Breaking down Dell’s 19-hour battery life claims


E4200_5f00_2_2Hp_2710p_thumbKevin and I attended Dell’s online press event today where they unveiled 10 new Latitude notebooks including the one that caught our eye, the 12-inch e4200 ultra-portable.  Dell had a recurring theme during the press event with their claims of extended battery life, in fact they kept mentioning a 19-hour possible battery life.  They explained that this extended battery life was possible due to the use of a 9-cell primary battery along with a slice battery.  Since I have been using the HP 2710p for over a year with a similar setup I wanted to take a look at Dell’s claim for high battery life and see how I think that will work out in the real world.

First up I went to Dell’s web site and went through the informationthey provide for the e4200.  This is the only notebook they announcedtoday that uses the Ultra-Low Voltage (ULV) processor which willprovide the best battery life, far better than the standard Core 2 Duoin the other models.  Surprisingly I found that the e4200 is onlyavailable with either a 4-cell or 6-cell primary battery.  I comparethis to the HP 2710p which has a 6-cell battery, the same size screenand roughly the same size and weight.  In fact if you compare thetechnical specifications for the two notebooks they are surprisinglysimilar even though the 2710p has been out for quite some time.  Notetoo that the HP is a Tablet PC with a swivel screen which adds roughlyhalf a pound in weight and should use a tad more battery as a result.The 2710p with the 6-cell battery provides about 5.5 hours of life on asingle charge and I expect the Dell e4200 will provide about the samesince the components are roughly the same.

Dell’s claims of 19 hour battery life will not then apply to the e4200with only a maximum 6-cell battery.  In fact the cheapest configurationof the e4200 is a 4-cell battery which I wouldn’t expect to last forover 4 hours.  A 5.5 hour life with the 6-cell is decent enough solet’s use that in the rest of our analysis.  Dell says to pair thatinternal battery with a slice battery to get up to 16 hours of life onthe e4200.  Search though I did I can’t yet see an option for a slicebattery for the e4200 but that’s probably because it’s not availableyet.  I use a similar slice battery for the 2710p which adds anotherthin 6-cell battery that clips on the bottom of the notebook.  Togetherwith the internal battery that totals 12 cells of battery and I getabout 11 hours total which is darn good.  The beauty of the HP slicebattery is how thin and light (1.24 lbs.) it is so even if Dell goeswith a higher capacity (and thicker) battery it won’t be bigger than 8cells in my opnion.  Since battery life is directly related to how manycells the battery contains I’d estimate about 7.5 hours of battery lifeon an 8 cell.  Note that the 8-cell battery would likely weigh near 2lbs. making it as heavy as the e4200.

Based on my calculations the Dell e4200 with a total of 14 cells ofbattery would likely last about 13 hours, a decent battery life to besure but a far cry from the 16 hours that Dell is claiming.  Now it’spossible that Dell is looking at bigger batteries, maybe an extendedprimary battery that sticks out of the e4200 and a bigger slicebattery.  Both of those options will be bulky and heavy andthus defeat what the thin and light e4200 brings to the table.  I wouldestimate that 16 hours of battery life would require a good 3.5 lbs ofbatteries pushing the weight of that svelte e4200 up to over 5 pounds.That’s not a bad sacrifice for such high battery life but it’simportant for those who are interested to realize that in spite of howDell glossed over that fact there is still a stiff weight penalty forhigh battery life.  Dell hasn’t invented some new battery technologyhere, they are simply attaching much bigger batteries to the newLatitudes.  One thing that has surprised me from this analysis is howadvanced the technology is behind the HP 2710p compared to this brandnew Dell.  It’s almost the same computer with the addition of theTablet bits.



Came across this while searching for something else. The article says:
“Breaking down Dell’s 19-hour battery life claims”
This seems to be a theoretical calculation of the matter! And please,PLEASE Mr. Kendrick, This article does’nt make no sense. Please do this again, but please place the two computers beside each other and unplug the power source at the same time and see how long time it goes until they shut down. That’s what I call a test! We can all do meaningless calculations.


This entire article is an epic failure. Stating that the HP 2710p and the new E-series Dell is the same technology is just flat out wrong. I didn’t even read on after than since all credibility was lost at that point.


There are more than the number of cells in battery to save the battery life, though that’s the biggest contributer. Power Management is one of the variables, Audio low power, Windows theme and by controlling power consumption of some of the devices power can be saved while notebook is in DC mode. Therefore, please do not come to conclusion before actually testing it. Even without using a slice, you can compare the HP and Dell battery life using the Dell software enabling all day battery mode. Please try that.

My request is please don’t be biased because you are using a HP notebook. A lot of effort was put on this feature (in fact for any commercial product) and a fair comparison is what it takes before getting prejudiced in public forum.


This extra battery life does come at a cost; the widley popular spontaneous combustion feature available in earlier models has been dropped.


Is your review really a review, or a imagination indeed?
First, Dell claims 19h battery life on E6400, not E4200. You are already totally off-topic at the very beginning.
Second, Dell battery slice is 12 cell, not your imagined 8 cell.
And then the rest is worthless to read on.

James Kendrick

Bruce, thanks for jumping in here, it’s appreciated. I look forward to seeing how big those batteries are to give 19 hours. As I stated I’m pretty sure they are very big and quite heavy, a willing trade-off to many I’m sure.

Bruce Eric Anderson (aka bruceericatdell on twitter)

James: glad to hear you were able to attend (virtually) today’s news conference. While a majority of this post relates to the E4200, I would like to clarify which system and battery configuration resulted in the 19-hour battery life. I chatted with one of our engineering execs who told me that it is the E6400 configured with with the battery slice (~9 hours) and 9-cell battery (~10 hours) that gives you the 19-hour life. These figures were obtained using standard PC mode running MS Windows — measured through standard industry benchmarks (Mobile Mark 07). There’s been a lot of chatter on the 19-hour battery life and the Latitude On feature so we plan to do a post in the coming days on clarifying what we announced. Hope this helps.



yep i believe i heard the Acer was coming with a 6-cell 5200mah, which is ok but not great. it should be able to get about 5 hours real world.

but some of the EEE 901’s are coming with batteries as big as 6 cell 6600mah & many of the users are reporting near 7 hour runtimes.

so its not so much about cells as it is the capacity of each cell.


“Since battery life is directly related to how many cells the battery contains”

thats not true at all, you can have 2 machines with 6-cell batteries but both have wildly different capacities.

Sean Brady

I did ask about this in Twitter during today’s event. They stated ” Digital_Nomads: @seanabrady all day power mode 19hours single click option that sets various peripherals to lower power state includes screens drives modem “
I still have to wonder if they are not talking about getting 19 hours when using the non-windows OS they talked about. Although they did refer to that as multi-day.


Didn’t Dell say the 19-hour life was with the E6400, not the E4200? You’d need at least a nine-cell battery to have a hope of meeting those claims. The E4200 is more all about its size and weight than endurance.

Either way, if you really can get a 14-inch notebook that will run all day even with stressful conditions, that’s good for me.

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