Questions tagged [low-battery]

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Dual cell protection using DW01

I am using GS7001B-84 dual cell charger to charge battery. Now I want to protect these two cells. I have DW01 battery protection IC and AP2302B N channel mosfet. How can I protect battery using these ...
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64 views

Relay Buzzer Circuit

I'm trying to set up a circuit to protect a battery in a battery box, using some parts I had lying around. Its job is to open the primary relay (load/charging) and sound a buzzer when the supply drops ...
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3 answers
342 views

Can we use Zener diode as battery low voltage cut off?

Suppose we have 150 watt and 300 watts portable photovoltaic system with 13.5V battery (50Ah) and we want the low voltage cut off point to be set at 10V. Can we achieve this simply by using zener ...
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113 views

Wake up MCU with radio signal using a battery

Currently I have a project that runs with the chip from Arduino (Atmega328p). This is what it does: It wakes up. Powers the NRF24L01 module. And it configures it to only send one packet ...
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1 answer
76 views

Under what conditions does a p-FET gate have to be at a higher voltage (or more negative) than its source?

Is there a general rule for p-FET's that explains when Vg can can be higher (or more negative) than Vs? I had posted a while back and a helpful person explained I needed to keep Vgs higher than Vds, ...
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1 answer
115 views

12 V, 7 Ah SLA battery reads 0 (zero) volts

I have a new 12 V, 7 Ah battery which reads 0 (zero) vokts. Let me explain the situation. I have a 800W UPS (for pc) whose battery wasn't giving enough backup. So I decided to replace the battery. I ...
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0 votes
1 answer
96 views

Battery Charger Cut off

I need to confirm that this circuit will protect battery against over charging or not. https://bestengineeringprojects.com/12v-7ah-smart-battery-charger-with-pcb-diagram/ Which is better circuit for ...
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3 votes
2 answers
240 views

Why does this lithium battery have such a flat discharge curve?

I'm trying to understand some apparently anomalous observations of the discharge profile of a 1S lithium battery. I'm using this battery to run a Raspberry Pi Zero W, back-powering the Pi via the +5V ...
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1 answer
51 views

How to estimate Li-ion battery health for an unused smartphone? [closed]

I am considering purchasing a new smartphone that is several years old and could use a little electrical engineering help from the EE geniuses here. I've performed quite a bit of research, and found ...
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0 votes
1 answer
39 views

Questions about Li-Ion batteries

I am working on integrating single 4.2V Lithium battery(400mAh capacity), charger IC, and battery fuel gauge for an embedded project. I have watched several TI training videos about battery management,...
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1 answer
166 views

Li-ion vs Li-Po batteries cut-off protection

I am confused with the differences between Li-ion batteries (like 18650) and Li-Po (the flat ones). I know that basically they are both lithium ion, but when I want to buy I see that LiPos have always ...
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1 vote
3 answers
490 views

Running a 12v fridge and protecting the battery from low voltage

I want to run a 12V (65W) fridge from a battery circuit on a boat. However, I want to protect the battery from being drained and potentially damaged by the fridge if the voltage drops too low so I ...
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1 vote
5 answers
123 views

One battery slot kills its sitting battery

My kid has a battery-operated toy, it runs on three AAA batteries, connected in serial. Once, the toy suddenly stopped working, but all batteries were good. I decided to disassemble the toy and look ...
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1 answer
69 views

Abracon AB1805 RTC IC - additional resistance on VBAT pin?

I intend to use Abracon AB1805 RTC in designed device, powered by a CR2032 battery. IC datasheet contains a note: * Total battery series impedance = 1.5k ohms, which may require an external resistor ...
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2 answers
447 views

What should a 12v solar battery read while in use?

I have a 12v solar system with 2 12v batteries (One marine, other a car battery). My inverter has a minimum voltage input of 11.0v and peak of 15.0v, but when I'm running it under load, I get a ...
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0 votes
2 answers
594 views

How does the TP4056 overdischarge protection work?

I want to buy this integrated circuit (IC) to charge li-po battery. TP4056 Type-C 1S 3.7V It looks nice for charging but I am afraid of the overdischarge protection of this IC because in the ...
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1 answer
388 views

How to use Voltage Supervisor and MOSFET to switch off ESP32 supply?

I am planning a solar project using following components: Solar cells 18650 battery TP4056 MCP1700-3302E TC54VN2902EZB Voltage Supervisor IRLZ44N and an ESP32 I have only seen a block diagram for ...
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27 views

Charger says 5-cell li-ion battery at 17.7 volt OCV dead or deeply discharged, what could the cause be?

I have a lawnmower with two lithium-ion batteries. I charged them after sitting during the winter period. One battery charged happily to 19.15 volt open circuit voltage (OCV), whereas the other had ...
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2 answers
181 views

What does it mean when a battery still has high voltage but doesn't deliver current?

All the dead batteries I tested had very small voltage and no current under load except one strange battery that had about 2 volts but no current. What causes this different type of dead battery?
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1 answer
275 views

How to use LBO on Powerboost 1000C as input for Arduino

I am using a project which uses an Arduino Uno and a powerboost 1000C. in the manual it says, LBO - not a leveraged buy out! this is the Low Battery Output. By default it is pulled high to BAT but ...
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1 vote
2 answers
404 views

Should I add an undervoltage protection for lithium battery-powered projects?

I am designing a board with a microcontroller (an ESP32) that will be in deep sleep most of the time. The board will run on a 1-cell lithium battery (not sure if I will use a Li-poly or a Li-ion). ...
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2 answers
983 views

Reason why an inverter will drop the battery voltage from 24 to 10V after turned on and then immeadetly shut down?

I reacently modified an off-grid solar system, nothing fancy just included an automatic "turn on" switch for the Victron Phoenix 24/220 1200VA inverter. Then I connected the loads (2 computers, ...
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0 votes
0 answers
58 views

Is the SkyRC B6 Nano charger suitable for charging single 18650's from 2.4v-2.6v

I have salvaged six 18650's from a laptop we've owned for years. Battery voltage: four of them are ~2.63v, two are ~2.46v I have a SkyRC B6 Nano charger (https://www.skyrc.com/Charger/B6nano). I've ...
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1 answer
47 views

How to prevent circuit from shutting down when motor drain too much power

I have a device which has motor and circuits with PLC. This device is connected to a 12v battery which is powering the PLC and motor. Everything is working fine but when the motor's load is heavy, it ...
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1 vote
1 answer
779 views

6v battery low voltage cut-off circuit

I have a circuit that draw 150 ma and i use 6V/4Ah dry cell to supply. Voltage regulator of this circuit needs minimum 8V so I use boost converter to draw the battery voltage to 8 volts.This converter ...
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  • 109
2 votes
3 answers
334 views

Real thing or just misinterpretation? Rotating batteries to make TV remote work

When TV remote isn't working, I rotate the batteries in the remote in their place and it begins to work. I don't see any kind of deposit between the batteries and the contacts. Rotation of battery ...
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9 votes
10 answers
4k views

Would a 7805 5 V regulator drain a 9 V battery?

Doing some DIY as a hobby, I'm making a small humidity-temperature radio sensor. An ATmega328 is reading from a DHT11 sensor and then transmitting data to a Raspberry Pi by an STX882 radio ...
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0 votes
1 answer
366 views

PNP Transistor Switch for Relay

simulate this circuit – Schematic created using CircuitLab Hi, I have a low battery detection circuit here. When the voltage of the battery goes below 10.5, I have an LED flashing (Uses the ...
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3 votes
0 answers
94 views

Ultra low power battery

I am currently in the middle of a project and I am quite unsure of what type of battery and battery charger I should be using. To be honest I have never worked with battery or battery charger yet. In ...
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0 votes
2 answers
276 views

Need a solution: Why does the battery voltage drop for custom PCB?

I have a custom PCB to control a solenoid or DC motor. Input voltage 6-7 volts with 4 batteries in series. I have a few questions: Why does the voltage drop by 1V to 1.5V when the switch is pressed ...
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2 votes
2 answers
618 views

Monitor coin cell voltage without loading it when power is off

Is there a good way to monitor a CR2032 coin cell's voltage, that does not load it down when other power is off? We are using a CR2032 coin cell for a battery-backed real-time clock. When main power ...
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8 votes
1 answer
3k views

Is it normal for a lithium ion battery to read with a very low voltage on a multimeter?

I have a PS Vita and I suspect the battery is dead and needs replacing, as the Vita won't charge at all. But the issue could also be the charge circuit, as when plugging it in to charge the charging ...
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1 vote
0 answers
32 views

Deep Discharge of Cells and Batteries

This is a question related to What makes primary batteries leak on very deep discharge? What are the dangers of deep discharging a cell or battery? I've seen a LiPo battery getting puffy most likely ...
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0 votes
1 answer
156 views

MCP73831: VBat Voltage drop with new uncharged batteries

I made a circuit for charging a 40mah lipo battery (381018), my problem appears when a new uncharged battery is connected. The battery measures 0V at the begining, when it's conected the VBAT pin ...
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1 vote
1 answer
62 views

Calculate battery duration [duplicate]

Maybe this is a trivial question, but I am struggling with it for a while. I have an alkaline AA battery which is consuming 80mA for 8 seconds each 30 minutes. I need to calculate how many days it ...
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0 votes
1 answer
157 views

Why doesn't my charge pump work with 1.5v supply?

I have been trying to get the following circuit to work with 1.5V AA battery but it does not work, even though it works fine with a 3.3v supply. I built the multivibrator circuit by discrete ...
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-1 votes
1 answer
239 views

9v battery voltage goes down very low when connected, but shoots back up when it is disconnected?

Whenever I leave a 9v battery connected to my circuit (simple circuit connected to a motion sensor) It goes down to about 3.3v, but when I disconnect it again, it will slowly go back up to about 8v. ...
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0 votes
3 answers
2k views

Battery Life Calculation, Sleeping and Wake modes

I have a circuit that consumes 1.6μΑ during sleep mode and 40mA during awake mode. The awake period lasts for 3 seconds and the circuit is on awake mode every 30 minutes. The circuit is powered by ...
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0 votes
3 answers
562 views

Battery Tester Circuit with 3 LEDS

I'm designing a small system that uses an ATMEGA328P and a LoRa module that runs on 3.3V using a AAA 1.5V battery. The battery is connected to a Boost Converter which steps up the 1.5V to 3.3V to ...
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0 votes
1 answer
483 views

ON/OFF push button circuit with battery under voltage protection

I have put together the push button circuit explained in TI's SCEA048B application report with an under voltage protection using TI's LMS33460 chip. I ended up with the circuit attached. The idea is ...
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0 votes
1 answer
132 views

Battery level on battery indicator drops when i connect a load? [closed]

I've got this cheap battery level indicator that has 4 battery level segments, it is connected to a 12V-18AH lead acid battery that I to charge my laptop and my 1W light bulb. I really can't seem to ...
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0 answers
45 views

Batteries have spare capacity when unused for minutes after running out? [duplicate]

I tested it with NiZN batteries: After they ran out of power, I measured their voltage. 0.9V. I waited 15 minutes, measured again without charging, and it was at 1.5V. I continued operating a CD ...
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0 votes
1 answer
372 views

current limiting filament bulb, revisited

I'm trying to size a bulb to limit DC booster pack current (harbor freight viking lithium) from overloading the 12V aux port (cigarette lighter) wiring which is fused at 15A. I'm ideally looking to ...
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1 vote
1 answer
506 views

Adding Blinking LED to Low Battery Circuit

I'm thinking of designing a PCB based on this low battery indicator circuit: It hooks up to your battery of choice and has a green and red LED, and uses a trimmer pot to adjust at what voltage want ...
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0 votes
2 answers
1k views

Low voltage disconnect with no quiescent current

I'm a noob. Please correct my mistakes. I'm making a circuit where I'd like to protect my Li-ion battery (3.7V, 3500mAh) from discharging too much. The batteries have a protection inbuilt which shuts ...
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1 answer
435 views

Q: Can I use the LM3914 voltage indicator IC as a low-voltage cutoff device?

I came across these two circuits, and tried them out successfully: LM3914 Battery Monitor, drives 10 LEDs in a linear relation to the input voltage. NE555 Low-Voltage Cutoff, uses a 555 timer to ...
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0 answers
287 views

VBAT transistor switch is unsymmetrical

Hei, In relation to my other topic for the VBAT cutoff circuit, I have now gotten my hardware back to measure the functionality. What I have encountered is that the switch-ON is as planned ~2.3V, ...
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  • 137
1 vote
2 answers
6k views

Can I wake up a sleeping Li ion battery pack without dismantling it?

I have three dead lithium-ion battery packs - two of these and one of these. My multimeter informs me that the voltage of the batteries and they both read 5.6V. I understand that by dropping below ...
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0 votes
3 answers
96 views

Need help with modeling an overloaded battery

I wish to model a battery for a small computer game, a battery which will be subjected to heavy loads and deep discharge. The model doesn't have to be high-fidelity, just a rough approximation will do....
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  • 111
-1 votes
1 answer
129 views

how does a device running on a lithium battery measure the amount of energy left? [closed]

I have a wireless phone and recently i had to replace it's lithium battery. The previous battery was totally dead and would work for like 30 minutes or 1 hour before it showed the "low battery" ...
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