Date: Sat, 29 Sep 2001 20:07:37 From: "neil barnes" <[EMAIL PROTECTED]> Subject: Re: Homebrew battery packs
>Date: Sat, 29 Sep 2001 16:47:04 +0800 >From: Raymond <[EMAIL PROTECTED]> >Subject: Re: Homebrew battery packs > >Gee I really like this mailing list already! Some mailing lists I'm on, >no-one knows or says anything ... at least here I can really learn things! We're a very opiniated lot! >Hmm ... I dunno about boosting to 15 volts but to cut the power so the >libretto knows its on internal battery, couldn't you use those cheap $5 >battery monitor kits with 3 LEDs that you could buy from the local >electronics store (the ones you'd normally use in your automobile to warn >of low battery voltage)? Instead of the 'power good' LED, one could hook up >a relay (perhaps through an optoisolator if the coil has a chance of >confusing the circuit) so that when the power good LED goes off (signifying >insufficient voltage) it totally disconnects the pack. Of course, you'd >need a switch to temporarily bypass that circuit to get the relay to turn >ON in the first place. It occurs to me that you could probably also use >that same switch to temporarily connect the extra cell to give the Libretto >the 15 volts it needs to start ... anyone see any potential issues with >such a setup? No reason why not - or one of the power supply monitor chips would do the trick also. You don't need the extra cell if you're going to drive at 15v :) or if you drive at 12v (there's a little boost circuit that uses a capacitor and diode). However, designing a power supply that both bucks and boosts so it can be used for inputs above AND below the output (e.g. a lead acid will start at maybe 13.8v and deliver useful charge to maybe as low as nine or ten volts) is a mite harder than one which always converts up or down. > >Also regarding charging NiMH packs, Not my area of expertise I'm afraid...but those nice people at Maxim have excellent data sheets (if you worry hard enough at their web site) and if you ask them nicely they'll even send free samples. > >- Raymond > >P.S. I'm still having trouble seeing how that light bulb icon can be >described as being 'hairy'... > The three great Libretto Legends(tm): o Unscribble o The Hairy Lightbulb o Miniskirts Neil (no, no clues. That's what the archive is for :) _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp ************************************************************** 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 **************************************************************
