Batteries and how we should use them.

blaze_zero

So, people who have more knowledge than I do, tell me how to use batteries.


Or more specifically, rechargeable batteries. Like for your laptop, phone, DS, PSP, ect.

Should I let the charge go all the way down before recharging it? Or should I recharge it when it gets to be about half full? Is there any difference? Also, should I be keeping a watchful eye on the charging and remove them as soon as they reach 100%?

The only thing I know is that it should not be charging constantly. I've heard various things from various people, but none from those who I think know what they are talking about.

Barrakketh

blaze_zero wrote: »

So, people who have more knowledge than I do, tell me how to use batteries.


Or more specifically, rechargeable batteries. Like for your laptop, phone, DS, PSP, ect.

Should I let the charge go all the way down before recharging it? Or should I recharge it when it gets to be about half full? Is there any difference? Also, should I be keeping a watchful eye on the charging and remove them as soon as they reach 100%?

The only thing I know is that it should not be charging constantly. I've heard various things from various people, but none from those who I think know what they are talking about.

Never leave them charging constantly. NiMH batteries can overheat and vent gas (those 15 minute chargers you see for AA batteries practically always make them do this), and you do bad things to the chemicals inside the batteries (namely making them form large crystals which isn't a good thing for their capacity).

If you continually charge lithium ion batteries you throw off their internal fuel gauge, which results in devices thinking the battery is close to dead when it has plenty of juice available.

Ultimately you should be charging them according to your usage. If you're not playing your DS a lot there's no reason to keep it topped up, especially if you're playing it at home where a charger is available. If you're a heavy smartphone user you'll probably have to charge it every day unless you have a spare battery since their battery life isn't fantastic.

It's generally not necessary to remove them from the charger immediately. More intelligent chargers will either stop charging or switch to a trickle charge. I'd keep an eye on any "fast charger" variants, though.

ArcSyn

The only thing that I'm aware of that modern batteries have a problem with is that they still have a limited number of charges. So if you're constantly plugging it in after using 5% of the battery, you may be limiting your lifespan of the battery. Though considering a lot of batteries have thousands of charges, you can plug it in each day and it'll last years. Every battery will degrade though.

Letting them drop to 0% is probably not a good idea, but 10% or so is probably fine. Most devices that have internal rechargeable batteries will automatically cut off the charge or trickle charge when it's full, so leaving them plugged in (like your laptop) shouldn't have any effect on the battery as it will simply draw power from the plug.

At this point in technology, you don't really have to think about it. Just as Barrakketh said, just charge them as it fits in how you use them. I charge my cell phone every night just to keep it topped off in the off-chance I forget to charge it some day or don't get a chance to. I charge my laptop through the day at work (it's in a dock) and then use the battery almost entirely while at home in the evening, plugging it in only if I need some extra time before I shut down for the night and go to sleep. My DS hasn't been plugged in for a while, but that's because I haven't played it in a while. The battery is probably at some percentage, as it was full the last time I used it, but I don't bother keeping it plugged in at night or anything. I'll just have to make sure to charge it when I go to use it next.

Paladin

The most important thing to worry about is heat. Heat kills batteries.


Taking out the battery if you leave the device plugged in for long periods of time is a good idea just because normal operation produces heat, which kills the battery. Charging produces heat, which kills the battery. Discharging produces heat, which kills the battery. Typing in your ejournal in the park on a hot summer's day kills the battery, and also you might get ice cream on the keyboard and short something.


Don't discharge all the way, or really even close. 10% charge is actually 10% average charge, which means some cells can be 5% or 15%, and some cells will be 0%. If a cell ever hits 0%, it's dead forever.


If you're going to store the computer for long periods of time, discharge it to about half capacity and leave it like that. I forget the rationale, but I know I'm right.


Sometimes, your computer will forget how much charge it has. Recalibrate by discharging most of the battery, then recharge it. Really only do this every month at most.


Buy a new battery after a year or two. Don't ever buy a used battery or even a mint condition old battery. Batteries degrade over time whether or not they've been unpacked from the retailer.

blaze_zero

Ok, thanks guys. I've already been doing most of what you said, but I wanted to make sure I wasn't destroying my batteries early or anything.

Mostly just came up as a thought when my wireless mouse batteries died and was recharging them.

Arrath

So, whats a good brand of rechargeable batteries? I'm (and my roommates are) getting tired of my mouse batteries dying at the worst moment and having to poach spares from the TV remote.

blaze_zero

I'll check exactly what type they are when I get home, but I have these green Duracell ones that came with their own charger.

I've been using them for over a year and I only have to charge them once every two-three months or so.

Barrakketh

I like Eneloops. They're a bit more expensive than other hybrid batteries, but they've worked well and have never given me any trouble.

I hear the Rayovac Hybrids are also pretty good if you want a cheaper solution.

Mugsley

This is why I've moved back to wired mice.

Bamelin

What about netbooks?

My netbook runs at a faster clock speed when plugged into the wall ... but this also charges the battery. I almost always have it plugged in, hope I'm not killing the long term battery life.

Paladin

Operation generates more heat than idle. Charging generates more heat than not charging. Heat kills batteries.

Generally, a person who heats their battery every so often will only get an increased rate of deterioration noticeable at near the end of the battery's life. If you're willing to buy a new battery every year or so it will not really be a problem.

But if you can afford to charge and use your device at separate times then yeah, I recommend it.

electricitylikesme

I think you're way overstating the effect of temperature on battery internal chemistry.

Generally speaking, batteries will work more efficiently at higher temperatures (have more capacity) because you improve ion mobility. This is offset by the consequent rise in internal resistance though - the ideal temperatures for battery operation are basically the same as those human beings like (remember, we're big bags of electrolytes as well!).

Depending on the battery chemistry you are dealing with, their are various modes of failure: Lead Acid for example generally die from sulphate crystal build up on the electrodes, but there's a secondary failure mode from the lead deposition resulting stalicite type growths bridging the cathode and anode (dropping the battery can snap these off and restore function in some instances).

Nickel-Metal Hydride have their own range of quirks. The worst thing that can happen is overcharging the cells because you cause hydrogen gas build up, which in turn pressurizes them. Most have a vent to prevent this, but obviously it is problematic to be electrolyzing water out of the cell. Heating is mostly problematic because you increase gas pressures - it won't directly harm the cell at any reasonable range.

Polarity reversal is likely to be your biggest problem with rechargeable batteries around the house - if you have a few in series, like in a mouse, then if one discharges before the others, it gets driven in reverse by the other batteries which does cause permanent damage. This is exacerbated by low temperatures - since the weakest cell's capacity can be reduced to zero, and it'll be polarity reversed sooner.

"Heat kills batteries" is kind of useless advice really. Look up the type of battery you are dealing with, and you'll be able to take reasonable precautions.

ArcSyn

Arrath wrote: »

So, whats a good brand of rechargeable batteries? I'm (and my roommates are) getting tired of my mouse batteries dying at the worst moment and having to poach spares from the TV remote.

I've got Eneloops and Energizer and they both work wonderfully. I use the Eneloops in my camera flash (as they are supposed to hold the charge longer) and the Energizers in my Wii remotes and 360 controllers.

Paladin

electricitylikesme wrote: »

I think you're way overstating the effect of temperature on battery internal chemistry.

Generally speaking, batteries will work more efficiently at higher temperatures (have more capacity) because you improve ion mobility. This is offset by the consequent rise in internal resistance though - the ideal temperatures for battery operation are basically the same as those human beings like (remember, we're big bags of electrolytes as well!).

Depending on the battery chemistry you are dealing with, their are various modes of failure: Lead Acid for example generally die from sulphate crystal build up on the electrodes, but there's a secondary failure mode from the lead deposition resulting stalicite type growths bridging the cathode and anode (dropping the battery can snap these off and restore function in some instances).

Nickel-Metal Hydride have their own range of quirks. The worst thing that can happen is overcharging the cells because you cause hydrogen gas build up, which in turn pressurizes them. Most have a vent to prevent this, but obviously it is problematic to be electrolyzing water out of the cell. Heating is mostly problematic because you increase gas pressures - it won't directly harm the cell at any reasonable range.

Polarity reversal is likely to be your biggest problem with rechargeable batteries around the house - if you have a few in series, like in a mouse, then if one discharges before the others, it gets driven in reverse by the other batteries which does cause permanent damage. This is exacerbated by low temperatures - since the weakest cell's capacity can be reduced to zero, and it'll be polarity reversed sooner.

"Heat kills batteries" is kind of useless advice really. Look up the type of battery you are dealing with, and you'll be able to take reasonable precautions.

Laptops in general only use one type of battery nowadays. If I had a nimh battery I wouldn't know what to do with it

electricitylikesme

The original post is talking about rechargeable batteries, mentioning mice and scrounging from the remote. Those sorts of things run on NiMH cells.

And like I said, you're way overstating the effect of heat. Heat doesn't directly effect anything at the temperatures you're likely to reach in normal operation of a battery.

Paladin

electricitylikesme wrote: »

The original post is talking about rechargeable batteries, mentioning mice and scrounging from the remote. Those sorts of things run on NiMH cells.

And like I said, you're way overstating the effect of heat. Heat doesn't directly effect anything at the temperatures you're likely to reach in normal operation of a battery.

In the long term, it's been shown to reduce total battery life. If you want to stretch a battery's total charges as far as you can, then heat is a good simple control factor.

Barrakketh

electricitylikesme wrote: »

"Heat kills batteries" is kind of useless advice really.

Heat also increases NiMH cell self-discharge rate. Don't leave them in the car or a warm area of your home (more of an issue if you only have window units for cooling), ideally keep them stored in a location with a temp of less than 70 degrees.

Also, fast chargers. The internal resistance of NiMH cells rise as they are charged, so heat and internal pressure will rise fairly quickly:



Then there are chargers they don't have a per-battery circuit, because if you have two batteries with different capacities it'll overcharge one of them and only look for the combined voltage.

Gihgehls

I'll just quote myself again again.

Gihgehls wrote: »

I'll just quote myself again on this one.

Gihgehls wrote: »

Lithium ion packs are limited to a (estimated) number of charge/discharge cycles. This number goes up as stress on the pack decreases. You will get far more life out of your lithium ion batteries if you just leave them on the damn charger, as charging from near zero is more stressful for the battery than charging up from 80%. The only possible downside of constantly charging a lithium ion battery is that the smart guage will slowly lose calibration. But that is only a meter, it isn't the actual capacity of your battery that is changing.

Also, lithium ion batteries cannot be taken down to 0% without permenant damage to the pack. This is why it is dangerous to let most lithium ion devices discharge too much. Eventually that little clock we all have in just about all devices will ruin the battery, and it will never hold as much power as it used to. (side note: if your Li-ion device shows no battery remaining, it is still probably hiding 5 or 10 percent from you, for its own safety.)

For what it is worth, lithium ion batteries also have a "shelf-life" which is usually a few years from their date of manufacture. Eventually they will just wear out, even if you don't use them, which is why it is also a good idea not to stress out too much about the number of charge/discharge cycles you have left, because the pack is going to die anyway no matter how much you baby it.

Most battery packs are made of seperate cells (think of those battery packs that look like a bunch of AA batteries strapped together.) The reason they tell you to charge it so long is to ensure that all the cells are balanced. Heat, age, and manufacturing variances affect the internal resistance of a cell, and the internal resistance affects how quickly current is drained from it. In a severely unbalanced pack, many of the cells might be doing no work at all and will drastically affect the appearent capacity of the battery.

tl;dr: Keep that shit plugged in as often as you can for the best possible performance from your battery.