57 votes
Accepted

Can this battery be charged?

It's a lead acid battery. The second bullet point wraps to the third line (terrible layout). Do not charge in a gas-tight container In other words, you can charge it, just ensure that it can ...
JYelton's user avatar
  • 33.8k
51 votes

Why charging Li-Ion batteries in cold temperatures would harm them?

'Cold temperatures' is awfully vague. First, let me actually specify some real, hard numbers. Do not charge lithium ion batteries below 32°F/0°C. In other words, never charge a lithium ion battery ...
metacollin's user avatar
  • 28.4k
36 votes
Accepted

Lithium Battery Protection Circuit - Why are there two MOSFETs in series, reversed?

It's for two reasons. Well, actually just for one, but with two factors. A MOSFET can conduct in both directions when turned on, as it truly is just a resistive channel that is opened or closed. (...
Asmyldof's user avatar
  • 18.4k
35 votes

Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

It's marketing, like PMPO watts. Big numbers sell! If the battery is 1.2V nominal, there won't be a big difference between W.h and A.h numbers. But if the battery is 3.6V nominal, the W.h number ...
bobflux's user avatar
  • 74.6k
30 votes

Can I disable a battery powered device by reversing half of its batteries?

If the batteries are not perfectly balanced they would still have some net voltage. And that is assuming that the batteries are connected in series. If the batteries are connected in parallel, ...
Dampmaskin's user avatar
  • 3,797
28 votes
Accepted

Why some phones need a 5V charger although the battery needs 3.7V only?

If you look at the charge profile of a lithium battery you'll see that at certain points it changes from constant current to constant voltage charging: - This means that some form of "in series" ...
Andy aka's user avatar
  • 451k
27 votes

Can I disable a battery powered device by reversing half of its batteries?

You can, but as per @Dampmaskin's answer, it's not really the best plan. Why not do as often seen in new electronic devices, and inserst a plastic slip between a battery and one of the terminals (or ...
Birger Bech Jessen's user avatar
27 votes

How do rechargeable 1.5 V batteries work?

The batteries you show use Li-ion cells internally and include a step-down and a USB 5V to Li-ion charge controller. They’re essentially power banks that output 1.5V with a step-down instead of 5V or ...
hacktastical's user avatar
  • 52.7k
27 votes

How come modern electronic devices support charging with various voltages through USB-C?

Do they internally convert the input voltages to a specific voltage? Yes. The external "charger" is just a power supply, the actual charge control is done inside the device.
pjc50's user avatar
  • 46.7k
26 votes

Is temperature the only battery charging speed limitation?

Can I charge as fast as I want, provided that I cool down sufficiently? No. To charge faster you need higher voltage to overcome internal resistance. If the voltage is too high it may cause damage ...
Bruce Abbott's user avatar
  • 56.2k
25 votes

Takes days to charge phone from 10W solar panel

First make sure everything is working as intended. Point the solar panel at full sun and see what kind of current you can get at 5 V. Try a 5 Ω power resistor. That should draw 1 A, which ...
Olin Lathrop's user avatar
22 votes
Accepted

Is temperature the only battery charging speed limitation?

You certainly cannot charge as fast as you want, but you can indeed increase the charging rate if you keep cooling the battery in the process. Though the point is not to make the battery colder than ...
Dmitry Grigoryev's user avatar
21 votes

Takes days to charge phone from 10W solar panel

You're hooked up wrong. The meter's big rotary switch has a legend around the outside indicating range. Obviously, there are as many range markings as there are switch positions. Only two of them ...
Harper - Reinstate Monica's user avatar
20 votes
Accepted

What does a dashed rectangle and an encircled dot mean?

The dashed rectangle typically means a remote part, off-board, or removable. In context this is a battery charger for a removable battery pack, as you see in the description right above that typical ...
Passerby's user avatar
  • 72.9k
20 votes

Can you charge and discharge a Li-ion powerbank at the same time?

"Battery" and "power bank" do not mean the same thing. A battery is a relatively simple thing, and you can find one inside any power bank. A power bank is a more complicated ...
Solomon Slow's user avatar
  • 3,053
19 votes
Accepted

Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

cIt's complex, and some of the answers are "soft" and some of you assumptions are (reasonably enough) inexact. Li-ion are measured in mWh LiIon cells are frequently measured in mAh capacity. LiIon ...
Russell McMahon's user avatar
  • 150k
19 votes

Do phone chargers communicate with the phone?

USB-PD (power delivery) lets the phone communicate with a power supply to pick a voltage/current that both support. For example, a power supply might support 5, 9, 12 and 20V, but a phone might only ...
user1850479's user avatar
  • 16.5k
19 votes
Accepted

For how long should I charge my dead car battery without damaging it?

A typical Pb-Acid car battery is charged with around 13.8V. So 13V will be fine. A battery trickle charger is a voltage source, meaning that as the battery voltage rises, the charger puts less ...
Aaron's user avatar
  • 7,532
18 votes

Extending the backup runtime of a UPS with an external car battery

I have used external batteries on several old, out-of-warranty UPS models over 15 years, ranging from 500VA to 1500VA (about 400 watts to 1000 watts). I prefer sine wave UPSs for their universality ...
John's user avatar
  • 181
18 votes

Do phone chargers communicate with the phone?

You will find the answer if you research "USB charge negotiation". What you are calling "chargers" are power supplies. The charge controller is in the phone. The phone tries to ...
Transistor's user avatar
  • 175k
17 votes

What does an EV "wall socket charging cable" do?

It is for safety. It can't be omitted. The box tells the car how much current is available at maximum so the car knows how much is the maximum current it can draw. The box also turns on mains voltage ...
Justme's user avatar
  • 143k
17 votes
Accepted

Windmills generate electricity by the spinning blades. Why can't EV vehicles recharge their batteries from their spinning wheels? Is that too hard?

They do. It's called regenerative braking. The only time you can practically recover energy from the wheels is during braking. Taking energy from them slows them down. If you do it while they are ...
GodJihyo's user avatar
  • 21.9k
17 votes
Accepted

How come modern electronic devices support charging with various voltages through USB-C?

The thickness of a wire in a cable is factor in the current it can carry. Whereas the voltage a wire can carry is determined by the insulation between it and (a) other wires or (b) the outside world, ...
TonyM's user avatar
  • 22.7k
16 votes
Accepted

How can I use two TP4056 with two li-ion batteries, but single load?

Don't. Just use one TP4056 and connect both cells in parallel after balancing them first. Don't connect batteries with more than 0.2V difference in parallel as this can risk fire and explosions (...
Jasen  Слава Україні's user avatar
16 votes
Accepted

How does laptop 'limit battery charge' work?

Charging a LiIon battery to the highest possible voltage gives it maximum capacity, so that is the preferred setting if you intend to use your laptop as a portable computer, because it will run for a ...
bobflux's user avatar
  • 74.6k
15 votes

Batteries in Series

If you connect the 39 + 3 batteries to a load and that load is connected for a longish time you might find that the higher ampere-hour batteries are still running OK and trying to push current to the ...
Andy aka's user avatar
  • 451k
15 votes

Can a 12V LiFePO4 battery be charged using a car battery?

If you just hook the LiFePo up to a car battery, you'll get a lot of smoke from both the cables and the batteries involved, and it can also cause the LiFePo to ignite or explode. The problem is that ...
Jonathan S.'s user avatar
  • 17.7k
14 votes

Why are there 3 pins on some batteries?

For Nokia batteries, one of the pins may be a BSI (Battery Size Indicator) pin, which contains a fixed resistor to ground, enabling the handset to identify which battery is connected. Examples of BSI ...
PkP's user avatar
  • 7,647
14 votes

How do USB charging and "smart" charging ports (e.g. Anker's PowerIQ) work?

In practice, 'smart' chargers use a special chip called a Dedicated Charge Port Controller. A DCP controller can act like different chargers, and picks the mode which seems to work best. That's ...
florisla's user avatar
  • 311

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