The Adafruit battery packs are supposed to have over charge and over-discharge protection built-in. Additionally, the PowerBoost should be providing all of those functions and more. That's why I purchased it, among other reasons. It has charge shutdown in the charge circuit, it has a current limit, it has over temp (is you mod the board and add the 10k NTC thermistor which I did), and has over discharge detection. The question to me is becoming, is the LBO configured to do its job correctly.
Putting that aside, the topic of this post (and a few others currently) is how does the LBO pin work or why does it not. I would like to know why the schematic values do not correspond to the datasheet. Why does the LBO turn on at 2.5V (some speaking that it is designed that way) instead of 3.25V which is (a) more reasonable as that is where the boost circuit stops working and (b) corresponds to the values in the datasheet versus the schematic.
powerboost battery cutoff
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- adafruit2
- Posts: 22749
- Joined: Fri Mar 11, 2005 7:36 pm
Re: powerboost battery cutoff
it should be turning on at about 3.2V - there's no firmware or anything on the boost converter - its completely solid state so if you follow the schematic and datasheet, all functions are as indicated in the datasheet. that said, the LBO is a friendly reminder, it does not change the behavior of the booster itself.
the powerboost DOES NOT have over-discharge protection - that is only provided by the battery protection circuit in the battery.
the powerboost DOES NOT have over-discharge protection - that is only provided by the battery protection circuit in the battery.
- ADWSystems
- Posts: 57
- Joined: Sat Feb 25, 2017 10:10 pm
Re: powerboost battery cutoff
I didn't say it has protection I said it has "detection". There appear to be several people here reporting, myself included, the LBO pin does not go low until the battery voltage is under 3.0V. Where should we look for the issue?
- adafruit2
- Posts: 22749
- Joined: Fri Mar 11, 2005 7:36 pm
Re: powerboost battery cutoff
with regard to:
"The Adafruit battery packs are supposed to have over charge and over-discharge protection built-in. Additionally, the PowerBoost should be providing all of those functions and more."
the powerboost DOES NOT have over-discharge protection - that is only provided by the battery protection circuit in the battery. the powerboost, without circuit protection on the battery, could over-drain and damage/destroy a lipo!!
you can check the LBI pin on the TPS chip, between the 1.87M and 340K resistor, thats the detection pin! 500mV should be the threshold, see "9.3.7 Low Battery Detector Circuit—LBI/LBO" in DS
"The Adafruit battery packs are supposed to have over charge and over-discharge protection built-in. Additionally, the PowerBoost should be providing all of those functions and more."
the powerboost DOES NOT have over-discharge protection - that is only provided by the battery protection circuit in the battery. the powerboost, without circuit protection on the battery, could over-drain and damage/destroy a lipo!!
you can check the LBI pin on the TPS chip, between the 1.87M and 340K resistor, thats the detection pin! 500mV should be the threshold, see "9.3.7 Low Battery Detector Circuit—LBI/LBO" in DS
- ADWSystems
- Posts: 57
- Joined: Sat Feb 25, 2017 10:10 pm
Re: powerboost battery cutoff
OK. Poor choice of wording. But if the LBO functions as specified, then the powerboost can be shutdown to prevent damaging the lipo. Granted it is not built in, but can be generated from the available inputs/outputs.adafruit2 wrote:with regard to:
"The Adafruit battery packs are supposed to have over charge and over-discharge protection built-in. Additionally, the PowerBoost should be providing all of those functions and more."
the powerboost DOES NOT have over-discharge protection - that is only provided by the battery protection circuit in the battery. the powerboost, without circuit protection on the battery, could over-drain and damage/destroy a lipo!!
Oh silly me. I was looking in section 10.2.1.2.2.adafruit2 wrote:you can check the LBI pin on the TPS chip, between the 1.87M and 340K resistor, thats the detection pin! 500mV should be the threshold, see "9.3.7 Low Battery Detector Circuit—LBI/LBO" in DS
I did not think to actually meter the LBI pin while I was reviewing the datasheet. I will check it when I get home. And if the LBO does not come on when LBI < 500mV-510mV (including the 10mV hystresis), then?
- adafruit2
- Posts: 22749
- Joined: Fri Mar 11, 2005 7:36 pm
Re: powerboost battery cutoff
10.2.1.2.2 is also relevant (for the calculation) if it doesnt trigger at 500mV, you may want to build your own circuit for detection? not sure why it wouldnt be, TI fabs the chip and sells it to us premade :)
- ADWSystems
- Posts: 57
- Joined: Sat Feb 25, 2017 10:10 pm
Re: powerboost battery cutoff
I think these last few posts are important points in troubleshooting the boost chip and LBO. To check the LBI pin voltage directly and verify if it is greater than or less than 500mV +/-10mV (have to allow for the hystersis), both with LBO disconnected and connected to your load (if applicable).
Please be positive and constructive with your questions and comments.