I purchased a XT-60 Male to DC 5.5mm x 2.1mm Male Adapter Cord in order to power my Arduino UNO R3 with a LiPo battery. The cord is rated as: Current: 1-15A, Voltage: 12V, Power: ≤180W, Cable length: 30cm. My LiPo battery is a Gens ace 2200mAh, 3S, 11.1V, 25C. Before I connect the Arduino to the LiPo using above cord, I'd like to ask you some questions:
I have been told that “For safe and reliable operation with an UNO R3”, Arduino recommends “using a DC-DC converter to step the voltage down to approximately 7–9 V before connecting it to the barrel jack or VIN pin. Also, consider adding a power switch and a fuse or protection circuit between the battery and the board and avoid discharging the LiPo below its minimum safe voltage”. Why do I need a DC-DC converter to bring the voltage down to 7-9V when the barrel jack accepts 7 to 12 Volts??
Can I plug the cord I bought directly to the 5.5mm/2.1mm DC barrel plug on the Arduino UNO R3 directly from the LiPo??
Can I plug the cord I bought directly to the 5.5mm/2.1mm DC barrel plug on the Arduino UNO **R4 WiFi** directly from the LiPo??
I asked the Forum here because I am in doubt. If I follow Arduino’s docs I do NOT need a DC-DC converter because the barrel jack clearly says 7-12V. However, according to Arduino’s Tech Support I DO need a converter. So, who is right??
The converter acts as a current limiter. So either a fast blow fuse or a current limiting converter will work. if you feel really confident in your ability, then neither is necessary.
I honestly don't know how critical it is, but a fully charged 3S LiPo is 12.6V. Does that .6V matter? Have you seen a lithium fire? I would put an LM2596 buck converter between the battery and the jack. I would also add a fast-blow fuse. Put a SPST heavy duty switch between the jack and the Buck Converter.
Adjust the LM2596 taking into account the LiPo almost dead voltage, and the converter loss.
If you assume the Jack needs a minimum of 7V, and the voltage drop across the LM2596 is at worse 0.8V then the LM2596 needs 7.8V. Lets be conservative and call it 8V.
The 3S LiPo has a max V of 12.6 (4.2V/cell) and is not safely useable lower then 9V (3V/cell)
Then you are good to go because the battery minimum of 9V is > the 8V needed to power the UNO.
Why do you need such a large battery for an UNO. The UNO is not a great choice for a mobile app, a NANO or any of the smaller boards is better suited and they can run for a long time with a few AA cells, or Lithium 18650's are very common.
I am loving the SEEED XIAO esp32-sense (camera) for my game cameras.n The entire package will be about the size of a deck of cards.
The numbers range from 6V to 20V, as I told you in post 6, but if you look at the datasheet, you will see that the jack is connected to a SPX1117M3-L-5-0/TR and it produces 5V with the input from 2.6V to 15V. I suspect there is some sort of VR involved that explains the difference.
Do you expect an answer from someone on the forum? I doubt that will happen.
Instead of wasting your time here, just do as I said in post 8, or just plug it in, your battery ranges from 12.6 to 9 which is well within the ability of the jack.
Arduino datasheets seem to be writen by non-technical people.
That 800mA current rating is only valid at 6-7volt input.
That current rating drops to 100mA at 12volt input, due to thermal limitations.
You can't just quote max voltage and max current and expect you can have both at the same time.
It could be much easier (and safer) to power the Uno with a cellphone powerbank, through the USB socket. Use a model that doesn't switch off with low current draw.
Leo..
Lithium battery fires are reported in the UK on about a weekly basis.
Houses and entire processions, some times pets, sometimes people's lives lost. 11 people died from lithium fires in 2023, and over 1000 incidents recorded.
Increasingly, £250,000 refuse collection lorries with compactors are written off by suspected lithium battery fires.
Branded batteries, chargers etc., a little more to buy initially, but could save a lot long-term.
Yes, but remember there are many different chemistries. One of the safest is LiFePO4. Almost every RVer with a big rig today sleeps on top of 6 or more of them, as storing them under the bed is a convenient spot.
Also, remember that if people try to save money by purchasing cheap or wrong chargers, they increase the risk. By wrong I mean it is not programmed for that specific chemistry. Some people may not have proper protections and may be overcharged or discharged.
My charger has a 'storage' setting, so I have probably 20+ 18650s sitting in fireproof bags, and the big LiPos in steel fire safes.
I only ever had one Lithium battery 'go bad'; it swelled up, and I disposed of it. It was a major brand name, not some no-name.
I bet if you check the stats, more people die of tire failures than battery fires. Just educate yourself about the pros and cons of each chemistry, buy only high-quality chargers like SkyRC and store properly.
I literally live with one inside me.
It's lithium iodide and powers an implanted cardiac device.
21-years on them, about 10-years lifetime.
Without it, I would be very ill, so every heartbeat is a reminder.
There's some very robust software in it,
Battery life is monitored and when it goes below 2.8-volts it's time to change.
One did fail on me and the last one got to within 5-days of end of service.
Single use devices about £10k each, another £10k to fit.
Understood. I thought I was going to get a pacemaker, but my heart issue was addressed by a new medication.
That particular chemistry I don;t know but if I had to guess it's positive points are long life, no possibioity of thermal runaway but on the negative side probably cost and /or some other electrical characteristics that prevent it's use in storage or starter batteries.
Years ago, mid 50s, a guy working in his garage by pure chance put together a circuit for timing. He picked the wrong resistor value, but realised that the timing and output pulse matched the heart rhythm.
Just nine components then including the battery.
Early devices were proposed or actually were powered by nuclear generators.
The new ones have RTC, memory, an accelerometer, NFC and Bluetooth.
I download the data and send it to the hospital
