Building a pair of units. Battery suggestions?

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Hello! I’m having a very hard time determining which 18650 cell is best for the TTGO T-Beam ESP32. I can’t seem to find any documentation on what amperage the device will operate at. Any advice is appreciated. Sorry if this has been asked before.

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Amperage shouldn’t be of any concern with an 18650 cell. The TBeam won’t draw more than, at an educated guess, 500mA.

The battery holder doesn’t fit protected cells in it very well though as they are a few mm longer than unprotected cells so I would look at unprotected options.

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yep - any of the standard 18650s should be fine. Some of the ones sold as “overcharging protection included” are bigger than standard size, so I’d avoid that.

It should run about a week on an 18650.

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Thanks for the advice! :slightly_smiling_face: I picked up a sony murata vtc6. Does the ttgo charge the battery or will I need a separate charger?

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It’ll charge via USB.

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Thanks :slight_smile:

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No problem. I hope you get it setup all good!

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I’ve just measured a TTGO T-Beam with Meshtastic 0.6.1 drawing btw 0.07A - 0.13A, without a battery. Put an 18650 in it, and it’s drawing 0.31A (charging & operating). Turn off the T-Beam, and the current drops to ~0.28A.
Greg
BTW: Most of my 18650’s are harvested from old tool batteries and laptops. They’re fine.

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If it is useful here is a spreadsheet with measurements for the different operating modes: https://docs.google.com/spreadsheets/d/1ft1bS3iXqFKU8SApU8ZLTq9r7QQEGESYnVgdtvdT67k

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Quality 18650 cells are either high amps ~20A and lower capacity ~3000mah OR low amps ~6A and higher capacity 3500mah. Meshtastic has a very low current draw 0.28A peak when transmitting as someone else mentioned, and much lower than that on standby. Best buy big name branded ones, cheap and fake ones lie about their capacity, so buy from a reputable source too. Panasonic NCR18650B are a good low draw cell, the other big names are LG, Sony, Samsung. WIth all that said, due to meshtastic’s low requirements cheap cells will work ok too

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Is there any info on what the LEDs represent on the TBeam? I’m just wondering how to tell if the battery is fully charged.

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the LED represents CPU activity (that’s about it right now :wink: ). The OLED display has a screen that shows battery voltage. There is an open bug for someone to change that to a % full based on a table.