98
votes
Accepted
Duracell PowerCheck - How Does It Work?
According to the German Duracell website:
As you press the points, a current will flow through a metal strip getting warm. The display is a thermochromatic one. So the increased temperature will ...
- 18.1k
63
votes
Accepted
Wouldn't charging a lithium battery to 80% only defeat the purpose of putting the battery into longer use in the first place?
When you run, you cover less distance by sprinting for a short time compared to running at marathon pace. Same goes for batteries.
The longevity of Li-ion batteries is greatly affected by a) how deep ...
- 9,808
23
votes
Wouldn't charging a lithium battery to 80% only defeat the purpose of putting the battery into longer use in the first place?
I have a device in a remote location, in temperate climate, that uses a rechargeable lithium battery and solar panels. The device itself is underground where the temperature varies only a little bit, ...
14
votes
Accepted
Is 18650 battery capacity from 3V or 0V?
The rated capacity of a battery is measured between its rated full charge and rated end of life voltages. With lithium polymer, these are usually 4.2 V for full charge, but the end of life quoted ...
- 174k
12
votes
I need to power a device that requires 12V and 0.43A, with as small of a battery as possible
You have a 430mA load and want it to last 2-3 days. That's 48 to 72 hours. Doing the math, you need a 21 to 31 amp-hour battery. That's approxmately one large motorcycle battery.
- 172k
10
votes
Accepted
Excess capacity in the power grid
The short answer is no. There is not "potential" electrical energy present on a power line. Instead, the power company generators are always being tweaked to produce the power needed.
Think of your ...
- 61k
10
votes
Is 18650 battery capacity from 3V or 0V?
I understand that running an 18650 Lithium Ion battery below 3V causes
chemical instability and shouldn't be done.
Correct.
So what I am unsure on is if the value shown on the iMax B6 is the
"...
- 57k
9
votes
Is 18650 battery capacity from 3V or 0V?
First, finding capacity of a battery has nothing to do with its physical size and layout. "18650" refers to the size and shape of the battery, in this case the shape is cylindrical, 65 mm long and 18 ...
- 315k
7
votes
Accepted
How do I increase the current a battery delivers?
There is no default current that you get from a battery. The current delivered by a battery is determined by its voltage and the resistance of the connected load.
A battery will have an internal ...
- 60.7k
6
votes
Accepted
How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W?
80Ah means "80 ampere*hours" -- approximately, the battery can give 80 amperes * 1 hour, or 160 amperes * 0.5 hours, or 40 amperes * 2 hours.
1800W refers to maximum power -- if you draw more than ...
- 3,278
6
votes
I need to power a device that requires 12V and 0.43A, with as small of a battery as possible
For a battery-powered device, consider both the peak drain current and the average drain current, as well as the desired run time.
The peak drain current is the maximum amount of current the load ...
- 15.1k
6
votes
Accepted
How to find capacity of a battery in terms of mAh or Ah?
Here's your problem, in a nice graphic from Battery University. Most battery chemistries in use today (Li-whatever, NiCd, NiMH, lead-acid) have a discharge curve that features a short downward drop ...
- 47.1k
5
votes
Accepted
Wire capacity - Total power or just current?
The wire will heat up because of its resistance and current passing through it, and this also makes a voltage drop over wire. The potential of the wire itself is irrelevant, assuming the insulation ...
- 172k
5
votes
Wire capacity - Total power or just current?
However, I've always thought about a wire's capacity by total power transmitted, not just the current.
That is indeed your prerogative. You have every right as an independent human being to think how ...
- 174k
5
votes
Accepted
Maximum bit rate over a communication channel
The formula is an upper bound, indicating the best performance that any modulation scheme could hope to achieve in a given bandwidth at a given SNR. QAM on its own will likely not achieve this ...
- 20.6k
5
votes
Wouldn't charging a lithium battery to 80% only defeat the purpose of putting the battery into longer use in the first place?
It's down to how many years, or charge cycles, you want the battery to last for.
If you limit the charge to 80%, then you will have to charge more often. But the increase in battery life will be ...
- 20k
5
votes
Accepted
UPS vs portable power station capacity ratings
Power semiconductors in the inverter are rated based on current, not output power. If you use a load with a bad cos phi, that draws a lot of reactive current compared to its actual power, what matters ...
- 81.8k
4
votes
What is the valid capacity ranges of Lithium Ion 18650 batteries?
I bought some 9800 mAh Li ion 18650 batteries on eBay and tested them with my genuine SkyRc charger/tester. maximum capacities were between 990 and 1080 mAh each with a sample set of four cells. Yes ...
4
votes
Solar battery draining too fast
The battery's capacity is specified for 20 hours of use, so 9 A. That means they specify that when you pull 9 A, the battery's capacity is 180 Ah.
Unfortunately, that does not mean you can pull 18 A ...
- 9,310
4
votes
Accepted
Impact of Bandwidth Increase on Shannon Capacity
Recall the statement of the Shannon-Hartley Theorem, which gives a theoretical bound on the channel capacity1:
$$C = B \log_2\left(1+\frac{S}{N}\right)$$
Under your assumptions, the bandwidth doubles, ...
- 20.6k
4
votes
How do I increase the current a battery delivers?
The C and discharge rate is limited by the battery internal resistance, which leads to heating during charge and discharge. If you add cooling to the battery it can sustain a higher discharge rate, ...
- 58.4k
4
votes
RMS or average current in battery lifetime
Neither RMS or average will be completely accurate. The capacity of a battery will generally be different for different load current levels, so you would need to estimate the fraction of time at each ...
- 31.7k
4
votes
UPS vs portable power station capacity ratings
VA is used instead of W because not all loads are purely resistive so it better describes how much load and what type of load can be powered with an UPS, due to power factor between VA and W. And it's ...
- 172k
3
votes
Boost Converter: Low voltage high current VS. High Voltage, low current?
Boost converter losses are lower when boosting less .This is still true when switching loss reduction schemes are employed .Your proposed parallel circuit is safer due to its 35V output .This should ...
- 15.6k
3
votes
Accepted
Any side effects when substituting bigger capacity battery in place of smaller capacity?
If the thicker 2032 battery does fit into 2025 coin place of your key fob, there is absolutely no side effects. Your keyfob will just last longer.
The rumors you heard are utter nonsense. If a ...
- 42.4k
3
votes
Excess capacity in the power grid
From a legal standpoint the court argument would be who owns the equipment where the power was dissipated?
Speaking for residential customers in the United States:
1.) The power company owns the ...
- 1,033
3
votes
Conventional way to measure Li-Ion cell capacity?
The cell capacity is dependent on the charge voltage, the discharge rate, and the end point voltage. The charge voltage and end point voltage also affect the cell lifetime.
This means there is no one ...
- 174k
3
votes
Why or when does battery capacity matter in a series circuit?
Lithium cells like 18650s are damaged if discharged too deeply.
When you have several cells in series to make a battery, then you need to make sure that you monitor the voltage of every cell, and ...
- 174k
Only top scored, non community-wiki answers of a minimum length are eligible