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Old 01-22-2008, 07:17 AM   #31
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Thank you Ling. This is EXACTLY what we need to read and educate ourselves with.
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Old 01-22-2008, 09:09 AM   #32
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Thumbs up Great info...

Thanks for another very informative thread on Lipos!
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Old 01-22-2008, 11:04 AM   #33
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I probably missed this somewhere but who uses the Saehan Enertech cells? I know some who use Kokam and Enerland but don't know Saehan. Thanks for the info Linger!
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Old 01-22-2008, 12:12 PM   #34
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Curious, few questions I wonder if you can answer:

1. What are the cells exactly that the Maxamps packs are using.

2. Do you feel the external skin that maxamps will be using will be sufficient?

3. If it is sufficient, do they need to use 1 skin, or two skins?

4. Do you know what cells Trinity is using in there Li-Pro packs?

5. what are your thoughts on the A123 cells?

6. What are you thoughts on Hyperion Cells and there chargers?


Currently, I run a maxamps 6000mah 4S setup for my 1/8 scale buggy, and charge it with a MRC989 charger combined with a LBA10+ Hyperion Balancer in a liposack. Works well, and I love the convience of lipo compared to the battery voodoo of NIMH. But if this class takes off, I figure that a hard case will be necessary.
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Old 01-23-2008, 01:01 PM   #35
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Quote:
Originally Posted by TryHard View Post

Didn't specify use of a LiPo sack, as personally I would prefer to see a pack expanding and be able to do something about it, rather than trust a sack to work.

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I have heard some other people voice the same opinion about wanting to be able to see the battery go rather than charging in a lipo sack, why? I mean I imagine that people want to be able to react to the situation but how much time do you really have before "all is lost"? Is there enough time to pick the pack up and toss it into a bucket of sand?
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Old 01-23-2008, 01:48 PM   #36
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My support of the LiPo Sack comes from the fact that we don't always watch & supervise our packs. Too many times we go off for a quick soda, then 30 minutes later mosey back to the pits... We're all guilty of it...
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Old 03-11-2008, 05:18 PM   #37
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Quote:
Originally Posted by Wild Cherry View Post
only need to purchase Orion 3200 Carbon`s....




Then sleep with peace as they are the best and safest battery`s you can purchase today....


but dont fall alseep while charging..

i use nothing but maxamps. and have owned carbon packs.. but i use maxamps due to them being heavier. well the 6000s are and i dont need to add much weight to come up to minimum

i belive as long as you take care of a KNOWN lipo its just as safe as any other one.
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Old 03-11-2008, 07:00 PM   #38
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Two questions:

First, How long will a lipo burn?

Second, Will a burning lipo burn through a ammo box?
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Old 03-12-2008, 08:57 AM   #39
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As a follow up, has roar decided that receiver packs are going to have to be hardcased too? Seems that if the issue is that you can eject the pack from the vehicle, it needs to survive on its own without some vehicle based shell around it, they should have to have that requirement as well if that is how the rules are going to go for packs that are used in vehicles. Or, then it seems you could just make a battery tray in a vehicle that seals the battery in it, basically doing the same as the receiver pack boxes on nitro vehicles.
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Old 03-12-2008, 09:08 AM   #40
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The fumes from Lipo fire are rather nasty in nature and should definitely be avoided.

I haven't seen this issue addressed yet.

Can we get some words of wisdom from LIng on this matter please.

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Old 03-12-2008, 09:19 AM   #41
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Great information. Thank you.

Is there a way to determine which typr of cells a supplier uses in its packs?
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Old 03-12-2008, 09:22 AM   #42
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Quote:
Originally Posted by Victor Vector View Post
The fumes from Lipo fire are rather nasty in nature and should definitely be avoided.

I haven't seen this issue addressed yet.

Can we get some words of wisdom from LIng on this matter please.

Jacko
I second this question. We know that the fires will damage equipment, but what, if any, are the personal health issues cause by the fumes?
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Old 03-12-2008, 10:59 AM   #43
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Another discussion that I have not seen anywhere and perhaps deserves its own thread is how to determine the rated discharge. There is no standard currently.

Is it one cycle without destroying the battery?

Is it 100 cycles without damaging the battery?

Is it temperature?

Is it one cycle that will provide 90% capacity, or 80% capacity.

Is it a number that is decided for marketing to make the products compare well to other products?

We have tested many batteries that claim 20C discharge that either selfdestruct under the load or are junk a few cycles later. Is that really a 20C battery? We have tested many batteries over the last year that claim 20C under a moderate 30amp load that are junk within a just a few cycles. That is less than 10C in most cases.

So what does this number really mean? Who is deciding the rating and how is it being determined?

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Old 03-12-2008, 11:29 AM   #44
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I believe people in the LiPo business consider "C" rating a marketing term, and pretty much a joke. It appears to be arbitrarily measured across manufacturers. It's too bad consumers focus on this number at all, because it's really not comparable between brands.

I suppose R/C could adopt its own testing standard to judge cells based on how they will meet the needs of our hobby. But thus far, all the companies have been throwing around their possibly meaningless C rating.

So, where's that Tekin LiPo? You guys dropped a hint that you went with a very high-quality cell. I'm keeping my fingers crossed for a certain Korean company that even Kokam is afraid of. :-)
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Old 03-12-2008, 11:39 AM   #45
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I've been discussing it here: http://www.rctech.net/forum/showpost...&postcount=421

But I think you're right - it does deserve it's own thread. Here's my take:

Quote:
This is where the lipo industry has gotten ugly in the flight side of the hobby, and unfortunately it's fixin' to get ugly here with cars as well.

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

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 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 in actuality).

5 amp hours divided by 100Amps of discharge capability = 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 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 20C and the other was 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 consumer is really facing right now. What does 15-20-25-30C really mean???? By what (and who's) definition was the C rating determined? Were packs actually discharge tested? Are the brands just using what 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 my claims wrong?

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 products they're selling? Do they really know everything about it in order to support you with accurate advice and safe usage guidelines? Personally, I think these reasons plus a good dose of honesty are :-)
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