R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 03-12-2008, 03:35 PM   #1
Team Tekin
 
Tekin Prez's Avatar
 
Join Date: Mar 2005
Posts: 1,047
Default Claimed Lipo Discharge Rates

All 20c lipo batteries are not the same. There is no standard for determining the maximum discharge rate of a lipo battery currently. So what should it be?

One cycle without completely destroying the battery?

100 cycles without damaging the battery or reducing capacity more than xx%?

Max temperature under the rated load?

Currently it is just a meaningless marketing number that seems to be increasing faster than the technology is improving. It has never been more true that you get what you pay for in the long run.

Tekin Prez
Tekin Prez is offline   Reply With Quote
Old 03-12-2008, 03:39 PM   #2
Tech Champion
 
Join Date: Oct 2005
Location: Cincinnati, OH
Posts: 5,360
Trader Rating: 38 (100%+)
Default

Quote:
Originally Posted by TeamTekin View Post
It has never been more true that you get what you pay for in the long run.

Tekin Prez
Did you mean to say less true? This statement doesnt seem to fit in with the rest of your post.
or8ital is offline   Reply With Quote
Old 03-12-2008, 03:43 PM   #3
Tech Initiate
 
Join Date: Aug 2004
Posts: 34
Default

So....... what are you trying to say?
Biff Malibu is offline   Reply With Quote
Old 03-12-2008, 03:43 PM   #4
Tech Regular
 
Join Date: Feb 2008
Location: France
Posts: 259
Default

I you really want to do better than other brand keep the 20C on package and provide true value with CBA test and capacity after 100 real world cycle (something that represent typical harsh A main). True racer a not blind, that will at least prove that you did test your battery... (not just put a stickers on it)
Mister-T is offline   Reply With Quote
Old 03-12-2008, 04:13 PM   #5
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

Hi Tekin Prez - excellent points there.

This is how we feel about ratings for our CORE packs:

Firstly lets define "C" rating:
Oh wait - that's right, no one has a standard definition of what that number actually means! (and I'm being serious)

To ME: The C rating means that the pack can output "X" many amps for the duration of it's capacity WITHOUT doing either of two things:
1) dropping below 3.0v/cell, and
2) heating up beyond 140degF (max safe lipo temp).

The C rating comes from the following math, again using the CORE pack as an example:
First, you must actually have and use some serious discharging equipmnet including voltage and current monitoring/reporting along with a temp gun. Hook up the pack, and throw a load on it. The CORE 5000's were reportedly 20C packs, so I conservatively threw 80A at one to see what happened to the voltage and temperature for the first discharge test cycle.

5000mah of capacity, so again /1000 to equal 5 amp hours of capacity.
Find the maximum amps you can discharge with (for the whole capacity) without dropping voltage below 3.0v/cell or the pack heating beyond 140degF. In this case we'll use 100A as that figure for round #'s (it was a touch higher than that in actuality).

5 amp hours divided by 100Amps of discharge capability = 20 times the capacity, or 20"C".

Again: that's MY OWN definition of what C rating means. Unfortunately, most packs out there DON'T live up to the ratings given for them, according to my my own personal definition/testing/determination.

And here's where the problem lies (whoops - did I just say lies?).
1)Not many folks have access to 100A+ discharging equipment.
2)From the simple answer above - if you have the choice between two packs with the same Mah capacity, and one was labeled 20C and the other was labeled 23C, everyone would buy the 23C pack.
3) There's no real testing/performance standard either in the lipo industry, or the hobby industry.

So when you add up all three of the above items, you begin to realize what the racers are really facing right now. What does 15-20-25-30C really mean???? By what (and who's) definition was that C rating determined? Were packs actually discharge tested? Are the brands just using whatever the factories tell them the C rating is? (and again - by what standards are the factories using?) Are they just flat making up numbers higher than anyone else's just to sell packs?

When it comes right down to it - If I wasn't restricted by my own morals and professional integrity, I could advertise the CORE pack as 35C and probably sell 10x more than we already are. Think about it - WHO out there is an unbiased party and has discharge equipment capable of 175 amps to prove that it's not?

So the moral of the story here is a repeat of what I've already said should be important to the consumer: Do you trust who you are dealing with? Do they have years and years of application and industry experience with the lipo products they're selling? Do they really know everything about it in order to support you with accurate advice, accurate performance claims and safe usage guidelines? Have they been asked what their C ratings mean, and by what method they were determined?

Personally, I think the questions above are important for the racer to have good solid answers to, and I'm proud to do just that for customers of our CORE brand packs.
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 03-12-2008, 04:38 PM   #6
Team Tekin
 
Tekin Prez's Avatar
 
Join Date: Mar 2005
Posts: 1,047
Default

Quote:
Originally Posted by or8ital View Post
Did you mean to say less true? This statement doesnt seem to fit in with the rest of your post.
Assuming the high quality batteries are more expensive, you get what you pay for. Right now I think you may be right that it may be less true since it is a crap shoot. Tons of new batteries flooding the market with all different qualities and prices all claiming 20C or higher. This will be interesting in 6 months to see who used marketing numbers and who used engineering numbers.

Quote:
Originally Posted by Biff Malibu View Post
So....... what are you trying to say?
I thought it was pretty clear.

Brand A can handle 20C one time, maybe, and then it is soft and looses a large amount of capacity

Brand B can handle 20C for 100 cycles and still perform at 90% or better

They are both rated at 20C but not really the same product, so this number is pretty useless unless there is a standard for determining it.

Quote:
Originally Posted by Mister-T View Post
I you really want to do better than other brand keep the 20C on package and provide true value with CBA test and capacity after 100 real world cycle (something that represent typical harsh A main). True racer a not blind, that will at least prove that you did test your battery... (not just put a stickers on it)
I agree. We have tested many, many cells over the last 2 years. I have a pile of junk to show for it. If we had found a good cell before now it would have already been on the market. We now have a great cell that could be called 20C or could really be called a 25C or even 30C depending on how you choose to define it. My marketing head says it is a 30C to clearly show it is better than most current 20C batteries. My Engineering core and moral standards say it is a solid 20C and even by our strict standards maybe a 23C. We do not get the chance to explain this to an average consumer. So this rating system needs to be ignored or validated. The burden and expense of validation unfortunately falls on the consumer at this point.

Shawn…

Unfortunately doing things right does not always make you successful in today’s markets. The reputation of the brand helps, but the products must speak for themselves in the end.... assuming they get the chance in a sea of choices.

Tekin Prez
Tekin Prez is offline   Reply With Quote
Old 03-12-2008, 04:56 PM   #7
Super Moderator
R/C Tech Elite Subscriber
 
Join Date: Oct 2007
Location: Rochester Hills Michigan
Posts: 7,232
Default

Mr. Palmer and 'Tekin', your honest approach and concern is refreshing and appreciated. For the record I am a very happy customer of both.

For the rest of us, let's keep it in some perspective. As Shawn refers to, these are pretty incredible numbers. Way above the alternatives. So while I would suggest we continue to recommend and support such quality companies and products, if your battery only really does, oh lets say, 80 amps continous, not 100 or more, IMO there really is no reason to get all that concerned.
Dave H is offline   Reply With Quote
Old 03-12-2008, 05:04 PM   #8
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

Quote:
Unfortunately doing things right does not always make you successful in today’s markets.
Tounge in cheek here:
If it takes marketing dishonesty and ignorance of your own product to be a success, then I'll happily stand up and declare myself a failure

BUT - I'm a failure with tens of thousands of happy fully informed customers over a long span of years that have products they've purchased from me that do EXACTLY what I've said they will do. Sometimes the measure of success lies in the amount of personal integrity you can take home with you each day. I've taken all of mine home with me for years in this industry, and the companies I've worked for have all benefitted greatly right on the bottom line because of it.

Don't get sucked in to the hype wars because you'll make a few extra bucks today. Those particular bucks will bite you down the road, and you'll have nothing left BUT the hype to hang your hat on because the customers trust will have left just about the same time you threw your integrity out the window.
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 03-12-2008, 07:02 PM   #9
Suspended
 
Join Date: Mar 2003
Location: Back That Thang Up!
Posts: 3,468
Trader Rating: 11 (100%+)
Default

Just a few months ago we kept hearing from "industry leaders" about how lipo would blow up in your face.

Now those same "industry leaders" are trying to get on the lipo bandwagon because they know NIMH is (or will soon be) DEAD for for the future of racing.

Always beware of the bias and agendas behind the the statements!
403forbidden is offline   Reply With Quote
Old 03-12-2008, 07:22 PM   #10
Tech Initiate
 
Join Date: Jun 2007
Posts: 28
Default

Anyway

if you see one pack with 5000mah 30C with only #12 awg wire

you are sure than the pack never pass the test at 150A

all #12 wire flame at more than 120A

and the C rating doesnt include the lifespan of the pack only attractive number to sell more

when i have very good pack in hand i discharge it to 6V and all cell reach 3V in same time and when i recharge it i don't need balancer all cell was exact same capacity


and for the 3V / cell when you see the spec of manufacturer at 2.75V min and 2.7V discharge this is for the capacity and for the C rating also
ironxxx4 is offline   Reply With Quote
Old 03-12-2008, 07:44 PM   #11
Tech Lord
 
syndr0me's Avatar
 
Join Date: Dec 2004
Location: 5280 Raceway
Posts: 13,140
Trader Rating: 32 (100%+)
Default

In R/C racing, one thing that will really differentiate one brand of cell from the next is its voltage under low to medium load. Stock racing will be especially affected by these measurements. LiPo seems to hold its voltage well under high load, but are we really using it in such a manner, especially as we trend toward slower, more efficient motors?

This reminds me of the old Mhz wars for CPU's back in the day.
syndr0me is offline   Reply With Quote
Old 03-12-2008, 08:20 PM   #12
Company Representative
 
Danny/SMC's Avatar
 
Join Date: Oct 2001
Location: Elkton, VA
Posts: 3,097
Trader Rating: 2 (100%+)
Default

Actually it's my understanding that C rating is the ability of that cell/pack to handle the maximum current(C rate) and still retain 90% of it's rated capacity. If you look at graphs from various manufacturers you will see they test at different C rates and the capacity goes down as you increase the C rate. I know that our 28C packs are tested this way.

I have asked our manufacturer for the graphs of our 28C packs and as soon as I get them I will post them.
Danny/SMC is offline   Reply With Quote
Old 03-13-2008, 12:25 AM   #13
Tech Champion
 
oXYnary's Avatar
 
Join Date: Dec 2003
Posts: 6,301
Trader Rating: 4 (100%+)
Send a message via AIM to oXYnary Send a message via Yahoo to oXYnary
Default

Nice to see some Manufacturers in here trying to come to a consensus. Maybe you could work together to create and promote a standard that at least your companies could use and promote?

Specific equipment and/or graphs that must be linked to the batteries website showing the testing method did indeed follow the method you all decided upon.

That would increase the faith in at least the companies that choose to follow the methodology. Plus, give us a 1 up on the airplane guys whom have had a much longer time to try to establish a consistent baseline.
oXYnary is offline   Reply With Quote
Old 03-13-2008, 02:36 AM   #14
Tech Elite
 
Bob-Stormer's Avatar
 
Join Date: Dec 2001
Location: Glasgow, Montana USA
Posts: 3,518
Trader Rating: 8 (100%+)
Default

Quote:
Originally Posted by oXYnary View Post
Nice to see some Manufacturers in here trying to come to a consensus. Maybe you could work together to create and promote a standard that at least your companies could use and promote?
Absolutely, a good idea, but away from the rest of us. 2 things you don't want to see made, Hot Dogs and Law. I think the latter applies.

<---likes hot dogs.
__________________
www.stormerhobbies.com "Where the world shops for radio control."™
www.facebook.com/stormerhobbies
www.twitter.com/stormerhobbies

looking for....vintage 1/10-1/12 pan, need Schumacher 1/12th cars and parts.
Bob-Stormer is offline   Reply With Quote
Old 03-13-2008, 04:48 AM   #15
Super Moderator
R/C Tech Elite Subscriber
 
Join Date: Oct 2007
Location: Rochester Hills Michigan
Posts: 7,232
Default

Remember I think in this case that this bench spec racing is somewhat irrelevent. As noted by others this performance is beyond how we are actually using these things. Which is exactly opposite of back in the day.
Danny, how do you know that the packs are being tested this way? Seems a little surprising to me, isn't the company name Superior Matching Concepts, not Superior Manufacturer Commision? Which if represented properly can be a legitimate biz model. But as an established industry player, you are claiming the best numbers, and you apparently aren't verifying the manufactures claims? I may be off base here, my apologies if so, feel free to call me out, but how is what you have offered so far different from all the other resellers jumping in? That seems to be at least one point of the thread to me.

Last edited by Dave H; 03-13-2008 at 05:34 AM.
Dave H is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Lipo Discharge Rate Questions jk racing Electric Off-Road 14 08-14-2011 12:55 PM
Saved a 11.1V TX LiPo from discharge to 1.8V? ESWLFSE Radio and Electronics 1 04-28-2008 12:07 PM
Orion 3200 Lipo Discharge voltage? ioxqq Electric On-Road 9 12-20-2007 11:36 PM
Octane Booster: Does it really work as claimed? RC Dumb Nitro On-Road 1 09-03-2004 07:43 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 04:05 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net