Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [cell]

18 questions
8
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7 answers

A battery is not connected to anything. Is there a voltage between its plus and minus poles?

Here's one mental picture of a battery: The electro-chemical reactions inside the battery happen only when there's a closed circuit. When you place a voltmeter across the poles, then you create a closed circuit (with very low current) - the…
John
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2 answers

BMS for two parallel protected 14500 Li-ion batteries

I have two li-ion 14500 850mAh protected 14500 Li-ion batteries and a BMS 1S (for example) I would like to connect the protected 14500 Li-ion batteries in parallel in order to get more current (for twice longer use) Thought of connecting BMS (mostly…
user1673206
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2 answers

How many times a power bank can charge a smartphone?

I am creating a power bank with 3000mAh 18650 cells in a 3S5P configuration. This will give me 189Wh, 12.6v, and 15A. Assuming an iPhone 8 has a battery of 1821mAh or 6.96Wh, how many times it can be charged? I found that it is 15A/1.821A or 8.2…
Awais Saeed
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2
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2 answers

Debate on wiring risk of positive/negative wires along a path

I came across a design of a battery pack. As you see on the photo, the red wire is positive and black is negative. The red wire lays across the top of the battery pack and comes to the connector. One of my classmates said to me that, there is more…
Habib Anwari
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1
vote
1 answer

Cell heat generation calculation

I am trying to calculate the heat generation by joule heating due the internal resistance of a Sony US18650VTC6 battery cell during its discharge (Pheat = R·I2). We need to calculate the heat generation of a cell to design a cooling system to cool…
Joey
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Charging a large array of LiFePO4 prismatic cells: How many is too many?

48 large (150Ah) LiFePO4 prismatic cells were wired in parallel (48P) for days to bring them all into balance; each cell metered 2.800 volts. Perfect! It would seem possible to initially charge the cells using a bench power supply. When connecting…
MorningCloud
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0
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1 answer

Solar panel output

I have a mosquito lamp that runs off a solar panel or it can run with a USB-C. I don't need the solar panel so I thought I would keep it in my emergency supplies to power a cell phone if needed. The solar panel doesn't have a USB output. Is there…
ssp74
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"phase gradient", what is it?

I have found an interesting paper published on the website of Huawei "Very-Low-Earth-Orbit Satellite Networks for 6G" I have a question regarding the following part: "3D UE- centric cell-free communication ..... On the other hand, spatial…
Aid22
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Standard cell design flow in an ASIC design flow

I have a question regarding the standard cell design flow in an ASIC design flow. That being said I understand what a gate array design flow is. It being more or less a fixed logic FPGA. Structured design flow directly follows, which basically means…
patvax
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Is it okay to double wrap 18650 cells?

I’ve got some salvaged 18650 cells here that I’m looking to sell. Most have perfectly intact wraps/sleeves, but some have small nicks showing bare metal that I’d like to fix. I want to rewrap these ones, but in doing so I’d be removing the original…
Danny Beckett
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1 answer

Designing battery low indicator for a 3.7 V Li-Ion battery

I am looking for a solution to create an indicator for a li-ion 3.7 V single cell lighting red if the voltage of the cell is ≤ 3.3 V. SG3546 was an ideal option, but it looks that this chip is not available these days. Is there any other option or…
Karl Simmons
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How do power banks like the OmniCharge, convert 3.7V to 120VAC?

I've noticed the cells are all put in parallel in these devices and it lead me to asking myself what kind of inverter could they be using? Like isn't it a bit inefficient to convert from such a low voltage all the way up there to 120VAC? Please…
BELSmith
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1 answer

What could happen to my cells? I overcharged them a bit

I left my 3.7 V Li-ion cells charging for a long time with a low current 5 V charger. Now when I check the voltage, it is at 4.31 V. The cells didn't get hot, not even warm, but I'm afraid of what this could mean, since they were only supposed to…
BELSmith
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MCP73831 charger - how to control low voltage cell

Does the MCP73831 have a way to set a protection to shut down the main output if the supply voltage is too low? I would like to implement (without coding) a protection which disconnects the cell if its voltage is below 3 V. For example, in the…
Karlsson
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Change just the cell on a LiPo battery

This question is more to understand why it hasn't work for me, this is the case: I have an old Kindle 2nd generation e-reader, the batteries are almost depleted, working just a few minutes. So I have this other batteries, from a phone, same voltage…
jarayama
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