636

Every cell phone (as well as laptop and nearly everything with a rechargeable battery) uses LiIon/LiPo (essentially equivalent for the purposes of this discussion). And you're right: In terms of actual incidences, lithium-ion and lithium-polymer are the safest battery chemistry to be in wide use, bar none. And the only reason this now ubiquitous chemistry ...


101

A 400mAh 9V battery will last a year with a 40µA current draw. Now consider a smoke detector. It is low power analog circuitry, most likely drawing less than the 40µA figure above. If you wanted to power it from a boost converter and AAs, then you'd need a converter with very low idle current. But... when there is fire, now you need quite a bit of power, ...


89

First a AA is not a battery.. it's a cell. A battery is a "battery" of cells, i.e. more than one cell. A 9V battery contains six 1.5V cells. Rip one apart and see. As for why we still use 9V batteries, it really is a matter of the design. The nice thing about 9V batteries is they give you a fairly wide operating voltage range during their life without being ...


79

mAh (or mA·h) is not how many milliamperes a battery can deliver in an hour. That would be mA/h. Current, measured in amperes, is already a rate of stuff. Specially, one ampere is one coulomb per second. So, if current is like speed, then mA/h is like acceleration, and mAh is like distance. Rather, mAh it is a unit of charge. It is what you get when ...


76

To use Lipo batteries safely, you must treat them with the same respect you would anything that can store and rapidly release a large amount of chemical and/or electrical energy. The bigger the battery and the lower the internal resistance (e.g. higher C rating) the more you need to be careful. They can be used safely... just like gasoline can be used safely ...


71

So, obvious answer first: why do batteries still weigh 20kg? Because they're still the same lead-acid batteries. Simple as that. No other technology came near the low cost per Ampere (and ampere-hour) of those, near the reliability and near the ease of handling. 20kg isn't that heavy, if you consider that "fuel economy" still means your average new car ...


70

Most likely cause is that you need to replace the battery in your multimeter. When the battery is very weak, the voltage drops to the point where the internal reference can no longer maintain regulation and it, in turn, also drops. A low reference voltage results in a high reading, which is exactly what you are seeing. Usually there will be a low battery ...


63

So, now after the answer to your literal questionto your real question, that you sadly didn't ask Battery technology has moved so far in the last 100 years. The lead-acid starter battery became common in cars in 1920, lead is essentially poison, and sulphuric/lead acid isn't any less dangerous. They tend to fail in cold temperatures, especially if not ...


61

It is not practical. I do not know why people do this, there is no benefit whatsoever. It amounts to misuse of something useful. Simply put, those videos are by people who don't know what they are doing and are misusing supercapacitors for a bizarre and senseless application they are neither well-suited to nor even practical. And they are offered on the ...


55

In most ordinary circumstances, 12 V isn't even enough to feel, let alone cause a shock. However, it's really current that you feel and that shocks you, not voltage. So when we say that 12 V is safe, we're making implicit assumptions about the resistance of your skin. Electrically, you're basically a bag of salt water. Your insides have low resistivity, ...


54

**WARNING: Lithium Ion cells ** While this question relates to non-rechargeable AA cells it is possible that someone may seek to extend the advice to testing other small cells. In the case Of LiIon rechargeable cells (AA, 18650, other) this can be a very bad idea in some cases. Shorting Lithium Ion cells as is test 2 is liable to be a very bad idea indeed....


53

When a big company wants to make a LiPo charger, they can: A. Have experts on staff and do extensive testing to make sure the charger will work safely across the full range of operating conditions. B. Buy pre-made ICs or assemblies that have been given that same level of care. C. Subcontract out the work to people who know what they're doing. When you ...


48

"Ground" is just a code word which, in this case, refers to the "current return common" circuit node. There is a complete circuit because everything electrical in the car, such as the starter motor, also connects to ground in order to return current to the minus terminal of the battery through the ground. The car's chassis is used for this return network, ...


47

Lithium batteries come in many different chemistries, and it is the chemistry that governs the voltage. The most common chemistries are on the order of 3-4V, but there are chemistries which have a 1.5V terminal voltage. The wiki page for Lithium batteries has a list of many different chemistries and their voltages. A Lithium anode with an Iron Disulphide ...


44

Don't. The battery manufacturers specifically tell you not to do this, as the batteries are quite heat-sensitive. If you manage to set one on fire, you can't extinguish it either: it reacts explosively with water, so you have to bury it in sand or powder. The correct solution is to get spring-loaded contacts or "pogo pins", attach them to a PCB or piece of ...


44

Congratulations for having the wit to know something was wrong! simulate this circuit – Schematic created using CircuitLab Figure 1. Parallel and series arrangements of batteries will have the same VAh rating. I will effectively have a battery of 20 V with a capacity of 2 Ah. That's the error. In parallel they can supply 1 A each for one hour. ...


42

Your meter is affecting the measurement Your voltmeter is also connected to the circuit, and in a different position for each of your two measurements. A "perfect" voltmeter would have an infinite resistance, but any real voltmeter has a non-infinite one. So some current flows through it, and that affects your measurement. So your actual measurements look ...


41

So, first of all, CR2032 is a Lithium Battery type, so, yes, overheat it and it has a good chance of exploding/combusting. I'd really just go and use some cable to get the sensor into your oven, and keep the battery on the outside. Less trouble, more reliability, less isolation that could fail.


39

[Though this late answer may get little exposure now that the question has exited the hot-list, I think it is essential to further emphasize the contrast between the comprehensive safety features in devices such as laptops and cellphones vs. the typically far less comprehensive safety features in hobbyist or DIY devices.] Context is essential when ...


39

Boost circuits have a quiescent current; some energy is wasted simply by having the boost converter. They also get very inefficient at low duty cycles. So if you have a circuit that usually draws a very small current but occasionally needs to draw more, it's difficult to address that with a single boost converter. The main users of 9V batteries are things ...


39

A wrench does not have a resistance of 0.5 ohms, it's way lower. Your basic multimeter cannot measure resistances to better than an ohm or so, the resistance of leads, and the unreliability of contact resistance make it impossible. The way resistances as low as a wrench are measured is to use a 4-terminal Kelvin method. What you do here is to pass a ...


36

My wife has an HC-150, which is smaller than yours because she only uses it at night. However, as Olin said, a smaller unit might be an option if you only need it for a few hours. The other answers talked about the peak current ratings, but what's important for battery capacity is the average current. My wife's unit peaks at around 90W, but only runs at ...


36

It means that the battery has a capacity of 25 Ah when discharged in 10 hours. 25 Ah is 25 Amps for 1 Hour which is equivalent to 2.5 Amps in 10 Hours. So if you load the battery with 2.5 Amps it will last 10 Hours. If loaded with a higher current usually battery capacity decreases so that is why the 10 Hours is mentioned, it results in a higher battery ...


36

The problem assumes you understand something that is not clearly spelled out: the wires and the (unknown) load are in series. Therefore they share the current, not the voltage of the battery. That's the situation: simulate this circuit – Schematic created using CircuitLab As other have pointed out, the voltage drop across the wires is small given ...


35

Its a thermistor like this (photo from internet, not spam related): This kind of resistor depends on the temperature of both batteries. EDIT: In this photo, is a Negative Temperature Coefficient. There are also Positive Temperature Coefficient resistors. The main difference between them is how the resistor decreases or increases when the temperature grows, ...


33

10 years =~ 87650 hours. 1 uA drain will require 87.75 mAh in 10 years. With som shelf life degradation that's close enough to = 10 mAh / uA / year or = 100 mAh / uA / 10 years So your cited 163 mAh battery will supply 1.63 uA mean. Pushing technology, size and luck may get you to say 5 uA mean. There are 86400 seconds/day. There are 1440 minutes/...


33

60A through a 0.01ohm resistance gives a 600mV drop. That is the voltage you need to use in the equation.


33

My multimeter uses a 9V battery and maybe draws about 10mA to function. It is very accurate. If it is powered by a 3V battery, the average current will be 40mA with a 75% efficiency. However the surge current have to go up 80mA, thru an inductor. Basically the trace, battery wire and the inductor now act as an antenna giving off energy to my sensitive ...


32

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 will be 3.6 times more bigger than the A.h number! So a 1200 mWh 3.6V battery sounds a lot better than a 330 mAh battery... even though it's the same battery of ...


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