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HomeAircraftHelicopterMain Discussion › A123 battery for the 700 class macjine....?
03-21-2015 01:07 AM  3 years agoPost 41
BobOD

rrElite Veteran

New York- USA

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Gassers fly forever and are cheap to fly.
A123's are more durable and safer.

Many things have some benefit one over the other.
It was just the odd claims that were made, which seem to be what's being refuted. That's all.

Team POP Secret

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03-21-2015 01:21 AM  3 years agoPost 42
Trexwilly

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FL USA

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+ 1 Bob, I had a long post with quotes and all, but decided it wasn't worth the heartache...

I bet you could build a A123 800 and have a blast flying it, but it would be heavier, same all the way to a 450, if you want the same ah and voltage, it will weight more.

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03-21-2015 01:51 AM  3 years agoPost 43
Four Stroker

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Atlanta

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I think I will build a 3S A123 for my Kyosho Concept EP. It will weigh much much less than the original 1400 7-cell NiCD pack. Hell I will probably get 7 minute flights instead of the original 3 minutes. I will probably get shot down on channel 30 though.

Some of you guys figure out the weight penalty of a 14S2P A123 pack instead of a 12S 5000 LiPo.

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03-21-2015 05:07 AM  3 years agoPost 44
es1co2bar3

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winnetka california

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Aaahh a lightbulb just went off,I know what is going on.Escobar either saw in person or on video a guy flying a 450 using a123.He problably just dropped a 4s pack into
Hahaa

LOL I fear the sarcasm coming from the LIPO lover bro I am glad we can agree and disagree on
this front about the A123]

there's a Advantage and the disadvantages between the
LIPO and the A123]

Base on your posts its like a being there done that
kinda thing and that fine.

There are folk reading who may have just started in the hobby and
had no knowledge of the A123 so I don't want them to
have a wrong impression on the A123.

I am sure if they try the cell they can live upto
the hype and don't have to worry about burning down
their hut

If you go to HF you can see a lot more setup and info,
I copy someone's on RC group, at the time I wanted to
fly for half of what it cost for LIPO.

I don't know why you move on but i think you just got lazy

You know the Advantages of the A123 and you just cant
out live it for the more dangerous high cost LIPO

tell me I M wrong......!

I am going to look for some video for you

I was waiting on some honey but there aren't no Queen bee,

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03-21-2015 05:28 AM  3 years agoPost 45
es1co2bar3

rrKey Veteran

winnetka california

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https://m.youtube.com/watch?v=vkDgoXikI_8

The wiring this how it done, someone said you can
regulate the cell and use less of them I don't know
how accurate this news is.

This would be nice to reduce the flight weight on the
700 for 3D flights, they would be awesome on the Trexer] 800 because of the lift Advantage from the
bigger blade.

I was waiting on some honey but there aren't no Queen bee,

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03-21-2015 06:15 AM  3 years agoPost 46
Aaron29

rrProfessor

USA

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But is A123 really less expensive? You know after buying all the cells and doing wiring?

Assuming one can stomach the weight penalty. A123 is a more stable chemistry. Just how much heavier are we talking about? Will it outfly a gasser?

I guess everything's a trade off.

As for reducing weight. I really don't see how you can. What part of a TRex would you remove? If this is your hurdle, consider the Logo as a platform instead of trying to drill holes or remove parts from a TRex. The Logo is super light.

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03-21-2015 07:08 AM  3 years agoPost 47
Funky Trex

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Westerville, OH - USA

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The only time I thought I could possibly make something work with a123s was on a 450 size. I thought about trying to run a 2 cell a123 using a high kv motor (scorpion -6, I think it is around 4400kv). This way i could save weight over a 3 or 4 cell a123 pack. The high KV motor should help compensate for the lower voltage.

I never did try it. There are too many great lipos, motors and proven setups to try a downgrade like this. It could work and there might be a good compromise of some heli size/voltage/motor/etc where a123s might make some sense but overall lipo wins in so many categories it is hard to go against them.

Just do a search for a123 heli vids on you tube. That should be a pretty good indicator of how well they work with RC helis.

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03-21-2015 07:28 AM  3 years agoPost 48
Aaron29

rrProfessor

USA

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I'm trying to keep an open mind. Sure it might not be as powerful. But neither is nitro and nitro is a perfectly viable and enjoyable source.

If an A123 powered heli could be built, fly perhaps as well as a nitro, and have much safer chemistry than Lipo, the only other factor is cost.

A little thought on this, and little things shine through:

-Imagine not worrying about batteries exploding on charge or after a crash.
-Consider that a beginner to intermediate 3D flyer or sport flyer has no need for a 65C lipo when something safer will do!
-Imagine being able to confidently charge batteries in the heli.
-Imagine being able to store the battery in heli without worry.
-The charging would be so fast, you may be able to get a lot of flying in, and not have to change batteries, just ram it on a 10 minute charge with the thing in the heli and you're up again
-If you can really get 1000 cycles, that's pretty cool and should factor into discussions of cost and desirability.
-Finally...it's not a REPLACEMENT for Lipo. It just an alternative. Nothing saying you can't bring both to the field.

I apologize for my earlier dismissal. There's no need for the community to have ONE or THE OTHER. We can have both! Sure, it won't be the choice of the 3D master, but for a lot of folks, it just might be the ticket.

Carry on and let us know what you find. I maintain that the power/weight will disappoint, but you might find that it's not a totally useless venture for other balancing considerations.

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03-21-2015 02:16 PM  3 years agoPost 49
rexxigpilot

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Florida

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The A123 cells are perfect for a scale model where you need to permanently install the battery and the added weight is not a big deal. With A123 there's no worry about fire and the cycle life is outstanding compared to LiPo. I've got some A123 packs that are going on 9 years now.

The US military testing on the A123 cells showed almost no loss in capacity after 2000 cycles. So the answer to which cost more is LiPo, by far, when you consider usable cycle life.

A123's only disadvantages are weight and volumetric efficiency. The form factor of cylindrical cells and the aluminum canister for cell protection are the culprits here, not the A123's chemistry. In terms of energy density, the A123 chemistry is superior to LiPo.

Back in about 2006-07 I was flying the first, large heli designed for a LiPo (excludes early Mikado helis), a T-Rex 600E. Around that time I got a survey from Tower Hobby asking about whether or not I would be interested in buying A123 batteries. I told them no due to the size and weight issues.

Looking back, that was a premature response, and probably made because of the low power of the 6S T-Rex and lack of aftermarket electric equipment back then. I didn't want to sacrifice any power to weight. The thought of using more than 7 A123 cells was not even a consideration since motor and ESC choice was limited to what Align offered. My response to TH's survey would be different today.

This discussion brings to mind the old Harley-Davidson commercial where they compared a Harley to a Japanese bike using cigarette lighters as a metaphor. The Harley was a Zippo, while the universal Japanese bike was a disposable BIC.

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03-21-2015 02:21 PM  3 years agoPost 50
Aaron29

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USA

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A123's only disadvantages are weight and volumetric efficiency. The form factor of cylindrical cells and the aluminum canister for cell protection are the culprits here, not the A123's chemistry. In terms of energy density, the A123 chemistry is superior to LiPo.
I just have to think that there are reasons A123's are the way they are, and didn't take off in the hobby like Lipo did. Perhaps the form factor is necessary?

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03-21-2015 02:54 PM  3 years agoPost 51
Four Stroker

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Atlanta

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" I just have to think that there are reasons A123's didn't take off in the hobby like Lipo did. "

It was not their marketing plan. They wanted the electric car market and cordless tool market. The RC market is tiny.

As rexxigpilot said, for scale or sport or even old man 3D, nitro, gas, A123 are all viable and a tradeoff.

There are other sizes and shapes of A123 cells that you never see in the RC world. A123 cells are very popular with (full size) electric motorcycles and drag racers. I guess wiping out with LiPo's would not turn out well. Tesla has gone to 18650 LiIon cells for energy density and weight density and volume density. A 12SNP pack of these might beat LiPo's - especially for low current flying like sport, scale.

If you want to dump 160A for 3 seconds LiPo's are king.

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03-21-2015 03:12 PM  3 years agoPost 52
Aaron29

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USA

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In terms of energy density, the A123 chemistry is superior to LiPo.
If this is the case, there needs to be a renewed effort to bring RC appropriate A123's to market...the PRIMARY complaint of electric is flight time, which energy density would purport to provide. The SECONDARY complaint of electric is safety concern, and the THIRD complaint about electrics is the lifecycle of batteries that are expensive and have to be replaced often. All of which A123's would provide based on stable battery chemistry and increased cycle life.

If what you state regarding energy density is true, the top dislikes about electrics would be fixed just by moving to A123. If what you say is true, there HAS to be a market for this.

But it begs the question. If there is this potential market, why would it go ignored and have to be examined by Esco? Absurd is the only word I can find.

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03-21-2015 03:21 PM  3 years agoPost 53
Aaron29

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USA

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If the energy density and chemistry is superior, it seems someone could further develop A123's and squash the Lipo industry in a second. In fact it would be so threatening that, if true, and I were a Lipo manufacturer, I would further develop A123 and fill that market position myself to avoid extinction.

Sorry but I guess until I see more I just remain skeptical, as it offers no satisfactory explanation how a chemistry that is purported to be superior in nearly every way does not dominate.

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03-21-2015 03:38 PM  3 years agoPost 54
Four Stroker

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Atlanta

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I don't think the can is a significant amount of the weight. I think but it could be easily measured that the A123 has maybe 60% of the WATT-HOURS PER POUND as a LiPo. I ASSUME that LiPo has a pop tart wrapper precisely because it can swell and explode. A can would be a bad thing.

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03-21-2015 03:41 PM  3 years agoPost 55
Aaron29

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USA

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Ok I'm having trouble understanding terms. Efficiency and energy density are equatable in my head. So it seems to me we're saying A123 is both superior to and 60% of Lipo.

What do you mean by efficiency?

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03-21-2015 04:12 PM  3 years agoPost 56
jharkin

rrApprentice

Holliston, MA - USA

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What does energy density have to do with efficiency of the cell?

Cell efficiency is the ratio of energy you get back at discharge to the amount of energy you put in at charge. Both LiPo and LiFe are extremely efficient - high 90s at slow to moderate discharge rates - compared for example to NiMH where you have to put back as much as 40-50% more at recharge than you can usefully get out of it.

LiFe as marketed today definitely has lower energy density. Some of that is due to the hard case but as others have speculated I dont think that alone is enough to explain the weight difference.

LiFe has definite safety, storage and lifetime benefits and for that reason I love using them as receiver packs. I can leave them charged up, leave them flat, leave them in my garage at -10F, charge them in the car without fear of fire. use them for years and years without capacity loss. I love 'em. But I wouldn't bother for E power packs... not for helis and planes at least.

-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks

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03-21-2015 04:35 PM  3 years agoPost 57
Four Stroker

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Atlanta

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The discussion is about energy density - WATT-SECONDS/MINUTES/HOURS per POUND.

The old high rate red Sanyo NiCD cells were very efficient (charge/discharge) well into the 90's..

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03-21-2015 04:49 PM  3 years agoPost 58
Aaron29

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USA

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So pound for pound, an A123 compares to a lipo how?

Seems to me in evaluation A123 vs. Lipo It's going to come down to ability to deliver current, capacity, and weight.

Regarding current, I saw a post that an A123 with 60C is out there, so it seems we have current sufficient for 3D flight, no?

That leaves capacity/weight. Which are essentially one and the same if you term this density. Which compares to a lipo how? Because what I'm reading here suggests that this is SUPERIOR from A123. If that's the case, A123 yields absolutely no ground to Lipo and we should move over to A123s.

I heard A123 had inferior "volumetric efficiency". But if that's what I think it is, how big a battery has to be (not weight), I don't think that would be a concern. Could just make a larger battery tray.

So it boils down to this weight factor. Is that what we're discussing with energy density? If so, why don't we get to work on this?

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03-21-2015 04:49 PM  3 years agoPost 59
Four Stroker

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Atlanta

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An example:

1) 14S2P A123 battery = ~2296 grams
2) TP 45C 6S 5000 x 2 (advertised weight) = 1564 g

The difference other than size is roughly 732 g or 1.6 pounds.

Energy Density Ratio = 1564/2296 = 0.68

The A123 and LiPo will behave differently.

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03-21-2015 04:50 PM  3 years agoPost 60
Aaron29

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USA

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OK you beat me to post, so claims that A123 has superior energy density are false?
A123's only disadvantages are weight and volumetric efficiency. The form factor of cylindrical cells and the aluminum canister for cell protection are the culprits here, not the A123's chemistry. In terms of energy density, the A123 chemistry is superior to LiPo.
Rexxig...sorry for bringing you in but can you explain this?

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