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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1answer
47 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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1answer
46 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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4answers
178 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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3answers
94 views

What is a “safe” amount of amps to draw from this pack

I've been working on a quadruped project, and need some help determining the... safety... of my power system. To start, there's two packs, a larger "main" and a smaller "reserve" the two packs are ...
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1answer
72 views

Using “modern” batteries with old devices

I have a Sony Vaio p-series laptop which is a tiny computer build in 2009. It is a wonderful device but the battery is only 2500 mah and lasts about 1.5 hours. My phone battery on the other hand is ...
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1answer
62 views

Battery run time question

I’m hoping you can help me as my head is spinning attempting to calculate the run time of a Dometic Fridge on a portable power bank, which I will eventually add solar panels to the system. Im ...
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1answer
27 views

Preservation of power when wiring batteries in series - battery life is reduced if load is kept the same

This is really just a "sanity check" type question. Am I correct that if you place two batteries in series, that the battery life is effectively halved relative to just one battery, assuming the load ...
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1answer
88 views

Calculating the internal resistance [closed]

I have build a circuit: The power source is a battery. The rectangle (below the amperemeter) is a resistance. I have measured U (in Volt) and I (in Ampere) for the whole discharge process. Now I ...
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0answers
40 views

Do li-po batteries need esd protection?

I bought some li-po batteries and they were in antistatic bags. They have protection circuits. Do they need esd protection (grey bags)?
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6answers
3k views

Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

Looking around Amazon, it seems that different types of batteries are measured differently: Does anyone know why? Li-ion are measured in mWh 1200mWh ALTIZURE (Cheap-Os) 3200mWh Deleepow 3000mWh ...
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0answers
65 views

Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)? [duplicate]

Looking around Amazon, it seems that different types of batteries are measured differently: Does anyone know why? Li-ion are measured in mWh 1200mWh Cheap-Os 3200mWh Deleepow 3000mWh AmpTorrent ...
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1answer
32 views

How do I calculate the duration my solar battery will last when fully charged? [duplicate]

How can I calculate the duration my solar battery will last after charging to full? I want to know how to calculate the battery back up time.
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1answer
57 views

Is heating the nichrome wire with phone battery possible?

I want an nichrome wire to heat instantly red hot when connected with phone battery using 2 copper wires. Do I need any extra circuit to convert the volts into current for heating? (H=I^2Rt) Would ...
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2answers
144 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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2answers
103 views

What did I feel testing a car battery?

Was trying to test the voltage of my car battery but accidently had the multimeter set up for Amps (was using it for an old project and forgot to switch cables/turn the dial). Turned my multimeter on....
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1answer
55 views

Can I use the main power battery as a RTC battery as well?

Im currently thinking of a Nixie-Watch. Because I have almost no space on my PCB, I would like to use the 3.3v battery which powers the whole system also as the RTC Battery. I could connect a 3.3v ...
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1answer
53 views

If you have a BMS, will current be limited at some points to a DC motor and affect performance?

I am part of a group in a senior design project. We are designing an electric bicycle. Our professor proposed an issue to us and we are having trouble figuring it out, as we can't really seem to find ...
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0answers
87 views

Designing a circuit to replace AA batteries with a LiPo battery

I’ve been looking at ways to replace 2 AA batteries in an older device I have with a LiPo battery and USB C charge board so that I can easily charge it up and save on batteries. The biggest barrier to ...
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2answers
93 views

DC to AC inverter calculations [duplicate]

I have purchased a 300W Modified Sine Wave Inverter. I am also connecting a 12V 18A/hr SLA battery to it. I am using it to power an RFID reader. The input power characteristics of the power block are:...
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2answers
337 views

Can a low amps 48v battery handle big DC motor

I have a 48V DC motor, 3500W at 300A, combined with a dc controller with 60A constant and 120A peak discharge rate. Can a 48v li-ion battery with 20A constant and 40A peak discharge rate, safely ...
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1answer
85 views

Is it possible to get a continous power with a constant current demand from a battery

So lets suppose I have to design a battery which has a continous power rating , if my load draws constant current ofcourse the battery will discharge and the SOC drops and so does the voltage. How in ...
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3answers
61 views

Lead acid battery charging too fast [closed]

I have an ebike. I usually charge my lead acid battery for 6 hours until the charger shows green light, and I can travel for 30 Km or so. But since last week, green light indicating full charge ...
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0answers
105 views

Can you identify the name of this battery discharging plug (photo attached)?

I am trying to source the male/female sides of this connector that fits on a 48V Lithium Ion battery. Can you please identify the name of this type of connector?
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2answers
381 views

How are symmetrical +/- voltage supplies obtained in a final (standalone) design? [duplicate]

Assume, I need to use an opamp with +9 V and -9 V supplies. While prototyping, etc., I can and probably would use a DC power supply. Since it has multiple channels, it is easy to have +9 and ...
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3answers
118 views

What is reason of having 3 phase in the transmission in cities?

What is the reason of having 3 transmission lines as three phases ?
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0answers
23 views

Charging of Li-ion battery fails after voltage was cut-off

I designed a charging PCB using this Li-Ion charger IC: https://datasheet.octopart.com/BQ24072RGTT-Texas-Instruments-datasheet-5404322.pdf In my tests, the charging works as expected when using ...
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0answers
43 views

Any problem with this simple supply switching circuit?

Is there anything wrong with this circuit? The goal is to have a battery powered device that is occasionally plugged into computer via USB. When plugged into the computer, I want to switch power ...
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0answers
37 views

is briefly connecting same voltage/different capacity batteries safe

Ok, so I am working on a project that has two battery packs: a: 7.4v 2Ah - 8 x 3.7v 500mAh b: 7.4v 500mAh - 2 x 3.7v 500mAh These packs will be powering a raspberry pi clone, a handful of servos, ...
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2answers
54 views

Coupling DC adapter and battery

In the picture below, I am connecting a constant power resource and a battery to each other by a lipo charger. The circuit should consume power from the adapter (NOT battery) while it is available. ...
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2answers
316 views

Why does it take so long to trickle charge an AGM battery to the point where it matches the self discharge rate?

I did an experiment where I used a "regular" smart-charger set at 12A max AGM mode on a 12V 100Ah rated AGM battery to what it told me was 100% charged. The charger then automatically went into ...
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2answers
145 views

Wich battery configuration I should use to supply raspberry, arduino and stepper motors

I'm working on a project about a self-stirring robot with sensors to avoid walls. This project is composed by one Raspberry responsible for all the algorithms, one Arduino to deal with the sensor ...
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1answer
31 views

Using a small Li-Po as a backup power source for a model

I am building a model of a trolleytruck (similar to a trolleybus but with a truck) and I'm adding an Arduino to get data. The microcontroller should never lose power because it would restart. I was ...
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2answers
160 views

What is the best way to acquire voltage information of a battery powered microcontroller project?

I would like to track the battery that supplies my microcontroller. I was thinking at a simple voltage divider bridge wired to an ADC input. As my divider bridge will be permanently connected, I ...
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1answer
34 views

Connecting a lower voltage load to a series of higher voltage batteries in halfway?

I have a battery supply source which is a series of lead acid batteries up to 72V. I have a 48V motor system (few kilowatts) and peripherals to be installed on to this power source. Due to limitation ...
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2answers
156 views

Can an LED run by harvesting energy from mains hum? [closed]

One morning 2 weeks ago I found a green LED in a carpark attached to a deflated ballon. It had obviously landed overnight. I left it there and when I returned in the evening it was still glowing quite ...
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1answer
65 views

How to calculate voltage drop on lead acid battery

I have a motorcycle with an alarm on it. I left the bike for 5 days and the battery dropped from 12.5v to 11.9v a 0.6v drop. The bike still started. 12v battery 9.5 Ah sealed lead acid battery I ...
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1answer
96 views

Maximum current drawn from a small 12V A23 battery?

How much current can be drawn from a A23 12V battery? I've looked at the Energizer datasheet, this Wikipedia page and on this answer: Powering 5W generator with A23 but I haven't found the exact ...
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1answer
37 views

Confused about battery rating specifications [duplicate]

I'm confused about how to understand battery capacity by its ratings. I though I understood Amp-Hours, as a nominal rating where they usually specified a period of time where that rating was ...
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1answer
90 views

High Short-circuit protection for LiPo Battery

I will be using a LiPo battery for a project, and I want to make certain that I fully understand the safety features of the Protection Circuit Module included with the battery, so that I have a safe ...
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0answers
37 views

Detec if board is connected to switching power supply or external battery

I am working on a project where board can be powered by either a 24V switching power supply or external 24V battery. Both of them use the same connector. How can it be detected the source?
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1answer
57 views

Applying Ripple to a DC Source?

I have a system that is powered by a 25V Lithium ion battery pack. I need to test the system with a 1 Vpp sine applied on top of the 25V supply, so 25V +/- 0.5V ripple. I know theoretically to get ...
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1answer
54 views

Measuring a 18650 cell

I just ordered some 18650 batt and out of curiosity, I want to know the correct capacity of it. I have an usb meter, which read the following: Charge: 5.25V, 5683mAh Discharge: 5.09V, 2927mAh The ...
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1answer
49 views

Charging battery with external charger while powering load

I am building a device which I would like to be able to charge with several different types of external battery chargers (different Icharge within spec of battery, of course). If I understand ...
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2answers
32 views

Battery emulator based on an array of buck converters for BMS testing

Problem: How to quickly and cheaply test if a given BMS (Brand: Daly / Tiny BMS / etc) or battery-powered system behaves as intended for various cell voltage combinations without waiting for actual ...
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2answers
122 views

How to increase watts going to my lithium battery? [closed]

I have a 48V 50Ah 2000W lithium battery for my ebike, I am currently using a 12V 160W solar panel with a GVB charge controller with MPPT and getting my battery to charge but only getting 350W, how can ...
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2answers
65 views

How to design a switched mode battery discharger

I have a very basic understanding of switched mode power supplies and know that this is a simple buck converter suitable to e.g. charge a 12 V car battery from an input of, say, 24 V, with a dc ...
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2answers
159 views

Circuit to know when two batteries are connected to each other

I'm using a Victron Cyrix (12V 120A) Smart battery combiner to connect the starter and the leisure battery in my RV. I wanted to know when the two batteries are connected to each other, but ...
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2answers
81 views

Slow usb charger for my smart phone? [closed]

I read that the optimal charger for smartphone batteries is 3.92v (to reduce degradation). Is it possible to implement a system that allows an external "charger" to cause charging to stop at this ...
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1answer
64 views

Effect of Rapid Switching between Charge/Discharge of Lithium Batteries

I have made a DIY offgrid solar generator that utilizes an arduino to determine when to dump excess energy to a water heating load. I have programmed the arduino to activate the load circuit when the ...
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3answers
117 views

Where do USB ports on laptops typically source their power when the laptop is charging?

Suppose you are at a coffee shop and your phone battery is low. You decide to plug it in to your laptop via USB to charge it. At this point the laptop's battery serves as our energy source for ...

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