18650 battery recommendations for T-Beam?

Anyone have any recommendations for 18650 batteries? Any differences as to recharging, lasting time, recharging with solar, etc.?

Good question. I have “button-top” batteries… they are a tight push to get them into the holder.

Does anyone use the flat top batteries… or the pro’s and con’s .

I bought the Sparkfun batteries from Digikey: I have not received my t-beam from aliexpress so I cannot confirm the fit…UPDATE: the batteries fit fine. I recommend this model.

Thanks, I bought some “button-top” Samsung 30Q. I’ll let you know how long they last.

I got the sanyo ncr18650ga recommended by meshtastic on their site. i’ll let you know how that goes.

If they are sold as “protected” they are a couple of mm longer and are a not a good fit in the standard holder. They do fit but are sub-optimal.


Has anyone fit a protected 18650 into the holder? Can you share a picture?
The TBeams are only sold with the 18650 holders?
Looking at my Lora32 board I really like how thin it is with a flat battery…

A friend tried a protected battery but he had to really mangle the holder to get it to for. I would not recommend.

Btw (no guarantees - might burn your house down etc) but the tbeam 1.0 or later actually has a pretty smart charge controller that should be at least as good as those protected batteries.


Well Using a protected battery in the T-Beam doesn’t make sense as the T-Beam itself has a dedicated chip that takes care of charging and discharging the battery.
However, if you have bought some protected batteries or already have a pair and you are waiting for the T-Beam to arrive to make sure your batteries work, the answer is yes they fit in the socket anyway, a little harder than normal flat ones.
Here are some indications of the size of the socket and the lengths of protected and unprotected batteries.

Unprotected: Recommend

Protected: I don’t recommend them.

The protected ones have an extra length of =4,48mm


I also learned from the web link below–so don’t use button top:
And they are hard to fit into the t-beams holder

Please note this is a PROTECTED (PCB) 18650 Panasonic Battery. The PCB is a safety feature and acts as a fuse to protect the cell from short circuiting, overcharge, and undercharge. Please note once the PCB is tripped it cannot be reset and this will stop the battery from functioning.


I’ve been eyeballing the Boston Power 5300s. They’re basically double 18650s in parallel which look to have protection built-in. Spec sheets also say they charge at -20°C.

Not the choice for pocket use, but potential.


I felt it’s time for a little update to tell you what I am doing. :slight_smile:
Yesterday I brutally slaughtered two Ryobi battery packs. They are from 2009 and I bought new batteries for them to replace the old. I bought batteries that were exactly the same:

So the question is: batteries that have been sitting for years - will they work?
The new batteries I bought are also old (2016). I am hoping they will be able to charge and work in the Ryobi. I don’t need top performance, just a working drill/screwdriver! My budget is very limited so I need to try to save a bit.

The batteries I remove will be used for LoRa! This means I will be able to salvage a couple of batteries to use for my project. I would like to make some Nodes with the CubeCell:

I intend to put them “here and there” by giving them to friends and family!
Do you think I would be able to run them with a 10 year old 1300mAh Samsung INR18650 13Q battery? Or perhaps if I connect several. It would be nice to be able to power them with solar. I think it’s only possible in the summer here, as it gets pretty cold and dark during winter.

For this winter/spring:

Another idea I had was to place devices in cars! Do you think that could work? Perhaps not with the CubeCell but with the “fully functioning” boards. I would then connect it to the 12v-port with a USB-adapter of the trunk (many modern cars have those) and hide it in the side of the car where the medic kit or tire shifting stuff is usually hidden. Most cars have a small hatch for that somewhere.

It could then be charged every time someone uses the car which means I don’t need to worry about solar charging etc! Please give me any input on this. I could also insulate the battery properly so there is no need to heat it during the winter?

I imagine doing this with about 20 friends all over the city which means it would be possible to “pick up” messages here and there which would then be distributed once someone is near another persons home or car! For cold climates, car mount is the way to go!!

So say something like this:

  • Fully capable Meshtastic LoRa in car powered by battery charged every time someone drives the car. I would need to disable GPS here? Would it be possible to make a “car version” of the firmware?
    The antenna could be placed close to the window for maximum reach.
    Say that the care is used 20min per day on average. I guess that would be enough to keep the battery alive 24/7?

  • Node Cubecell on the roof or somewhere near the house or apartment, which would require low power and be charged with our weak sun. Perhaps insulated and painted black? Would temperature variation destroy it?

  • Fully capable Meshtastic LoRa placed in apartment, powered by USB-adapter and battery added for power outages.

1 Like

I guess I could use some sort of ceramic heater which is powered on when the car is running in close proximity to the battery to heat it up. Then wrap heater and battery in insulation to keep it warm when the car is turned off.

I purchased a 10-pack of these to use in T-Beams: JOUYM 18650 Battery INR18650 35E 3500mAh 3.7V Li ion Rechargeable Battery|Replacement Batteries| - AliExpress

I also purchased one of these (after watching this Project Farm video) to test out how much power various 18650 cells are really putting out: BT C3100 v2.2 Digital Intelligent 4 Slots LCD Battery Charger For Li ion NiCd NiMH AA AAA 10440 14500 16340 18650 Batteries|Chargers| - AliExpress

Turns out, I’m getting just over 3200mAh on the JOUYM cells, which is very similar performance to the Samsung 35E cells Project Farm tested, so I’m quite happy with them. Not as happy with the cells that came with this ‘POWOBEST’ flashlight, as they test out at under 1900mAh and are marked as 3000mAh.

I also have some 26650 cells and holders (will need to do some desoldering on the T-Beam) on the way to see how those might fare in comparison.


Addendum: After striking out twice with 26650 cells with capacities far lower than advertised, I found a unicorn! Cells that actually test out better than advertised! I purchased a pair of these Tewaycell 5000mAh cells: 26650battery High Capacity 26650 5000mah 3.7V Li ion for Flashlight power Bank 26650 lithium rechargeable battery|Rechargeable Batteries| - AliExpress

Testing showed one to have a capacity of 5676mAh and the other was 5775mAh - I’m delighted.

On this test Will China's 18650 Battery Beat LG, Samsung, Sony & Panasonic? Let's find out! - YouTube looks like LG MJ1 has the best quality to price ratio.