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Questions tagged [battery]

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2
votes
1answer
42 views

Is it a good idea to intentionally discharge lithium batteries to 80%

Manufacturers recommend keeping lithium batteries between 40 and 80 percent charged. I tried, but sometimes I let my phone get higher than that. Then I try to bring it down soon as possible, either ...
0
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1answer
34 views

What is the voltage at the ground electrode of a spark plug?

Since the voltage required to bridge the gap between the central electrode and the ground electrode of a spark plug can reach up to 40 000V and even more, my question is, how does the battery not die ...
0
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0answers
27 views

140 km/h 11 kW motorcycle battery calculations help

This is my first post on endless sphere. For a while I have been planning an electric motorcycle build, inspired by the 11 kW Zero motorcycle model. Now while I love the tech of zero motorcycles, I am ...
0
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4answers
132 views

Why aren't gravity batteries everywhere?

The problem of energy storage, especially with regard to renewables, remains unsolved. Or at least there do not seem to be any popular solutions. Why not gravity batteries? I love the idea, and they ...
0
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4answers
46 views

How can I measure the amount of voltage stored in a sealed lead-acid battery?

I know that the simple way to measure the voltage stored in a lead-acid battery is to simply measure the positive and negative using a voltmeter. In my case, I think that my battery has a builtin ...
2
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2answers
69 views

Should lithium batteries be recharged after every use , or when they are exhausted?

For a small unit like a drill: Is it better to charge after any use or wait until the lithium battery is exhausted ?
1
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2answers
81 views

How can batteries in electric/hybrid cars charge at such a high rate?

If I were to look at "normal" batteries online, they often have charging C-rates of less than 1. However, with a car that uses regenerative braking, obviously such a low charging rate would not be ...
0
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0answers
53 views

Where is the positive terminal on the laser pointer

I want to connect this to wires , I know where the negative terminal is on this ( the spring) but I can’t figure out where the positive terminal is, I can’t find and answer online anywhere else either....
0
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0answers
52 views

Can a Tesla Powerwall 2 be rate limited?

Can a telsa powerwall 2 be rate limited (discharge/charge)? I have access to realtime electricity rates (30 min update interval) and also access to 12 hour predicted look ahead. So I wish to limit ...
2
votes
2answers
78 views

Questions regarding CR-P2 battery specification

I am working with CR-P2 batteries. I have a few questions that I am trying to answer. I would appreciate if anyone kindly help me with these questions. Thanks in advance. I have found in google two ...
1
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1answer
193 views

What is the capacity of a WWII Submarine battery in kWh?

After reading about submarines in World War II, I was curious about their battery capacity, specifically in comparison to modern Battery Electric Vehicles (ie Tesla, Bolt, Leaf, i3, etc). I haven't ...
1
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1answer
82 views

Why are phones not getting charged when I supply 5 V and 0.3 A?

I'm using thermoelectric module to get the voltage. With the help of it, I'm getting 3 volts Open circuit voltage. I've attached DC-DC converter which regulates this voltage to 5 volts. I've attached ...
0
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2answers
33 views

Larger battery from 18650 batteries - using a case?

I want to build a battery for an electric bicycle using 18650 batteries. But I'm not into spot welding so much. Would it be possible to build a large case for the 18650 batteries with these types of ...
1
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0answers
33 views

Best way to communicate data wirelessly with specific conditions

So I need two modules to give each other data with the following conditions: They are relatively short range. They need to be near each other to transmit the data, say around 5 cm. They are ...
1
vote
1answer
64 views

Li-ion batteries storage

I am going to store used li-ion batteries for some long time >1 year, and I have read that optimal storage conditions are: cool ambient temperatures, like 2-5 ...
4
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1answer
113 views

Simultaneously charging and transmitting data to an android phone using usb

Dear engineers, I have to make an engineering project which is a portable solar phone charger. One thing I need to do in it is to somehow charge the phone (android) from the battery (which is charged ...
3
votes
2answers
66 views

Battery Swapping in Electric Cars

What are the advantages and disadvantages (technical, financial etc.) of having battery swapping system over charging stations for electric cars? As per my reading, battery swapping seems feasible for ...
-1
votes
1answer
76 views

How would I measure this battery circuit with a multimeter?

The wire is attached to the bottom of each D battery. I already know that I have to put the bottom of the light bulb on the positive side of the battery. My multimeter looks like this: I'm not sure ...
1
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2answers
83 views

Why lead was chosen as the metal for lead-acid batteries?

I was always curious why lead was chosen as the default for metal acid batteries. This article describes lead-acid battery operation and there are plenty of resources like this on how lead acid ...
2
votes
1answer
2k views

Specific energy vs Specific power in batteries

When looking at the Wikipedia page for Lithium-ion batteries, one can see that there are some technical details such as Specific Energy and Specific Power, but I don't know how to connect them. For ...
1
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0answers
45 views

Batteries for electric airplanes [closed]

I'm interested in the development of electric small airplanes with 4 or 6 seats, that could really happen in the following decades. One of the main problems related to this project would be the ...
1
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0answers
39 views

I would like to run a smartphone using a primary battery instead of rechargeable for a project. What are the 4 contacts used for on the factory LiPo?

Most phone batteries will have a connector of some type with 4 contacts. Of course two of those I'd expect to be +- Voltage, but the other two compose some sort of mystery input to the phone (...
-2
votes
1answer
51 views

Which Generator is “Better”: DC or AC? [closed]

So, I have a project where I have a bicycle that powers a type of generator. I have everything else done, but I need to pick a generator. My first problem is that I don't really know which type of ...
0
votes
1answer
739 views

Torque and Speed of a DC Motor with Pulleys and Wheels

I want to know how to calculate the speed of an electric skateboard If i have that situation(from the picture below) i will need an acceleration=0.16m/s^2? and a force F~=15N? So i will need a ...
1
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0answers
29 views

Charging a Li-po battery (battery output current)

I would like to design a buck converter to use a PV panel to charge a 11.1V 3000mAh 3S 30C Lipo battery. I want to choose the minimum inductance for a CCM ($L=\dfrac{V_{out}T_s}{2I_{out}}$), what is ...
2
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0answers
2k views

Batteries AA - industrial R6 vs normal LR6

I have the following issue: One year ago or so I bought a toy for my kid. Worked fine, then the battery got low (still working though but under performing). I checked the battery type, see is an AA (...
-1
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2answers
543 views

How do you increase the horsepower of an electric motor?

I read that a Tesla Model S P100D achieved 730 horsepower on a dynamometer. Would increasing battery size increase the horsepower? If not, what would?
0
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1answer
51 views

How many batteries can I charge and how long would it take?

Using a hydro generator which gives an output of 4.838KW, I am trying to figure out how many batteries I can charge and how long it would take. I am doing the calculations based on 12V, 17Ah ...
0
votes
1answer
42 views

Uneven split of amperage from battery

I'm currently trying to replace a broken battery for an electric moped, but the old one had two power ports, one for the engine and one for the lights/horn. I haven't been able to find anything that ...
2
votes
2answers
126 views

Battery mAh ratings

I have a laptop computer (Dell L701X) which requires an 11.1 V battery with a rating of 8400 mAh (Battery Type R795X, 9 cell, 11.1 V, 90 Wh, 8400 mAh, other battery ID are: R1122J-733 & B052R796-...
1
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3answers
108 views

Why is electrical energy most commonly stored in metal acid batteries?

Why is electrical energy most commonly stored in relatively expensive metal acid batteries, which have a short life, rather than hydrogen gas accumulated through electrolysis? Hydrogen is a ...
2
votes
2answers
174 views

What type of batteries are used in smart wristband?

I'm making one project for my class, some kind of smart wristband, but not sure which type of battery should I use. I found a lot of good wristband online, I see that they usually have 60 - 100mAh ...
0
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2answers
41 views

How much of a battery needs to be replaced for it to be a fresh battery?

If I take a battery that is "dead" and completely replace the electrolyte and maybe the terminals, would it be a "fresh" battery? So instead of pulling up to a charging station in your electric car, ...
1
vote
1answer
104 views

Charging a battery pack using a motor

I want to fit a Hub motor ($15kW$ BLDC motor) to my car to convert it into a hybrid vehicle. Would it be possible for me to use the same motor (as a generator) to charge my battery pack, while the ...
-1
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1answer
40 views

What tools to use for a solar powered backup? [closed]

Recently, we experienced complete outages for around 8 hours, due to construction on a nearby road. We have decided to install a backup battery and solar array to prevent this from happening in the ...
2
votes
1answer
96 views

Looking for a device that breaks the circuit if the voltage gets too low

I'm looking for a device that breaks a circuit once the voltage of my battery gets too low. This to protect the battery. Example: I have a 12V battery, once it reaches ~11V the huge voltage drop ...
0
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2answers
94 views

Low voltage, high ampere battery safety

I want to power an Arduino project for several weeks on a remote location. At the location, data is gathered and sent over the internet. The project runs on 5V and draws 200mAh max. I need a power ...
-1
votes
1answer
85 views

Do commercial fuel cells actually exist or it is just hype?

I keep reading about how great the energy density is for hypothetical fuel cells, but as far as I can tell these objects do not exist in any practical form outside of laboratory prototypes and "...
5
votes
1answer
2k views

In the Apollo 13 mission, how could the batteries have “no Volts” with two Amps of current?

In the movie Apollo 13 there's a scene when the LEM is losing power; when they switch the module on, one of the astronauts reads the levels and says that one battery has no Volts but 2 Amps. What did ...
7
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4answers
4k views

Charging a smartphone battery while using it

While this question pertains to smartphone , it is being asked from purely an electrical engineering view (My electrical knowledge is very basic) Trying to understand if charging a cell phone and ...
0
votes
1answer
56 views

Are super-batteries theoretically possible? [closed]

Is it theoretically possible and/or economically viable to construct batteries capable of supplying an entire city with electricity for a day or two? One of the big problems with power plants of any ...
0
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3answers
288 views

Is battery-charge-stop-at-XX-percent circuitry not cheap? [closed]

I'm curious why IBM/Lenovo ThinkPad line is basically the only manufacturer/brand of mobility devices that includes circuitry and software that allows one to vastly prolong battery life of laptops ...
4
votes
2answers
353 views

What are the consequencies of intermittently charging a smartphone battery?

I would like to build a little water mill to place under the sink of the kitchen to produce electricity. Considering that the mill will work when the user opens the tap to wash a dish, using a dynamo ...
3
votes
1answer
13k views

What is the minimum current required to charge a smartphone battery?

I am planning to make a portable charger for my smartphone. My input current is 300 milliamps and I am not sure if that will be enough to charge my phone's battery. What is the minimum current ...
6
votes
3answers
382 views

How to prevent shorts between exposed battery terminals and racing vehicle chassis

I have a small issue that is causing a lot of problems. I'm on a Formula SAE team and our battery is consistently shorting between our positive terminal and our chassis. Our chassis is the grounding ...
6
votes
4answers
997 views

Why do rechargeable Lithium Ion & Lithium Polymer batteries explode or catch fire?

There are many Lithium Ion and Lithium Polymer rechargeable battery related accidents. Are some of these accidents are battery design related? Are some of them misuse of rechargeable batteries. What ...
13
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1answer
669 views

What causes rechargeable batteries to age? What can be done to extend life of these batteries?

These days most of modern electronics use rechargeable batteries as a power source. Also, these days most modern rechargeable batteries are Lithium Ion or Lithium Polymer based. Like any other devices,...