# Questions tagged [capacity]

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### RMS or average current in battery lifetime

For the purpose of estimating the lifetime of a battery which supplies an irregular load (the current waveform is more or less arbitrary series of pulses - Bluetooth radio). The current is a pulsating,...
• 57
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### Bandwidth distance product

A fundamental principle of communications states that for any given transmission medium, bandwidth-length product is constant. I know that optical fibers, for example, are used for high data rate ...
• 125
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### Maximum bit rate over a communication channel

Shannon formula C= B log (1+S/N) Is this formula applied for baseband transmission only? or for both baseband and passband modulation? Can we apply it without any changes to any modulated signal? What ...
• 125
59 views

### What is the capacity of this battery (details in the body)

Can someone give me the capacity (in Ah) for this battery?
166 views

### How do I increase the current a battery delivers? [closed]

Let's say there's a 2Ah battery with a C rating of 2C. So this means that I could discharge 4 amperes for half an hour at best. Now, there is a default current that we get from a battery right? How ...
105 views

### Battery capacity in mWh instead of mAh [duplicate]

I know that the capacity of a battery is expressed in mAh, i.e. A/s (international system of units). Today I used a command in PowerShell (*) in order to get the battery capacity, but the unit of ...
1 vote
134 views

### How to swap 3 AAA batteries for a rechargeable battery with a charging module [closed]

I have this table lamp that uses 3 AAA batteries to function, but the batteries run out pretty fast, so I'd like to swap them for a rechargeable battery that I can plug into a USB charger without ...
55 views

### Impact of Bandwidth Increase on Shannon Capacity

What is the impact of doubling of bandwidth on Shannon Capacity, assuming noise power spectral density and signal power remain the same?
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1 vote
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### Can I connect batteries of different capacity in parallel?

I don't think this has been covered in other posts. I have a 3.7V 6000mAh li battery pack and three 3.7V 2000mAh li battery packs. If I wire the three 2000s in parallel to make a 6000mAh cell, then ...
1 vote
98 views

### Node voltage increases in voltage divider

I am planning to use a voltage divider in order to measure the capacity of a group of lithium batteries; in order to minimize power consumption, I biased a common-emitter switch (Q1) with the ...
• 553
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### How to find capacity of a battery in terms of mAh or Ah?

I know that this question has been asked a number of times and even received negative feedback but I want to find a shortcut method of determining capacity of a battery in terms of mAh instead of ...
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### Why the does channel capacity not increase as the number of subcarriers increases?

We usually consider multi-carrier (interchangeably multi-channel) communications. By using the multi-carrier system, instead of one-broadband system, we can obtain many advantages, for example, able ...
• 145
868 views

### I need to power a device that requires 12V and 0.43A, with as small of a battery as possible

Basically, I have a device that MUST be powered by battery and it requires according to the item description an operating voltage of 12V and 0.43 Amperes. There are small batteries (A23 batteries) ...
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### how to determine the Remaining useful life of lithium battery given charging discharging voltage, load, temperature of different cycles?

given 3 datas 1st-dataset contains charging details with fields:Voltage_measured,Current_measured,Temperature_measured,Current_charge,Voltage_charge,Time. 2nd-dataset contains discharging details with ...
40 views

### Peukert's Law with all batteries

I was wondering if Peukert's Law applies to all types of batteries, and if not, is there another law, formula, and/or expression that either explains or quantifies the effect of the rate of discharge ...
85 views

### Determine a known battery's instantaneous capacity through voltage? / voltage's relation to capacity

Is it possible to approximate a battery's current (the "right now" kind of current) capacity, given its absolute capacity and a voltage measurement? An example: I have a 1s 260mAh LiPo that ...
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1 vote
144 views

### If a Li-Ion cell has 3000mAh capacity shouldn't I be able to pull 3A from it for 1 hour?

I have these brand new Li-Ion cells that are rated for 3000mAh and I'm trying to get their actual capacity. I have a discharger and its max current it can draw is 2A. However when I set that and run ...
709 views

### What is the derivation for Shannon Hartley theorem?

I know by Hartley's theorem that information is proportional to bandwidth and time. The capacity corresponds to information and bandwidth is there. I don't get how the logarithmic part corresponds to ...
• 429
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### Measuring capacitance of Metal-Insulator-Semiconductor (MIS) structure with LCR meter

I can not get my head around what a LCR meter measures. My LCR meter measures my device (MIS) which is displayed as C_p and G_p (other components can be neglected). My LCR meter displays C_p, G_p, the ...
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1 vote
42 views

### Capacitive distance sensor - humidity influence?

We are using a capacitive sensor to measure displacement (from here: https://www.micro-epsilon.com/displacement-position-sensors/capacitive-sensor/?sLang=en). However, we seem to notice a significant ...
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1 vote
196 views

### Is a VL3030 coin cell battery a suitable replacement for a ML2430

Hi i am attempting to replace a battery in my electronic compass and im supposed to use an ML2430 however this is proving to be hard to get hold of and expensive. Im concidering using a VL 3032/HF5N ...
69 views

### Measuring the capacity of a 40v lithium ion, lawnmower battery

I purchased a 40v Greenworks lawnmower battery, and it's listed capacity (6,000 mah) doesn't seem to be accurate based on what I'd expect to get out of it when mowing a lawn. How would you go about ...
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1 vote
37 views

### Difference between capacity and output current rating [duplicate]

I'm linking to this example, but all battery packs i see on Ebay and Aliexpress are like this. https://www.ebay.com/itm/4800-20000mAh-Rechargeable-Portable-Power-Li-ion-Battery-DC-12V-For-Camera-PVD/...
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### Same mAh, same volt - different current

I need to replace the 18650 battery of one application. The battery doesn't have any marking about volts, mAh or amperes. Because it's 18650, the voltage is fixed - done. mAh - will use 2000mAh (let'...
277 views

### How long will my x 2 23a 12v battery last running a 300mah camera?

I’ve brought some WiFi cameras to run in bird boxes but the battery life on them aren’t very good at all. I’ve tried running them from battery power banks but they switch off after the cameras have ...
70 views

### Preservation of power when wiring batteries in series - battery life is reduced if load is kept the same

This is really just a "sanity check" type question. Am I correct that if you place two batteries in series, that the battery life is effectively halved relative to just one battery, assuming the load ...
94 views

### Is it normal to have 40% capacity after 1.5 years of charging Li-Ion? [closed]

I have a laptop computer that spends 99% of its time plugged in. The last time prior to today I used the computer not plugged in was 1.5 years ago. Today morning, I put the computer to sleep (with ...
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### Is there a reason why lower voltage batteries are preferred for high AH?

I was looking at these batteries and considering whether to use a 12V battery or multiple 2V batteries for backup power. In any case, I came across this battery by Exide Tech - GNB Flooded Classic H1T ...
378 views

### 18650 pack building - is it better to have similar batch or similar capacity?

I'm gonna build battery packs. I have quite a lot of experience with 18650 Li-ion cells, but there's one thing I still don't know. I will buy CCA 100 new cells from seller (for example LGEBHE21865). ...
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1 vote
256 views

### Wire capacity - Total power or just current?

So I've gotten myself into a healthy, educational Facebook discussion. Link is here if you're a member of that group. When I thought about it, everyone defines wire capacity by current only. The ...
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1k views

### How to calculate remaining battery capacity from charge discharge data?

If a dataset contains data collected over time from a re-chargeable battery and includes information such as voltage, current, average discharge rate and peak discharge rates. how can the remaining ...
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### Usability of a deeply discharged Li-ion batteries

I have a question about Li-ion batteries. About three years back I bought two Sony VTC 5 batteries for my vape. They are rated as 2500 mAh 30 A. But I quit smoking about a year ago and I left these ...
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### MW of installed capacity

I am conducting research on wind turbines, specifically into how many hectares wind farms use. I have come across the phase 'installed capacity'. If wind farms typically use up 10 hectares per ...
1 vote
3k views

### How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W?

How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W? I was looking for 12V 80Ah Deep Cycle Batteries on Amazon and most of them were 1800W. Like this one: https://www.amazon.com/Cycle-Battery-...
131 views

### How to calculate losses from a DC-DC converter and their effects on battery life

I have a project that requires an odd voltage of 15VDC. The power pack that I plan to build will be two 12VDC 7AH SLA batteries with a DC-DC converter. So I know that my starting conditions will be: ...
294 views

### Choice of wire diameter for doll's house?

I'm constructing a 1:12 scale doll's house and I'd like to use enamelled wire run within the walls for lighting. Each room would have its own circuit controlled through a switch and then to a common ...
35k views

### Calculate battery state of charge percentage

What is the correct formula to calculate battery state of charge percentage based on the battery type (12v, 24v, 48v and so on) and the current battery voltage. For example if I have a 12v battery ...
1 vote
199 views

### Which capacity measurement is the correct way to measure?

So I've seen batteries showing their capacity in mAh and I've seen others showing in Wh. Phone batteries are always measured in mAh, while for some reason BatteryInfoViewer on my computer only shows ...
1 vote
109 views

### Why or when does battery capacity matter in a series circuit?

I have 3 sets of doubled 18650 cells from a laptop battery, and I gather that it can be dangerous to use cells of different capacities in series. This question is more about the theory than practice. ...
71 views

### Will a standard 9V alkaline battery (300mAh- 400mAH) be able to supply 2.5A for 5-10 second at a time? [duplicate]

For example, I have a motor that needs a surge of 2.5A for a short amount of time from a 6V power supply. Will any 6V battery able to supply that current? Even if let's say it has only a 500mAH. How ...
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### how to understand the capacity in binary symetric channel (BSC)

According to the wiki about the BSC (binary symetric channel), given the bit flip rate p, the capacity is derived as : H(p) = -p*log2(p) – (1-p)log2(1-p) C = 1 - H(p). the error probability p ...
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### Battery Pack Life Rating

I am working off of a schematic where I was given a battery pack with the following specifications. The battery being used is a panasonic NCR18650 lithium ion cell. https://engineering.tamu.edu/media/...
5k views

### whats better? 20,000 mAh 5V Battery or 9Ah 18v battery to use as portable power charger?

So I bought battery brick from Amazon.ca it was a 20,000 mAh, it's a 5v battery pack. I also just bought a Milwaukee 9 Ah 18v battery for my tools and beside it I saw an adapter that let me click onto ...
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### How Can I Find “temperature coefficient” of a Battery?

I am studying mathematical modeling of a battery in simulink and for this it is necessary to determine some parameters. I'm stuck in the part where I need to determine an alpha parameter, which would ...
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22k views

### Running a desk fan off a car battery: How long will it last? [duplicate]

I'm going on a road trip and will be sleeping in the bed of the truck at night. I want to be able to have a fan running during this time. I have a couple old car batteries sitting around, and I was ...
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### Optimal Capacity of Wireless Relaying

"Optimal approach to relaying occurs when transmission is recieved simultaneously at the destination and relay." Is this still valid in the light of recent research? Are there trade-offs involved? ...
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### Stepper Motors Calculations

I am currently working on a project for PV tracking systems. I have two stepper motors, one for each axis to track the position of the sun and the power generated would need to primarily recharge the ...
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### Designing a battery capacity monitoring system for AGM lead acid battery

I would like to design a battery capacity system for my AGM lead acid battery (12v, 40Ah). My idea is that I have values of the battery voltage and its corresponding capacity, which I will use to plot ...