Comments on: External laptop battery pack

By: external laptop battery

external laptop battery — Sat, 15 Sep 2007 04:35:30 +0000

http://www.sales-battery.com/External_laptop_battery.html

By: external laptop battery

external laptop battery — Sat, 01 Sep 2007 07:22:14 +0000

20000mah high capacity external laptop battery,so nice so useful in http://www.all-battery.co.uk/external-laptop-battery.html

By: John Smith

John Smith — Mon, 27 Aug 2007 15:43:06 +0000

Wonder what the weight of it was. That many D-Cells can’t be light. Still I like the idea though.

By: lory

lory — Wed, 01 Aug 2007 04:04:40 +0000

i just wonder what the running time about it was and i suppose that it will cost much.

By: andrew

andrew — Wed, 25 Jul 2007 05:56:24 +0000

all right, yea i think we’re pretty much done here. i’m not trying to start anything, but i thought i might add that right now i’m running an old 166MHz pentium tablet pc that’s rated for 16V at 2.5A on a regular ol 12V wall wart. the wall wart is rated for 1A max, and it isn’t even warm. it’s been like that for an hour. that’s 12 watts or *less* !! even i was shocked :)

so, basically what i’m saying is that, from experience, the ratings on laptops are usually quite conservative. often you can get by giving them less voltage, and they’ll usually pull a lot less current than they’re rated for, too.

By: Blind Tree Frog

Blind Tree Frog — Mon, 23 Jul 2007 05:31:29 +0000

I would like to apologise. I was blind and did not see the second page of comments and did not realise that this issue was resolved as it currently is.

On top of that, it may have been snarkier then it should have been.

By: Blind Tree Frog

Blind Tree Frog — Sun, 22 Jul 2007 22:57:36 +0000

I have to say that it is unbelievable that a bunch of people on the interweb are telling someone else that he couldn’t possibly have done what he claims to have done.

Like he really has anything to gain from lying to people online.

By: silvershovler

silvershovler — Sun, 22 Jul 2007 18:19:27 +0000

i thought the idea was to use less power to due the same work load. low power use. back light switched to led. hard drive to cf or solid state. low power usage via’s might be a way. make it cheap and robust.

By: Hebby

Hebby — Sun, 22 Jul 2007 09:28:51 +0000

lol, this isnt about adding up amperages, as you cant add 5v amps and 12v amps and expect that to be a total, all depends on the internal power converters, switch mode psus as used in pcs and laptops, will pull close to a ratio of power depending on the voltage, so, with the 24v said here as the battery pack level, if you needed 5v at 1A, it would draw close to or about (5/24) * 1A = 0.2A at 24volts (+10-20% for inefficency).

also harddrives use significantly less power when idling, the quoted power is usually slightly higher, and, has to take into account power needed to spin up, and power to move the head, moving the head randomly uses up quite a lot more power. (P.S. i have measured various drives with a Clamp meter at one point, also various power draw on the AC side of complete systems) most things will give a rating close to or exceeding the maximum expected power useage.

Energizer quotes there alk D's as having 20500mAH and Eveready SHD as 8000mAH, even the SHD should last over half a day constant.

so, talking AMPS is useless, have to talk total power, hell, if you talk about the amps a CPU itself draws, its somewhere between 10-80 odd depending on how old / new, but you wont be seeing that current taken from the input power (considering AC sockets are only rated to 10A @ 240v)

By: TJHooker

TJHooker — Sun, 22 Jul 2007 05:11:54 +0000

Once again my theory was/is that it isn't practical, not that it wouldn't work. The Duracell and Apple documents actually reinforce what I've said so far.

A whole laptop, no matter the processor would pull in at least 1 amp. A 40+ Gigabyte drive alone is commonly .79 amps.

I find it retarded, in a literal sense, that people think a whole system could not pull in 3 amps on a DC source even at low processor and I/O loads.

To further stress my point look at the amp rating on any hard disk drive. Even setting idle it consumes most of that.

This isn't even complex math, simple addition of the idle amp ratings on hardware are all that's needed.

By: andrew

andrew — Sun, 22 Jul 2007 02:42:06 +0000

tjhooker: i find it very unbelievable that on average a laptop with a 150MHz pentium (so they do exist — my bad) will pull 50 watts because i have had many old laptops from that era and none have come close. and if you are simply reading what the ac adapter says that would be the extreme maximum as most systems will pull much less (#23 agrees).

#21-#24, you are all correct in the power output of D-cells. i have no idea why someone would think that D-cells could not give 500mA for hours, unless, of course, they were thinking of heavy duty batteries or something…

By: steve diraddo

steve diraddo — Sat, 21 Jul 2007 20:52:19 +0000

a good d cell is about 18,000 mah on standard usage. using a lot of them in series with a regulator will both lower the total voltage and raise the amperage. i dont doubt this things ability to power a laptop for a long period of time.

laptop batteries:
8 – 12 a-size liion or nimh cells (~900mah each)
this thing:
20 d-size alkaline cells (~18000mah each)

By: Hebby

Hebby — Sat, 21 Jul 2007 13:17:58 +0000

an Alkaline D cell would have something like a few thousand mAH so 500mA for a few hours is belivable (hell even new AA nihm’s are reaching 3000, that’d be 5-6 hours on a pack of AA’s), and computers rarely use anywhere near the quoted power levels on the manufacturers site, so, 20w is plausable, and likely true aswell, because that regulator isnt speced to do much more, was thinking how unsafe that setup was, due to the fact that if it did draw 30-40watts try and charge the battery or something, would likely have ended up smoking the regulator, and that would have been fantastic fun on an aircraft, likely caused a hell of a fuss.

but yea, I think they are starting to make buck/boost regulators that are almost a slot in replacement for common linear regulators, think it was a project listed on this site only a few months back even that used one.

By: jimmys

jimmys — Sat, 21 Jul 2007 11:26:53 +0000

http://www.duracell.com/oem/Pdf/new/MN1300_US_CT.pdf

By: jimmys

jimmys — Sat, 21 Jul 2007 11:18:56 +0000

Alkaline D cell batteries are often 20Ahours capacity.
From apple's website : http://support.apple.com/specs/ibook/iBook_G4.html

the iBook G4 has a 50 to 61 watthour battery that they say will run the iBook for 6 hours.

you can do the math from there to figure out if it's possible...