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What do I Need to Build an External Laptop Battery Pack?


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#1
WhydoIask?

WhydoIask?

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I'm buying a new battery for my laptop, but my laptop is not the most efficient thing (battery lasted just above 50 minutes when it was new,) and I'm not always around a power outlet, so I wanted to see if I could build a pack of batteries to keep in my bag that I could plug my charging cable into. I know there's a few out there, but they are all big and boxy, and frankly won't fit in my bag. However, there is a little bit of room around the inside rim, and I could make an arch of Li-ion cells on the inside edge of the bag. As far as my limited electrical experience tells me, I'd need a DC to AC inverter, like this (I could solder wires directly onto the bare connections.) So my question is: IF it's possible to piece together a series of (high mAh count) Lithium-Ion cells that add up to exactly 12 volts, what other parts (I'd obviously need a way to charge it) would I need to make this theoretical document saving device?

I'd like to point out that my "limited knowledge" of electricity doesn't extend to safety. I know about insulation, bare wires, and all that jazz, enough to prevent me from catching myself on fire, or blowing a fuse.

Thanks for reading.
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#2
phillpower2

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Hi WhydoIask?
Not sure if what you are suggesting is possible or how it would or would not work - I have another suggestion for you to consider, what about a couple of powerpacks such as http://www.energizer...oducts/xp18000/

NB: What about taking additional fully charged batteries with you.
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#3
WhydoIask?

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Well, I like a good project once in a while, and if this is possible, I'll try it. I found some 3V, 900mAh rechargeable batteries, and if I put them in a series to make 12 volts, and put a few of those series in parallel, which would make enough power to charge my laptop for a while.

...I just realized I completely missed the part of the Inverter's description where it said it uses 75 watts (literally the first part of the title.) So now that that's out of the question, I realize I'd have to skip my charging cable and wire a plug up to the batteries along with a fuse, which would mean I need enough batteries to make 19V and 6300mAh.

This might get expensive.
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#4
phillpower2

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Might give you some ideas as it allows you to daisy chain two or more batteries together http://www.bixnet.co...slloruntie.html

This might get expensive.

Agreed.
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#5
WhydoIask?

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We're thinking of different things, here. I'm taking about cells like these. 5 in series make 18.5 volts, and 3 series in parallel makes 7200mAh, enough to charge my laptop for a little while.

Edited by WhydoIask?, 01 April 2012 - 05:51 AM.

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#6
phillpower2

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Yep I was thinking you meant notebook batteries - sorry!
Good luck with it and please let us know if you achieve this.
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#7
WhydoIask?

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Thanks. I've been reading up while waiting for you to respond, and I found that I should charge my laptop at EXACTLY 19 volts (the mah doesn't matter as long as it's at or above 6300.) I'd have to add another battery the the series, and find a voltage regulator that can output 19v, and at least 6.3 amps. I haven't found any so far.

**Edit** I did some more reading, and found that half a volt less shouldn't be a problem, as long as I have a slightly higher amperage (which shouldn't be a problem, what with the 7.2 amps the batteries will give)

Edited by WhydoIask?, 01 April 2012 - 06:52 AM.

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#8
WhydoIask?

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I also just found this. I think I can start building this within the next 2 weeks.

Edited by WhydoIask?, 01 April 2012 - 07:20 AM.

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#9
phillpower2

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Keep us posted and good luck.

NB: I thought I had found a couple of videos for you before but they were using a single 9V battery, the videos themselves were not brilliant play wise either but if you want a look google Techzilla episode 1.
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