Author Topic: Rechargeable AA batteries as extra power supply for minibook????  (Read 5183 times)

sharpo

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With my CnM Mnibook I haven't yet completely flattened the battery when out on my travels, but was wondering if it was practical and safe to create an extra power supply using 6 x AA rechargeable batteries and appropriate power lead to fit.

If so, this should extend the number of hours use I can get from it. Unfortunately when I am out there are no power sockets that I can use to plug in the charger, and a solar charger would not be practical

Whiskers

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #1 on: April 27, 2009, 04:20:07 PM »
I've thought about this, although I haven't tried it.

The input voltage of the CnMbook is 9 volts.  Six 1.5 volt disposable alkaline or zinc batteries in series would give that, or eight rechargeable NiCd or NiMH cells (which are nominally 1.2 volts each).  But I'd be inclined to either use fewer batteries, to get a lower voltage, or build something with a voltage regulator to prevent the machine from getting too high a voltage - which could damage it.  (Batteries can sometimes deliver more than their nominal voltage).

The machine needs at least 1.5 Amps (or 1500 milliamps) to run and charge the internal battery and work the WiFi or a dongle.  Maplin should be able to sell you the right sort of chip for £1 or so - and perhaps give advice about using it (which I would need if I were to go ahead with the idea!).  Don't worry about getting a regulator that can handle more than 1.5A - the machine won't draw more than it needs.

rodonn

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #2 on: April 27, 2009, 06:12:38 PM »
I'd consider the 6 NiMH and go go for the high drain ones...most electonic devices will accept under voltage, as long as they can still pull the current...

sharpo

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #3 on: April 27, 2009, 06:36:02 PM »
Thanks for the replies so far. I'll probably call in Maplins in the next day or so, as I will need a plug to fit the minibook.

Any other comments/suggestions welcome in the meantime.

Leven2e

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #4 on: April 27, 2009, 07:51:38 PM »
Please let us know how you get on! Cheers!

Artus Irbe

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #5 on: May 13, 2009, 05:49:46 AM »
Interesting idea! :D I would love to hear how you got on, because if it could be a solution that keeps the laptop running after the charger dies (because they do that! :D) we could just use these untill the supplier sends our replacement!

Good luck!

rodonn

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #6 on: May 23, 2009, 11:44:27 AM »
BTW, I'd say that going for an internal cell unit replacement using a Japan(ese) Solderless Terminal plug into the 6cell batery carrier, rather than taking it in through the DC jack, since the battery pack probably won't take charging the internal battery well... Over drain will just screw the batteries in the 6-cell

Interestingly the NiMH composite cell lead tails in my Cnm is soldered to the tails of the leads into the JST plug... not quite sure what I'd do with it yet but I have the fringes of an idea...

worge

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #7 on: January 17, 2010, 06:17:59 PM »
Sharpo.
I may be a little slow in this reply but I hope it helps you.
I have concocted an 8 cell (AA rechargeable 2.300 mAh)power pack.
It will Boot and run  a flat battery cnmBook.
With what succsess I will later test.
I am presently making a dummy load to pre condition the power pack batteries.
The Maplins L46ay will no fit well, as it is 1.5 mm short of the cnmBook plug. It connects but no click.
Plan B. Use 2.1 / 5.5 mm sockets - plugs
Cut the power cable at a suitable place on the power pack,and add the plug and socket to accommodate the plug on the power pack.This will allow you to use another plug and socket to install an ammeter and voltmeter in the power supply.
A few of the readings as of yet.
Mains power supply.
No load 9.41 volts
Pluged in not on. flat battery 9.27v    510 ma
booted                         9.10v    950 ma
Wi Fi started                  9.06v  1,040 ma
Screen asleep                  9.17v    750 ma 1 hr
Screen asleep                  9.20v    680 ma 3 hs

Battery pack Ish full? startup run.
Battery pack used 8.2 volt no load
Battery pack      7.9 volt 20 ma running just.
As from this very pulmonary test it may be seen that a power pack may be of some practical use.I hope to get back to you with  better results.
                worge               


sharpo

  • Guest
Re: Rechargeable AA batteries as extra power supply for minibook????
« Reply #8 on: January 17, 2010, 06:43:20 PM »
worge,

Glad to see you are making progress. My days out with the minibook haven't been too long & the battery seems to just last long enough for what I need. Look forward to hearing about the rest of your tests.