A123 Batteries for Dummies.

[Kiwi]

A123 Batteries for Dummies.

Well the thread title is aimed at me. It seems that there is a very good alternative to the power setups we are using in some of our planes these days. Hidden way down in the bowels of another thread on the site is a discussion on the pros and cons of the A123 battery technology.

These things may be just what the doctor ordered so I hope the likes of Dick Hanson and anyone else who is experimenting with these packs or cells can enlighten us all here.

Fire away please guys. I need to know more about them and I prefer to learn it here.

[sprice50]

Never heard of this... interesting. Can't wait to see what it is all about.

[F3AFlyer7]

I've used them in a modified electric E-maxx and they work great! They are surprisingly light for their size and seem to perform much like a Li-po. They are still heavier than Li-po's for their capacity and take up more space. I know some people are running them on 90 sized helis with great success. But thats as far as my knowledge goes.

[krashmaster81]

Standing by to be enlightened...

-Matt

[tobytorkn]

I would love to hear the following.

a. where can we get them outside of a123 racing, (ie. supporting hobby distributor)? i think horizon just did a deal with them? cost per battery/pack?

b. what kind of chargers can i use? will a triton,hobbico elite, etc, work by doing a little programming?

c. what are some actual field reports.

d. for people making larger packs are you doing balance charging or is this even necessary.

by what i've read you litterally can do a dump charge while your fueling and they'll take the abuse.<---lets here some actual field reports.


thanks for the info.... toby silhavy
www.silhavyaerosports.net

[toprudder]

The topic in the other thread was about using A123 cells instead of Li-Ion for powering rx/servos. One advantage is the lower voltage per cell of A123, no regulator is needed.

I've heard some people buy the A123 cells by purchasing Dewalt tool batteries on eBay. I don't know which model number battery, and I know a lot of the Dewalt tools use Nicad packs, so the model number would be useful information.

Bob R.

[Kiwi]

Here's what I do know about them.

They are a nominal 3.3 volt cell so by putting two cells together you get 6.6 volts. Definitely no need for a regulator.

They are capable of delivering 70 amps pretty much continuously with a burst for 10 seconds at 120 amps with voltage loss. That humongous amperage for a 35% plus sized plane with these new 8711 type servos.

The ability of the cell to take such a whopping load yet hold voltage is one of the key advantages.

You can charge them at 8 amps and in 15 minutes your fully charged and ready to go flying again (talking electrics here but the same for flight packs I suppose)

You don't need fancy chargers, 100 dollar charger from FMA Direct is available now.

I will get the De Walt battery number but the 36 volt De Walt pack on Ebay runs for around $100. That must have ten or twelve batteries in it.

I will find more this weekend but I know Dick is using them and swears by them.

[exeter_acres]

Toby has a good question... as I don't do business with FMA...
is that a special a123 charger... or can we use our current LiIon/LiPo chargers?

[hybris]

You don't have to buy the Cellpro from FMA but I like it the best. There is also a new Astro A123 charger coming out. The are some other chargers also. You cannot use a regular Lion/lipo charger, it will overcharge the cells. 3.6v per cell is full charge vs. 4.2 volts for lipoly. Check out my thread:

Flew on A123 batteries today.

Now up to over 2.5 hours on them in my Extra.

[hybris]

Tanic packs sells them: www.tanicpacks.com

I got mine from ebay. Dewalt DC9360 battery (36v) for about $110 delivered.

Instruction on taking apart a Dewalt pack: http://www.slkelectronics.com/DeWalt/packs.htm

[JoeKelley]

I have some ideas of how I would like to use these cells but am watching and waiting. The weights are not far off from nickel batteries. If I were to get into them today I'd buy off ebay and or http://www.tanicpacks.com , that guy knows his stuff from what I can see. I use a mix of futaba receivers and JR servos and am not sure they like anything over 5.5 volts together. There is also IMO a lack of real easy and cheap chargers right now that will show up later if these cells get popular. The price of them is steep for what they do IMO.
Good luck Kiwi.

Joe

[toprudder]

A standard LiIon or Lipo charger will not work, it must have a special charge mode programmed in with the different cell voltage. The charge algorithm is the same (current limited, constant voltage) as Lipo/LiIon, just a different voltage. As I understand it, the FMA charger will handle Lipo as well as the A123. Most chargers could be modified by the manufacturer with updated firmware, but whether they do it or not....???

I'll probably do what Dick Hanson talked about, build a charger with a simple three terminal power supply regulator, like the LM317. Should be easy to do.

Bob R.