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.

I'm in the research phase of doing my own 1/8th scale buggy conversion. What settings are you using to charge the A123 cells on your ICE and are you charging the pack in a 5S2P or 10S1P configuration? I'm trying to decide between using my ICE or buying a new higher capacity A123 capable charger when it becomes in available in a couple months.

10 cells NiMh mode, set to a 15 mv/cell peak detection (so it won't cut out). The capacity value is rather arbitrary, but I set it to 9900mah.
The ICE can't put out the voltage to do 10s1p, so I charge it as 5s2p (the same way it's configured when I run it in my Revo).
Another possibility is the Astroflight 109 charger. Soon there's supposed to be an update for it that will allow you to charge A123 cells. Right now there's a hack shown on another forum that will let you charge the cells on the AF109. Recently I also got a 109, so I will try the hack on it.

Where did you hear about a different A123 charger?

There's an update that will add native A123 capability to the Hyperion 1210i (a 12S capable, 10A max, 180 total watt charger) currently in the works as mentioned in this thread on rcgroups.com. My current plan is to run two 5S1P packs in parallel in my buggy conversion. I can then connect them in series as 10S1P pack and charge at 10A (roughly 4C) which should let me charge the whole pack in 15 minutes. My ICE is suffering from left button failure so I don't need much of an excuse to start looking for a new charger :dft012:

Oh, I thought you meant A123 themselves are going to come out with a better charger.

I almost got the Hyperion 1210i (and would have gotten the update when it came out), but I got an Astroflight 109 for almost half the cost of the 1210i.

There are other chargers out there that can also charge A123 cells. The TME Xtrema is one of them. It's more expensive than the 1210i, though.

I've read about the Xtrema and it looks like a very nice charger but it doesn't apppear to charge NiMH/NiCD cells and I already have a wattmeter and a Hyperion balancer which is why I'm leaning towards the 1210i. I seem to recall reading about sporadic problems with the Astroflight 109 incorrectly detecting cell counts for Lipo batteries, was that problem resolved?

The AF109 has a first stage that displays the # of cells it detects. IMO, it's up to the user to make sure the AF109 displays the correct # of cells. Usually it's chooses properly, but sometimes it will detect a pack as a cell lower than what it really is, which just means that the pack is discharged more than the 109 likes.

Soon I'll be ordering the parts to "hack" my 109. I'll be able to do 1-9s on one side of a switch, 10s A123 on the other, and then normal Lipo in the middle position of the switch.

MM
I thought the AF109 was not a true CC/CV charger so you could only charge to 80-90% capacity.
Is that true or does it charge through the CV phase as well?

Its not a CC/CV...

If the AF109 doesn't charge through the CV phase then the LipoDapter makes more sense to those of us that already have NiMh/NiCad chargers.

Where did you guys hear that it's not a CC/CV charger?

I think it's a CC/CV charger. All the time I have read about it on rcgroups I don't remember anyone saying it's not a cc/cv... and it certainly gives a complete charge, not just 80-90% or people wouldn't be using it.

For a long time it was THE most popular lithium charger for 2000mah+ packs.

No matter what it is, it's pretty easy to tell. The current will stay constant while the voltage climbs. When the voltage reaches 4.2v/cell, the voltage stays constant and the current drops. Pretty simple to me.

When using the lipodaptor, it uses pure CC until it hits the volts/cell threshold and simply stops (from what I've read and understand). It's not the charger in this case, it's the adaptor. Maybe that's what is causing the confusion here??

The AF109 is a CC charger (in phases 1 and 2), and then it goes into a pulse mode in phase 3. What it does is it pulses the full charge current and monitors the voltage, attempting to keep the voltage at 4.2v/cell. It decreases the occurrence of these pulses as the battery gets more full. This is why some balancers will say they aren't compatible with the 109, since the voltage briefly spikes up, and then drops.

So, the 109 can still do a 100% charge, it just does it differently than normal LiPo chargers. With the hack I'll be doing (adding a couple of resistors), the 109 will see a voltage higher than what is really there (it will display 4.2v when a cell is at 3.6v).

The reason why I got the 109 is because it costs $110 and it can do 170watts. For reference, the Hyperion 1210i costs ~$180 and does 180watts, the ICE can do 120watts for ~$125, and I think the TME Xtrema can do 170watts for ~$200.

From what I've seen, most "CC/CV" chargers do something like the 109, except they don't pulse. They really do CC throughout the whole charge and then when it gets to the "CV" phase. Then, it's not really CV; they continually adjust the current to keep 4.2v/cell. That's why I call this adaptive CC. :)

The Xtrema is the opposite. It is a CV charger that continually adjusts the charge voltage to push the required current in "CC" mode. In CV mode, it simply locks the voltage at 4.2v/cell. This is directly from the maker via email. When I saw what was going on via V meter and C meter, I emailed hime and he confirmed and explained it. BTW: you are correct; it is 170w.

The Multiplex LN-5014 (same as Hyperion EOS5i) seems like it uses the "adaptive CC" since it reduces the current at the end of the charge before it gets to 4.2v/cell. The Duratrax ICE seems to be more of a CV charger, though. It goes all the way to 4.2v/cell, and although it may go up to 4.21v/cell and then go down to 4.20v/cell, it stays at that voltage while the current is reduced.