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Questions tagged [cell]

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Charging 1.2V batteries with a solar cell

I have a pendulum driven by an electromagnet that I've been powering by two 1.2 volt 2000 ma Ni-mH rechargeable batteries in parallel. I've gotten the pendulum to swing for 3 months on this setup. I ...
Wylie Wisnewski's user avatar
1 vote
1 answer
193 views

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 ...
Joey's user avatar
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1 vote
0 answers
143 views

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 ...
MorningCloud's user avatar
0 votes
1 answer
210 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 ...
Danny Beckett's user avatar
0 votes
1 answer
120 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 ...
Karl Simmons's user avatar
0 votes
1 answer
132 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 ...
BELSmith's user avatar
  • 146
0 votes
1 answer
63 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 ...
BELSmith's user avatar
  • 146
8 votes
7 answers
6k 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 ...
John's user avatar
  • 469
0 votes
1 answer
605 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 ...
Karlsson's user avatar
  • 113
0 votes
0 answers
47 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 ...
jarayama's user avatar
2 votes
2 answers
500 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 ...
Habib Anwari's user avatar
0 votes
2 answers
279 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 ...
power machines's user avatar
0 votes
2 answers
341 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 ...
Nareik Seivad's user avatar
0 votes
1 answer
62 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 ...
Nownuri's user avatar
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