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2s LifePO4 battery packs above 2Ah & under 400g

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Old 12-16-2009, 09:18 AM
  #16  
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Dawn,

I apologize, if I had known in your emails that what you were advising me was not to be posted on a public forum or wasn't concise as what you have stated I wouldn't have put it here. You never stated this was private information, so I assumed that it was something that anyone could have received from you in general by asking and wasn't private info. I shouldn't have assumed that, and I again, I appologize.

With that said, please let me know what exactly was posted that you feel was incorrect, and I will update / remove the offending information accordingly. I have updated the post concerning the approval of packs to better reflect what you have stated. Please let me know if that is sufficient.

again, sorry for any confusion this may have caused.
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Old 12-16-2009, 09:51 AM
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Old 12-16-2009, 10:17 AM
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So how do you guys propose to make up the difference in voltage between LiFE (2S=6.6v) and LiPo (2S=7.4v)?
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Old 12-16-2009, 10:24 AM
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Old 12-16-2009, 10:28 AM
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for me personally at least I am just looking at this time to see them be legal, that's all.

I would think then people who want to adopt the technology will have to work in the framework of the rules as they are. Sort of like (going off of memory here) people who have ran in say a mod class using 5 cell Nimh instead of 6 cell Nimh. They were down on voltage, but made up for it probably will motor choice. I would think the same could be applied here, at least for mod, basically a max allowable voltage type deal.

And for those people who do not want to do lipos for safety concerns but are wanting to get away from nimhs, could be something they would be interested in. Yeah, in spec classes they will have less power, but, in some instances who knows, maybe less grunt is what they want, or, they deal with it via gearing, not sure. But, having the option I think wouldn't be a bad thing.

In 1/8 electric offroad at least, sounds like the LiFePO4 packs that Maxamps has in a 4S configuration have been working well when matched with the appropriate Kv motor and gearing.

Others may be expecting something else, me though, thats what I am looking at.
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Old 12-16-2009, 10:59 AM
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In case you guys haven't noticed,

Nimh is gone from the racing scene. They were dropped so fast it wasn't funny.

There have been very few catastrophic failures of lipo batteries. I was one of the people pushing for more safeguards for lipos. Fortunately they have not been necessary.

Very few people run mod on road. See the speed control thread to find out why.

What I'm saying is I don't think there's a market for these batteries in the racing community. Everyone's gone lipo, and the rules have been changed to reflect that. For these batteries to be competitive the rules would have to be drastically changed, and ROAR isn't going to do that.
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Old 12-16-2009, 11:17 AM
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there are racers using NIMH combinations in there stuff because they are worried about lipo fire issues and see a benefit to the new LiFePO4 technology. I don't agree with them as far as there concerns with regular lipo as I run both softcased and hardcased packs in 1/8 electric down to 1/16 electric, but it doesn't mean they are not out there.

As for the various classes being ran, at least to me I think you have to start somewhere as other techologies have (I think brushless started first in mod correct?).

Initially this could be done in that manner or something similar (keep max voltage limits the same), and then let the racers decide with there wallets if its viable tech. Others probably have better ideas on how to do this.

And in my case, at least from what reports I have gotten from those running the packs in classes like 1/8 electric and 1/10 offroad electric mod, they do work well when matched with the appropriate motor and gearing. It could possibly apply to other classes, or it might not. But, its an option I wouldn't mind seeing them allowed within the current framework of rules, in particular the maximum voltage limits for the various classes.
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Old 12-16-2009, 12:35 PM
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I'm having 2 cells coming soon to test and they might be of interest to you guys. I will do some testing to see if they can hold their voltage well under load.
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Old 12-16-2009, 12:45 PM
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good stuff. I would be curious to see how they perform.

I do recall an article a bit ago about the A123systems 2200mah car pack. sounds like it worked well.
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Old 12-16-2009, 01:14 PM
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There is some really good info over on rcgroups in the battery section.
The A123 cells do drop to under 3V under heavy loads. They are flat when they hit 2.5V but can go to 2V without damage.
Good way to regulate the insane speeds of mod.
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Old 12-16-2009, 01:17 PM
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They are pretty resilient from what I have heard, which for those who want to go with new tech but not the lipo worry, could be a good thing.

Will give the rcgroups thread a look.
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Old 12-16-2009, 03:18 PM
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Old 12-16-2009, 03:54 PM
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Originally Posted by ozvena
Most of the folks here would do fine with NiCd.

I think LifePO4 is the best technology available today. It is safer than LiPo, good capacity/weight ratio and way less cells to maintain in comparison with sub-C cells.

LiPo cells are so cheap that you would think there is a production hybrid car powered by these but there is not. ;-)

It is the glossy magazines that made us believe that we need NiMH and now LiPo. 'It' is not about need but about want. I think most folks have 'it' mixed up.
Okay, now you're just giving a sales pitch. Go to any major on road event and they are all using LiPo. The fact that LiFE batteries are nearly a volt lower means no one is going to use them, at least not for racing.
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Old 12-16-2009, 04:36 PM
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Old 12-16-2009, 04:44 PM
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Originally Posted by jiml
The fact that LiFE batteries are nearly a volt lower means no one is going to use them, at least not for racing.
I would be curious to see if they are used with 1/12 via a booster.
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