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Old 12-05-2006, 02:37 AM   #61
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Originally Posted by SlowerOne
In no particular order...

The technology is still very young, and it is generally accepted that the LiPo combination is not where we will end up. Also, there are 5v cells on the way. In the next few years those sticking to NiMh will spend less than those trying to keep up on the Li** front. When I see Li** technology in general use in power tools, I'll know its OK and it has settled down enough to be worth buying. Until then...
Yes, one day Li** will be here, and it is already here in 12th for receiver packs. But that isn't today, because there are too many issues we can't resolve at this time.
I saw an add today for Craftsman power tools with Lipo batteries. Cross that one off the list...
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Old 12-05-2006, 04:13 AM   #62
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i have a question about the different lithium battery technologies. ive seen lithium ion, lithium polymer and lithium manganese, but how much of a difference is there between them in performance, production cost, and safety? i've read that lithium manganese is the safest one, but i assume its more expensive to produce?
for Mr.Black, if a lithium based battery technology turns out to be a better choice later in the future, would orion drop the lipos and take up that technology?
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Old 12-05-2006, 05:32 AM   #63
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Originally Posted by Stealth_RT
Also, anyone who attended the Champs saw or heard about 4200's exploding in at least one car.
That was my little buddy that happened to. Saddle packs+T-bone=exploding cells. We have guys that run BL/Lipo in our stock class. They add weight(a lot) to equal things out. There is no noticable difference except that they have more time to eat Ho-Ho's and suck down Mountain Dew. I think the advantage of Lipo is in practice. Run a couple minutes, make a change, get back on the track with the same voltage you had 15 mins. ago.
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Old 12-05-2006, 10:10 AM   #64
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I hear alot of talk about people running there packs pretty low. 10 minutes is the most we've tried. You all are making me brave, I Only run mine 6 min. then let them relax for a round. Then repeak and run again. My packs when I start the repeak process are consistantly 7.65 volts and some times higher. If I set my GTB just right They start at 7.75, My reason is that the warnings say try not to discharge lower than 80% that is my goal. I'm sure I'm dicharging more though.
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Old 12-05-2006, 10:47 AM   #65
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I had always thought they meant don't take more than 80% of the cahge out for maximum life span, not safety. I have been running mine till my sphere shuts down in Li Po mode for several months. Are some reading the advice to say don't take any more than 20% of the charge out for safety reasons?
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Old 12-05-2006, 11:12 AM   #66
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Well the way I understood it was. If you dont discharge below 80% of the capcity you should never have to worry about balacing. And I dont have that feature on my speedo. So I've gone pretty easy on my packs, but I'm getting braver the more I read.
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Old 12-05-2006, 11:14 AM   #67
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This will be a good one for Mr. Black.
Heck there might be some more power in there?
Yoo, Hoo, Mr. Black.

Last edited by UN4RACING; 12-05-2006 at 11:45 AM.
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Old 12-05-2006, 11:30 AM   #68
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I think it was mentioned that you can charge them at a higher rate and get a little more voltage, but it will greatly shorten the life of the pack. I'm not positive about that, though, maybe one of the LiPo experts can clear it up.
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Old 12-05-2006, 11:44 AM   #69
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Also, anyone who attended the Champs saw or heard about 4200's exploding in at least one car.
Yes sir....I beleive I have first hand knowledge of that particular incident.
That kid's car hit the sweeper hard...and I mean hard. When I picked the car up, the batteries had already dead shorted on the chassis and began to sizzle while I was trying to find the switch...after which, one exploded in my face and the other detonated after I threw the car.
First off...they weren't 4200's...they were 3800's. Second, I think we could all agree that this incident is not the norm, and could have happened with any exposed cell involved in collision of that magnitude. Lastly, I've seen more cells pop due to extreme heat either from improper charging and/or usage than anything else.
I've also seen a similar impact and result in a 4-cell oval pan car. As long as we're using exposed cells, those rare incidents have the possibility of occurring.
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Old 12-05-2006, 11:49 AM   #70
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You have a point awareness is the 1st step to prevention. Although quik thinking in a spontanious situation is a different story HUH?
In the roar 2000 Gas nat'l's we had to wear glove's and safty glasses,to marshall. I havent seen it sense.
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Old 12-05-2006, 12:50 PM   #71
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I want to say I saw some data on the FMA site (Maybe Kokam) about charging and discharging. Basically the less you go towards a complete charge and complete discharge(3v per cell) the longer the life of your cell. If you do not charge the battery over the last 10% and do not discharge the last 20 % they are estimating 1000's of cycles or something like that. If I remember correctly if you are using the ends of the pack they were looking at 300+ charges on a pack before you would consider the battery spent. Most of what I have read is that the last bit charging and the last bit discharging are where you actually cause the most wear on your batteries. Would be nice is some other companies could verify the effects.

If I am not mistaken some companies are talking about a 3.2 voltage cutoff now in some cases.
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Old 12-05-2006, 03:55 PM   #72
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Quote:
Originally Posted by SSJChar
i have a question about the different lithium battery technologies.ive seen lithium ion,
This is the oldest form of Li-Po and is what is found in most laptops ( the Sony issue) and the majority of Cellphones and other lower voltage devices. These batteries do not have the ability to output the voltage we use in our R/C cars in a safe manor. Plus Li-Ion is not the most durable but it is widely felt to be the cheapest hence the usage in consumer electronics.

Quote:
Originally Posted by SSJChar
lithium polymer
This yields the best performance per price and weight and is why we and many others have chosen to go this route. If done properly it can also be just as safe as some other methods. We believe based on our customers experiences and feedback as well as testing that our Li-PO are just as if not even more safe then Ni-MH.

Quote:
Originally Posted by SSJChar
lithium manganese,
These batteries do not yield the performance provided by Li-Po. This technology is not new and was passed over by us as we wanted the best of all worlds and felt that it was too heavy and did not provide the performance we wanted.

Quote:
Originally Posted by SSJChar
but how much of a difference is there between them in performance, production cost, and safety?
Above I have stated what we have found in the different chemistries. Beyond that there are also a huge difference in quality in each category. We have done extensive testing and tried cells from over a dozen manufacturers and found a supplier that stood out by huge margins ahead of the others. Yes they may not have been the cheapest but we were more concerned with quality than price as the technology was something many feared as the experiences with cheap cells had given the technology a bad name. Because of this we have a less then .01% defect rate which includes a couple of packs that in the end tested out to have failed due to abuse.

Quote:
Originally Posted by SSJChar
i've read that lithium manganese is the safest one, but i assume its more expensive to produce?
I am not sure it is the safest as all the claims that I have read can almost all be said about our own SLPB KokamŽ cells. As far as expense we did not even get this far as the other factors made Li-Po more desirable for our application.

Quote:
Originally Posted by SSJChar
for Mr.Black, if a lithium based battery technology turns out to be a better choice later in the future, would orion drop the lipos and take up that technology?
Li-Po is a Lithium technology? I am not sure what you are asking? Do you mean would persue other avenues of chemistry and or technolgies? Of course we would we work heavily with our own supplier KokamŽ who is very much ahead of the curve when it comes to technology. We constantly test there cells and work on developing new tech with them.

We also receive info from many cell manufactures who constantly send us samples and information hoping to one day work with us.

Some speak of a new Li-?? or 5V cells and I can say that a lot of this stuff already exists and it is nothing new, however having it suitable for the purpose of R/C related applications is something that is still aways away.

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Old 12-05-2006, 04:05 PM   #73
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Quote:
Originally Posted by UN4RACING
This will be a good one for Mr. Black.
Heck there might be some more power in there?
Yoo, Hoo, Mr. Black.
If you never discharge the battery below 80% of it's capacity it will last indefinitely. This was told to use by KokamŽ who manufactures the cells. However many people run there's down until there car dumps and have been doing it for over a year now with out seeing any loss in performance.

I personally run mine until the car dumps about 3-4 times a month during practice and I have the very first battery we ever built and it is still running strong after 20 months in operation.

Also charging at 1C or 1Amp per 1000mAh will also give you longest life we regularly have charged our cells at 2C (9.8A) and have seen no noticeable loss in lifespan however we have yet to kill one under normal use either. Charging at a higher Amp rate only makes charging faster. It does NOT increase performance, this is another great part of Li-Po as it put's everyone a more even plain. We have tried all sorts "voodoo" to get more performance and nothing works plain and simple the performance is set. Decide for yourself how long you want them to last. We are working on somethings that may help the charge times but that is all I can say.
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Old 12-06-2006, 12:07 AM   #74
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Thank you very much Mr. Black. And Your right, The journey is the best part. Read you later. Appreciate It.
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Old 12-06-2006, 12:39 AM   #75
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Mr. Black, looking at voltage discharge curves for LiPo, it does seem as though the voltage of the batteries will decrease during a 5 minute race. Would you say this is noticeable on the track?

I feel like my car is a bit faster (top speed) in the beginning, and starts to feel a tiny bit soft by the end, very much like a NiMH pack, though less drastic. What doesn't change, however, is that the punch is always there, even if the top speed seems to fade a bit. I suppose this could be due somewhat to the brushless motor, but does the lower IR of LiPo lend to this as well?

Also, if we took the 4800 pack and 3200 pack and measured their voltage during a 5 minute race, they should be about the same, right? The increased capacity doesn't affect the voltage curve during discharge with LiPo, does it?

Hearing about new stuff makes me jealous. The opportunity to test new products before they hit the market sounds like one of the biggest perks of being a team driver, or company employee. :-)

Also, it looks like laptops are starting to use LiPo. My fancy new MacBook Pro is LiPo rather than LiIon. If it's good enough for the world's most popular brand, it's good enough for me!
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