Espritmodel.com Telemetry Radio
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Old Feb 06, 2013, 05:14 PM
Balsa addiction since age 3
ScottSails's Avatar
Upstate NY
Joined May 2005
1,221 Posts
Quote:
Originally Posted by dharban View Post
There ARE applications where high C batteries are necessary and appropriate. Some of the ALES planes out there require small battery packs because of physical space limitations and to keep weight in the nose down. (It doesn't make much sense to put big bucks down for a light weight plane and then to stuff lead in the tail to balance a heavy battery.

I use a lot of small (850 and 1300 mah) high C packs in my planes. The best, by far, that I have used are the TP 65C packs. They deliver the goods and they last a long, long time -- even when you hit them hard on every launch. I generally run these packs at 50C for 40 percent of their capacity in a single launch and then recharge them at 5C. I have been using them since they came out and have hundreds of flights on them without a single failure. Most of my rechareges are logged on my computer and I have yet to see a pack which showed any deterioration of capacity or internal resistance. I have measured the temperature rise on these packs in actual service and they still stay below the 140 F max that manufacturers recommend for LiPos.

I realize that this is a special application (much different from your applications), but I have looked at some of the cheaper packs and their C ratings are generally overstated. Given the temperature ranges I see when I run my TP's at 50C for 40 percent of their capacity, I am fairly certain that there are guys running some of the cheaper packs at higher temperatures than they should be.

If you are running cheaper 45+ C packs close to their C rating, you may be playing with fire -- literally. (BTW -- on warm days, I have seen my TP packs run MEASURED temps approaching 125F -- and before I started measuring actual temperatures, I would have called that "warm to the touch"). 140F is not as hot as you might imagine.

There may be nothing wrong with running cheaper packs substantially below their ratings (probably in the range of 1/2 of their continuous max. C rating), but if you are buying cheap 45+ C packs with the notion of running them close to their ratings, you may not end up with the savings that you expected.

Happy Landings,

Don
I agree... I would never intentionally run some of these no name Batteries at rated currents without testing them on the ground. I also do expect that the no namers will need to be replaced after 2-3 years but at $20 a battery, I am ok with that.

My real point is that acceptable tradeoffs can be made for many of our aircraft components that allow us to either have more for the $ or save some $ for say our wives

Scott
PS - I have never had a battery above 130F (finger touch without having to pull away). I have had motors....
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Old Feb 07, 2013, 09:36 PM
turn, turn, turn.
Athol, Massachusetts
Joined Oct 2005
10,154 Posts
I just realized that I should have posted this is the electric sailplane forum... sorry guys.
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Old Feb 09, 2013, 09:51 PM
Balsa addiction since age 3
ScottSails's Avatar
Upstate NY
Joined May 2005
1,221 Posts
Well if you move it there I can tell you about my $15 motors
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Old Feb 11, 2013, 02:09 PM
Registered User
LI, New York, USA
Joined Mar 2003
23,928 Posts
There is a lot that goes into price and there is a lot that goes into reliability. And most of all, there is a lot that goes into TRUST!

A couple of notes:

If we look at USA market, the major radio brands are Futaba, JR, Airtronics, Hitec and Spektrum. Note that 10 years ago Spektrum didn't exist and now it is a major force in the RC market.

The spread of servo brands is larger than radios. There reports from many of the small electric pilots is that a lot of these under $5 9 gram servos are top notch. But I tend to buy Hitec for this size stuff for 2 to 3 times the price.

Today's no name product is tomorrow's brand name.

Some of the best rated RF/Receivers come from FrSky, a vitually unknown name only a few years ago. And many pilots flying expensive stuff are flying on FrSky. Their receivers are 1/4 the price of the "brand name" guys.

So, how do we judge good vs. bad and expensive vs. cheap?

When you buy brand named stuff you are betting on the reputation of the provider. But brand name stuff fails too.

When you buy low priced off brand stuff you are taking a chance on an unproven product or you are depending on the reports from other pilots that this stuff is really good and those brand name guys are ripping you off.

I have read posts by some pretty respectible names that when they try something new they put it in a beater plane, or a foamy or something they feel they can afford to lose. After they prove it there then they move it to something more valueable.


I typically by brand name for my pricy stuff. Why? Faith and trust.

But I am willing to take a bit more risk on my lower priced items or things that are more easily fixed.

When I went to 2.4 on my Futaba 9C I spent over $500 on Futaba FASST stuff. If I had known about FrSky I could have done the same for under $200 and gotten telemetry too. And this stuff is highly regarded by glider, giant scale and glow guys alike. They are on the verge of brand name status in the module and receiver market. And soon they will be coming out with their own radio.

So, if you buy FrSky, as an example, are you buying cheap or are you buying good?

And FrSky offers FASST compatible receivers. Great reports. So if I get those am I buying junk or am I buying just as good for 1/3 the price?

Probably depends who you ask and when you ask them.
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