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Old 01-06-2009, 12:57 AM   #16
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I was sold by all this too, spent big $$ on 2 * Hypersonic A123 2s2p packs, a 3s1p pack and a 2s1p pack and their "Hypersonic" charger (after they advised it was the only one that could balance the packs correctly).

The packs all had dead cells within 5 months.

A123's customer service became non existant.

I charged everything by the book.

My advice, avoid these like an ex girlfriend!
That sounds really crazy. With what motor/esc combo did you use them? In what car?
My A123 cells (1x 2S2P, 1x2S1P) are nearly one year old, and they work like at the beginning(charged with max. current of 6A). I know people, who charge this cells to 4.2V (Lipo-Mode) and they are still alive.

And don't avoid ex-girlfriends
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Old 01-06-2009, 08:06 AM   #17
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Hi again.

Here is a picture of my setup. I used 6 diodes in paralel, of 3A each. Thats because those were the only available at my local electronics store at the time :P
Alright, very clear. But one thing; can you use other diodes with higher AMP values? Or is that a no-go? And could you (if you don't mind) please explain the mathematical/psysical approach to all this?

@gotan: I already emailed rcmushroom. They listed the 720 at USD 299 before I pointed them out that other stores sell them for 100 bucks less. Now they corrected it. Now the price is a lot more appealing.

@nexxus: That's odd, cause the only stories I've read are all happy ending
From what I've heard and read is, there are different LiFe cells for sale with different quality standards. Maybe that's the thing in your case (?). Just guessing...
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Old 01-06-2009, 06:10 PM   #18
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Hi, you can use other diode. Like i said i only used 6 because those were the only ones i had access to.

The diode is there to lower the voltage that comes from the charger. It will drop by about 0.6v, wich will make the li-on mode perfect for a123 cells
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Old 01-06-2009, 07:10 PM   #19
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That sounds really crazy. With what motor/esc combo did you use them? In what car?
My A123 cells (1x 2S2P, 1x2S1P) are nearly one year old, and they work like at the beginning(charged with max. current of 6A). I know people, who charge this cells to 4.2V (Lipo-Mode) and they are still alive.

And don't avoid ex-girlfriends
Mine were the genuine A123 packs and charger from A123racing.com and as many of you know, they aren't cheap.

They were being used in an E-Savage with a Mamba Max ESC pushing a Medusa 3300 kv motor, I hooked a Watts Up metre in and found the PEAK amp draw I had was 95 Amps, so the two 2s2p packs I had in there with a 4600 capacity and a 30c rating shouldn't have had any issues.

The problem I believe in hindsight was their charger, it says it's balancing for over 1-2 hrs which isn't right, the one pack that didn't play up I changed the balance plug to a JST XH and charged it on my Swallow EQ (Hyperion clone) and that pack (a 2s1p) was fine when I gave it to a mate.

Just want people to be aware not all stories with A123 are all roses and sunshine, for me, it was a VERY expensive lesson not to get caught up in the hype of a battery that's not really proven in the RC world as yet.
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Old 01-06-2009, 10:58 PM   #20
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Go and build a 2s 3p pack w/ the 1100 cells.
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Old 01-06-2009, 11:42 PM   #21
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I charge my A123 packs with the iCharger 106B+. It is compact and works very well. I can charge one 2300mAh pack in 15' at 10A.
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Old 01-07-2009, 12:29 AM   #22
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Originally Posted by Govert View Post
Lipo's don't fit my needs, because of a few things: expensive, 1C charge for lipo, A123 lasts 10 times longer than lipo, A123 delivers higher C-rates and all the other lipo disadvantages lipo-lovers don't like to talk about (no flaming)
The SMC C-Max lipos are rated at 40C and can be charged at 2C. I'm not sure how long you expect to keep your cells for but my 2 lipos have done me a year and perform the same as when they were new. Just some food for thought...
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Old 01-07-2009, 05:45 AM   #23
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The problem I believe in hindsight was their charger, it says it's balancing for over 1-2 hrs which isn't right, the one pack that didn't play up I changed the balance plug to a JST XH and charged it on my Swallow EQ (Hyperion clone) and that pack (a 2s1p) was fine when I gave it to a mate.
Not to argue with you, but you state the problem could be your charger, so not the cells, right? I think, based on what I've heard and read, these cells can handle abuse very well (to a certain limit offcourse). What was the cut-off voltage on your charger?

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The SMC C-Max lipos are rated at 40C and can be charged at 2C. I'm not sure how long you expect to keep your cells for but my 2 lipos have done me a year and perform the same as when they were new. Just some food for thought...
Well, I would like to keep my cells as long as possible offcourse. The thing is, right now I drive 5-cell modified. So the gap between 6 V and 7.4 V is enormous. A123 will deliver something around 6 V or little more under load. This approaches the 5-cell configuration a lot more.
Another thing is the cost of it all. Lipo's cost a fortune (especially here in Europe). Since I drive mod, I'm only interested in cells rated 4600mAh or more. Lipo's that have a capacity of 4600+ mAh cost quite a lot. Here in Europe the A123 cells a relatively cheap compared to lipo. Other than that, I like the charge current you are ably to aply to these cells. Since I do 10 to 15 charges per training day/evening, I like to charge fast. Also you can use these cells, finish driving, charge them imediately and use it again.
I can mention a lot more positive aspects, but like a stated, I would like to keep this topic clean. There are so many other threads about lipo.
But I do appreciate your food for thought .

@Itchy: Thanks again!
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Old 01-12-2009, 07:11 AM   #24
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So, I finally tested the A123/LiFe battery this weekend and I must say I'm quite satisfied. My new Hyperion EOS720I charger (thank you Itchy) will be available in 3 weeks, so me and my buddy used the Overloader with Li-ion mode. We were able to charge with 8 Amp, and used a few diodes to bring down the voltage cut-off. This all went pretty good. But still the voltage would rise to 8.20 Volt and then it went down as it approached it's max capacity, meaning: full battery. This is more than the recommended voltage of 7.2 Volt (2p2s). But we didn't notice any disadvantage in performance. Based on the fact that the second and third charge was done by a Graupner Ultramat 17 with LiFe mode. Charged at 10 Amp and that went great.

So regarding track performance; the battery actually performed the same as a sub-c pack. The same punch, same rpm's, really amazing. My laptimes were exactly the same as sub-c, so this was exactly what I was looking for.
The battery didn't get warm at all, stayed fairly 'cold' the whole process. Meaning during charge, after charge and after driving there was no remarkable temp rise noticable (little more than ambient temp).

The only disadvantage was fitting the battery in. The battery stuck out a little bit. Both the TRF416 and Xray 009 had that issue. For me this isn't a real issue, with the right balancing the battery size is negligible. just tape it well and nothing will happen, and nothing did happen. We weren't able to weigh the battery (well prepared as we are), but the LiFe battery seems to be slightly lighter than a sub-c 5-cell pack. Next time we'll do some weighing.

We ran on carpet, one was using a brushed Element 19t motor and one was using a Orion 10.5 bl motor. Runtime was impressive, after approximately 18 minutes poking the throttle a gave up and ended my session. After recharging the pack, we came to the conclusion the pack stil had a 1000 mAh left in it. Impressive.


Overall personal conclusion:

Performance +
Punch +
Comparability with 5-cell sub-c +
Weight +
Charging process +
Charge-run-charge+
Capacity+
Balance +- (have to work on that)


We weren't able to take pictured this time, but will try next time.
To make the battery fit, I'm considering to rise the topdeck a little with a carbon spacer, same as the t009. But first do some more testing.

Thanks everybody for your help!
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Old 01-13-2009, 01:03 PM   #25
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So, I finally tested the A123/LiFe battery this weekend and I must say I'm quite satisfied. My new Hyperion EOS720I charger (thank you Itchy) will be available in 3 weeks, so me and my buddy used the Overloader with Li-ion mode. We were able to charge with 8 Amp, and used a few diodes to bring down the voltage cut-off. This all went pretty good. But still the voltage would rise to 8.20 Volt and then it went down as it approached it's max capacity, meaning: full battery. This is more than the recommended voltage of 7.2 Volt (2p2s). But we didn't notice any disadvantage in performance.
How did you measure the voltage? Using diodes the charger will show the usual 8.2v but if you measure the pack it should be lower.

If its not that maybe your diodes are different. Are you using regular diodes or shotky ones? I think the shotky have a lower voltage drop.

Great to hear its working for you.

I also have a good experience (aside from the fitment).

When you have pictures please share!
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Old 01-13-2009, 01:37 PM   #26
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How did you measure the voltage? Using diodes the charger will show the usual 8.2v but if you measure the pack it should be lower.

If its not that maybe your diodes are different. Are you using regular diodes or shotky ones? I think the shotky have a lower voltage drop.

Great to hear its working for you.

I also have a good experience (aside from the fitment).

When you have pictures please share!

Hi there,

Voltage was measured by the charger during charge. I didn't measure the pack with an external voltmeter. So you mean if I measure it with the voltmeter the voltage should be lower than 8.2V? It's just that a forgot a voltmeter .

The diodes we were using were normal ones, not shotky diodes (like you had right?) Mine look like FET's, if you know what I mean. I'll take a picture as soon as possible to show you.

Yeah, the pack just works great, no complaints actually. All good.
Only the fitment like you said, but could be worse.

As soon as I can get a hand on a camera I'll take some pictures and post it, no problem.
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Old 01-13-2009, 05:34 PM   #27
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Hi there,

Voltage was measured by the charger during charge. I didn't measure the pack with an external voltmeter. So you mean if I measure it with the voltmeter the voltage should be lower than 8.2V? It's just that a forgot a voltmeter .
Yes, the charger will display 8.2v (charge voltage for li-on), but the batery should be at max ~7.6v

You can check with a voltmeter.

And yes, im using a regular diode
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Old 01-15-2009, 02:16 PM   #28
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Hi again,

Promised you guys a few pictures. I was only able to take some pictures of my TRF416. The overall fitment could be better, because I should redirect my wires. Now they go underneath my topdeck, but they should go over it. They should actually go through the hole in the topdeck. Anyhow, I just made 2 photos showing the configuration. Still no weighing opportunity and no voltmeter has been used yet. Due to the fact my motor broke down and I called it a day. Still managed to take some pictures though.





I know my wiring could be much better, but my whole setup is in an experimental phase, so I have to clearify my bad wiring!
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Old 03-02-2011, 08:37 PM   #29
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I am also thiking about getting some a123 batteries, they are 4s tanick packs & I just want to know how the runtime & performance will compare to the 7 cell nimh batteries I have now. I'm running a slash with a mamba max pro & a velineon motor. can anyone tell me what to expect? thank you!
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