Teach us about A123 batterys- Pros/Cons?

[bstock]

Hi Guys,

Keep hearing mention about A123 batteries... but do not know much about this Battery option.

Know they are heavier... but that is pretty much the extent of it :dontknow

Thanks!!
Brent

[cholyoake]

the good thing about A123's is they can be charged in 15 minutes.

[spork]

They can be charged in 15 minutes, they don't explode, and they're significantly more robust. One over-discharge won't ruin them. Also, a 4S pack runs you about $40.

I'm running 4S A123's in my T-Rex 450. Because of the extra weight, they're probably not the ideal solution for hard-core 3D, but they have plenty of ooomph for the flying I do.

[kidjetta]

Spork, I know you're an advocate of A123 power. I'm squarely in the heli noob category, and all of my experience is with lipo, as well is most of the common knowledge. What is involved in using A123 power? Aside from new cells and charger, what are the compatibility issues. New motor? ESC? BEC? Do they need to be balanced? If so, will they work with a lipo balancer? Is flight time affected? Etc...

[rcboosted]

You don't need a new motor or pinion, just lower your throttle since 4S a123 are 13.2v instead of 11.1v You can also keep using all your electronics the same way, but since the voltage is higher now, I'd keep an eye on the temp of the bec in the esc. If it gets too hot, go seperate bec. I didn't have any problems with mine. They can go without balancing but I've been balancing mine every charge. I know they can handle being overcharged due to imbalance, but why do it on purpose? Not sure if every lipo balancer will work, but I believe so. Just gotta make sure the charger isn't sending out 4.2v. Flight time is increased despite doubled the battery weight due to the extra cell and 2300mah capacity.

[n2wizard]

I am flying on 3 cell A123 with good results. Switched pinion from 11 to 13
to keep up head speed. I get about 7 min. on a charge, thinking about
going all A123. Here are screenshots of the same heli on 3 A123 and 3 cell 2100 lipo. No 3D, just learning figure 8's and nose in. Ya gotta love it.
Herman

[spork]

Spork, I know you're an advocate of A123 power.

I use them and like them, but I have nothing against LiPo's either. If you're willing to take extra care not to damage your cells or burn down your house, an argument could certainly be made that LiPo's are the better way to go. For me, the A123's are the ticket until the next better thing comes along (hopefully something that doesn't explode, takes a fast charge, and puts out lots of current).

What is involved in using A123 power?

In my case I simply swapped out the 3S LiPo's for 4S A123's. Because of the weight my battery configuration is very different (two up front and one on each frame side). This balances well. I don't use a separate BEC, and haven't had any trouble with heat etc. I also didn't change the pinion or throttle (I use the 11T pinion with the Align 430L motor). I had been using the MMM-32 ESC, and switched back to the Align 25A ESC because the MMM misinterpreted the 4S A123's as 4S LiPo's and cut out WAY too soon.

You should balance them (IMO), and you should try and avoid overcharge and over-discharge. However, they are far more robust than LiPo's in these respects. I found the attached PDF to be extremely useful.

Most of the better chargers seem to handle A123's now (although some require a free firmware upgrade). If you have a charger like mine that doesn't charge A123's you can get the LiPoDapter for $40.00 (including shipping), and use pretty much any charger. The other one I really like is the CellPro 4S. It's small, inexpensive, and I think an excellent charger for A123's. I get 8 minutes flying my T-Rex 450 pushing it reasonably hard.

[rcboosted]

I just put my JGF 500TH on governor at 3000rpm using A123. Holy crap it flys so nice. This seems to be the ticket for A123's.

[tppjr]

They can be charged in 15 minutes, they don't explode, and they're significantly more robust. One over-discharge won't ruin them. Also, a 4S pack runs you about $40.

I'm running 4S A123's in my T-Rex 450. Because of the extra weight, they're probably not the ideal solution for hard-core 3D, but they have plenty of ooomph for the flying I do.

Rick,

You have any pics of your setup?? And where did you pick them up for $40??

Thanks,

Thomas

[spork]

You have any pics of your setup?? And where did you pick them up for $40??

That's my setup two posts up. You can see a cell on this side of the frame, and there's a cell on the other side, and two under the canopy. Did you want a pic with the canopy off?

I got mine on Ebay. They were typically running around $100 for the DeWalt 10 cell pack.

Search for "DeWalt DC9360 36V"

It looks like the last two sold went for just a hair over $100 with shipping. Yesterday it looks like two had starting bids at $49 and got ZERO bids.

[tppjr]

You have any pics of your setup?? And where did you pick them up for $40??

That's my setup two posts up. You can see a cell on this side of the frame, and there's a cell on the other side, and two under the canopy. Did you want a pic with the canopy off?

I got mine on Ebay. They were typically running around $100 for the DeWalt 10 cell pack.

Search for "DeWalt DC9360 36V"

It looks like the last two sold went for just a hair over $100 with shipping. Yesterday it looks like two had starting bids at $49 and got ZERO bids.

Thanks, I saw the pic after posting but let it ride to get the cost info. A couple pics with the canopy off would be nice.

Thomas

[smw]

Here is the site that sells pre built packs http://www.bigerc.com/
I have not purchased any from him, but the owner was very helpful in referring me to others when I was looking to obtain a single Emoli cell for replacement in a 7cell pack.

[tppjr]

Here is the site that sells pre built packs http://www.bigerc.com/
I have not purchased any from him, but the owner was very helpful in referring me to others when I was looking to obtain a single Emoli cell for replacement in a 7cell pack.

Yes, RC Accy. sells them too.

Thomas

[JKos]

> Search for "DeWalt DC9360 36V"

Also search without the DC9360. Not everyone puts that in. You'll have more stuff to sift through, but you will find packs that the above terms don't match.

- John

[tppjr]

> Search for "DeWalt DC9360 36V"

Also search without the DC9360. Not everyone puts that in. You'll have more stuff to sift through, but you will find packs that the above terms don't match.

- John

Any more info on how you formned your packs?

Thomas

[spork]

Here is the site that sells pre built packs http://www.bigerc.com/

Wow - $100 stones for a 4S. That's about 2 1/2 times what I paid by buying the DeWalt cells.

In my case I just wrapped the cells with black gaffer's tape and added a Dean's connector and balance tap.

[smw]

Wow - $100 stones for a 4S. That's about 2 1/2 times what I paid by buying the DeWalt cells.


Labor??? Some may not want or have the supplies to build their own. Though, I have to agree that price seems pretty high.

[spork]

Seems like a good money making opportunity for someone looking to augment his (or her) hobby fund. Just build a pack for $40 and sell it for $70. Make $30 and save the customer $30 at the same time - eh?

[bstock]

What is the weight difference of the A123 cells - over regular lipo cells? Twice as much?

n2wizard - are you able to get that 3S pack to fit well under the canopy?

Do the A123s have a better cycle/ life expectancy?

If we run 3S - do we really notice much difference in the performance of the motor/ ESC?

[JKos]

Each cell is spec'd at 70 g. In a 10S configuration with balancing leads mine came out to an average of 78 g per cell (total weight/10).

- John

[n2wizard]

It's a tight squeze, but canopy fits. Frame is Helidirect's superframe, which I like a lot. To help with balance, I moved tail servo way back. Motor is an old Aveox which had a planetary gearbox. With box removed, shaft was to short, so I sweat soldered two spur gears face to face, and was able to fit it in. Be sure to re-set cutoff on ESC for lower voltage or you will have a very short run.
Herman

[spork]

Do the A123s have a better cycle/ life expectancy?

You should take a peek at the doc I posted just a few items up. My take is that a LiPo might give you similar lifetime if it's treated VERY well. If you let your batteries get hot or over-discharge even a little, and just on occassion, I believe the A123's are going to outlast LiPo's very significantly.

[rcboosted]

n2wizard, what is your head speed and what style of flying? 3cell sounds interesting, much better fit and easier than (2) 2-cell packs to work with and less weight! If it can sustain 3000rpm using 3 cell, maybe I will convert mine to 3 cells.

[bstock]

Thanks Rick... I surf HF in the evenings with my Treo... and I'm not able read PDFs on it. (live in the boondocks... no high speed out here) I will look it over tomorrow in the office.

Thanks for posting it, and also for the photos!! Very Cool

[spork]

Thanks Rick... I surf HF in the evenings with my Treo... and I'm not able read PDFs on it. (live in the boondocks... no high speed out here) I will look it over tomorrow in the office.

Thanks for posting it, and also for the photos!! Very Cool

Gotcha. Sorry I haven't posted any "canopy off" photos yet. I'm in the middle of swapping to the STK frames. I'll try and remember to post the arrangement on the new frames.