16
votes
Accepted
Why do drones use Li-Po instead of Li-Ion?
For this answer I'm going to define LiPo as flat packs, and Li-Ions as 18650s. The reality is more messy than that, but I believe this way of defining the terms will help answer your question as you ...
- 3,807
14
votes
Accepted
How much can I overcharge a 4.35V LiPo?
The charge (termination) voltage level of Li-ion batteries is specified by manufacturer. The specification is based on reasonably accepted number of cycles ("battery service life") a battery can ...
- 41.9k
14
votes
Calculate battery percentage on LiPo battery?
According to some empirical values I found on the *net, this seems to be a quite accurate estimation of remaining energy (in percent) of a typical lipo (rated 3.7V, fully charged at 4.2V):
$$123 - {...
- 141
14
votes
Accepted
Is this MOSFET upside down?
It is correct. You normally see PMOS connected like this to act as a reverse-polarity "diode".
simulate this circuit – Schematic created using CircuitLab
It has much less voltage drop ...
- 57k
12
votes
How much can I overcharge a 4.35V LiPo?
Charging Li-Poly and Li-Ion is not as simple as just pumping a voltage across it. It's a two-stage operation involving both constant current and constant voltage.
Apply a constant current of (say) 1C ...
- 56.3k
12
votes
Accepted
Power bank or fire hazard?
Those are a fire hazard. Even if someone can sell something, it does not mean it should be sold.
I recall seeing a picture of similar device that had melted itself. What likely happened was bad ...
- 164k
11
votes
How do/can I charge a Li-po battery without a fancy charger (just using a current)?
You need a proper charger to charge Li-po batteries safely, using the right algorithm; "just using a current" won't do and could damage the batteries.
For your purpose, you need a solar ...
- 9,290
11
votes
Why is charging with Lithium batteries with a small load dangerous?
If your charger outputs 1 A in CC mode, and has a 500 mA constant current load connected, then 500 mA goes to battery and 500 mA to the load. So the battery will also charge slower because only half ...
- 164k
9
votes
Understanding LiPo charging / protection circuit
Protection circuits are usually distinct from charging circuits. Many battery packs are designed with the intention of being charged by a dedicated unit that will control the charging process.
The ...
- 304
9
votes
Are lithium ion batteries damaged by strong magnets?
It should not have an affect on the battery, the magnetic field my deviate the path of ions and electrons slightly but not have any effects on the battery itself.
If the magnets 'slam' into the ...
- 87.1k
8
votes
why do laptops have 10 or 20 volt batteries if most components only use logic level voltages
Because while total power stays the same, voltage droop across a cable due to high currents can be avoided with higher voltages and lower current. Copper is expensive, and it's simpler to deal with 2....
- 73.3k
8
votes
How do/can I charge a Li-po battery without a fancy charger (just using a current)?
If you can keep the voltage of each cell individually to less than or equal 4.1V (4.0V safer still) then you can charge with current from solar panels.
If solar panel max current into battery is never ...
- 151k
8
votes
Why is charging with Lithium batteries with a small load dangerous?
Basically you want to charge the battery until the end of charge condition is reached (voltage >= Vthreshold and current <= Ithreshold) and then end the charge and let the battery rest.
The end ...
- 80.3k
8
votes
How is the output of an MPPT solar charge controller connected to a battery?
MPPT is a technique. "An MPPT" is a somewhat meaningless term unless it's in the context of some load that can take varying power gracefully (i.e., the system is a battery charger, a grid-...
- 46.7k
7
votes
Why is there so much fear surrounding LiPo batteries?
All great answers. Here is a short one. A 7.4 volt. 5 amp-hour battery has 37 watt-hours of energy, or 133,200 joules. Compare to a .357 Magnum's 873 joules of muzzle energy. The trick is not to ...
- 11.7k
7
votes
Accepted
Is it safe to charge a Li-Po battery at a lesser C rate than its usual routine?
You can always charge a Li-ion or Li-Po battery at less than its specified rate provided that all the normal charging requirements (CC followed by CV, don't overcharge, don't trickle-charge, don't let ...
- 48.6k
7
votes
DC-DC Boost converter in Parallel
In your post you said that you wanted 1A out at 12V, and that you calculated that you needed 3.24A in with no losses. You didn't state what input voltage you were using, but it can be calculated. ...
- 12.4k
7
votes
why do laptops have 10 or 20 volt batteries if most components only use logic level voltages
Ohm's Power Law:
$$
P = V*I = I^2 * R
$$
Power lost in copper, and needing to be dissipated as heat, goes up with the square of the current.
Consumers don't like thick cables or hot laps.
So ...
- 4,214
7
votes
Accepted
Block battery if USB is plugged in
With the drain and the source connected as you show, it will do what you want — the body diode is pointed in the correct direction, as shown below. But you do need a diode in the USB path, so that the ...
- 177k
7
votes
How do/can I charge a Li-po battery without a fancy charger (just using a current)?
With lithiums you need a battery management system. No other choice. If you don't want a BMS, use nickel metal hydride.
A BMS is a Battery Management System - it protects the battery from conditions ...
7
votes
How is the output of an MPPT solar charge controller connected to a battery?
The MPPT charge controller you describe actually is a DC-DC converter (a buck converter). The input to the controller is the solar panel voltage. The output is the battery voltage. Conceptually, all ...
- 29.4k
6
votes
Controlling a DC Motor 48v with a 63v power supply
You actually have a few issues when driving a DC motor with more than the boilerplate voltage rating.
Max Current: At no time should you exceed the maximum current rating of the motor. It will ...
- 46.9k
6
votes
Accepted
Why don't some 2S LiPo packs include a balancing connector?
If a lithium-ion battery with more than one cell has no provision for balancing, it's a blatant safety risk. As a battery ages, one cell will drop in capacity faster than the other, causing the lower ...
- 8,661
6
votes
Accepted
What's inside power bank car jumper
Not sure which "thingy" you refer to. The smaller lump has protection circuits. But the secret sauce to these emergency car starter power packs is in the big lump. The reason they can put out so much ...
- 3,616
6
votes
Accepted
Candle light flashing LED (max. 5V) burnt by attaching LiPo battery (3.7V)
Perhaps you connected it backwards. This kind of part has an internal IC that should operate from a 3.6V battery directly, at least by my reading of the current datasheet downloaded from the ...
6
votes
Candle light flashing LED (max. 5V) burnt by attaching LiPo battery (3.7V)
The burned LED is what should be the expectation by connecting it directly to battery. You seem to have a misunderstanding about the LED.
The lithium battery won't be 3.7V. It will be about 4.2V when ...
- 164k
6
votes
Accepted
How is the output of an MPPT solar charge controller connected to a battery?
An MPPT (Maximum Power Point Tracking) charger gives whatever is specified as its output, whether it's a 4.2V Li-Ion cell, or a battery of any other voltage, that should be specified on the charger. ...
- 5,546
5
votes
Can I swap a USB power sources for a 3-AAA battery source?
My question: Is anything bad going to happen if I hook up 5V USB
power-pack in place of the (3.6V total) batteries?
The LEDs will likely fail
If I need a resister in series, how do I tell what ...
- 467k
5
votes
DC-DC Boost converter in Parallel
So I've decided to connect 3 DC-DC Boost converter in parallel, so
each of them share the load and keep everything cooled down
Scenario 1
The device that produces the highest output voltage (...
- 467k
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