On Sun, Apr 17, 2005 at 09:55:41PM +0200, Stefan Smets wrote: | Hmm, this tread got me thinking about the batteries I use ... How | can one know the impedance? I'm using Duracell AA cells with these | data on them "AA/HR6/DC1500NiMH/1,2V/2050mAh".
Ultimately, you'd measure the voltage produced by the batteries with a few different loads (and no loads) and through some math you could calculate the internal resistance. Or you could short circuit the battery and measure the current, though I don't suggest that. Personally, I prefer the term `internal resistance' as `impedance' implies that there's AC involved, though it's use really isn't wrong here. Though few people really do calculate the internal resistances of their batteries like this. Ultimately, AA cells tend to have relatively high internal resistances, and AAA cells higher still. (They're made for high capacity rather than low internal resistance.) Sub-C cells generally have low internal resistances. NiMH cells generally have higher internal resistances than NiCd cells of the same physical size. | I don't know if the name Duracell is known in the USA, but it | certainly is over here, with a very good reputation. Duracell is well known for alkaline batteries over here, and not so much for rechargables, but I've got some and they've been fine. | Until know, no problems in both a F3J Esprit and a Corrado II, both | 6 servos, and no problems in a Raptor (heli) either (5 servos). The | gliders use analog servos, the Raptor Futaba 3151. | | Should I worry ? Probably not. But if your plane needs some lead in the nose to balance, you might consider a second battery pack or a larger pack instead of that lead -- I'm guessing that your battery is fine as long as none of your linkages bind, but a little extra headroom wouldn't be a bad thing. In a helicopter, mechanical gyros use a lot of power, so you'll want a large battery. I'm not sure how much the new piezo gyros use, so I can't really comment on that. There aren't really many hard and fast rules -- but it's definately better to have too much battery rather than too little. -- Doug McLaren, [EMAIL PROTECTED] Greetings, Professor Falken. Shall we play a game? RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
