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Old Jun 30, 2001, 05:29 PM
CharlieR
bay area, california
Joined Nov 2000
315 Posts
Best Lithium Battery

What's the best lithium battery (at a good price) that would work for a Ifo Mark3, Lil hornet, and litestick? Where's the cheapest place to puy them. Will I see an increase in power over a 9.6 volt 225AE battery? Are they lighter than normal batteries?

thanks
chazz

P.S. do I need a special speed control?

[This message has been edited by spy0o7 (edited 06-30-2001).]

[This message has been edited by spy0o7 (edited 06-30-2001).]
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Old Jun 30, 2001, 10:17 PM
CharlieR
bay area, california
Joined Nov 2000
315 Posts
anyone???
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Old Jun 30, 2001, 10:27 PM
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Ralph Weaver's Avatar
Indianapolis, IN USA
Joined Nov 2000
2,305 Posts
You've got no reply because there is no good Lithium battery at a low price. You an get surplus cell phone and laptop cells for a low price, but they are pretty big for these applications, or you can get Tadirans which are great, but cost a lot. See www.magtechinc.net for Tadiran details.
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Old Jun 30, 2001, 11:06 PM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Ralph is right. Some people have had some luck with some lithium phone cells. But they're nowhere near as good as the Tadirans. Just do a search for Tadiran (or Tadrian, as it is sometimes misspelled) on the E Zone, and you will find all of the information that you ever needed about these cells -- cost, availability, what to use to charge them, special ESC considerations, etc.

I have two 3-cell Tadiran packs and a JMP lithium charger that, altogether, cost me more than $150. For me, they are worth the price. No other cells offer the combination of light weight (58 grams for a 3-cell pack), long flights (800mAh) and the ability to handle the current requirements of any motor smaller than a Speed 280 (2A).

While NiMH technology is getting better every day, and you can now get an 8-cell, 720mAh NiMH pack that will handle twice the current of the Tadirans, at 103 grams it is nearly twice as heavy. If weight is critical, there is no substitute yet for Tadirans.
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Old Jun 30, 2001, 11:11 PM
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cyhyam's Avatar
Highland, CA, USA
Joined Jan 2001
1,006 Posts
I saw some AA size Tadirans in an electronic store the other day, They were still in the package, 1 cell per, they were not rated but only $3.50 each. Is this worth looking into?
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Old Jun 30, 2001, 11:16 PM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
The bargain-priced Tadiran AAs are non-rechargeable.
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Old Jul 02, 2001, 10:46 AM
Registered User
Warsaw, IN, USA
Joined Jun 2001
56 Posts
I use lithium ion cellular phone batteries with great success. Two 600mah batteries that weigh 84grams when made into a pack. I have bought new surplus packs with two cells inside for $6.00 each. I strip the cells out and remove the internal pc board. I built my own charger that charges the cells separately. For the money it is hard to beat, rigging up the charger is the trick.
I have 6 packs made up so I can fly for two hours before heading home.
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Old Jul 02, 2001, 11:57 AM
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Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Jastown, you're right about your method being hard to beat for the money. For those who don't have the knowledge or desire to experiment with cellular phone batteries, there are alternatives that aren't outrageously expensive. For instance, you can get the same 7.2V from the same 84 grams with a higher 720mAh by spending about $20 on a 6-cell Sanyo NiMH AAA pack.
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Old Jul 02, 2001, 02:03 PM
Registered User
Warsaw, IN, USA
Joined Jun 2001
56 Posts
Neopoint 1000 batteries are what I use.

Similar batteries are rated a max discharge rate of 2C meaning these would be good to 1.2 amps. The DX-A motor pulls alittle more , but I have cycled mine many times and have had no problems except for the one that was stuck up in a tree overnight and was fully discharged. Even that pack seems to be OK but the first recharge got quite warm.

I found the Rayovac 9v disappointing after using these.

Why fight over every gram on your airframe when your batteries make up so much of your weight problem.
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Old Jul 02, 2001, 09:22 PM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Jeff, you're right about the extra NiMH cell. That would raise the cost of the pack by a couple of bucks and the weight by half an ounce. But it's kind of a moot point now that Jastown has cut the weight of his lithium pack in half. I wish I could take weight out of my slowflyers that easily! ;-) Seriously, I was thinking that those must be some really inefficient lithium cells to be so heavy. I'm a believer in lithium cells or I wouldn't have spent so much to buy Tadiran packs. Maybe I should start studying up on some of these bargain cell phone cells.
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Old Jul 03, 2001, 12:20 AM
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Warsaw, IN, USA
Joined Jun 2001
56 Posts
Ooops, Sorry I had my pack weight wrong. That is 42grams. I was thinking of my 4cell pack.
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Old Jul 03, 2001, 12:55 AM
"Simplify, then add lightness"
Raleigh,NC
Joined Nov 2000
2,700 Posts
Jastown - What cell phone are your 600mah cells from. I am using 830mah cells from Qualcomm PDQ phones. They are 53 grams for two cells. I would like to try some lighter cells.

Dave - I really think you have to have 7 NIMH cells to perform like two Lithium Ion cells. A 6-cell NIMH and a two cell LI both start out at 8.4 volts fully charged, but the NIMH rapidly drops to 7.2v or less, and the LI doesn't get down to 7.2 until it is almost fully discharged.
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Old Jul 03, 2001, 09:41 AM
Registered User
Warsaw, IN, USA
Joined Jun 2001
56 Posts
I will say a few words of caution before everyone runs out and starts ripping up cell phone packs.

Lithium ion batteries are not all alike and are not standard by any means. Separating the cells from their designed chargers and safety circuitry is a risky business and great care should be taken. Yes, your battery could explode ect.

If you don't like messing with electronics or and like to expirement I would recommend NiMH batteries.
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Old Jul 03, 2001, 10:31 AM
"Simplify, then add lightness"
Raleigh,NC
Joined Nov 2000
2,700 Posts
I want to second what Jastown said. Lithium-Ion can and will explode very violently. That is why they are only sold to manufacturers who include the proper protection circuitry which includes under-voltage, over-voltage, and over-current protection. I leave the protection circuit attached on mine. It only adds one gram, and makes me feel a lot more comfortable. If you are not sure what you are doing, stick with NIMH.

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Old Jul 04, 2001, 12:33 AM
Mountain Models Wannabe
CoClimber's Avatar
Ithaca, NY USA
Joined Mar 2001
4,370 Posts
I want to third what Jastown said. When I first got into slow flight, I experimented with Li-Ion packs and now I just use NiMH.

For the record, I am an electrical engineer and work for a company that designs hand held test equipment. I finally decided that with 20+ minute flights out of the 300mAH NiMH packs, it's hard to justify the Li-Ion issues.

Doug
www.mountainmodels.com
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