Questions tagged [batteries]

An electric battery is a device consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy

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61 views

Identification of round, keyed, two-pin high power connector

I just got a new electric bike and I'm thinking about adding an extra 36V 20Ah battery to get more range. What I'm thinking is to pull out the main battery when it runs out and connect the second ...
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39 views

Utilising patchy DC to charge a battery (from generator)

I am currently studying first year engineering at my college and would like some help with energy storage. Note that this is an industry project and not homework, so I am not breaking any rules. My ...
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1answer
58 views

Why is actual SOC of a battery actually higher than what is displayed

So I read a document today which said that a higher SOC level (around 20%) is displayed as 0% to the user in vehicles, thus reducing the total capacity of the battery. My question is that why is that ...
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53 views

CN3791 not charging battery?

I have a CN3791 module wired up to a 18650 cell and that is powered up by a 18v 10W solar panel. I don’t know why, but the battery is barely charging (0,1V in three hours). Can someone tell me if they ...
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37 views

Calculating battery percentage after voltage drops

I would like to display a battery percentage based on the remaining charge in the battery. I do not know if there is a better way of doing it other than measuring the voltage across the batteries. ...
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2answers
125 views

Looking for a explanation/cause of lithium polymer battery failure

I'm hoping that someone on the EE StackExchange could give me some insight into what is going on with some lithium polymer batteries that I have under test. The question I am trying to answer is: ...
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1answer
26 views

Current going into the positive pole of a battery while discharging a capacitor

Please bear with me if this is a fundamental question. Let's suppose we have an RC circuit, charging a capacitor up to the voltage of a battery of 9V. The capacitor is currently at 9V, we switch the ...
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1answer
69 views

Battery for Specialized Device

The battery on a specialized device has gone bad. The company wishes to charge me an exorbitant amount of money to replace it. I do know that it is a 12 volt battery, however I don't know the amperage ...
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1answer
66 views

Car battery voltage readings different with no load - normal?

Typical car battery, 12V. While connected to the car, It read 12.38V on my multimeter. Using the absolutely same multimeter, I measured it once I disconnected it from the car - voltage went to 12.56V. ...
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1answer
41 views

Charging a big battery with small solar panels very very slowly

I have a 6V, .7amp solar panel that typically puts out 2-5V under normal conditions. I would like to charge a 12V 5 amp hr lead acid battery over a few days to weeks. The device that I want to ...
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1answer
57 views

Does current split when we connect battery in OR configuration

Please check the below circuit. Edited the circuit as told. I have connected two batteries (Max 3A) in OR configuration to the load as shown below. Once, the power is ON, does the current (assuming ...
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41 views

How to make a phone think it has a battery on it and run it from a charger

Im trying to run a samsung galaxy s7 edge without a battery on it but it just turn on shows a logo and then turns off again i think it knows that there is not a battery inside so if anyone knows what ...
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6k views

Improve a car battery's performance with capacitors

These days, it got very cold in my area, and I started to think I need a new car battery. But then, as long as temperatures are above -10°C, my battery works fine. It just can't support the high ...
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1answer
40 views

Upgrading Xiaomi HIMO C20 battery

Does any one know what is the charger port is for Himo C20 Ebike battery? I ordered mine it's on its way now I couldn't find the information online. Also I was wondering if I can add this battery to ...
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52 views

Potential difference between battery negative and battery cover

I built a 30P12S battery pack using 18650 cells (3.7V Nominal). To house the pack I made a frame out of square tube Mild Steel. When I install the pack in the frame I get a positive reading on the ...
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1answer
63 views

Need help in understanding the working of battery level indicator

I have got hold of a battery level indicator on net. I works but I am not able to understand how it is functioning. I am new to electronics and I just dont want to build a circuit from a diagram. I ...
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2answers
317 views

capacitor or 2nd battery for invertor situation (automotive)

Background I have a power inverter in my car that I installed about 4 months ago. I bolted the ground on it to the ground terminal connector of my car battery and the + to the positive side of it. ...
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1answer
933 views

Connecting a super capacitor to the solar battery in parallel

I find some people connect a super capacitor like (16v 88F capacitor bank) in parallel with the 12v 100Ah solar battery to optimize the surge current draws from the battery due to running heavy ...
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1answer
489 views

3 AGM batteries in parallel; does it matter what battery they are charged from

simulate this circuit – Schematic created using CircuitLab I have 3 AGM 12v batteries in parallel. Between Battery 1 and 2 I have a BlueSea SI-ACR Automatic Charging Relay - 12/24V DC 120A; I ...
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1answer
450 views

Protect battery from overvoltage - DC brushless motor overspeeding condition

I'm trying to figure how to protect batteries from overvoltage on my electric skate. Specific condition is : motor would run above max RPM based on system voltage. Motor is 85Kv, battery voltage is ...
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4answers
2k views

How to power a phone with no battery properly?

I have an LG G3 phone that I want to use as a stationary device and leave it hooked up permanently. I prefer not to do it with a battery for various understandable reasons. My questions are: What ...
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0answers
72 views

How to connect a 12V battery to a 24V system?

I have a 24V battery (two 12V lead/acid in series) connected to solar panels and I'm looking for a way to have a 12V battery and circuit. (But the solar array will charge the 24V system so i need the ...
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1answer
36 views

Issues encountered when adding DC adapter to light powered by battery

I have an LED light bar powered by 6 AA batteries connected in series. There is also an RF control unit to turn the light on/off. The light eats through the batteries rather quickly thus I decided to ...
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1answer
65 views

Steal 5v from USB Module in 3v Mode

My project includes an ESP8266 (runs at 3.3v) and a USB C-Serial breakout. The USB module can optionally run at either 5v or 3v, and there's are solderable jumper pads to make that switch. Here's ...
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1answer
44 views

Power output neccesary to power multiple USB devices at once?

If I have a device that requires 5V and 2A to function, what kind of power supply would I need to power 4 of these devices at the same time to their full capacity? Here is an example setup: Power ...
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71 views

Lithium battery charger and balancer circuit (or IC)

I am working on a project which sould charge and balance 4 to 6 (maybe 8 in future) serial connected lithium cell batteries (~4000 mAh capacity) with about 4A of charge current. First I looked for IC ...
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4answers
26k views

charging a 12V calcium battery

I have recently purchased a Halfords 12V calcium battery second hand off facebook. I was told it was about 6 month old ( it does look new ). The problem is it will not charge using my trickle charger'...
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2answers
73 views

laptop batteries charging myths - Long life OR short life

I'm very conscious about the life of battery. Some people say that don't keep plugged-in laptop all over the time and remove battery charging at 70% and again charge at 40% so your battery cells ...
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4answers
712 views

Solved - FAULTY BATTERY - Solar power - 6149 Watt-hour battery bank but only 1 hour of inverter time at 300W after dark

Turns out one of the 4 batteries was bad. Many thanks to @SamGibson for his insight in solving this problem. The well-deserved Accept is on his answer. Here is what the charge plot looks like now:...
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51 views

Using Solar Charge Controller with AC Power instead of Panels

I'm working on a project here which needs to have a small SLA backup battery. I have a cheap PWM solar charge controller already and I want to use plugged into an AC power supply (48V DC out) in ...
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1answer
601 views

Supercapacitor or battery with capacitor

Maybe the question that I ask is completely dumb because I am a complete noob in this, but please help. So first off, my question is that if I want to charge a 2.7v 500F supercapacitor, can I charge ...
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1answer
41 views

Fairy lights dimming over time

I have had this cheap set of fairy lights for a few years. Powered by 3xAA batteries. Recently when they are turned on they start bright as they always were then proceed to get dimmer and dimmer ...
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2answers
112 views

Vehicle Alternator/Inverter system

I have a food van with a stock alternator on the engine, and a 3000w inverter setup. The inverter setup uses 2 Trojan leisure batteries. Somehow the inverter setup is also linked to the alternator (I’...
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65 views

Which 18650 battery connection layout is best?

I am building a 5S6P battery with 18650 cells. I have limited space so the geometrical layout is constrained. I can think of 2 "optimal" ways to layout the cells connections but I don't know which is ...
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1answer
73 views

IATA battery rules

Following IATA guidelines two threshold limits are indicated: 20Wh for cells and 100Wh for multi-cell batteries. Question: Should I apply 20Wh limit also for cells in multi-cell batteries? Example: ...
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32 views

Charging a LiPo Battery with 1.5V Battery

I have a lithium-polymer battery with a voltage of 11.4V. If I want to charge it with a 1.5V power source (AA battery) and I boost the voltage to 11.7V will it slowly charge the LiPo.
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2answers
3k views

Does an inverter only draw power from a battery as-needed?

In other words, does a 1000-watt inverter, draw the same as a 500-watt inverter if they are charging only a laptop? The laptop will draw the same amount and the inverter capacity is really just that, ...
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2answers
52 views

Combining 12v Marine batteries of unequal capacities

I would like to increase my RV marine deep cycle battery capacity. I currently have a Group 24 battery with 64 amp hours. I would like to add a second battery to increase my capacity to the max. As ...
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2answers
119 views

Determine battery voltage

I have removed the battery from an old portable dust cleaner. The acid has oozed out, and that is the reason the device does not work anymore. I want to replace the batteries, but their voltage is not ...
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4answers
45 views

Device runtime with specified battery

How long will a 12V 30W device run on 12V 65AH battery, if the battery is first fully charged and the battery is dedicated to this one device?
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46 views

Battery Replacement - 3 pin Connector with 2 wire battery

I need help on using a 10k fixed resistor. I connected the red and black wire but I'm not sure what to do with the white wire. I know that this is for the thermistor. It is not charging if it is not ...
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2answers
376 views

How does distance between parallel batteries affect voltage drop/required wire thickness?

I'm looking to wire up an off-grid system. What I'm stuck on is battery placement. The likelihood is my batteries will need to be quite far apart (almost 2 metres). My question is how does this ...
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4answers
7k views

Function to describe alkaline battery voltage under constant current / load

Introduction Commonly used alkaline batteries (Duracell etc) have a pretty interesting discharge curve. For example, an AA duracell has the following voltage characteristics under constant load, and ...
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2answers
811 views

Creating a protected 18650 cells pack

I'm trying to create a 2s3p battery pack for a robot. I have 6x Eastshine e35 cells (which is a protected version of LG MJ1 cells). Is a 2s3p pack out of protected cells used with a balance/smart ...
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1answer
45 views

Back-up battery

for a project I would like to design a system which would allow me to feed my application's logic rail from a back-up battery if the main battery would somehow stop functionioning (most likely due to ...
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2answers
646 views

Backup power source from usb battery

I am trying to use usb battery bank as a backup power source for my diy project. Project is using arduino to control transistors and to turn few devices (like pumps and lights) on and off. Power ...
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4answers
173 views

How do computers power so many lights on a keyboard?

Beginner here. I am working on building my own keyboard PCB, and I wanted to add a backlight for my keys. However, I've been reading methods of powering teensy little 3mm LEDs and it seems like an ...
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4answers
505 views

How is the fuse amp rating determined for a 12V AGM battery bank?

I would like to put 3 x 130Ah AGM batteries in parallel and attach a fuse to the positive terminal of each battery. What size fuse should I use? How is the amp rating of the fuse determined? The ...
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1answer
42 views

Drone lipo battery not working properly

I'm having an issue with the lipo battery of a drone. When I normally plug it into the drone it won't power up the drone, but when I connect the battery to the balance charger even when the charger is ...
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Is there a way to visibly measure charge on CR2 battery?

I have a CR2 battery I’m using in a project. It is buried away in the housing and without opening everything up, I’d like to find a way to somehow measure the current charge on the battery from the ...