a123system batt and charger
 

has anyone tried these yet? im interested in the combo that comes with two batterys and charger , i think they are 2300 mah batts , about $175 so the price is right but i dont know if it is better to go with a higher voltage, these packs are 6.6 volts so it would be 13.2 volts in a revo with hvmaxx 4.5 system . any thoughts or suggestions would be great , thanks

A couple people run a123 cells here, they can take this thread.

thanks ill see what they have to say

Welcome to the forums entjoles!

will the hvmaxx system evan work with this low of voltage?

thanks i have been trying to learn what i can by reading other threads but i needed help trying to get this set up

I read somewhere that those cells really can't take much more than a 40 amp discharge....really can't remember where though...gonna go search...if I find it I'll post up..maybe in one of the rc airplane mags I have...:confused:

pinolelst

Ok found it in the 12-06 issue of quiet flyer..can't find the article online anywhere so I'll type in his conclusion here :

"What might this mean for most flyers? The cells should be good for applications that have current demand lower than 40 amps.At higher currents the useful capacity falls well below the 2300 mah spec and the cells get quite hot.While the cells might survive abuse at higher current it may not supply the voltage or capacity desired.So as with most all of the power systems being sold now it is necessary to be informed as to the limits and stay within them.Venture to the limts at your own risk !"/ quote

The article has graphs showing some pretty deep voltage depression at a 30 amp cont 50 amp pulse disharge cycle and a noted .010 ohms resistance vs a .006 ohms resistance for an old 3200 kokam lipo pack tested in the same way

as always YMMV

thanks i think ill avoid those packs

You gotta remember that these cells are much safer. They have a metal casing for more durability. There is little danger of overcharging - at least they are much more tolerant than lipos. And they can be punctured without flaming, a very good feature in a MT where batteries can fly out during a particularly bad crash.

IMO 2300mAh is not much capacity so you'd probably be using a 2P arrangement. That brings it up to 60A discharge. Not too many trucks require 60A continuous or runtime would be measured in the single digit minutes.

Like everything else; they have their uses. MetalMan has used them and so have BP-Revo maybe a couple others but I can't recall. They seem to like them...

These cells can actually take 60amps continuously without too much of a problem (they do get quite hot, but that only shortens their lifespan). Here's the graph I am referring to:
http://www.rcgroups.com/forums/showp...98&postcount=1
Remember that a 2v cutoff is recommended. These cells can do something like 120amps in quick peaks, so in 2p form you should be able to get ~200amp peaks (assuming your wiring and connectors can handle that).

I'm running 5s2p in my Revo (16.5v, 4600mah) with a 7XL and Mamba Max, and it's an awesome setup. I'll run the same battery and ESC in my 1/8 buggy. Just so they wouldn't have to share, I ordered another Dewalt 36v pack this morning to make another 5s2p setup.

what are you using to charge these? i was looking at the a123 web site and i think i could use the 2s2p 4600 packs , 2 packs and the adjustable voltage module and charger for $300 would that work good for a hvmaxx 4.5 system?

I'm using a Duratrax ICE, and I stop the charge manually. If it were me doing that setup (two 2s2p), I'd be able to do it for $245 ($80 for 8 cells from a Dewalt 36v pack, $125 for Duratrax ICE, and $40 for a Dapter [to stop the charge for you]). But this setup requires custom building, which might be something you would prefer to not do.

But to answer your question, two packs should work with the HV-Maxx 4.5, just don't use the adjustable voltage modules (apparently they aren't made to handle the high current of brushless motors).

I just got the Xtrema charger and it has an selectable voltage for the A123s or pretty much any Lithium cell out there.

Sorry to hijack, but, How often do you have to balance these? I'm interested in trying them but am getting mixed answers on balancing
Once again sorry for the hijack

I have been using a balancer during each charge cycle, but I'm not sure how necessary it is. Some time I'll have to see how the cells charge without a balancer.