Questions tagged [cell]

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90 views

Which cells to cut from the battery pack first?

I have disassembled an 18650 e-bike battery pack and have removed its BMS. I am looking to salvage the cells. I now have the battery pack looking like so: My question is whether it matters which ...
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0answers
52 views

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 ...
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1answer
55 views

Designing battery low indicator for a 3.7 V Li-Ion battery [closed]

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 ...
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0answers
12 views

Do we need to define the delay, power and constraint templates for characterising a library (.lib) file out of post-layout netlists (transistor level)

I am designing standard cells at the transistor level and I want the characterize these cells into a library file (.lib). Do I need to define the delay, power and constraint templates (sequential) ...
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1answer
52 views

How do power banks like the OmniCharge, convert 3.7V to 120VAC? [closed]

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 ...
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0answers
28 views

Optimal time needed to balance lithium cells

I want to balance a lithium cells with 65 Ah capacity, the threshold to start balancing is SOC=101%; In order to calculate the balancing current,I need to fix the balancing time, so what's the ...
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1answer
47 views

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 ...
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7answers
3k views

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 ...
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0answers
32 views

Controlling Li-Ion charging through USB

I am trying to design a circuit with power supply for a microcontroller with a li-ion cell depending on whether a charger is connected or not. I tried it first in the Falstad simulator. "USB 5V&...
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1answer
141 views

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 ...
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0answers
29 views

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 ...
2
votes
2answers
107 views

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 ...
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2answers
81 views

Switch individual MOSFETs connected across lithium-ion cell for passive balancing

I am working on a passive cell balancing circuit using N-MOSFET. The cell voltage will be monitored by the micro-controller and it can also generate corresponding logic level signal according to over ...
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2answers
97 views

Water's ability to short an L18650 cell?

Personally I no longer use 18650 cells, I use polymer packs with safety circuits. However having once or twice in the past I have briefly shorted a connection between the positive terminal and the ...
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1answer
47 views

How to calculate battery lifetime from datasheet

I wanted to understand how one can model the lifetime of a cell when it supplies power to a step-up converter. For this question, I want to focus on two products. Tadiran TL-4930 cell and Adafruit ...