I am having an Lithion Ion Battery running my µC. I want to switch off the µC when the Voltage is very low, and start it again when it is high enough. I did not found a IC what could do that, I also maybe thought my LDO could do this but he can not.
This link has code that allows an Arduino to measure the voltage of the battery that is powering it. No external components are required.
...R
Thanks I already know how to measure the Voltage. But the main problem is how do I use zero electricity when the Voltage is too low, for example shut down the Arduino. And start him when the Voltage is high enough again after loading the battery.
You can use a transistor to control the power to the Arduino. One of the Arduino I/O pins can keep the transistor ON and when necessary that pin can turn the transistor OFF and then Arduino will have no power. You could use a push-button switch to provide power at startup - hold the switch down until the Arduino takes over control of the transistor.
However if you want the Arduino to start working automatically when the battery voltage is high enough that won't work.
One option might be to put the Arduino into sleep mode when there is still enough power in the battery for it to wake up very briefly at intervals to check the battery voltage. But how long that could go on depends on how long until the battery is recharged. If it was left uncharged for several days the small sleep current may be enough to bring the battery dangerously low.
If you describe the project you are trying to create it will be much easier to give useful advice.
...R
TI makes a chip that I believe does what you want. With the super abundance of information given I have no idea if I am correct. Get the data sheet for the TI BQ29700DSET ic and read it. You will then know if my guess is correct or even close.
dagobertduck:
I am having an Lithion Ion Battery running my µC. I want to switch off the µC when the Voltage is very low, and start it again when it is high enough. I did not found a IC what could do that, I also maybe thought my LDO could do this but he can not.
If the uc is to be turned off/no power when the battery gets low, then you might consider getting one of the rechargeable battery packs like below. I think the pack shuts down when power gets too low to protect the batteries. I have a 4400ma one that powers my WeMOS ESP8266 development board for ~30 hours before it shuts down.
Those power banks may not work for an Arduino. Most of them have an auto-off feature which shuts them down when the load current drops below a certain level. That level could be 50mA or more.
But I think any LIPO protection circuit would automatically shut down the battery when the voltage gets too low. Your battery may have such a circuit already built in. Most have that these days. If not, you could use a TP4056 charger module that includes such protection. The charging part needn't be used, but the protection circuit will still work.
Problem with standard so called LiPo 'protection' circuits is that they cutoff at circa 2.4V.
Is safe to depend, repeatadly, on such a low shut off voltage ?
The TP4956 boards, can be modified to shut of at circa 2.9V by repalcing one of the ICs.
"Those power banks may not work for an Arduino. Most of them have an auto-off feature which shuts them down when the load current drops below a certain level. That level could be 50mA or more."
To check on that I just disconnected my USB battery pack (which has been powering my WeMOS D1 ESP8266 development board for ~24 hours, and connected an UNO clone. The UNO has two red LEDs that might up its power consumption, but the battery pack seems to be powering it with no issues.
srnet:
Problem with standard so called LiPo 'protection' circuits is that they cutoff at circa 2.4V.Is safe to depend, repeatadly, on such a low shut off voltage ?
The TP4956 boards, can be modified to shut of at circa 2.9V by repalcing one of the ICs.
I don't know the answer on the 2.4V cutoff, but there are many hundreds of millions of lithium batteries protected in this way.
zoomkat:
"Those power banks may not work for an Arduino. Most of them have an auto-off feature which shuts them down when the load current drops below a certain level. That level could be 50mA or more."To check on that I just disconnected my USB battery pack (which has been powering my WeMOS D1 ESP8266 development board for ~24 hours, and connected an UNO clone. The UNO has two red LEDs that might up its power consumption, but the battery pack seems to be powering it with no issues.
This is the 4400mAh version? Does it have a manual on/off switch? Does it stay on if it's not connected to anything?
Also, do you recall when you bought your power bank? I ask because I've already bought one that used to stay on, but the latest version I received has been redesigned with a new chip that includes the auto-off function. Not helpful.
I would love to find one of these cheap power banks that will stay on under low current, and which has a manual on/off switch. But the Ebay sellers don't typically know anything about what they're selling, and I'd rather not have to buy one to find out if it will work.
"This is the 4400mAh version? Does it have a manual on/off switch? Does it stay on if it's not connected to anything?"
I recharged the battery pack and connected to an UNO clone for a test rum, and it timed out and turned off after ~90 seconds. I'm going to try putting some load/resistors on the UNO to see how much it will take to stop the timeout. This bank is made by PNY which I think is the same company that makes computer memory. The battery bank does not time out with the ESP8266 board, which gets about 25+ hours on a charge.
ShermanP:
I don't know the answer on the 2.4V cutoff, but there are many hundreds of millions of lithium batteries protected in this way.
Indeed there are.
And mostly designed to go into equipment, such as mobile phones, cameras etc that have their own fit for purpose cutoff circuits.
I can see, given the risks of fire\explosion with Lithium batteries, that the manufacturers would fit last ditch type protection circuits to the batteries they sell, in case there is a fault with a phone or camera or a hobbyist tries something daft. But I would not take that to mean that the battery internal 'protection' circuits are the only ones needed.
zoomkat:
"This is the 4400mAh version? Does it have a manual on/off switch? Does it stay on if it's not connected to anything?"I recharged the battery pack and connected to an UNO clone for a test rum, and it timed out and turned off after ~90 seconds. I'm going to try putting some load/resistors on the UNO to see how much it will take to stop the timeout. This bank is made by PNY which I think is the same company that makes computer memory. The battery bank does not time out with the ESP8266 board, which gets about 25+ hours on a charge.
I think all of these power banks are designed to recharge a phone or something similar. So when the phone has been fully charged, the current it draws is reduced, and the power bank shuts off to save what's left of its own charge. The only one I've found that specifically claims to be always-on is this very expensive one:
https://www.amazon.com/Voltaic-Systems-Formerly-Battery-Samsung/dp/B07ZS3WYZY/
Anyway, back to the OP's question, I think there is a Great Scott video on a charger and boost converter, and I believe he switched the 2.4V protection chip for a 3V one with the same pinout.