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Old 03-13-2008, 11:36 AM   #31
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C rate should matter as it means better performing Lipos and also you normally pay more for higher C rating. I know as a consumer I would be upset if I paid more for a certain C rate only to find out it's lower.
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Old 03-13-2008, 11:40 AM   #32
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All of our discharge testing was done with the stock PACK. Stock wires, and stock connector just as it comes to the user.

Factory data is from bare single cells with no wires/connectors/intercell connections, and thus lower resistance/better figures than what happens in real life with an actual assembled pack.
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Old 03-13-2008, 11:54 AM   #33
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thanks, i stand corrected, (again, damnit)
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Old 03-13-2008, 12:02 PM   #34
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Originally Posted by Wild Cherry View Post
C rating means nothing to me.

I already know the "battery matcher`s" will always claim higher C number`s than other battery`s available, no matter what ....
I'm not sure it is the packs from the "battery matchers" that you need to worry about.
Besides, battery matchers that fudge numbers don't stay in business very long.
We encourage everyone to cycle their packs at 35 amps on a GFX and print the numbers on the box like we do. Like I said, we have nothing to hide.
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Old 03-13-2008, 12:17 PM   #35
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Jack, are you finding packs you need to eliminate based on the cycling? It seems if all packs come to you within some variance then cycling them is just an added cost (as Im sure you dont do it for free). Seems you could just take a sampling of packs and say the pack will fall into that range. Just a thought.
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Old 03-13-2008, 12:20 PM   #36
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how much does a stock motor, or BL 13.5 pull in amps. I guess this is where everyone is trying to get an advantage. I would just figure if this equation is correct (C rating x mah of lipo, divided by 1000). I wouldn't be concerened about the C rating. Just get a lipo of about 5K or 6K and that would be sufficient enough to provide punch/power through a 5 minute race.

Now i'm just a weekend racer, so I do not claim any expertise in Lipo or any r/c electronics. so I figure it this way. If this is wrong and way off and will learn by continuing to read this thread.

This is how I have concluded lipos:

I figure a 20c 6000mah lipo equals (20c x 6000 divided by 1000) equals 120 continuous amps while maintaining the required voltage?

While a 25c 3600mah lipo equals (20c x 6000 divided by 1000) equals 90 continuous amps while maintaining the required voltage?

So a lower C rating but higher mah rating can actually have a higher continous amp rating? is this right?

So I figure if I use a higher milliamp lipo, C rating is not that important to me and I get a longer run time.

Am I somewhat close?
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Old 03-13-2008, 12:34 PM   #37
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The reason why we cycle our Lipos is to make sure they fall in the range we expect them to be in. Yes there are some packs although very few that aren't what we expect them to be. As with any products there are some fluctuations but our goal is to try and eliminate the ones that are below the specs we expect from our packs. We do this extra step to make sure our customers get what they paid for.
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Old 03-13-2008, 12:36 PM   #38
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Quote:
Originally Posted by teabag View Post
how much does a stock motor, or BL 13.5 pull in amps. I guess this is where everyone is trying to get an advantage. I would just figure if this equation is correct (C rating x mah of lipo, divided by 1000). I wouldn't be concerened about the C rating. Just get a lipo of about 5K or 6K and that would be sufficient enough to provide punch/power through a 5 minute race.

Now i'm just a weekend racer, so I do not claim any expertise in Lipo or any r/c electronics. so I figure it this way. If this is wrong and way off and will learn by continuing to read this thread.

This is how I have concluded lipos:

I figure a 20c 6000mah lipo equals (20c x 6000 divided by 1000) equals 120 continuous amps while maintaining the required voltage?

While a 25c 3600mah lipo equals (20c x 6000 divided by 1000) equals 90 continuous amps while maintaining the required voltage?

So a lower C rating but higher mah rating can actually have a higher continous amp rating? is this right?

So I figure if I use a higher milliamp lipo, C rating is not that important to me and I get a longer run time.

Am I somewhat close?

You are partially right as a higer mAH pack will have better average voltage and lower IR but a higher C rate pack will have better IR and higher average voltage as well. So C rate does come into play when looking for Lipos with the best performance.
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Old 03-13-2008, 12:46 PM   #39
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This thread is interesting. I thought there was something in the ROAR rules about Lipo batteries having to pass some tests. I'll be honest and say I can not remember what they were apart from some drop test of the casing. Do any of the rules cover true C ratings or at least a standard test so that people who buy a 20C battery know they are getting a battery that has passed ROAR approved 20C testing?

I can understand why they wouldn't as that really isn't a ROAR thing (more a battery matcher thing). Some kind of industry standard testing would be sweet though.
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Old 03-13-2008, 12:52 PM   #40
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The voltage is not depending of the C rating

i tested 22C cell who are more voltage at 30A (12C) than 25C cell from same manufacture

not same raw material

the bug is to compare cell between other when person tell where he take is pack and not make real spec sheet from manufacture

can be that one has all the same manufacturer
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Old 03-13-2008, 12:56 PM   #41
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Originally Posted by GreaseMonkey View Post
This thread is interesting. I thought there was something in the ROAR rules about Lipo batteries having to pass some tests. I'll be honest and say I can not remember what they were apart from some drop test of the casing. Do any of the rules cover true C ratings or at least a standard test so that people who buy a 20C battery know they are getting a battery that has passed ROAR approved 20C testing?

I can understand why they wouldn't as that really isn't a ROAR thing (more a battery matcher thing). Some kind of industry standard testing would be sweet though.
Most of the tests ROAR conducts are to ensure safety, since that is really the most important aspect.
By cycling the packs, we are hoping to at least establish some relative parameters consumers can relate to. I'm sure an industry standard of testing will evolve and the cream will rise to the top, as others have mentioned.
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Old 03-13-2008, 01:01 PM   #42
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Originally Posted by dgaumond View Post
The voltage is not depending of the C rating

i tested 22C cell who are more voltage at 30A (12C) than 25C cell from same manufacture

not same raw material

the bug is to compare cell between other when person tell where he take is pack and not make real spec sheet from manufacture

can be that one has all the same manufacturer
We have seen this too. This is why I stated on another thread (and got mauled for it) that some R/C manufacturers MAY purchase cells from different cell manufacturers.
This just proves the original statements by Tekin regarding variations in C ratings not only from brand to brand, but perhaps within the same brand.
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Old 03-13-2008, 01:20 PM   #43
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Another factor that can influence the voltage and resistence of a lipo pack is age. Although we are still doing tests on this, it is known that storing a pack with a fair amount of charge may be good for the longevity of the cells, but it does decrease performance. Again, this probably makes no difference to the average racer, but it will impact the numbers on say, a GFX. This may also be why one pack checked out lower, despite a higher C rate.
Just throwin' ideas around here.....
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Old 03-13-2008, 01:49 PM   #44
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the chinese manufacture play a game

with +- 2 raw material type and i see only difference on assemblage quality and size
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Old 03-13-2008, 02:04 PM   #45
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Default All these Li-po worries

I am by no means a pro or a semi-pro and by no means attend the big nat races but have been in this rc world since we used to pre set what we wanted a car or plane would do and then went wow.
Now on these li-po batt this is my what I have gone though, I joined in last april and looked at li-po and brushless and had to drive 1 1/2 hours to another hobby store cause the store I go to said those blow up u don't want those. We'll went down there and they had maxamps and orion, the orion was 149 and a 3000, the max amp was 90 and a 5000, decision decision? The orion was cool looking but I think I'll try the max amp, well also picked up a gtb and 6.5 combo and oly crap this is fun now. Last summer I drove to alot of different tracks in my area and have done well, now I can't say how many times I have charged my pack but I go to a race jst about every weekend and what charge it 2 times a race so for almost a year, we'll say 40 races times 2 so 80 cycles and thats not counting all the practice times? and what I have noticed i'm still getting close to te same numbers I had at the start, and this was with a $59 charger I got called rc power that a flyer friend told me to check out, and I didn't have to buy and make all kinds of charging leads or buy a balancer it was all in one shot, not like some $150 plus chargers out there, last on this part I kept hearing balance charge so before indoor started I read my charger and did a balance charge, did it increase my numbers, sure little, did it increase the run time, how to tell the races are 5 mins? Do I think u should balance sure but these are not ni-cd or ni-mh where one cell starts dropping and that draws the rest of the pack down so that u start to lose a secor 2 in lap times 3 mins in.
So this guy who says they don't last and are expensive I'll break down this- 1 battery-$90, 1 charger-$60=focus on driving and relax---before li-po-
carry ur 6 best matched packs for practice and runs $40 plus each, that $350 turbo 35, the building jig, discharge trays,that $100 soldering station, batt bars,wire batt tape,shrink wrap do I need to keep going=alot more$$$$ and countless nights working on and building packs trying to keep up with one or 2 sponser driving and he still gets 1/2 second a lap and u walk by and catch sight of one of there batt then run to the hobby shop and cry he's got better numbers and they go he gets his from company x y z cause he's sponsored.
With the rating of 20c,23c,30c,or35c i'm a simple guy(not electric professor) and I at from my experience,I own a trucking company and years ago I built a service truck to handle breakdowns and the first time a truck had a dead batt my littlr service went out and tried to jump it and it wouldnt I then took the truck to my dealer and told him my problem and told him I wanted bigger battery's put in and a bigger alt, he then said dude u have all that where's ur cable's then it was dude get bigger cables u can only push so much current though those so I bought 1/2" thick cables and now it works great, or think of it this way u got 2 tankers 1 is 10000 gal and other 12000 and ur filling 2 pools same size, u hook up 2"hoses to each tanker, which pool will fill faster? the same right but if u put a 4" hose on the 12000 tanker it would fill faster right.So now u got a batt rated at 20c and see a batt rated at 35c and u think more power, but to get that power to the motor u have to put in #4 wires(lets not think of the speed control going poof or the motor ) and u think my last main I had an average of 21mph now if I put I run this 35C rated batt I should have a 31mph average but how are u going to put that power to the track with the new brushless and li-po most people are dialing out power to stay in control? Look at nitro with engines in the last few years coming out with so much power what are people doing smaller air inlets and lowering compression to tame the power and increase run times.
Do I think orion, trinity,or the other top company's battery are better sure and I ran agaisnt these this winter and won some races and lost some races(then I would have to go home and beat the wife --well maybe she beat me but fun either way) What I have seen at my track is the sponsored driver whom comes there doesn't out power everyone now and my prediction for 2008 maybe 2009 is there is going to be less big names winning races.
These are my opinion is that alone and not all that smart but have alot of fun and love reading all these ideas and learning new things.AND IF U MADE IT TO THE END OF THIS U GET A GOLD STAR got a little winded
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