Re: [RCSE] battery choices
Personally I'd recommend the 1100MAH NiCd. They have plenty of capacity for thermal duration. Although I own and use NiMH batteries I prefer nicads for receiver packs. Either technology will do but in either case be SURE to do a FORMING charge FIRST. Don't get new cells and start quick (peak) charging them until you have done a 150% capacity (time x ma) slow wall wart charge cycle! Of course you already know that, Jim ;-) Hope this helps Rick At 02:41 PM 4/17/2005, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 Richard A. Eckel, PE, NSPE Eckel Associates, Inc. 1757 W. Broadway St. Suite 3 Oviedo, FL 32765 Professional Engineering for Petroleum Facilities Office: 407-366-8852 Cell: 407-733-6380 [EMAIL PROTECTED] 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
Re: [RCSE] battery choices
James, Actually, sailplanes can draw quite a bit of power, especially 6ch planes with digital servos. I have long been convinced that the reason for many crashes is due to catastrophic voltage drop-offs caused by high current loads. If you've ever seen a plane that was thoroughly preflighted, linkages checked, etc., zoom straight into the ground on launch, you may have seen this in action. Usually, people blame radio interference but never think to look at their batteries, because in the post mortem, the pack seems ok. However, how many people think to check their packs under load? I have measured loads as high as 6amps on an Icon fitted with 3 DS3421s and 3 DS368s. Packs made from AA cells were fine in the days of RES planes with analog servos and light wing loading. But today's high performance molded planes with digital servos are far more demanding on the power source. High loads caused by hard winch launches, aggressive landings, and fast flying can easily cause a high impedance AA pack to suffer a voltage drop long before they are fully depleted. Cell capacity is only one part of the equation and, unfortunately, the only number that most people look at. For today's high performance molded sailplanes, we need battery packs that can deliver high current right up to the edge of depletion without dangerous dips in voltage. Look to the kinds of low impedance cells that people use for motor applications. Here are some examples of the low impedance cells that I am using in my planes: F3J Icon: Sanyo CP1700 Sub C Nicad Graphite Electric: KAN 1050 2/3A NiMh Tragi: GP2000 4/5 A --Jim Laurel On Apr 17, 2005, at 11:41 AM, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 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
Re: [RCSE] battery choices
Jim Laurel wrote: James, Actually, sailplanes can draw quite a bit of power, especially 6ch planes with digital servos. I have long been convinced that the reason for many crashes is due to catastrophic voltage drop-offs caused by high current loads. FWIW I have calculated that my average current draw in a 6 digital TD ship (both an Artemis and a NYX) works out to around 325 mA. Compare that to my giant scale 40% aerobatic planes with 10 LARGE high torque digitals where I have an average draw of 2 amps. This was done based on calculating the amount of capacity consumed for a certain amount of flying time. A similar set up with 14 digitals recorded an in flight average of 3 amps with a single 5 ms peak of 10 amps during a series of consecutive snap rolls. This of course assumes that you are not stalling servos. And by stall I do not mean fully deflected under load. I mean mechanically stalled, which should not happen in a good installation anyhow. I have never experienced a plow voltage lock out under any flight condition in either a glider or my large aerobatic planes. I know this for a fact since the Futaba radios have a low voltage lock out feature that moves everything to a preset condition and then releases it when you move a predesignated control (like the throttle/flap stick). This activates at either 3.6 or 3.2 volts. A I said, I have never had it engage under even extreme flight conditions. I am running a 2100 AA pack in my NYX right now. 4.8 volts and everything, seems to be just fine. Even in the aerobatic plane I have with high internal impedance NiMH I have never seen this happen, even when getting close to the end of the useful charge. However, how many people think to check their packs under load? As far as I know this is the only useful way to check packs. Of course the voltage tells you nothing about remaining capacity, but it does tell you what the pack is delivering under a certain load at that instant in time. I have measured loads as high as 6amps on an Icon fitted with 3 DS3421s and 3 DS368s. How did you measure this?? Seems unreasonable high to me. That is near full stall current on those servos, which I believe is around 1 to 1.2 amps. 6 amps means you stalled ALL of them. can easily cause a high impedance AA pack to suffer a voltage drop long before they are fully depleted. True enough, which is why it is a good idea to get the lowest impedance cells possible. In my big plane I run 3300 Sub-C cells with an internal impedance of 5 mohms. Under a 1.5 amp loaded check they drop only 0.24 volts. Compare that to a 2700 pack (A cells) with an internal impedance of 25 mohms. That drops off .85 volts under the same 1.5 amp load. But the point remains unchanged, put the biggest capacity, lowest impedance cells in your plane that you can fit. 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
Re: [RCSE] battery choices
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. I don't know if the name Duracell is known in the USA, but it certainly is over here, with a very good reputation. 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 ? Thanks, Stefan. - Original Message - From: Jim Laurel [EMAIL PROTECTED] To: soaring@airage.com Cc: James R MacLean [EMAIL PROTECTED] Sent: Sunday, April 17, 2005 9:07 PM Subject: Re: [RCSE] battery choices James, Actually, sailplanes can draw quite a bit of power, especially 6ch planes with digital servos. I have long been convinced that the reason for many crashes is due to catastrophic voltage drop-offs caused by high current loads. If you've ever seen a plane that was thoroughly preflighted, linkages checked, etc., zoom straight into the ground on launch, you may have seen this in action. Usually, people blame radio interference but never think to look at their batteries, because in the post mortem, the pack seems ok. However, how many people think to check their packs under load? I have measured loads as high as 6amps on an Icon fitted with 3 DS3421s and 3 DS368s. Packs made from AA cells were fine in the days of RES planes with analog servos and light wing loading. But today's high performance molded planes with digital servos are far more demanding on the power source. High loads caused by hard winch launches, aggressive landings, and fast flying can easily cause a high impedance AA pack to suffer a voltage drop long before they are fully depleted. Cell capacity is only one part of the equation and, unfortunately, the only number that most people look at. For today's high performance molded sailplanes, we need battery packs that can deliver high current right up to the edge of depletion without dangerous dips in voltage. Look to the kinds of low impedance cells that people use for motor applications. Here are some examples of the low impedance cells that I am using in my planes: F3J Icon: Sanyo CP1700 Sub C Nicad Graphite Electric: KAN 1050 2/3A NiMh Tragi: GP2000 4/5 A --Jim Laurel On Apr 17, 2005, at 11:41 AM, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 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 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
RE: [RCSE] battery choices
I just returned from a two hour flying outing. I use two Sony 18650 cells (aprox. 1600 milliamp each) in parallel for my battery. I charge them to 4.46v with an old cell phone charger that only puts out that much voltage. I had one 5-minute flight and one 30-minute flight. I also had a few other shorter flights. I left the plane on a lot of the time and when I was done I checked the battery and it showed 4.43v. I lover the Li-ION cells for my planes. If I forget and leave the plane on for lunch (or just leave it on all day for convenience) I don't have to worry, John -Original Message- From: Rick Eckel [mailto:[EMAIL PROTECTED] Sent: Sunday, April 17, 2005 1:53 PM To: James R MacLean; soaring@airage.com Subject: Re: [RCSE] battery choices Personally I'd recommend the 1100MAH NiCd. They have plenty of capacity for thermal duration. Although I own and use NiMH batteries I prefer nicads for receiver packs. Either technology will do but in either case be SURE to do a FORMING charge FIRST. Don't get new cells and start quick (peak) charging them until you have done a 150% capacity (time x ma) slow wall wart charge cycle! Of course you already know that, Jim ;-) Hope this helps Rick At 02:41 PM 4/17/2005, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 Richard A. Eckel, PE, NSPE Eckel Associates, Inc. 1757 W. Broadway St. Suite 3 Oviedo, FL 32765 Professional Engineering for Petroleum Facilities Office: 407-366-8852 Cell: 407-733-6380 [EMAIL PROTECTED] 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 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
Re: [RCSE] battery choices
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
Re: [RCSE] battery choices
James, I have just read this thread and there is a lot of very good information being passed. I prefer NiCd's wherever I can, I will use NiMH cells if I need to keep the weight down only. There a lot of NiMH cells coming out that are of poor quality, and some of them will NOT take a fast charge, and even the slow charge doesn't fill them correctly. The smaller the package the higher the internal resistance, and don't forget the wiring. small wires develop higher resistance, which equates to the Rx seeing a lower voltage. In other words, higher current load, lower voltage with the higher internal resistance, Receiver can actually shut down momentarily looking like interference, current load drops and the voltage returns plane flies fine. The modern digital servos can draw more than 1 amp at stall. A 6 servo sailplane on launch with flaps and ailerons down can easily draw 4 amps while on tow, then as you load it up for the ping the elevator servo will draw more pushing the current even higher, after the zoom current loads drop dramatically during normal duration flying. Again, if I have a choice I will always choose NiCd's, they will last longer, they are easier to safely charge, they have lower internal resistance. They RARELY fail once they have been properly formed and cycled. I have had NiMH cells fail after normal forming and cycling, just 2 weekends after they were installed in the plane. Fortunately I was following my own advise and charging between flights or I would have lost the plane on takeoff. A loaded volt meter is a good tool if used correctly, but it will never tell you how much capacity you have left. I recommend using at least a 1/2 amp load and keep it on for at least 15 to 20 seconds before giving it a go. Smooth Landings George At 02:41 PM 4/17/2005 -0400, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 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
Re: [RCSE] battery choices
I've found that the best and most convenient choice for AA receiver packs are the Energizer 2300 or 2500 MAH NiMh cells available from local department stores for around $10 per four-pack. I use them in all my sailplanes and radios and have never had a pack come close to reaching a discharged state. (And that's even after a long and extremely enjoyable day of slope soaring on the east coast of Florida, such as our club had yesterday.) It's time to face the fact that NiCd cells are now essentially obsolete. They may have had some advantages over the early NiMh cells, but modern cells are available with equal or lower internal resistances, at least equal dependability and lifetimes, and much greater capacity. Mike -- Winch Solenoid Safety Buzzer - http://www.vvsss.com/buzzer/ _ \__|__/ (O) 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
Re: [RCSE] battery choices
The modern digital servos can draw more than 1 amp at stall. George, you are confusing stalled with fully deflected under load. The JR 368 has a full stall current of 1 or 1.1 amps. Can't pull more than that or it will fry. The flaps are NOT stalled when loaded under full deflection, and certainly NOT under normal launch camber. As I tried to say in another post, a company that makes a load sharing device flew a 14 LARGE digital servo plane (3 meter Extra with a 150 cc engine on it) they only recorded a 3 amp average load and 1 single 5 millisecond spike of 20 amps during a series of consecutive snap rolls. Now the digitals they used can pull 2.5 amps at full stall so even that 20 amp spike was an average per servo of 1.4 amps. Clearly way less than their fulls stall current. 6 amps on a 6 servo TD ship is TWICE what they measured on the 14 digital Extra . This is hard data too, so I tend to believe it. If anyone out there has actual in flight recorded data showing me that a full house TC ship with 6 368 servos is pulling 6 amps on launch, I'd love to see it. 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
Re: [RCSE] battery choices
No Way!! For the same package size decent (Sanyo) nicads have higher terminal voltage under load, lower internal resistance, faster dependable charge and discharge rates and a much longer charge retention time. I will admit that NiMH cells have more capacity per volume than NiCads but you must use it within a day or so and can't get it out at high rates with high terminal voltage. Stick any AA NiMh cells you can get in a digital camera and put it in your pocket for a month - then try to take 8 or 10 pictures with flash, Didn't work did it? Now try the same thing with a pair of 650 to 850 mAh NiCads. No Problem getting the pictures! NiMh cells are fine if you charge every day, don't need high terminal voltage, and have no need for real reliability. Great product for mp3 players but not for anything critical. You can get NiCads with some of the same problems as NiMh cells if you pick the ones that have boosted capacity by using foam plates to increase the capacity. -- Dick Barker Port Angeles, WA 20 years of battery evaluation for defibs. - Turning HLG Around - I've found that the best and most convenient choice for AA receiver packs are the Energizer 2300 or 2500 MAH NiMh cells available from local department stores for around $10 per four-pack. I use them in all my sailplanes and radios and have never had a pack come close to reaching a discharged state. (And that's even after a long and extremely enjoyable day of slope soaring on the east coast of Florida, such as our club had yesterday.) It's time to face the fact that NiCd cells are now essentially obsolete. They may have had some advantages over the early NiMh cells, but modern cells are available with equal or lower internal resistances, at least equal dependability and lifetimes, and much greater capacity. Mike 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
Re: [RCSE] battery choices
I've been flying with NiMH flight packs since starting in this game (about 5 years ago) with open-class ships. The 1600-ish sized packs seem to be the sweet spot for hydrides with regard to consistent performance. The 2000 and above packs are (I think) pushing the limits of capacity in the AA-form factor and I noted erratic test results with them. Decided to switch to 5 cell packs for the new ships I'm building and for that the 2/3A cells (1200 MAh in NiMH) are a perfect fit. At a ~350 MA/hr draw for a 6-servo plane, they're still good for 2+ hours of flying with a healthy reserve. Tom James R MacLean wrote: What do you think? Any data / experiences to suggest the better choice? 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
Re: [RCSE] battery choices
Hi James, NiCD's will deliver the most PWR on demand, but offer the least watt/Kg. THis may require recharging at some point in the day. AA NiMH's have significantly higher internal resistance (lack of reactive surface area in the form factor), and will demonstrate a lower voltage under a similar load. Add to this they discharge at almost double the rate compared to NiCD just sitting waiting for the next flying day. Contrary to the suggestion NiCD is history, this technology will be around for a long time to come. No other technology at present can offer similar PWR demand for as many cycles. NiMH still has a long way to go to meet NiCD specifications in the areas of actual service life, charge degradation due to being endothermic by nature under a charge regime, and the obvious higher internal resistance to start with. Also be wary of AA NiMH cells claiming in excess of 2000mA. The manner in which these cells are rated is at relatively light loads...which means they deliver significantly less under loads in the manner we might subject them to. If you perform light-duty casual flying, NiMH may suffice. If you want maximum electrical performance, then employ NiCD's. On Apr 17, 2005, at 11:41 AM, James R MacLean wrote: Its too windy to fly here on the east coast of Florida, so maintanence time. (Yes, I know, what a wimp. I can and have flown contests in pretty bad wind but why risk a plane when there will be better days soon.) The question is about batteries. I need to replace a number of sailplane batteries. They all hold a square pack of AA size. It appears to me that there are only two packs which make sense: the 1100MAH NiCd and the 1650 NiMH. Both are nearly identical in cost, weight and size. I have the appropriate charger which is rated for either and does a good job in a reasonable time. Both cells are made by Sanyo which usually means excellent reliability and service life. Sailplanes generally don't draw extreme servo currents so I expect the hydrides to be sufficient in that respect - the nicads are usually superior in high current applications. What do you think? Any data / experiences to suggest the better choice? Thanks for your thoughts, Jim MacLean 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 Simon Van Leeuwen RADIUS SYSTEMS PnP SYSTEMS - The E-Harness of Choice Cogito Ergo Zooom 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
Re: [RCSE] battery choices
Consumer grade batteries fall short in a number of areas: - poor construction, do not meet the same vibration/drop test specifications as industrial cells - poor electrical performance, significantly higher internal resistance than the worst of the industrial offerings - exagerated specs to meet the consumer demand for more PWR At reasonable levels of current consumption, these cells fall short of the worst of the industrial NiMH's... Dick Barker wrote: No Way!! For the same package size decent (Sanyo) nicads have higher terminal voltage under load, lower internal resistance, faster dependable charge and discharge rates and a much longer charge retention time. I will admit that NiMH cells have more capacity per volume than NiCads but you must use it within a day or so and can't get it out at high rates with high terminal voltage. Stick any AA NiMh cells you can get in a digital camera and put it in your pocket for a month - then try to take 8 or 10 pictures with flash, Didn't work did it? Now try the same thing with a pair of 650 to 850 mAh NiCads. No Problem getting the pictures! NiMh cells are fine if you charge every day, don't need high terminal voltage, and have no need for real reliability. Great product for mp3 players but not for anything critical. You can get NiCads with some of the same problems as NiMh cells if you pick the ones that have boosted capacity by using foam plates to increase the capacity. -- Simon Van Leeuwen RADIUS SYSTEMS PnP SYSTEMS - The E-Harness of Choice Cogito Ergo Zooom 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
