Involving or pertaining to a circuit or device that is intended to be operated with cells or batteries (as opposed to mains power, for example).

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2answers
54 views

Wiring power supply, battery and charger for portable speaker

I'm planning to build myself a small portable speaker. I'd like to include a Li ion battery and a jack for an external 12V-ish power supply. I'd also like to add a jack that will be used to charge the ...
0
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1answer
31 views

suggestions for solar charging battery-operated device

My battery-powered wireless device draws about 50mA @ 5V. I’m thinking of powering this off a 12V 7Ah SLA battery that is topped up with a small solar panel (12V, maybe 500mA or so). 12V to 5V will ...
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1answer
34 views

What AC-to-DC adapter would I need to power two of these battery (3V) powered door contacts at once?

I'm new to electrical wiring. I understand circuits, soldering, and basic wiring in parallel / series but calculating and understanding draw, resistance, etc. is new to me. That being said, I have ...
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3answers
82 views

Car battery capacity in colder countries

The capacity of the battery is affected when the temperature drops, particularly Lead-acid batteries. So how in cold countries this situation is solved. In this PDF about automotive batteries at low ...
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0answers
62 views

What used to happen when the non-rechargeable CMOS battery ran out? [migrated]

I'm taking a uni course on electrical engineering and my textbook says that the CMOS battery used to last between 2 and 10 years. Since preserving BIOS settings seems quite important to me, I was ...
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1answer
151 views

Coin Cell Battery Safety?

I'm working on a wearable project that is really space constrained. Originally, I had planned to use a Li-Ion battery, but I opted out of it because the person wearing it won't be able to take the ...
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2answers
63 views

Bike mobile charger

Hi, I've made a battery operated mobile charger using this circuit. I am able to charge the basic phones (with 2100mAh battery) with it. But the problem is, I couldn't charge any smart phones ...
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1answer
36 views

LM2940CT-12 output measuring 9.6V when relay used

So I've got a 12V pump, and a car battery, and I'm trying to regulate the 12-14V from the car battery to 12V output. When using just the LM2940CT-12, it outputs 12V on the dot. But when I use an ...
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2answers
49 views

3V7 to 5V level conversion

In my product i am using a wifi module requires 3.3v and a bunch of other components requires 5v. For this i am using 3.7v 3000mAh battery. So here i have a doubt whether to use which case or any ...
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3answers
104 views

Area under voltage vs time discharge curve

Will the area under a voltage vs. time graph of a battery discharge curve (with a constant current load) give the amp-hour capacity rating of the battery? Thank you.
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1answer
45 views

Converting 3 seperate 4.5V battery operated devices to one AC power supply

I'm wanting to convert 3 battery operated marquee signs to AC power by following one of the many tutorials out there on sites like instructables.com. I'm more than capable of doing each one on its ...
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1answer
130 views

Selecting a battery for a DIY project

I am building myself a laptop (for fun, I know it doesn't make economical sense ;) ). I have now come to the problem of implementing a lithium battery for it. It will have to power the SBC and the ...
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2answers
38 views

How long will my circuit run normally if its battery level reduces? [closed]

I am using a 3.7V battery for my circuit. What will happen when the battery level reduces to 3V, 2.5V, etc? Won't some of my components stop working at these low voltages?
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2answers
67 views

Can you connect in series 2 unequally charged batteries?

So I have 4 batteries. 2 of them are charged (about 70%) and 2 about 10%. I have a flashlight (which uses 2 batteries in series) which I would like to power at small current and voltage because the ...
2
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2answers
57 views

OLED is garbled when powered by 3.7 battery but not when powered by USB or variable regulated power source?

I have an esp8266 on a breakout board for programming hooked up to an OLED via GPIO 0 and 2. It works fine if I power it via the FTDI/USB. It also works when I power it at 2.8-3.0V using a desktop ...
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votes
1answer
85 views

3.8V batteries to 5V

So I got me a raspberry pi 2, and a R2FX, both supplied with 5V, R2FX has a power consumpution of less than 1W. I own several accumulators from old phones & smartphones which got 3.8V . Maybe a ...
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0answers
42 views

480 VDC Series Battery Bank - Intelligent Discharge Control Circuit

I have a Lead Acid Battery Bank (40 x 12 VDC 50AH Batteries in Series) that services a small variable DC load of lighting and small heating elements. I want to protect the battery bank from being deep ...
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4answers
375 views

What is the simplest way to turn off some circuit when supply voltage reaches a minimum level?

Knowing I have only a 12V battery to supply my circuit, how I can turn off the circuit if the voltage reaches 11V? I cannot use simple comparator CI since I don't have another supply voltage. I could ...
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0answers
52 views

Mains hum on battery-powered prototype

Beginner's question. I have a battery-powered MSF ("radio-controlled") clock running on 1.5-volts. I am aiming to use it's alarm output to provide an accurate "time signal" for other equipment. The ...
2
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1answer
125 views

Battery and Voltage Regulator for ESP8266 and HC-SR04

I'm working on a project that includes an ESP8266 (requires 3.3v input (250 mA peak)) and a HC-SR04 (requires 5v 20 mA peak). I'm making it battery/solar powered. I'm trying to keep costs down as ...
2
votes
5answers
130 views

Fan Needs 12V, only have 9V

I recently bought a 12V small computer fan(about 1"X1") and it was running rather slow when I checked it with a 9V. The package says that the fan requires 12V to run at an optimized speed, so is there ...
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1answer
60 views

How to create a system where battery power exist as backup power source

This mainly applies to design of a clock but can be applied to many other circuits. The idea is that a device with PIC microcontroller is usually powered via external DC power supply which obviously ...
2
votes
1answer
71 views

Rechargeable battery Backup circuit

I have seen this rechargeable battery back up circuit on web.The resistor is used to limit the current.The diode in series is mainly to prevent the back feeding the power supply during battery ...
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0answers
39 views

RC car circuit power optimisation

So... a bit of a long question I'm afraid. For a project, I have to design and build a 4x4 RC car with a few electronic functions. At the minute everything works but the battery (9v) seems to deplete ...
4
votes
2answers
65 views

Efficiently sensing the voltage of a battery pack

I'm looking to sense the voltage of a battery pack that is powering a device by the device. Depending the the level of the pack (2 cell LiPo 1200mAh) the device will change it's behavior. As the pack ...
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1answer
137 views

Charging 12V Battery from AC-DC Converter

I am planning to charge my 12V sealed Lead Acid battery from AC to DC Converter. The output of the AC-DC Converter is adjustable so that I can set my voltage to be 14.7V(considering diode voltage ...
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3answers
148 views

Powering NiChrome wire from battery

I'm looking to power nichrome wire from battery. The problem I ran into is that desired length/width of the wire has very small resistance ~ 8 Ohm. Several kinds of batteries I've tested have ...
0
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1answer
169 views

How to measure Open Circuit Voltage of a Battery in Charging and Discharging state

I am working on a battery(Li-ion) operated device, in my attempt to get the SOC of the battery i have to acquire the battery OCV (open circuit voltage) first and have to interpolate it to the SOC ...
2
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0answers
73 views

Rough Battery (9V Alkaline) Level Estimation with Analogue Reading

I'm building a portable desktop weather station using an Arduino Nano micro-controller. The system is being powered by a consumer 9V alkaline battery, with the voltage being regulated by the Nano's ...
0
votes
1answer
71 views

What are the effects of running a PIC μC slightly above its rated working voltage?

I experiment with the PIC24 series of μCs fairly often and have noticed that I can run them successfully from a 3.7v LiPo battery pack without a regulator. The batteries charge to around 4.2v fully ...
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0answers
56 views

12V input with 12V and 5V (USB) output?

So say that I have a 12V DC power supply like this and I need to power a 12V DC device (LCD controller board) and this USB port / 5V regulator. Is this all safe to wire in series (parallel in edits) ...
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1answer
71 views

Simple inline latching power switch

What's the simplest circuit for an inline latching power switch? I have a 12V lipo going into a step-down converter powering an Arduino. I'd like the Arduino to be able to completely power itself off ...
0
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3answers
104 views

Is there a way to step up voltage without consuming power when there's no load?

Is it possible to take a lower DC voltage, such as the 1.5v from a AA battery, and step it up to a higher DC voltage, such as 5v, which keeps that 5v potential even when there is no load, and which ...
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2answers
75 views

Using two batteries to increase current sourcing capacity

I'm working on a project where I am planning to use two 5V USB Power Banks because one cannot supply sufficient current. These Power Banks are 20,000mAh each and have built in circuits to regulate ...
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5answers
3k views

How to solder wires on Li-ion cell phone batteries?

I am making a obstacle avoiding robot and wanted to power it with mobile phone batteries. But wondering how to solder wires on battery correctly for no inconvenience. p.s. I am a new arduino ...
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2answers
139 views

Will battery drain if only positive terminal connected to circuit?

Lets say I have one quite large circuit consists of many components including winding and light bulbs. The positive terminal of the battery goes directly to a winding. If I disconnect only negative ...
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0answers
53 views

What are considered main input filter capacitors?

I have chosen a LDO (LT3028) for my battery powered system, which will be some sort of a wireless audio generator (WiFi + Audio Codec + SAMS70 ARM processor), but I have some questions regarding what ...
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1answer
94 views

I am building a simple reverse-polarity circuit using two relays. Will it create an endless loop?

I am planning on using the following circuit for my motorized value. But I'm bit skeptical about how this might continue to work. Although I'll be using two identical relays, my fear is that at one ...
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1answer
57 views

Voltage Supervisor IC for PIC

Im using a DS1233A IC with a battery (Li-Ion 4V) powered PIC18F26J50. The battery powers a LM1117 3.3V regulator. The problem i have is when lights go out for long period of times, the battery ...
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1answer
124 views

What could be this component and what is its work? Is it a fuse or may be a protection resistor?

I opened before some laptop batteries. But this is the first time I see it. This is an IBM ThinkPad cell battery. See picture below, the two pins to the left are connected, resistance between ...
3
votes
1answer
101 views

When a load draws more current than a source can give

I'm planning to use the LM2623 to boost a single AA for a 5V load that draws 400mA. This graph seems useful The graph seems to suggest that at Vin=1.5V, there's no way 400mA could be drawn without ...
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3answers
644 views

Regulating AA to 5V and achieving high efficiency

I'm trying to regulate a single AA battery to 5V for charging a USB device. I know even at perfect efficiency, it won't provide much juice (1.5v * 1500 / 5v). But what is the expected efficiency for ...
0
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1answer
384 views

3 phase AC motor 220V powered from 12V battery

I need occasionally drive watergate with gear box (e.g. http://www.servomech.com/main/screw-jacks.htm). Because location is far away from 220V I suppose powering from SLA 12V battery charged from ...
1
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3answers
83 views

Conductive body of flashlight

I have a flashlight that seems to use the inside of the metal body to conduct the negative terminal of the LiPo battery inside. The outside isn't conductive - likely anodized. Would there be adverse ...
5
votes
2answers
527 views

5 year run time on small battery

I am working on a project that checks a sensor every 12 hours and reports the status via cellular modem to our server .. Power consumption is less than 1mA during sleep mode and spikes to 900mA ...
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1answer
39 views

Load regulation and battery charging

With the MCP73871, the load regulation is 0.08%. Does that mean it expects the battery voltage to increase strictly monotonically? That is, if the device consumes 2000mA at 5V (around 3000mA at 3.7V) ...
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1answer
42 views

Do I need any special equipment to make my circuit run off power from a phone/laptop charger?

Is it safe for one to replace a 5v battery source with a phone charger without installing any other components to prevent power surges or injury to any people in contact with the device? Also, is it ...
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1answer
129 views

LiPo charging module used as backup?

I am running small stm32/gsm module project and would need battery backup in it. Is it possible to use cheap lipo charging module to do exactly that. I would charge my battery through input terminals ...
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1answer
78 views

Is it possible to calculate capacity of a battery using a resistor

Is it possible to measure the capacity of a battery if the discharge curve of the battery utilizes a resistor as the load? For example, if a 100 ohm resistor is connected to a battery and then the ...
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0answers
34 views

How to determine load to use in a battery discharge curve

I am making a discharge curve of a battery I am testing. So for the discharge curve, what load should I use? (This was kind of answered here, but it was kind of a guess in that the load is based on ...