15C? 20C? Whats it mean? (Full Version)

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gadget463 -> 15C? 20C? Whats it mean? (4/22/2008 11:16:02 PM)

I'm just ordering my heli and am wondering about the batteries, there is 20C's for $50, or 15C's for $40. I know these are the ebay hong kong cheapos but have heard good things about them. I don't know what the 15C/20C means, Cells maybe? Is there a difference? Also they are mostly 2200mha not the "recommended" 2100's. Will they still fit?

If anyone knows of a good page that teaches this stuff PLEASE let me know. Thanks!



Red Scholefield -> RE: 15C? 20C? Whats it mean? (4/23/2008 12:38:55 AM)

Ask the battery vendor what they mean. [)]



Red Scholefield -> RE: 15C? 20C? Whats it mean? (4/23/2008 12:39:15 AM)

[8|]Ask the battery vendor what they mean.[>:]



gadget463 -> RE: 15C? 20C? Whats it mean? (4/23/2008 1:33:25 AM)

Wow what happened to "resist the urge to curse, flame, degrade, insult or embarrass". I thought your website said "For a great exchange of battery information visit the Battery forum found
at R/C Universe".

Just trying to get some info.



nikg -> RE: 15C? 20C? Whats it mean? (4/23/2008 2:27:33 AM)

GadgetI don't think Red meant it in a degrading or mean type of way. (I don't think)

Anyway, the C rating for these batteries refers to their current output. 1C is one times the capacity of the battery, so 10C is ten times, 15C is fifteen times and so on.

Using a 2000mAh battery for simplicity of the math, a 10C would be able to deliver 20 amps, a 15C would deliver 30 amps, and a 20C would deliver 40 amps.

So, the 2200mAh batteries in your case would deliver 33 amps (15C) and 44 amps (20C). Usually higher amps are more desirable, but I run an electric truck where bursts of high current are needed. I have no idea the requirements for a Heli, but I'm assuming they may not be as high. I'm not sure, though.

As far as their fit you would need to know the dimensions. The difference between the 2100 and 2200 packs are most likely little or nothing, but again you would have to check. For NIMH and NICD sub-c cells, 3300mAh and 4600mAh cells are just about the same size because they are classified as sub-c. I would think in Lipo the more important consideration is the S and P numbers. The S indicates how many cells are in series (2S are 7.4v and 3S are 11.1v etc) and the P is how many of these groups are in parallel. The higher the S, the higher the voltage and the higher the P the higher the amperage (typically). So if your Heli takes 2100 2S 2P packs and you are getting 2200 2S 2P packs, then I bet they will probably fit.

I would make sure I did my research before investing in batteries, it will pay dividends in the long run.




gadget463 -> RE: 15C? 20C? Whats it mean? (4/23/2008 3:36:21 AM)

Thank you i really appreciate it. I am just trying to get into this hobby and working my way up from a Blade CX2 that comes with everything you need and fully assembled, so stepping into this one that can be built with a million different parts in 10million different ways is so frustrating. I'm just trying to get the information because I am on a very tight budget and I can't afford to make a mistake and have to buy the same parts twice. This is frustrating enough as I feel like an idiot having to ask questions that I'm sure everybody else knows. I wish there was a book that explained everything.



Rodney -> RE: 15C? 20C? Whats it mean? (4/23/2008 3:26:18 PM)

Be very Leary of taking these C ratings literally. I think that is what Red was implying when he said check with the vendor as different manufacturers use different meanings. In general, it should mean what nikg said but: if you run at those rating for any length of time, I doubt your batteries will last very long. The "check with manufacturer" is excellent advice as the rating could be "Burst current for ? seconds only" or have some other definition.



Red Scholefield -> RE: 15C? 20C? Whats it mean? (4/23/2008 5:37:48 PM)

Let me put it in simpler terms. Few LiPo vendors have a clue as to what their C ratings actually mean. They are 99% marketing, "My C is bigger than their C"., It should mean, if you can give it a meaning, that the maximum continuous discharge you can sustain without taking the batteries over a temperature that will significantly reduce their lives. This temperature is thought by some of the more knowledgeable vendors to be 140ºF (60ºC) as I recall. I can tell you, and others will agree, that if you push the discharge of a LiPo pack to the maximum continuous overcharge allowed by the vendor that you will be buying a lot of replacement packs. That may be the real meaning behind these ratings. [:(]



gadget463 -> RE: 15C? 20C? Whats it mean? (4/23/2008 7:10:35 PM)

Thank you, could anyone recommend a good (preferably lower priced) battery and a good place to buy them? I will just be hovering for the first while so I'm assuming I don't need a high end battery till I get in to 3d stuff, and I don't know how long they last, but I'm sure I'll have thrown these out by the time I'm ready for that.



nikg -> RE: 15C? 20C? Whats it mean? (4/24/2008 2:40:49 AM)

You might want to ask in the heli section or even a car section. Lots of people in those forums who have the same equipment or have been through similar circumstances. Since the batteries are the heart of the vehicles you are sure to get lots of responses.

I forgot to add what Red said about the ratings. They can be totally misleading. Even in NIMH cells, some manufacturers claim 4500mAh capacities and high discharge rates, but real users experience that the cells hold much less than that 4500 claim and are not very punchy.



gadget463 -> RE: 15C? 20C? Whats it mean? (4/24/2008 3:16:02 AM)

I'll ask there then thanks, the LHS is great, but the costs of batteries here is quite high, around $90 for a 2200mAh. Same thing with parts, I bought the T-rex there cuz it was reasonable, $200, and I want to support them, but the Transmitter was an extra $100 here so I got all the rest at helihobby.com.



jester_s1 -> RE: 15C? 20C? Whats it mean? (4/26/2008 11:08:19 PM)

Don't skimp on batteries. Considering the cost of the whole vehicle, good batteries aren't that costly. Bad batteries are, since a failure virtually guarantees a crash.



BarracudaHockey -> RE: 15C? 20C? Whats it mean? (4/26/2008 11:40:50 PM)

Do yourself a favor. It will be better to spend the money on two Flight Power or Thunder Power packs than to spend the same money on 3 cheapos that you will be replacing all the time because they can't keep up with the current delivery.

Hikg, depending on the setup, helis can put a very demanding load on batteries. Most guys won't fly a Trex 450 for example on anything less than 18c and most of us run 25C



Bosley2 -> RE: 15C? 20C? Whats it mean? (4/27/2008 6:35:10 AM)

Get a hyperion pack. they are made in south korea ( where all the best lipos are made from) and You can normally get 200+ cycles out of them if treated properly



nikg -> RE: 15C? 20C? Whats it mean? (4/29/2008 3:42:20 AM)

Hey Barracuda, what's with the "HikG" comment? You callin' me a hick?!!!

Just kiddin'

Thanks for the info. I had no idea what kinds of loads helis ran. I guess the resistance of the blades trying to keep it aloft is a constant drain at high rate even if they don't exactly call for the bursts of power that cars/trucks might demand. On the other hand, maybe they call for bursts as well. Never flown anything so I don't know. Lipos seem perfectly suited for these applications with their light weight and high current capabilities.

I agree that aircraft are a different game than cars or boats. Failed batt in car or boat is not a problem, they just don't move. Failed batt. in aircraft means...well...lots of duct tape or a trip to the LHS with a wad of cash.



gadget463 -> RE: 15C? 20C? Whats it mean? (4/29/2008 3:56:53 AM)

Ok this part sucks. I have a heli and now i have to sit here and stare at it for weeks while all of the parts come in. i have everything on order but only have the bird. I found Ebay is a horrible place as they have all sorts of cool stuff that I can't help but order while I'm waiting. I have 2 extra canopys coming as well as enough LEDs to put lights on every helicopter in the US air force!



BarracudaHockey -> RE: 15C? 20C? Whats it mean? (4/29/2008 9:36:38 PM)

Sorry, Nik!

Check out the magazine section, I just submitted a review of the new Great Planes Electrifly packs, its got Eagle Tree discharge charts for the new batteries and my exising flight power batteries, you might be surprised how many amps a little 450 size heli pulls.



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