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Old 02-16-2005, 09:20 AM   #1
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Default Lithium Poly batteries

With the rising costs of cells (matched 3600's and 3700's) how come more people arent switching over to Lithium cells? We all long for longer run times and longer mains, why hasnt anyone approached the sanctioning bodies and have them change (or at least slack up some) on the rules? Certainly if they allowed the obviously better cells, the price would come down and then we all could have some serious fun? Anyone care to elaborate.......
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Old 02-16-2005, 09:27 AM   #2
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I think the biggest concern about the Lithium Cells is safety. When these cells have an accident its a BAD thing. My guess is that is why manufacturers along with sanctioning bodies are dragging there feet a bit. In todays sue happy American society nobody wants to stick there neck out for fear of starting trouble.

Just my 2 bits
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Old 02-16-2005, 09:33 AM   #3
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Yeah, I can't wait for the day when some poor kids car gets T-boned on the straightway and his car burns to the ground.
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Old 02-16-2005, 09:34 AM   #4
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Quote:
Originally posted by Jack Smash
Yeah, I can't wait for the day when some poor kids car gets T-boned on the straightway and his car burns to the ground.
It'd bring us one step close to true scale racing.... hehe....

They'll be along in time....
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Old 02-16-2005, 09:42 AM   #5
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The real problem is in the puncturing of the cells which causes the KA-BOOOM facture to accure. Muliplex & Hitec are R&D'ing li-po cells that have a hard case around them (to portect them from punctures) and are the size of a stick pack as to fit in the current cars. The other problem in Li-Po is that if you let the voltage drop below a certain point the cells can not ever get back up. Sollution already in the works I think Novak has a voltage limiter (as to be used in an eighth scale buggies already)and is working on a voltage cutoff device to keep your cells from falling past the cutoff range. Once these two major problems are solved we should see Li-Po's everywhere, heck look in your cell phone. been there for a long time. Well one more problem of cource is those who don;t have a Li-Po friendly charger will have to pony up some $$$, and of cource little Johny trying to charge Li-Po with his Duratrax Intellipeak......That is the one I hope never happens.
Hope this helps shead some light on this topic.
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Old 02-21-2005, 05:28 PM   #6
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Milwaukee Electric is releasing the worlds first lithium-ion cordless power tools later this year. The packs are the same size as 18v packs but are 28v. Each pack has a small microchip inside to protect the pack from overcharging or dropping too low.

Technology like this will revolutionize RC. Either you will have the same size packs that we do now with much higher voltage or we will have the same voltage in a much smaller pack. Either way it will mean big changes to RC car design.
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Old 02-21-2005, 05:52 PM   #7
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I'm actually in the process of shopping the web for a small LiPo and voltage regulator to run in my 1/12th as a reciever pack....
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Old 02-21-2005, 07:29 PM   #8
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Li-Ion and Li-Po are two different battery formula. Li-Ion is very unstable in the presence of moisture. It has to be completely sealed. Li-Po is the latest and a lot more stable. it comes in foil casing (if you call that a case). It can not be fast charged as the Ni-MH but it can be discharged at up to 20C depending on the cell structure and the manufacturing process.
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Old 02-22-2005, 09:35 AM   #9
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I sell lots of cordless tools and I am obviously into RC so I have done a lot of studying on battery technology.

Its true that Li-Po probably has the brightest future but Li-Ion is still much better than Li-Po, Ni-MH and Ni-Cad in terms of energy density i.e. the amount of energy that can be stored in a certain amount of space. Also, Li-Ion batteries are almost zero maintenance, needing no cycling and having no memory problems. The main difference between the two lithium types is Li-Po uses a dry electrolyte which is sometimes "gelled" to decrease internal resistance while Li-Ion uses a traditional wet electrolyte. So Li-Po would be safer in terms of possible leakage. But Li-Ion has higher energy density and higher cycle count than Li-Po.

One problem that Li-Ion would have in RC is that the battery's performance goes down drastically as heat goes up. Also, Li-Ion has about a 2-3 year shelf life regardless of use and some reduced performance can be noticed within the first year so "freshness" would be an issue.

The main limitation to lithium batteries for RC is that they can't deliver the high current that is needed for competitive racing so until the technology improves we probably wont see lithium in our electric touring cars.
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Old 02-22-2005, 11:51 AM   #10
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Quote:
Originally posted by JosephatCRC
Li-Ion and Li-Po are two different battery formula. Li-Ion is very unstable in the presence of moisture. It has to be completely sealed. Li-Po is the latest and a lot more stable. it comes in foil casing (if you call that a case). It can not be fast charged as the Ni-MH but it can be discharged at up to 20C depending on the cell structure and the manufacturing process.
Joseph, I would lke to know where you are finding the information that lithium ion polymer cells can be discharger at a 20C rate. Basically that's saying that a 3000mAh cell could handle a steady 60 amp discharge. I don't personally know of any li-poly cells that can do that. I'm not bashing you so don't take it that way (I have a reputation of coming off as a smarta$$...LOL) I just want to learn. After posting this, I'm going to continue to look for spec sheets on cells that are rated that high.

On another note, I noticed Paul Cicarillo was using a small li-poly reciever pack on his 12th scale car at the Birds and I liked it a lot. I also know where to get 1/4AAA NiMH cells rated at 110mAh if anyone wants any. I can even build you custom receiver packs with them in any configuration. They would run around $20 for a 5 cell pack.
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Old 02-22-2005, 11:59 AM   #11
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I'm getting a 145mah lipo and 6v regulator for my 1/12th....
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Old 02-22-2005, 12:46 PM   #12
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Where did you find them?
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Old 02-22-2005, 01:08 PM   #13
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Batteries America and FMA direct, I haven't decided who I'm ordering from yet...
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Old 02-22-2005, 01:31 PM   #14
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vtl- thanks for the info. I found a couple of places the other day but those are great sources!!

Joseph- I found that FMA direct claims the Kokam packs are capable of a 20C discharge. Please accept my apology for doubting you. I wasn't aware the new platinum poly packs were rated that high... great news for us!!
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Old 02-22-2005, 09:34 PM   #15
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Quote:
Originally posted by vtl1180ny
Batteries America and FMA direct, I haven't decided who I'm ordering from yet...
Hey Allen go with FMA direct....that's where i got mine I gave you their number also. As far as the charger goes get one from them too..can't go wrong..
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