53 votes
Accepted

Does it matter if a fuse is connected to the negative or positive terminal of a battery?

[Should I] connect the fuse to the negative terminal of the battery since it's where the actual flow of electrons originate which is opposite to the conventional flow of current from the positive ...
Transistor's user avatar
  • 175k
41 votes

Lithium Coin Cell CR2032 battery specifications

I did my PhD thesis on energy management in wireless sensor networks and was working with sensor nodes using CR2032 batteries. We designed the nodes ourselves (my supervisor designed the PCB and I ...
lowtech's user avatar
  • 511
33 votes
Accepted

Unknown component in an electronic dictionary

That is a piezoelectric buzzer: Photo from the linked Wikipedia article.
JRE's user avatar
  • 70.8k
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
30 votes

My DIY RGB LED panel powered by 9V battery works but certain colors like blue, white, and purple don't work

It is a bit hard to see from the picture, but since each LED has six pins, and knowing that it is meant for 12V supply, it is extremely likely that the LEDs might be arranged so that there are three ...
Justme's user avatar
  • 143k
29 votes

Possible battery solutions for 1000mAh capacity and >10 year life?

First, let's see how much energy or capacity you need. 70 µA for 10 years comes out to 6.1 Ah, and you say this is at 3 V. That's a lot more than a CRxxxx battery can do. Another problem is ...
Olin Lathrop's user avatar
27 votes

Would a 7805 5 V regulator drain a 9 V battery?

What could explain such a short battery life? Could it be the 5v regulator? As mentioned, the 7805 has about 4mA of quiescent current. You need to find a data sheet for the battery (Eveready has ...
TimWescott's user avatar
  • 45.8k
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
23 votes

Possible battery solutions for 1000mAh capacity and >10 year life?

Long lasting (very low self-discharge) batteries usually doesn't have a very good discharge characteristics. For example Tadiran SL-360, 14500 form factor offers 2.1AH at 6mA discharge but can not ...
user3528438's user avatar
23 votes

Why do batteries in consumer electronics get used unevenly?

There will always be some variation in capacity between batteries. In toy use the current is typically drawn at a high level compared to many other applications, so the internal resistance of the ...
Spehro Pefhany's user avatar
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

My DIY RGB LED panel powered by 9V battery works but certain colors like blue, white, and purple don't work

Blue LEDs require a higher voltage than red and green. If the panels are designed to work on 12 V, there may not be enough voltage to light the blue LEDs when run on 9 V. The blue LEDs must work for ...
Peter Bennett's user avatar
16 votes

Why do batteries in consumer electronics get used unevenly?

In addition to the notes on battery manufacturing tolerances, I have seen (at least one) device that would split off battery electrical connections to different parts of the circuit. In my case, it ...
CoderTao's user avatar
  • 865
16 votes

Does it matter if a fuse is connected to the negative or positive terminal of a battery?

Since the negative terminal of the battery is normally considered "Ground" or "Zero Volts", a fuse in the negative lead would leave the rest of the circuit "hot" - usually Not a Good Thing. ...
Peter Bennett's user avatar
14 votes

Lithium Coin Cell CR2032 battery specifications

From the data sheet: Nominal capacity indicates duration until the voltage drops down to 2.0V when discharged at a nominal discharge current at 20 deg. C So, if you discharge at a steady 0....
Passerby's user avatar
  • 72.9k
13 votes

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

Very often, multiple batteries are series-connected. And the total voltage is used to power "stuff". In that case, flipping a battery to turn off current works just fine. However, the less-usual case ...
glen_geek's user avatar
  • 25.3k
13 votes

Would retro-fitting a DC motor as the blower motor in a residential furnace be more efficient than existing 1/2 hp AC motor?

Brushed DC motors do not have the longevity of induction motors. They are also not particularly efficient. You may be able to find a BLDC motor with built-in control that could run from DC and be more ...
user57037's user avatar
  • 29.3k
12 votes
Accepted

Using DC voltage instead of AC to supply SMPS

I have practical experience with PC power supplies. Pretty much any modern ATX PSU contains a main section (that delivers full horsepower when the PSU is on) and a tiny section to deliver +5VSB. In a ...
frr's user avatar
  • 2,768
12 votes

Would a 7805 5 V regulator drain a 9 V battery?

All those parts can run from 3 to 5V so use a battery that doesn't need a regulator, a 16500 Li-ion cell, or a 3xAAA battery pack are about the same size as the 9V and produce voltages in that range. ...
Jasen  Слава Україні's user avatar
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.
Justme's user avatar
  • 143k
11 votes
Accepted

How much current can lead acid batteries safely supply?

Lead acid batteries are fantastic at providing a lot of power for a short period of time. In the automotive world, this is referred to as Cold Cranking Amps. From GNB Systems FAQ page (found via a ...
manassehkatz-Moving 2 Codidact's user avatar
11 votes

Would a 7805 5 V regulator drain a 9 V battery?

The idle current of a 7805 regulator is around 4 mA so, armed with the ampere hour capacity of your battery, work out how long it will last with a continuous drain of 4 mA. If you establish that is ...
Andy aka's user avatar
  • 452k
11 votes

Nichrome wire not heating up with a 9 V battery

A 9V battery is a poor choice for providing electrical energy for heating. An Alkaline 9V battery can typically provide maybe a few watts of heat energy for a short while. If your wire resistance is ...
Russell McMahon's user avatar
  • 150k
10 votes

Using DC voltage instead of AC to supply SMPS

Yes, it can be done. Your device must use a SMPS only (no hidden transformer or blocking capacitors.) Your device must be double insulated (has no external connections or exposed metal parts that are ...
JRE's user avatar
  • 70.8k
10 votes
Accepted

Atmel SAM E70 (ATSAME70Q21, Cortex-M7) battery backup

The idea behind the Vbat input on chips such as the STM32 is that the RTC and other low-power peripherals will normally be powered from the main Vdd, automatically switching to Vbat when Vdd is absent....
Abe Karplus's user avatar
  • 2,621
10 votes

Would a 7805 5 V regulator drain a 9 V battery?

I'm running similar sensor nodes with much better results. My setup has a few differences to yours: I'm running the µc directly (no regulator) from rechargable 1S LiPo batteries (3.7 V nominal) ...
AndreKR's user avatar
  • 2,999
9 votes

Possible battery solutions for 1000mAh capacity and >10 year life?

As someone posted in the comments, Lithium Thionyl Chloride primary cells are a solution to this problem. Such cells exist in various form factors, from 1/2AA through D, and various battery pack ...
Lior Bilia's user avatar
  • 7,475
9 votes

Does it matter if a fuse is connected to the negative or positive terminal of a battery?

Think about your failure modes You have to ask yourself, "What happens if one of the wires or some of the electronics shorts out to something else?" Suppose I have a + and - pair of wires going out ...
Harper - Reinstate Monica's user avatar
9 votes
Accepted

When connecting two battery grounds together, which battery specifications can tell us the limits?

Figure 1. There are two current-loops in the circuit: control and power. Notice that provided the transistor's ratings are not exceeded that no current flows from the power circuit back into the ...
Transistor's user avatar
  • 175k

Only top scored, non community-wiki answers of a minimum length are eligible