Two shorter-life battery, one longer-life battery, which better?

Suppose an m-cell battery lasts x hours, and an n-cell battery lasts 2x hours. Is it better to use 2 m-cell batteries, one after the other, or to use 1 n-cell battery--considering the what's good for the battery life, battery lifespan, and the laptop?

(I don't know the answer to the above, but one thing is pretty clear: two m-cell batteries are likely to weigh more than one n-cell battery.)

 

If you want to carry an extra battery around go for it =)

 

its quite obvious, the n-cell is better in terms of cost and charges faster than 2 m-cells individually.

i know this as i have a 9cell and a 4 cell x200

 

Depends on how you are evaluating 'better'. Two will take up more space, but probably not be much heavier. Most the weight is in the cells themselves and if 'n' lasts twice as long than 'm', it most likely has twice the cells.

One thing to keep in mind is that if you are using 2 smaller batteries, you'll probably develop less memory on one of them since you'll be mostly charging the discharging one battery while the other is only used when necessary. Another perk is that you're hauling the extra weight only when you need it, though conversely, you'll always have the extra battery life if you need it with the 'n' cell.

 

If you are going to have two seperate batteries, I would actually suggest they be of different sizes.

For example, if you were considering an x200s, get a 4 cell and a 9 cell. On days when you would expect to have AC readily available, take the 4 cell and AC adapter. Conversely, when you can't count on AC, take the 9 cell w/o AC adapter (should provide 3x the battery life, and comparable weight). For long trips (e.g. trans-Atlantic flights) you should take both.

If you only buy one battery, just get the one that provides enough battery for your needs (figure this at 80% as batteries will degrade over time), and you are still willing to carry. In terms of battery health, a larger battery is a better choice. You can leave it half charged most days (far better on the battery), and still get superior life to the smaller option.

 

Thanks a bunch! Yeah it didn't occur to me that with large battery I could just keep it half charged all the time.

 

Weight and battery wear come into play. As jon said get 2 batteries with different sizes. I have a 9cell and a 6cell for the x200. That makes it 3.24lbs and 3.6ish. The 4cell is really low capacity...but if you want the laptop under 3lbs go for it.

 

OK, I got another question:

If you could have two batteries for your laptop for free (i.e. without regard to prices), would you prefer, say, a 4 cell and a 9 cell, or both 9 cells-- assuming the 4 cell only lasts very short time, like max 2 hrs? The only point to have both 9 cells is to use the other when the first is dead (you hardly need to carry two 9 cells at the same time). The point to have a 4 cell and a 9 cell is to use them according to the circumstance, but a 4 cell lasting 2 hrs or less is hardly worth anything, in my opinion--why would you carry your laptop out only to use for no more than 2 hours?

 

I would get the 4 and 9 cell for most circumstances (again price not a factor). That way, you can use the 4 cell only for short bursts, the 4 cell and AC adapter for events where you can count on AC, and the 9 cell when you can't count on AC.

The only occassion where I would consider two 9 cells (on a device as efficient as the x200) would be if I frequently made long International flights (e.g. Hong Kong to New York with a mid air refueling) and had no access to any form of recharger. Otherwise, it would be very hard to run through two 9 cells (we're talking 5-10 hours per battery depending on usage [video playback uses more watts than typing]) in any reasonable period.

 

Well, in that case it comes down to how much weight bothers you. Personally, I would take 2 9-cells for the X200, although if given the same choice for the T500 I would opt for one 6-cell and one 9-cell.

 

yea i'd do the 4 and 9 cell. as for reasons stated above as it really depends on your usage but i can't see a reason why you would HAVE to get 2 9 cell batteries. i mean a 4 and 9 cell would last you 10-12 hours.

 

I'd go for a big and a small one.
My audio recorder, which happens to use the M-series' bigger brother's batteries (the L-series) (camcorder batteries, that is), I have a couple of big batteries and a single small 2-cell one. I only use one big battery most of the time, and I carry the smaller one as a "back-up" to be able to record three more hours, should the big one run out or just die for some odd reason. This allows me to carry as little weight as possible on any given day, yet allowing me to do whatever I please, no matter how long the day runs on.

Granted, a portable recorder is a little different than a computer, because when you're actually working on it, you don't want to be plugged in.

For computers, I prefer the same sort of set up, even if the usage is different. With the new computer on the way (X200s), which happens to have a 9-cell (it's a prebuilt, I think), I will be purchasing a 6-cell as well. The only reason I won't be buying the 4-cell is a matter of economics (mine, that is), and because the 4-cell only have half the wattage of the 6-cell.

In general – like Jon said – I don't see the purpose of having two huge batteries , unless you really have a specific need for that amperage. It's just too much weight and bulk for no good reason, considering the battery life the X200/s gets (supposedly, I might add, since mine's still not here).

 

Thanks for the comments! Originally I was thinking, since batteries die after a few years (3 years?), it makes some sense to have two 9 cells. But in view of what most of you are saying, and also according to some, batteries die even if you don't use them (though die more slowly?), the spare 9 cell will not have full charge when the first one dies anyway, it seems a small and a large ones have more advantages.

 

This is a valid point.

I have an 8 cell for my x200 Tablet. In a year or two I expect that my 8 cell will only hold about 60% of the charge that it does today (it's still at design capacity after 40 cycles).

At that time, I will buy a new 8 cell. However, I will not carry both batteries with me on a regular basis. I will simply use the new one all the time, and leave the old one in storage at about 40%. Before a long flight, or similar excursion, I would charge up the old one as a backup.

This is the policy I used for my T40 (I used three 6 cells, each purchased about 2 years apart). However, if you are buying all of them at once, it makes sense to diversify the battery type so you can pick the battery that is most appropriate for a given day.