Note that buck converters have a significant voltage drop. Therefore, using a 3.3V buck converter with a 3.7V battery isn't that ideal, as the internal Schottky diodes can drop the voltage by 0.3 - 0.4V itself. This prevents the battery from being fully utilized. For example, Li-ion batteries cut off at 2.7V, but with a 3.3V buck converter, you can't utilize the entire capacity of the battery since the voltage drop of the converter itself reduces the effective range the LORA module or something else can be powered. Buck converters will work if the working voltage is much higher, for example, if you have 2 Li-ion batteries in series or a 12V lead-acid battery. Also, the power density of LiFePO4 batteries isn't as high as that of Li-ion batteries (if space is a concern), but they are much safer and are superior to lead-acid batteries. For powering a LORA module, it's better to use a buck-boost converter. It can regulate the output to 3.3V regardless of the battery voltage which ensures an efficient usage of the battery. On the other hand, adding few decoupling capacitors and an inductor on the DC output will help filter and stabilize the power supply! For reverse polarity protection, it's better to use a 1.5KE TVS diode series (like the 1.5KE6.8A unidirectional TVS diode) because it can dissipate a lot of power. Connect it in reverse and use a sensitive fast-blown fuse to protect the TVS diode from damage. If the batteries are inserted in reverse, the diode will conduct, causing the fuse to blow immediately. Alternatively, you can use a circuit with active components that won't blow any fuses but will prevent the circuit from starting up, but such circuits will consume a bit of power.
Amazing. You just gave a lot of usefull information in 5min including protection and charging options. That's why I subcribe, this channel does not waste my time.
Wow, such a lot of useful information on powering our projects in under 5 minutes! It should be noted that the charging voltage and current in 18650 lithium ion batteries is HIGHLY sensitive, down to tenths of a volt or damage will occur. I found this out the hard way , that even with a current limited supply that's not enough. I like your use of the lithium iron phosphate 18500. I will have to consider those in the future. I'm also a fan of the nickle metal hydride batteries. I have some Japan made Evergizers that I bought around 2006 that I bought for my 2 meg pixle digital camera that are still going strong. Watch what brand you buy. A lot of light weight cheap batteries out there that are complete garbage! Thanks for sharing and take care!
Yes, trying to find good quality batteries is not as easy as it looks. Many online vendors are putting out very poor products. I usually buy from Amazon hoping the review comments will weed out the junk. Thanks for the feedback and sharing.
For 5V projects, I use 4xAA NiMH batteries (2500mAh). Easy to recharge and I don't want to worry about lithium fire. For 3.3V project, I use smartphone batteries going through HT7833 LDO, as they have nice capacity and reliable safety circuitry.
With a Li-Ion 3.7 V battery, you could use a simple Schottky to introduce a small voltage drop and there you have your reverse polarity protection and also overcurrent protection (since a diode will blow much faster than a fuse). The price of this diode is not higher than a fuse and its holder
Last time I looked into charging circuits for small LFP batteries, they didn't really exist. I'm glad to see that we can get them now...which is very cool! I saw a few pictures of a TP5000 charging board similar as to what have and they show a resistor you can change to adjust the charge current. Looks like it might be 0.5, 0.1, and 0.2 Ohms for bulk charge (CC) currents of 2A, 1A, and 0.5A. I was curious as to what rate you were bulk charging your cell at. My knowledge of LFP exists with large prismatic cells...which most manufactures recommend a charge rate around 1C or lower. I'm also curious if your cells specified a recommended charge rate. For longevity reasons, prismatic manufacturers seem to recommend less than 0.5C. That said, considering the low cost of such a small LFP cell, I highly doubt anybody is trying to get 20 years and 10,000 cycles out of them.
I don't have specs on the batteries but the recommended charge rate is .5C and max 1C. The resistor to configure the charge current will differ with each vendor. Mine has .1 Ohm for 1C charge rate. If you want to be sure you can get chargers that come with a set of batteries that are compatible.
Finding batteries is always hit and miss. Most from Aliexpress are only 600 mAh and sometimes shipping batteries is not allowed. The ones I got (1000 mAh) were shipped from Amazon @ $10 each and came pretty fast. Most of the time they are shipped from China.
Great video. One of the things that I like about this channel are the real world solutions. Thank you. Take care.
Thanks for the feedback
Same, that's why I keep coming and have watch most previous videos.
So many good ideas in such a small amount of time. Thank you.
You are so welcome!
Note that buck converters have a significant voltage drop. Therefore, using a 3.3V buck converter with a 3.7V battery isn't that ideal, as the internal Schottky diodes can drop the voltage by 0.3 - 0.4V itself. This prevents the battery from being fully utilized. For example, Li-ion batteries cut off at 2.7V, but with a 3.3V buck converter, you can't utilize the entire capacity of the battery since the voltage drop of the converter itself reduces the effective range the LORA module or something else can be powered. Buck converters will work if the working voltage is much higher, for example, if you have 2 Li-ion batteries in series or a 12V lead-acid battery.
Also, the power density of LiFePO4 batteries isn't as high as that of Li-ion batteries (if space is a concern), but they are much safer and are superior to lead-acid batteries.
For powering a LORA module, it's better to use a buck-boost converter. It can regulate the output to 3.3V regardless of the battery voltage which ensures an efficient usage of the battery. On the other hand, adding few decoupling capacitors and an inductor on the DC output will help filter and stabilize the power supply!
For reverse polarity protection, it's better to use a 1.5KE TVS diode series (like the 1.5KE6.8A unidirectional TVS diode) because it can dissipate a lot of power. Connect it in reverse and use a sensitive fast-blown fuse to protect the TVS diode from damage. If the batteries are inserted in reverse, the diode will conduct, causing the fuse to blow immediately. Alternatively, you can use a circuit with active components that won't blow any fuses but will prevent the circuit from starting up, but such circuits will consume a bit of power.
Amazing. You just gave a lot of usefull information in 5min including protection and charging options.
That's why I subcribe, this channel does not waste my time.
Welcome to the channel. Glad it was helpful.
This is such an information rich video and yet so short. I really appreciate you making this kind of content. Thank you!
You're welcome
Wow, such a lot of useful information on powering our projects in under 5 minutes! It should be noted that the charging voltage and current in 18650 lithium ion batteries is HIGHLY sensitive, down to tenths of a volt or damage will occur. I found this out the hard way , that even with a current limited supply that's not enough. I like your use of the lithium iron phosphate 18500. I will have to consider those in the future. I'm also a fan of the nickle metal hydride batteries. I have some Japan made Evergizers that I bought around 2006 that I bought for my 2 meg pixle digital camera that are still going strong. Watch what brand you buy. A lot of light weight cheap batteries out there that are complete garbage! Thanks for sharing and take care!
Yes, trying to find good quality batteries is not as easy as it looks. Many online vendors are putting out very poor products. I usually buy from Amazon hoping the review comments will weed out the junk. Thanks for the feedback and sharing.
Thanks!! As usual all the best and most useful info
Glad it was helpful!
For 5V projects, I use 4xAA NiMH batteries (2500mAh). Easy to recharge and I don't want to worry about lithium fire. For 3.3V project, I use smartphone batteries going through HT7833 LDO, as they have nice capacity and reliable safety circuitry.
With a Li-Ion 3.7 V battery, you could use a simple Schottky to introduce a small voltage drop and there you have your reverse polarity protection and also overcurrent protection (since a diode will blow much faster than a fuse). The price of this diode is not higher than a fuse and its holder
Last time I looked into charging circuits for small LFP batteries, they didn't really exist. I'm glad to see that we can get them now...which is very cool! I saw a few pictures of a TP5000 charging board similar as to what have and they show a resistor you can change to adjust the charge current. Looks like it might be 0.5, 0.1, and 0.2 Ohms for bulk charge (CC) currents of 2A, 1A, and 0.5A. I was curious as to what rate you were bulk charging your cell at.
My knowledge of LFP exists with large prismatic cells...which most manufactures recommend a charge rate around 1C or lower. I'm also curious if your cells specified a recommended charge rate. For longevity reasons, prismatic manufacturers seem to recommend less than 0.5C. That said, considering the low cost of such a small LFP cell, I highly doubt anybody is trying to get 20 years and 10,000 cycles out of them.
I don't have specs on the batteries but the recommended charge rate is .5C and max 1C. The resistor to configure the charge current will differ with each vendor. Mine has .1 Ohm for 1C charge rate. If you want to be sure you can get chargers that come with a set of batteries that are compatible.
The nice thing about using AA size batteries is that you can use an alkaline batteries in a pinch.
Thanks
Welcome
Can you recommend a good (and affordable) source for those LiFePO4 batteries?
Bonus if it ships to Canada without tripling the price.
Finding batteries is always hit and miss. Most from Aliexpress are only 600 mAh and sometimes shipping batteries is not allowed. The ones I got (1000 mAh) were shipped from Amazon @ $10 each and came pretty fast. Most of the time they are shipped from China.
Another very useful video, well done!
Thanks John!
its a GREAT explanation, except my proyect is 5v. 2amps....
what can i use?
Google 5 volt power packs ... lots to select from:
www.amazon.ca/10000mAh-Portable-Charger-External-Compatible/dp/B08YNQPKFJ
i'm having trouble powering a esp32-cam via a 3.7v lipo. which boost converter do you recommend?
I use smartphone batteries going through HT7833 LDO to power ESP32-Cam low-power projects. Works fine even with WiFi
@@Friendroid thankyou very much