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Old Apr 06, 2002, 11:56 AM
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Lithium Rechargeables

Okay, fellow r/cer's, lets get some new discussions going on one of the most underexposed new additions to this hobby (at least in my neck of the woods), rechargeable Lithium batteries. This is a huge breakthrough in the low amperage-drawing aircraft (I assume 280 and smaller). For those who don't know about these batteries, let me give you a little hopefully correct info. If any of this is wrong, let me know. There are many different types of Lithium batteries. The ones I'm most familiar with are Lithium Ion and Lithium Manganese. They are rated at 3 volts nominal and 3.6 volts max. This means you can use half the batteries in your plane. So, I can put a 1400 mah 3 cell pack in my plane and it will be around the same weight as a 6 cell 700 mah NiMH pack. These batteries are touchy, though, since you cannot get them below 4 volts, which is what BEC's are for. Also, you can't draw more than around 3 amps, which limits the use to 280 and smaller motors. But, if used correctly, people have gotten flights of 1 hour 47 minutes with smaller planes, and probably 40 minutes with typical 280 size planes.

Now, in my opinion, every single manufacturer of r/c equipment should be jumping all over this, but they're not! Why? I don't know. There are several sources for these batteries and chargers, and maybe others will know of sources and post them here. Batteries America in Wisconsin carries these specifically made for rc airplanes. My only problem with them is that they don't have a 3 cell pack, only a 2 cell. www.batteriesamerica.com is the sight

So, now I call upon my fellow r/cer's to get out there and do some research on this! There is huge potential in these batteries, so let's tap the well. Also, if any manufacturers read this (yeah right) get out there and make these as readily available as NiCad and NiMH!
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Old Apr 06, 2002, 12:29 PM
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Search for Qualcomm and you'll find 100's of posts about lithium ion batteries.

Rick.
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Old Apr 06, 2002, 12:35 PM
DNA
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"to get out there and do some research on this"

Suggest you do some research on Ezone as Rick said.

Search phrases:

Lithium
Li-ion
Qualcomm
Neopoint
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Old Apr 06, 2002, 01:05 PM
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um... lithium-ion are 3.6v nominal, 2.4v the lowest voltage they can go before getting damaged, and 4.2v max... lithium-metal aren't even made any more (tadiran).

batteries america is a ripoff. hackett is the source. ~$1 a cell. if you need 3-packs, buy an orbit charger, I find hacking consumer chargers too much of a pain in the butt for different cell counts.

hobby lobby sells the paf wing, rtf minus crystal, its power source is 2x prismatic li-ions. li-ion hasn't caught on in a big way becuase of 'safety issues' with possible themal runaway (although this has more "my friend had a brother who had a friend that blew up a li-ion" evidence than first-hand, but do be careful). manufacturers won't sell batteries to you, you have to rip them out of cellphones/camcorders/laptops.

and no, 3 amps is NOT the limit. just like nicads and nimh, a 600ae nicad is not the same as a 500ar except 100ma less. each li-ion brand/package battery has different different discharge curves. some can go 1x capacity, some 2x, some even up to 5x in bursts (qualcomm 830ma). then, you COULD tie packs in parallel to multiply maximum current output.

there is a TON of info out there. for now, be glad it's a fringe thing and enjoy it while it lasts. chargers for $10, battery packs for $2 aren't going to be the norm when manufacturers start making li-ion power systems in mass.
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Old Apr 06, 2002, 03:50 PM
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For Rick and DNA, when I said go out and do some research, my point was not to find out info at other people's expense. There seems to be so much interest in Li batteries out there, but a complete lacking of knowledge (at least from my local pov). My point with all this is to get everyone to work together on this to make it a much more made-for-rc hobby, rather than scavaging the local cell phone company thing. So, please, no more posts simply stating "go out and do your own research". I am!
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Old Apr 06, 2002, 05:21 PM
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cineski,

I think that if you search Ezone, you will find lots of information. Like any new subject, there will be some misinformation and misunderstanding, but mostly, I think if you look with a critical eye, you will be able to tell what the real data is. If you find that you have questions, please post them. There are many knowedgable members that will answer stat.

Best regards,
Q
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Old Apr 07, 2002, 12:26 AM
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Re: Lithium Rechargeables

Quote:
Originally posted by cineski
Okay, fellow r/cer's, lets get some serious discussion going on one of the most underexposed new additions to this hobby, rechargeable Lithium batteries
The point was that there have been hundreds of posts covering this topic already on this board over the last year. An awful lot of slowflyers already use Lithium ion rechargeables and Tadiran Lithium Metal batteries have been in use indoors for 3 years.

If you are wanting to learn, we suggested you read what has already been written. If you have something new to offer, please let us know.

Rick.
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Old Apr 07, 2002, 03:24 AM
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I agree... actually, there are probably THOUSANDS of posts about lith-ion cells on ezone. although I think that big crash took a few of them away forever.

"everything" you ever wanted to know about lith-ion cells is written somewhere here on ezone...

discharge rates, charging, weight, care and feeding, home built chargers, hacked chargers, surplus cells, laptop cells... blah, blah, blah...

I can think of NO OTHER place on the internet currently that contains this much information pertaining to lith-ion cells and eflight.
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Old Apr 07, 2002, 05:07 AM
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Cineski posted:

But, if used correctly, people have gotten flights of 1 hour 47 minutes with smaller planes

It sounds like you are referring to Tom Herr flying the StarLITE. The batteries he used were NOT rechargeable.
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Old Apr 07, 2002, 09:13 AM
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cineski:

here's what i used to get started in Li-ons:
"The COMPLETE IDIOT'S Guide to the Qualcomm Lithium Battery Conversion" in the Parkflyers forum. It's on the third for fourth page or so.

i got the items from hackett's for a total of 36 bucks that included shipping. there were five packs and i only managed to screw up one of them. i ended up with four good packs, which translated to 9 bucks apiece. this compared with spending an average of over 20 on ready-made nimh units. less weight, fewer dollars, and increased longevity were well worth the expenditure in time - which really wasn't all that long in putting together the packs - maybe fifteen minutes per.

now i know this probably doesn't answer questions about discharge rates, esc voltage cut-ins, and such, but it's a good start and there are a number of links to further information throughout the thread.
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Old Apr 07, 2002, 11:53 PM
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I've done a lot of searching, and there is a lot of stuff on Lithium Cells! It's funny, but I just don't see a lot of people around me that use LiIon. In fact, I don't see any. I've got Dymond a mile from my house (I'm in Oshkosh, WI), and they don't have one Lithium Cell in the whole store. They don't even seem to have any info on them. And so goes my search for Lithium Ion on this sight.

I'm actually kind of suprised that a certain somebody (Rick) who has joined this thread is getting a little snippy about me starting a new thread on Lithium Ions! Lighten up, people. Look at my status, I'm new to these discussion groups, and to electrics in general. There's no rules for starting up a new thread so you don't have to search through pages and pages to find exactly what you're looking for. If it's a pain in the ass, Rick, don't answer. Thanks to everyone else for the great info!
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Old Apr 08, 2002, 12:10 AM
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Li-ion cells are not available retail, nor from most industrial sources. This is because of strict safety measures imposed on the use of the cells by the manufacturers. The manufacturer could not control the use and therefore safety of the battery if sold by these means. Only equipment manufacturers that qualify are allowed to purchase li-ion cells. This is why virtually all cells we use are from surplus sources--usually cell phone packs.

Q
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Old Apr 08, 2002, 12:37 AM
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I've seen single cells for sale at whack willy's (or something like this). They are surplus, I believe.

Is there any tricks to soldering Lithium Cells? I know how to do NiCads, etc., but since LiIon's are so much more picky and can explode, is there a trick to it? I'm assuming I should use a high temp gun so the solder happens quickly, and doesn't heat the entire battery up, just the tip. Am I on track here, or am I going to loose an arm and an eye?
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Old Apr 08, 2002, 12:57 AM
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Li-ion cells don't put out enough current to justify the need for soldering. I have no information about doing this. As you know, there is no manufacturer's data on soldering NiCad's. I'm sure Sanyo Energy winces when they hear of people soldering NiCad cells. I do know that the electrolyte in NiCad's will not boil below 212F, but li-ion's electrolyte is based on organic solvents. Most organic solvents boil at lower temperatures. Boiling will open the pressure vent and expel solvent. So my net reaction is to advise against it. Are you sure the cells don't come with tabs?

Q
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Old Apr 08, 2002, 01:21 AM
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I don't know if they come with tabs. The Sony cells I saw don't, but the few others I couldn't tell. How else can I solder them together? Do I have to solder? Could I do a pressure fit? This would make me nervous.
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