCalc, most of that won’t be as important. Protected batteries with button tops just barely fit in the Devterm and uConsole. I’m guessing they’d fit in the PicoCalc as well, but haven’t tested yet. Originally, the conscensus on the forums seemed to be that protected was necessary for all the Clockwork devices, or at least was wise, just to be safe. But over time it sounded like all the devices actually have necessary protection hardware, so unprotected batteries were not really a risk, as long as they weren’t cheap trash/fake batteries. In any case, you should always be careful which direction you insert the 18650 batteries, and always store them safely so there’s no chance they will short out. While they might not explode or catch fire, you could still ruin them.
I don’t have much experience with this, long term, as I only started using these batteries with the Devterm and then uConsole starting a few years ago… But based on forum posts it sounds like cheaper batteries don’t tend to last as long, even if they do work for a while. I’ve had the same Samsung batteries in my Devterm for years now, and they are doing fine. So my gut feeling is that you get what you pay for. And considering how difficult it is to get Clockwork devices in a timely matter, I didn’t want to risk ruining mine.
I always buy protected batteries and the reason for that is because I use my batteries interchangeably in other devices which don’t have charge protection built in or it’s simply quicker to charge with a wall charger other than USB within the device itself. Personally I would always buy protected cells as you never know what you’ll use them for. Just check the dimensions but generally the majority will be fine.
Thanks all, those responses were really helpful! All of the microcontroller/embedded boards I’ve used have relied solely on DC power supplies (or more specifically, increasingly USB) so 18650s seemed like a bit of a minefield to the uninitiated. Part of the appeal of these devices is the portability, so I wanted to get the battery choice right first time.
I’ll check availability at reputable suppliers here in the UK, and try to feed back here about which brand, configuration and supplier worked best for me once my PicoCalc arrives.
Sorry, I meant to provide a link to the ones I buy. I settled with RS Components because I trust them. I felt most online UK stores websites seemed untrustworthy and the ones I did trust either were more expensive than RS or they were unprotected which I didn’t want to buy. I’ve had nothing but great success with the ones below.
Thanks - I did look at the RS Pro, but wasn’t sure if the 2600mAh would be sufficient as a lot of the other threads suggest 3Ah-3.5Ah were the sweet spot (though on reflection, it does look like most of those threads were about the more power hungry devterm and uconsole devices). RS definitely are one more reputable suppliers.
In the end I opted for the Panasonic NCR18650BD 3200mAh 3.6V Battery Protected from Ecolux. It’s not a vendor I’ve used previously but they often come up on threads elsewhere about trustworthy 18650 suppliers.
The Panasonic ones also seem to be within spec for length (68.9mm, where the PicoCalc spec sheet says 69mm is the upper limit). I’ve seen a lot of 18650s that are between 69.1 and 69.9 so was keen to avoid those.
I have gotten some really bad ones from Amazon and now know that you basically can’t trust most batteries from them, so I bought mine at a local BatteriesPlus store. They sell decent quality ones and they back them up. That said, there have been a lot threads in the uConsole community forums that give links to legit good quality 18650s and I may try some of those at some point. If you check out Project Farm on YouTube, he did a very thorough test on them.
My PicoCalc arrived today and the Panasonic 18650’s I ordered from Ecolux seem to be working really well. Physical quality of the batteries seems good (wrap is tight and tidy, which I gather is fairly important) and they arrived with a little plastic container to minimise the risk of an accidental short. They fit perfectly well in the PicoCalc (to reiterate - they’re protected button top cells. Removing them was easy enough to do without the use of any pry tool (minimising the risk of any accidental puncture or physical damage).
I have only been using them for a short period, but initial impressions are good.
Just go to a vape shop to source batteries. If vaping is the scorge on society in your country like it is in the US, you have a pace to source batteries
I’ve been using this fake battery that came from a solar light. It feels light enough to throw around without damaging anything. Works great and provides hours of fun. If I use it in the Devterm I’m pretty sure it won’t even boot.
PANASONIC NCR18650B discharge limited 3.7v 3350mAh to 4.875A without protection circuit. These batteries are ideal for notebooks, PCs, portable devices according to Panasonic datasheet.
