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Old 08-11-2008, 12:23 AM   #76
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I don't want to be rude here, but what does this have to do with figuring out what a LiPo's specs mean? You have single handedly taken this thread WAYYY off topic, & I think it's time it got back ON TOPIC. If you realy want to keep this up, why don't you just start your OWN thread on it? Let this thread do what Danny meant for it to do...
I agree Bob.
First this thread is in the ONROAD forum and its turned into a "whats best for oval" thread.

Second... as you have posted... this so far off topic I doubt it will ever get back to its intended topic.

Third... Joe I know you mean well. I read your posts on Hobby Talk and on RCTech and imho they all seem to come from a guy who has very little to spend on his hobby, or is proud on how little he can spend to race. Nothing wrong with that but it means you see everything from the cost side of things.
Not all of us operate under those conditions... some of us enjoy buying new and better stuff from time to time. And we dont consider buying a new or better Lipo pack once or twice or even three times a year as something that would drive us out of racing.

Keep up the good work Danny!

Last edited by ottoman; 08-11-2008 at 01:02 AM.
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Old 08-11-2008, 12:37 AM   #77
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some of us enjoy buying new and better stuff from time to time. And we dont consider buying a new or better Lipo pack once or twice or even three times a year as something that would drive us out of racing.
...and good for you. I race against plenty guys who like to SPEND lots of money too, but just because they DO does not mean EVERYONE does. A large percent of the concerns I raise HERE and THERE may or may NOT be my own...but every race I put on, I get asked for info, and get asked questions about WHY things are the way they are. In many cases...I'll ask, comment and portray those views. YOU PEOPLE assume since I posted them - they are my own.

I don't believe anything about my comments here are strictly directed at OVAL either...

I put on OVAL and On-Road events, and on occasion direct an Off-Road event (usually NITRO) and am working on organizing a couple NEW classes (On-Road)

The OVAL series is just ONE project - has it's OWN rules, racers and products...that has NO bearing on the other ventures.

...also, too often guys who LIKE to spend alot get PISSY when hearing about guys who don't.

I don't spend much on my cars - they are built well, run well and last. You guys want things to stay ON topic, yet have no problem adding to the OFF TOPIC discussion... btw - while I'm NOT spending anyting cause ...well frankly I'm cheap...but, I've spent over 750.00 on R/C TIRES just within the past 3 weeks, 700.00 for TRACK Rental, $300.00 in travel expenses (To and From races) doesn't leave much to spend on the car.

Now, don't take that as a COMPLAINT, cause it AIN'T - they are JUST Facts.

- man this place can be full of a lot of PISS and VINEGAR sometimes -
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Old 08-11-2008, 12:59 AM   #78
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Danny-

Are there any charger attributes that need to be considered before buying a LIPO friendly charger for the SMC packs that can get the most out of the pack? I have been running LIPO for a few years and I have found that not all LIPO charges are created equally.

Are there any charger brands that you have found to provide the best possible charge?

Also can you through some steps to explain the proper process for charging a pack to get the best performance?
I agree, this is something that we all do need to consider, I found out a little myself with my two chargers, an Orion Advantage Carbon & the Core RC UDC-20(which I love, btw, I think it's a GREAT value for the money, even has built-in balancing for less money than the Orion or Duratrax Ice). But I found when I ran at the Memphis TCS regional that the two chargers definitely have a different effect on my packs(an Orion 3200 I got for my Mini & the SMC 5000 hardcase for my TRF416). I ran into this because Tamiya, like ROAR is doing, started checking LiPos with a voltmeter before they'd allow a car on track, & any LiPo showing over 8.44 volts they'd make them drain it a bit or else they wouldn't let that car run, & when charging my SMC with the Core, their voltmeter was showing something like 8.49 volts(though it always read 8.40 exactly on the Core, & no more than 8.43 when I checked myself with the leads from my old Tekin BC112a(when it's not charging, it kinda makes a decent little voltmeter). But, when I charged the SMC with my Orion charger, it read about 8.42 on their voltmeter. And I got similar results with the Orion 3200, though it never read over limit either way(& FYI, I used a 5 amp charge for both packs on both chargers). So it seems that different chargers affect the packs' voltage after it peaks, & it made me wonder if my example is typical, or if one of my chargers is a bit odd, or if that's common to MANY different makes of charger(& if it does, then that could affect which ones might be safest to use). Oh, & I should also mention that neither pack EVER got even slightly warm on either charger, never read higher than ambient temperature or showed any signs of puffing or damage(& still don't now, some 3 months later, both still perform beautifully for their intended purpose). So I think that's something else all of us switching to LiPos should take into consideration, & the more we learn, the better chance I think we'll all be able to use them safely....
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Old 08-11-2008, 03:47 AM   #79
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It's strange.. a few years ago when lipos were a rather unknown in the RC car industry, everything went by mAh and three C ratings. Then car companies started pushing a single C rating and people have fallen for it!

All that's being published is '20C!' '25C! '30C!' '35C!' with ZERO explanations as to WHAT type of discharge it is. Is it constant? sustained? burst? no one can tell!

so until there is a STANDARD way of measuring a C rating and what TYPE of rating it is, I'm not even going to bother paying any attention to it and looking at packs with a mah rating and published constant C rating instead. Meaning trakpower, team orion and any other 'new' lipos are OUT.


at least with maxamps, common-sense and polyquest packs they put every type of discharge right on their page.

Last edited by Sabin; 08-11-2008 at 04:05 AM.
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Old 08-11-2008, 04:50 AM   #80
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Danny, for 12th scale what do you think about 2 cell lipo with a smaller motor?
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Old 08-11-2008, 05:44 AM   #81
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Hi,

The 3.7 sounds like a good evolution.

Since now the entire top surface of a pack is available, could the discharge curve at a certain amp draw and cutoff be printed on it along with the regular numbers you already have? Average voltage doesn't always give the entire story. Seeing a discharge curve for each pack would help.
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Old 08-11-2008, 09:32 AM   #82
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Originally Posted by artwork View Post
Danny-

Are there any charger attributes that need to be considered before buying a LIPO friendly charger for the SMC packs that can get the most out of the pack? I have been running LIPO for a few years and I have found that not all LIPO charges are created equally.

Are there any charger brands that you have found to provide the best possible charge?

Also can you through some steps to explain the proper process for charging a pack to get the best performance?
I have only used the Lipo GFX and the Hyperion EOS style chargers. When testing the pack they both seem to provide a good charge. The cool thing about the Hyperion chargers is that it has built in balancing.

There is no real tricks when it comes to charging. You can safely use a 2C rate with our packs. Some have noted better performance by discharging the packs down to 6 volts and charging them back up. I also reccomend not to store them with to much charge as this seems to remove some capacity. I reccomend a maximum of 50% which is about 7.6 volts on the pack.
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Old 08-11-2008, 09:42 AM   #83
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Originally Posted by Sabin View Post
It's strange.. a few years ago when lipos were a rather unknown in the RC car industry, everything went by mAh and three C ratings. Then car companies started pushing a single C rating and people have fallen for it!

All that's being published is '20C!' '25C! '30C!' '35C!' with ZERO explanations as to WHAT type of discharge it is. Is it constant? sustained? burst? no one can tell!

so until there is a STANDARD way of measuring a C rating and what TYPE of rating it is, I'm not even going to bother paying any attention to it and looking at packs with a mah rating and published constant C rating instead. Meaning trakpower, team orion and any other 'new' lipos are OUT.


at least with maxamps, common-sense and polyquest packs they put every type of discharge right on their page.

For our C rate a single cell must be able to keep 90% of it's capacity under the full C rate discharge. You can see this on the graph. Some manufacturers use 80%. To rate the mAh we use a GFX and test the packs down to a 6 volts. Some manufcaturers use a .5C discharge down to 2.8v per cell to rate mAh.
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Lipo confusion-4000mah-graph.jpg  
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Old 08-11-2008, 09:45 AM   #84
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Originally Posted by wingracer View Post
Danny, for 12th scale what do you think about 2 cell lipo with a smaller motor?
The size of 7.4v lipo would probably require new chassis. I think the single cell in hardcase that is the same size as a side by side NiMh pack would be the easiest way to go and with all the current winds of BL motors I'm sure a motor that would be the same speeds as stock or slighlty slower would be easy to find.
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Old 08-11-2008, 09:52 AM   #85
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Originally Posted by Mini_Me View Post
Hi,

The 3.7 sounds like a good evolution.

Since now the entire top surface of a pack is available, could the discharge curve at a certain amp draw and cutoff be printed on it along with the regular numbers you already have? Average voltage doesn't always give the entire story. Seeing a discharge curve for each pack would help.

As were the only company who is cycling our packs and printing the info I doubt that we could print the graph for each pack easily.

I have been cycling cells/packs on T35 and Turbomatchers for the last 20 years and typically when you have lower IR and higher average voltage this equals to more available power on the track.
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Old 08-11-2008, 02:23 PM   #86
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Some manufcaturers use a .5C discharge down to 2.8v per cell to rate mAh.
yikes. at that voltage the pack is likely to be damaged. So when are you coming out with a 5000+mah pack that performs like this one?
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Old 08-11-2008, 03:08 PM   #87
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Discharging at 2.8v is per cell. The C rate and mAh is typically measured on a single cell.

Not sure what you mean about when we will come out with a pack that performs like this one ?
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Old 08-11-2008, 09:34 PM   #88
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same performance numbers, higher mah.
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Old 08-11-2008, 09:52 PM   #89
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Sorry I still don't understand. Same performance numbers as what ?
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Old 08-12-2008, 04:03 AM   #90
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as the 4000mah pack as shown in your graph you attached.
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