Date: Sat, 29 Sep 2001 13:59:37 +0800 From: Raymond <[EMAIL PROTECTED]> Subject: Re: Homebrew battery packs
Hi Pres, >I had a 50 and never got more than 40-50 mins on the standard battery, but >the extended gave almost 3 hours! Twice the milliamp-hour rating yet more >than 2x the life has to do with the RATE compared to the capacity of >withdrawal. Umm ... OK I'm confused ... what exactly do you mean by the 'rate'? One wouldn't have thought the Libretto would draw enough current for the internal resistance difference of the 2 packs to have any impact ... Of course, I guess that means the claimed '1.5-2h on standard pack, 3-4h on extended pack' claim by Toshiba is a pile of ____ .... >Why would you want 12v to run it when you have the 15v supply? The computer >has internal charging circuitry based on 15 v exactly. I'm hoping to make use of a 12 volt 3.5AH NiMH battery pack I've got lying around (it was a pack purchased for a laptop that died a month afterwards, its been sitting gathering dust ever since). Since the extended pack is 2.4AH, I'm hoping to get a few hours runtime on this 3.5AH pack ... if I can figure out how to charge it without blowing it up! I'm not too concerned if the external (12 volt) battery pack won't charge the internal (10.8 volt) battery pack (although it'd be nice if it did) ... of course, if it DOES charge each battery individually then why would it need 15 volts? (I was of the understanding that older laptops needed 13-15 volts because they needed to have an input greater than the packs they were charging which would have been all in series and charged all together). >The Libretto has LiOn battery technology. They can be lethal explosives if >charged improperly. They are charged INDIVIDUALLY. That's why there are many >terminals on the battery pack. There's also a charge controller PCB inside >the battery. THAT explains a thing or 2! I always wondered about all those contacts on LiIon packs that come with Tecras and Porteges ... >Before someone tries to point out that you can't have current without >voltage, look up the definition of a "constant current source" or a >"constant voltage source"... Hehe I may be unfamiliar with battery chargers but THAT much I've learned already ;-) I take it therefore using a constant voltage to charge NiMH packs such as plugging it into the Libretto's 15 volt regulated supply with 4x1N4004 diodes to drop the voltage (in the hope that once the battery pack reaches the charge voltage it'll stop charging due to a lack of voltage gradient) would be a dangerous way of doing things? - Raymond ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://libretto.basiclink.com/archive - Archives http://www.picante.com/~gtaylor/portable/faq.html - FAQ -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
