04-10-2009, 03:06 PM
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A123's
I'm thinking of experimenting with A123 cells. I would like to hear other's experiences with them.
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04-11-2009, 08:32 AM
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Some clubmembers are driving vith the larger cells in their 1/10 cars. They are awesome, you can charche them with 5C so in 15 minutes the battery is charged and have lots of power.
If you are racing competitions against Lipo and 6-cell powered cars then A123 is not the right choice (6.6 volt) but for a hobby driver they are the right choice.
I believe there are 2/3A size cells so you could create 2S2P, 3S2P or 2S3P batterypacks.
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04-11-2009, 10:52 AM
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I'm not racing so the limitations associated with racing don't apply to me. The reason why i'm looking at these as opposed to LiPo is because they are more stable and can take more abuse, not that i abuse my batteries but sometimes accidents happen. Frankly i'm just scared of LiPo, they are too unforgiving in the event of an error.
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04-11-2009, 11:04 AM
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Quote:
Originally Posted by Roelof
I believe there are 2/3A size cells so you could create 2S2P, 3S2P or 2S3P batterypacks.
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2/3 A really? Can you post a link to those? All I'm seeing are the large ones measuring 2.6cm dia. 6.5cm length.
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04-12-2009, 08:14 AM
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Quote:
Originally Posted by RERacing
By using those larger A123 cells you are the one limiting yourself.
Their larger physical size allows for more mAh capacity, but they also limit the voltage you can have available. It's really an old-school trick guys were doing for a while when there was no LiPO and the NiMHs of the era were very low in capacity. Nobody's doing it anymore that knows better.
I have news for you, but all the rumors you seem to havew absorbed relative to the instability of LiPO packs are greatly exaggerated.
All of last year, for example, I probably witnessed 8 or 10 NiMH packs blowing up or melting down and not one single LiPO explosion or fire. LiPO technology has advanced greatly the last couple of years, as has the chargers available and all but eliminated any potential problems if not handled by a total 'tard.
But if you're not carefull you can blow up anything, but LiPOs are no more unforgiving than anything else out there. People that aren't carefull are those that have accidents, those that practice safe procedures and a realm of caution seldom do.
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you are wrong. lipos are extremely unforgiving! when a nimh cell overdischarges you may lose the cell. when a lipo over discharges, you run the risk of burning down your house, losing everything you own and killing your family. this also applies to overcharging, charging to fast, puncturing, over discharge rate, temperature, etc. yes, nimh fires happen, but they don't EXPLODE with a 1500° fireball!
http://www.rcgroups.com/forums/showthread.php?t=209187
every lipo user should read that guide! the lipo fire documentation from that one forum alone is sobering! automatic chargers still pose a risk for fire! properly configured manual chargers also still pose a risk for fire!
a123's LiFePo4 chemistry and cell configuration is signicantly safer than any current LiPo available for the rc market.
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04-12-2009, 08:22 AM
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Quote:
Originally Posted by genitor
2/3 A really? Can you post a link to those? All I'm seeing are the large ones measuring 2.6cm dia. 6.5cm length.
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Those cells are about 1400mAh and could be ideal for a receiver pack for my 1/8 car.
Somewhere in the past I was told and I believe I have seen 2/3A size cells, they hold about 600/700mAh, at this moment I can not find them.
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04-12-2009, 08:22 AM
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Quote:
Originally Posted by genitor
2/3 A really? Can you post a link to those? All I'm seeing are the large ones measuring 2.6cm dia. 6.5cm length.
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they make a 18650... this size is most often used in laptops.
dia: 18.4mm
length: 64mm
Nominal Capacity & Voltage: 1.1Ah, 3.3v
Recommended standard charge method: 1.5A to 3.6v CCCV, 45min
Recommended fast charge current: 5A to 3.6v CCCV, 15min
Max continuous discharge: 30A
Pulse discharge at 10sec: 65A
Cycle life at 10C discharge, 100% DOD: Over 1,000 cycles
Recommended charge/cutoff voltage: 3.5v to 2v
Operating temp: -30 ~ +60degC
Cell Weight: 39g
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04-12-2009, 08:27 AM
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04-12-2009, 08:36 AM
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04-12-2009, 09:05 PM
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first off that thread is still active. secondly, what exactly has changed in LiPo technology that makes them so much safer now? you are clearly missing the point of my previous post and the objective of the original poster. if he wanted lipo advise, he wouldn't have started a post titled a123's. there is obvious concern for the risk of failure and the level of attention LiPo cells require. these cells demand respect as they have a elevated potential for failure with catastrophic consequences. the original poster understands that and very clearly requested information for a safe alternative.
im glad you've never had a incident with lipo. good for you! the fact that it has never happened doesn't exclude you from the potential for a accident. your "it'll never happen to me" attitude isn't going to help you out too much should the situation ever arise.
slow and behind the curve huh? show me a lipo that can safely deliver 21.9v @ 4600mah with over 200amps of discharge current on tap AND can recharge in 15 minutes? i run lipo and i've never had a problem, but you won't catch me with a lipo pack of that size anywhere near my house!
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04-13-2009, 12:28 AM
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wow, i really feel like a total ass now. you really put me in my place
these are the 18650 cells i referred to earlier: A123 Systems 18650 LiFePo4 Cell
Last edited by sonicj; 04-13-2009 at 12:36 AM.
Reason: forgot link
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04-14-2009, 09:12 AM
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Quote:
Originally Posted by RERacing
You should.
It makes little sense to try to stuff AA-sized cells into a car that wasn't designed for them to fit
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i never said anything about AA sized batteries??? 18650 is the battery i was referring to. (1st photo) you completely ignore my specific questions and then go rambling on like you're an authority on the matter, yet you don't even know what exactly it is you are talking about.
these weren't designed for lipos either... i don't get your point. if they fit, they fit.
Quote:
Originally Posted by RERacing
You should.
thereby requiring one to lose voltage and speed all for the sake of doing something outside the realm of accepted practice
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lose voltage? outside the realm of accepted practice? dude! where are you getting your information???
maybe you should go inform the rookies over at castle that they're using the wrong cells for their newly released Mamba Monster BL systems. Mamba Monster (a123 info is at the bottom of the page)
Quote:
Originally Posted by RERacing
and that requires a severe amount of stuffing or cobbling to make them fit.
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how do you figure? (see pics 2 & 3) looks like they fit ok to me! a 3s1p or 2s2p wouldn't be a problem either.
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04-14-2009, 02:29 PM
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Thanks SonicJ! You provided some valuable information.
Which charger do you use? I've been looking at the Fma cellpro multi4
http://www.fmadirect.com/new_applica...ti4_media.html
It charges every battery chemistry and only costs $75.
Last edited by genitor; 04-14-2009 at 02:34 PM.
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04-14-2009, 02:36 PM
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What type of runtimes do you get with those 18650 cells? And which motor are you running?
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04-14-2009, 02:52 PM
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Quote:
Originally Posted by RERacing
So you're running a 2-cell pack.... and a whopping total of 6.6volts??
Well below the 7.2v of a standard NiMH or the 7.4v of a standard 2S LiPO pack??
That's ridiculous.
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Actually :fully charged the cells are 3.65 volts per cell or 7.3 volts for 2 cells in series.
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