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700m battery 65whr vs 71whr - Page 2

post #21 of 40
4/27/05 at 5:18am
Quote:
Originally Posted by funkmasterta
i think that's what mine says too and i have the 71whr battery. if your pack is new don't worry about it. new packs don't operate at peak capacity till after 4-5 full drain/recharge cycles.
When you say full drain/recharge cycles, should i actually let it drain all the way? Or, to what percentage then?
Thanks.
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post #22 of 40
4/27/05 at 5:26am
You're not supposed to let Lithium-Ion batters discharge fully if you can avoid it. In fact, with Li-Ion batteries you're supposed to keep them as close to full charge as often as you can manage it. They last longer if you do a lot of shallow recharge cycles as opposed to a few complete discharges.
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post #23 of 40
4/27/05 at 1:27pm
the battery folks say you should only let the battery discharge down to 40% and then recharge. then they tell you that you should fully discharge the battery at least once per month. pretty silly stuff

the battery should operate fully after one full discharge, so don't know where you get 4-5 drain cycles thing
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post #24 of 40
4/27/05 at 3:35pm
Quote:
Originally Posted by funkmasterta
the 71Whr uses 8x2400mah cells, while the 65Whr uses 8x2200mah cells.

i got the 71 too! i guess Dell finally listened to all those bad battery life reviews and complaints.
the 65Whr is 4400mAh
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post #25 of 40
5/13/05 at 6:11pm
Quote:
I think before we start celebrating that our batteries are rated for 71Whr instead of 65Whr we should try to see if there is any quantifiable battery life difference.
Yeah - IS there a difference?

Mine came in the mail a couple weeks ago... I got the 71 whr
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post #26 of 40
5/13/05 at 7:19pm
I'd like to know this as well. Mine is the 71Whr and it still says 4 hours 57 minutes left on a full charge.
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post #27 of 40
5/13/05 at 8:03pm
i got one too finally...no appreciable difference to note after testing three 65whr and one 71whr for the past week.
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post #28 of 40
5/13/05 at 8:10pm
Quote:
Mine is the 71Whr and it still says 4 hours 57 minutes left on a full charge.
Mine says the same
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post #29 of 40
5/14/05 at 12:15am
Mine is 71Whr and I routinely get well over 5 hours on my running the WiFi and screen at about mid-brightness. I just watched 2 DVD movies on a plane flight including Ray (Ray Charles movie) at about 3 hours and I still had juice left.

I do have 1.25GB RAM but the slow 60GB 4200 rpm HD. The RAM will consume more power but the HD seems pretty efficient. I have tried using SpeedstepXP which seems to work pretty well for me too.
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post #30 of 40
5/14/05 at 3:39am
71Whr...display sez 5 hrs @ 100% charge.

Yesterday I ripped about a dozen CDs off battery be4 getting my first power warning.

BTW, can we get links for the manufacturer's advice from the battery folks?

ETA will try the "double DVD test" this week and report back.
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post #31 of 40
5/19/05 at 5:21pm

8 cell 71Whr Battery Test Result 1

Starting at full battery power, I played DVDs for just over 3hrs 20 minutes before my notebook gave up and went into hibernation with 10% left.

Note: I was also running the WiFi card with radio just to produce a good "stress test." I realize that most people probably don't surf the web while watching DVDs on battery power, and I do want a true "airplane test." Therefore I may do another with just DVDs to see if there's an appreciable difference in the cycle.

Yeah, I got some free time these days.
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post #32 of 40
5/19/05 at 5:29pm
that's about what i got with all the batteries. if you are testing for airplane, you may want to copy the dvd's onto hd to conserve batteries. disable the wireless not from the icon in systray but in network connections as well as disable the other network devices in there as well.
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post #33 of 40
5/19/05 at 5:36pm
From a chemical standpoint, there is no way to correctly deduce how much longer the battery will continue to operate.

Voltage only decreases slightly, current remains the same, and the calculation for percent remaining is measured by voltage. With discrepencies in voltage values as low as they are, never trust what Windows XP, Dell or anyone tells you, just try it out for yourself.

The equation, if you want to figure out for yourself, is the Neurnst equation, Ecell = Ecell* - (R*T*lnQ)/(nF) where R is universal gas constant, T is temperature (Kelvin), F is Faraday's Constant, n is number of moles of electrons transferred in the base equation, and Q is the relative concentrations of products.

Voltage varies in Li-on batteries by so little, it's practically impossible to tell.
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post #34 of 40
5/19/05 at 6:08pm
that's why i use http://www.time.gov/timezone.cgi?Central/d/-6/java
to time when i power up to when the computer shuts down
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post #35 of 40
5/20/05 at 6:11am
Thanks for the above. I may try this, but ...will disabling the network devices stop all power from flowing to them?

Now I'm really splitting hairs...
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post #36 of 40
6/23/05 at 4:30pm
Anyone got a good source for the 8-cell battery? I've been on EBay and Froogle, etc., and it looks like you get the best deals on EBay, with the price around $90 to $95, including delivery, tax, and insurance. Any suggestions on where to look for a better price for new, Dell-branded 8 cell for 700m?
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post #37 of 40
5/15/06 at 11:27am
Time to bring a thread back from the dead.

So did anyone ever actually test and compare the 65WH to the 71WH batteries?

I'd assume IF there were a difference in batt time it would be minimal.
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post #38 of 40
5/15/06 at 6:28pm
I thought the battery was lithium ion..? The 2400mah cells should give slightly better battery life. So I guess the cells are just standard AA batteries. Somtimes all those laptop battery case use are AA batteries. Rechargeable AA batteries are now up to 2900mah. So that should be a noticeable boost. I always wondered if I could make my won laptop battery by using AA batts. I will have to check mine this evening. I bought my 700m last year.

Quote:
Originally Posted by funkmasterta
the 71Whr uses 8x2400mah cells, while the 65Whr uses 8x2200mah cells.

i got the 71 too! i guess Dell finally listened to all those bad battery life reviews and complaints.
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post #39 of 40
5/15/06 at 6:43pm
I doubt you are getting 5 hours with wifi on. You can't go by what the battery meter tells you. You have to time it yourself. Normally I get about 5 hours with wifi off, about 4 hours with wifi on. To get the best battery life when watching movies, you should rip the movies to the HD. DVD uses up alot of just since the movie is cached on the HD as the DVD spins.

Quote:
Originally Posted by wavshrdr
Mine is 71Whr and I routinely get well over 5 hours on my running the WiFi and screen at about mid-brightness. I just watched 2 DVD movies on a plane flight including Ray (Ray Charles movie) at about 3 hours and I still had juice left.

I do have 1.25GB RAM but the slow 60GB 4200 rpm HD. The RAM will consume more power but the HD seems pretty efficient. I have tried using SpeedstepXP which seems to work pretty well for me too.
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post #40 of 40
5/15/06 at 11:00pm
I noticed the same type of thing with my 8600, and the comparable D800. The D800 had a slightly larger capacity battery, but both batteries work in either laptop. My guess is they just stopped making the 65whr ones and started using batteries that are used on the latitudes
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