magic mouse and batteries

[noledevil]

Got my i7 and Magic Mouse in early November. The keyboard (2 AA's) is still using the original set of batteries. I've replaced the Magic Mouse batteries twice (last exchange about 4 days ago). The Mouse gets about 6-7 hours of use per day. Not bad in my opinion. A rechargable option would be better, but overall I'm pretty happy with my battery life.

 

[Duncan C]

Normal NiMh batteries have pretty fast "self discharge". After 2 or 3 weeks of sitting in a drawer they are nearly dead.

There is a new generation of "low self discharge" batteries like the Sanyo Eneloops that have very long shelf-life. These would be an excellent choice for a device like a magic mouse. I would recommend getting two pairs just for the mouse, and keeping a spare, charged set. You should get very long life from each charge.

If you do go for NiMh batteries, spring for a more expensive "smart" charger with a separate charging circuit for each individual battery. That makes a huge difference in the lifespan of the batteries. Chargers that charge batteries in groups tend to overheat and damage the cells, greatly reducing their life. MaHa makes a range of very good, reasonably priced smart battery chargers.

Duncan
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[gwizard]

Hi Duncan,

please tell me where I can get the batteries or the chargers you speak of, I would like to purchase the items. Thanks

 

[Duncan C]

Hi Duncan,

please tell me where I can get the batteries or the chargers you speak of, I would like to purchase the items. Thanks

gwizard,

The Eneloop batteries are pretty readily available in retail, at least here in the states. You will frequently see them in a retail package that includes a (bad) charger. Avoid that package. It isn't a good deal because the included charger is junk.

There are other brands of low self-discharge batteries. I just don't know any brand names off the top of my head. Other brands should be good too.

There's a company here in the States called Thomas Distributing (link: http://www.thomasdistributing.com/ ) that sells MaHa chargers and lots of different kinds of batteries. I think they sell Eneloop batteries, although I could be wrong about that.

I don't know if you are in the States, nor do I know if Thomas Distributing will ship outside the US.

Some of the MaHa chargers have lots of features and a high price as a result. I got a fairly simple 4 cell charger that includes a wall adapter and a car adapter. (The MH-C401FS.) The more expensive ones have features like a numeric display that show the charge level of the battery, and have a conditioning option which can be helpful in reviving batteries that start to lose capacity. There are also models with a fan, which helps keep batteries cool while charging. (That's a good thing, because heat is actually what damages the cells.)

As I said, the key thing is that the charger have separate charging circuits for every cell. A couple of the low-end MaHa chargers don't have separate charging circuits fore each cell. Just be sure to read the descriptions and pick carefully.

Regards,

Duncan C
--
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[gwizard]

Thanks Duncan,

I live just north of you (MD) and will look at stores in my area.

 

[Marco S Hyman]

Normal NiMh batteries have pretty fast "self discharge". After 2 or 3 weeks of sitting in a drawer they are nearly dead.

Perhaps you meant months ? Or you've got some really bad batteries. Actual NiMH tests show much lower discharge rates. Depending upon how much you use your mouse you may find the eneloops (discharge of 15-30% after one year) are over kill. My mouse uses up a pair of batteries in 2-3 weeks, long before self discharge becomes a significant issue.

On the other hand, if I needed to buy new batteries for the mouse I'd certainly go for the eneloops. I didn't only because I still have a dozen or so 2000 or 2100 mAh batteries that aren't ready for the recycle bin.

 

[nagelestock]

Had the same problem - to do with Apple's Blue-tooth configuration. Apple provided an update last week and one can only hope - too early to confirm any improvement. Crap mouse either way...... use the Wacom instead!

nagelestock.com

 

[jfelbab]

FWIW Amazon has this charger on sale right now for $30. I have a similar La Crosse BC 900 and love it. I also have the MAHA MH-C 204W and while both are nice I find the La Crosse is much more functional.

La Crosse Technology BC-700 Alpha Power Battery Charger

http://www.amazon.com/gp/product/B000RSOV50/ref=s9_simh_gw_p79_t1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0KGTX2WRF2TZ7F1S38CF&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846

--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams

 

[jfelbab]

Normal NiMh batteries have pretty fast "self discharge". After 2 or 3 weeks of sitting in a drawer they are nearly dead.,,

Duncan

FWIW
Typical self discharge rates for common rechargeable cells:
• Lead Acid 4% to 6% / month
• Nickel Cadmium 15% to 20% / month
• Nickel Metal Hydride 30% / month
• Lithium 2% to 3% / month

Not 100% in two to three weeks unless they are defective.

--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams

 

[JEGG]

The batteries I use can be recharged from 500-1000 times before they need to be thrown in the recycle bin.

I share your enthusiasm for NiMH batteries-I routinely use about 40 or more batteries. Mostly AA, some AAA.

However, while it is true that manufacturers say that the batteries can be recharged hundreds of times; the fact is that those statements simply aren't true. More realistic numbers are 50-200 cycles, assuming quality batteries and quality chargers. For most people reading this forum, that still represents a very long period of use!

It depend on what is considered a cycle, and also what one judges as acceptable performance from a battery. In addition to charge/discharge cycles, there are many other factors which determine battery life.

But, yes, NiMH is a very good way to go for most, but not all, applications.

 

[jfelbab]

The batteries I use can be recharged from 500-1000 times before they need to be thrown in the recycle bin.

I share your enthusiasm for NiMH batteries-I routinely use about 40 or more batteries. Mostly AA, some AAA.

However, while it is true that manufacturers say that the batteries can be recharged hundreds of times; the fact is that those statements simply aren't true. More realistic numbers are 50-200 cycles, assuming quality batteries and quality chargers. For most people reading this forum, that still represents a very long period of use!

It depend on what is considered a cycle, and also what one judges as acceptable performance from a battery. In addition to charge/discharge cycles, there are many other factors which determine battery life.

But, yes, NiMH is a very good way to go for most, but not all, applications.

If you are only getting 50 -200 cycles from a quality NiMH cell I'd suggest that you may be doing something very wrong. I've been using this technology since 2004 and have some AA cells with over 700 full cycles that are still performing nearly like new.

BTW, many of the quality AA cells come with a manufacturer warranty that will replace them for free if they fail in under a year. (MaHa POWEREX, Sanyo, Duracell, etc)

--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams

 

[Marco S Hyman]

However, while it is true that manufacturers say that the batteries can be recharged hundreds of times; the fact is that those statements simply aren't true.

Are you using a fast charge or a normal charge? I notice that photographers especially those shooting with flash, want to charge their batteries in 10 minutes. You can do that... but don't expect the batteries to last very long. It also wouldn't surprise me to find that high discharge rates will also lower battery life.

I'll stick my mouse batteries in the charger at a 200 mA charge rate and leave them there until fully charge, typically over night.

I've not yet had an NiMH battery go bad... but I've recycled a few because I can do a lot better than 1200 mAh AA batteries these days.

 

[JEGG]

If you are only getting 50 -200 cycles from a quality NiMH cell I'd suggest that you may be doing something very wrong. I've been using this technology since 2004 and have some AA cells with over 700 full cycles that are still performing nearly like new.

OK, I'll bite. What are the batteries rated capacity, what is their actual capacity, and are you measuring capacity according to industry standards (a rather long process)? What is the voltage curve over the discharge cycle?

 

[JEGG]

Are you using a fast charge or a normal charge?

Neither. Normally I enter the charge rate I desire. It's rarely over 0.5 C.

I notice that photographers especially those shooting with flash, want to charge their batteries in 10 minutes. You can do that... but don't expect the batteries to last very long.

No, you can't do that if you want fully charged batteries. Also, I know of no charger that will deliver a 6.0C charge rate, except chargers not meant for consumer use-and then using a 6.0C rate would be a blunder. Do you know of such a 6.0C charger?

It also wouldn't surprise me to find that high discharge rates will also lower battery life.

You wouldn't have to rely on guesses or surprises if you read relevant technical documents. Both relatively rapid charge/discharge and relatively slow charge/discharge can both create and solve various sorts of problems. Generally, a continuous discharge of more than 0.4C should be avoided.

I'll stick my mouse batteries in the charger at a 200 mA charge rate and leave them there until fully charge, typically over night.

Depending on the capacity of your batteries, this may be on the slow side for maximum battery performance. Generally, batteries should not be charged

I've not yet had an NiMH battery go bad... but I've recycled a few because I can do a lot better than 1200 mAh AA batteries these days.

I've seen many batteries fail. All batteries will degrade/fail.

 

[JEGG]

Normal NiMh batteries have pretty fast "self discharge". After 2 or 3 weeks of sitting in a drawer they are nearly dead.,,

Duncan

FWIW
Typical self discharge rates for common rechargeable cells:

• Nickel Metal Hydride 30% / month

Not 100% in two to three weeks unless they are defective.

The questions and answers are more complex. And it depends even on the method of testing. And it depends on what one considers fully discharged.

Battery discharge and self discharge follow a curve that is unique to each battery model. It is not a straight diagonal line!

So, simply measuring to see when a battery reaches what anyone arbitrarily considers full discharge doesn't really give you an idea of the capacity of the battery, say 30 days out from being "fully charged."

You'd have to measure a given battery daily over a period of a year to draw such a curve. Of course, to do this with a single battery is, by definition, not possible. So you can group a very large set of batteries which seem to have similar performance, and then do the measuring.

As batteries are discharged, charged, and aged, the curves change. And the changes are determined by the rate and pattern of all of those variables, and according to many more variables, such as temperature.

You are correct in saying that good "traditional" NiMH batteries used with a good charger have a self discharge rate way below 3% day.

In the first couple of days, rate of discharge will be quite high, than the capacity curve becomes much more gentle, followed by a couple shoulders and drops.

 

[JEGG]

What is the voltage curve over the discharge cycle?

should read

What is the voltage and capacity curve over the IEC charge/discharge/charge/discharge cycle?

 

[JEGG]

Since I've already written at length......

Among the more important criteria not already mentioned is battery impedance, or resistance. This effects how much power can be delivered when needed.

As batteries age, impedance values rise. But impedance values also rise as the battery goes through a discharge cycle.

So, for example, if you're using NiMH in a flash unit, and the unit begins to take a little longer to recycle, the battery, by definition, still has all the power required, but it cannot deliver it as rapidly. Sometimes (of often), batteries will start to warm.

Batteries have different impedance values according to model, so even when new this is a significant variable in comparing batteries.

The impedance affects charging performance as well, as more of the charging current is dissipated by heat rather than being retained by the battery.

A telltale sign of raised impedance values (related to crystal formation-another topic), is that battery voltage will rise during discharge, but the battery will not deliver much current.

The point of all of this is to say that it is very difficult to cite "typical performance," and to speak in generalities, as there are simply too many variables in battery type, usage, and charging.

 

[Marco S Hyman]

I notice that photographers especially those shooting with flash, want to charge their batteries in 10 minutes. You can do that... but don't expect the batteries to last very long.

No, you can't do that if you want fully charged batteries. Also, I know of no charger that will deliver a 6.0C charge rate, except chargers not meant for consumer use-and then using a 6.0C rate would be a blunder. Do you know of such a 6.0C charger?

It's called hyperbole. I said that some want to charge in 10 minutes.

Perhaps they are the folks who buy the Rayovac 15-minute charger and batteries. I've not tried either and have no knowledge of the products charging or operating characteristics. The batteries claim to be 2000 NiMH that can be charged in the special charger in 15 minutes.

This has gone way off topic.... I'll continue to use NiMH in my mouse and won't worry too much if I only get 100 charge cycles instead of 1000. That's still longer than I'll likely own the mouse.

 

[jfelbab]

I agree that this has gone way off topic but for JEDD and others interested, I think this is a good primer on battery performance.

http://www.mpoweruk.com/performance.htm

--
Jim
'There are no rules for good photographs, there are only good photographs.'

• • Ansel Adams