Real or urban legend?

burst and burn. It's not said to be common. Look to youtube for examples and even guys trying to deliberately overcharge them to get them to blow. Use only the proper charger for the battery and you're probably ok. No, you cannot be electrocuted but severely burned.

on Telephone land lines, the current flowing along the wires but it is very rare. Possibly, the same thing is possible through the electrical cord to the charger and the phone.

I remember as a child seeing a lightening strike which we later traced from a huge pine tree near the house, across a wire (old time AM radio aerial) that connected the tree to the house, and jumped to the copper screen in the window, and then to a stainless steel bar top. There was blue radiation all over the counter top, but it went down the water pipes of the sink and so to ground.

Rob

I don't do it as much with my current cell phone because it has a long battery life, but I frequently have the cell phone plugged in to a charging cord in my car. When I make a call using my headset I don't unplug the phone. Does that scenario pose a risk for fire? If so, why is it not loudly and frequently discouraged in the users manual?

I suspect the fire risk is very, very small unless the user goes out of his/her way to create an overcharge situation.

and even some recalls. I don't think this is that much of a widespread problem. One rule is to not leave these batteries charging while unattended. So what are we supposed to do....keep them in view and never charge them overnight? Maybe we need to buy one of those containers for hauling away pipe bombs? I think this is probably an overblown scare. I'm sure that newer batteries have been designed to prevent this and charging devices improved to sense full battery charge and shut down. I remember years ago warnings about carrying nicads in one's pocket with car keys and coins...that they could short out and become a danger.

As for wearing a headset while charging the phone, the headset doesn't add to any electrical danger. The voltage is just too low. Besides, high DC current isn't of the type that causes arrhythmia but high enough voltage can cause burns.

Well, no risk other than making me look like a phone geek. Which is why I don't wear it unless I'm actually using the phone. It's a Blue Tooth set so there is no physical connection to the phone. I was thinking more in terms of whether the phone, attached to the car charger while in use, could burst into flames and damage the car. The only risk to me would be if there were a big fire.

We all want small size and long battery life, so industry obliges by flirting with unsafe watt densities. Can overheat on discharge (normal operating).

If I talk very much on my current cell phone it gets noticeably warm. On my prior cell phone it sometimes got so hot I could hardly stand to put the earpiece against my ear. Still, I don't think I've ever had a phone get hot enough to cause an actual burn.

the explosion or flameup of the battery itself.

I have been told by a cell phone provider salesman that charging a phone and continuing to talk at the same time will overheat the battery to the point of shortening the batteries lifespan.

That of course would be doing it a lot.

I can understand that point. The acts of charging and discharging both heat a battery due to current flow. Depending on the circuity both could generate heat at the same time. But I would think the charging current would normally not all flow through the battery if using at the same time based on some circuits in industrial use for charging that I have worked on a bit.

But by talking while charging, you will increase the charge time. So any heat generated in the battery at all during talking and charging will be additional. And overheating a battery is definitely detrimental to it's lifespan. Indeed, anything electrical is damaged to some degree by use that causes it to exceed it's design operating temperatures.

Roger

I don't know which would be harder on the battery. Battery life is shortened to some extent by repeated charge/discharge. OTOH you are suggesting that battery life is also shortened by keeping the device plugged in while using it.

My suspicion is that overall the repeated charge/discharge is usually worse than the use while connected to the charger but I don't really know. I usually leave my laptop plugged in while using it unless there is no convenient outlet. I hope that does not damage the battery more than just running it down and recharging it.

I figure that what's good for the laptop is probably good for the phone.

Of course I don't use my cell phone a lot. It's mostly an electronic leash/tether so people can find me when they need to.

regarding the charging/discharging cycle.

Older batteries also has a problem if you didn't discharge them enough before recharging. They "learned" a shorter cycle time. The newer ones, or most of them, claim to have overcome that problem.

Actually, I'm a bit skeptical of the use while recharging damage claim myself. I was told that by a cellular phone store employee. I've also been told by more than one that most car chargers are harder on the cell phone battery than a house charger. I believe that claim rest on the car charger output current or voltage is a bit higher than the house charger. I know with my former cell phone the car charger would recharge the battery faster.

Of course, the physical size and the electrical capacity of your laptop battery and the cell phone is much different. Heat dissipating may be much better with your laptop battery than the cell phone battery. Also, I have to think the current capacity of the laptop charger is designed to run the laptop and charge the battery at the same time. I'm not sure the cell phone chargers are designed to be used that way.

I suspect if there is more danger to the cell phone battery, it's because the charging current is so low you're running the phone at it's discharged chemical state for much longer than you could if it wasn't charging at the same time. That can damage a battery I would think.

I try not to "short cycle" my phone too often. I try to keep it charged on the a/c charger and not to talk on it while it's charging. It may not matter, but I normally avoid it anyway.

I use my cell phone more than my land line because all of my family and my wife's are long distance to my land line phone. About all my house phone is used is working calling me, sales people calling me, or wrong numbers calling me.

If fact, I'm very near doing away with my land line completely since I use cable for internet access. My wife and I both have a cell phone, and have good reception in the house. Unfortunately, giving my cell phone out to companies when it is needed will also probably end up getting it sold with address lists sooner or later. Currently, I have free incoming calls, so it would be an annoyance bout wouldn't use up my minutes. And I have really resisted so far giving my boss my cell phone number. If I'm not at home, I don't want him calling me wanting me to come to work or talk someone else through a problem I'm familiar with.

In fact, we don't really need but one cell phone. About the only time I use one when I'm not with my wife is calling her occasionally from work or before I go home from work. Most of the rest of the time, if I'm not home, I'm with her. The odd times I'm not I could certainly live without a phone, I did before we got married.

We don't get all that many calls on our landline, and carrying the cell phone around is easier than carrying a cordless phone. Long distance is 'free' on my cell phone. Actually, the cell phone is pretty cheap because my employer supplies it, but I do have to pay tax on the imputed income so it isn't really free.

If I lived in an area where I actually had reliable cell phone signal at home I'd probably ditch the land phone. But, alas, I cannot reliably make a call from inside the house. The local telco is safe for now.

One of my printers can function as a fax machine. That does not work well with VOIP and it would be a reason to consider a land line, though there are subscription based services that allow Internet fax. Depending on how often you need to send or receive fax messages that might be a consideration.

In the past, I have had a computer and scanner set up to fax.

Most now will take email attachments, so I can scan and email anything that isn't a electronic document already (Word, Excel, etc).

Of course, if I do get cut at the end of the year as right now seems likely, I may need the fax machine for job hunts too.


Roger

I used to think exploding car batteries were something of a myth till it happened to me. Drove from low elevation of Texas into high elevation of Colorado Springs, parked my truck. Battery must have outgassed overnight a lot in the lower air pressure and probably a bad cell caused a spark in it, but it exploded all over the underside of my hood, my engine, etc when I tried to crank it the next day. We had to quickly hose off the driveway to keep the acid from damaging it. LOL, the autopart place wasn't too happy with the "core" they got when I bought the new one.

I suspect most battery explosions are similar, due to hydrogen gas buildup, same as happened on motherboards with the leaking and exploding ESR type capacitors.

I suspect with caps it was the electrolyte or some waxy dielectric between the foil. I remember seeing the aftermath of some very large oil filled caps that exploded....ones as big as coffee cans in synchronous modem devices we had in our comm center. The injury threat was from the intensely heated oil and not flying debris. Those MB caps seem to be grooved deliberately to provide an weakened area that will split open if pressure builds so as to minimize damage.