everydayflyer

http://www.rcuniverse.com/forum/m_6477096/tm.htm

Only practical for groups of 3S however you could charge two ea. 3S packs in parallel and use them in series as a 6S.


Charles

hakank

Charles. How many amps are you charging with in the beginning of the cycle following your link?

/HÃ¥kan

everydayflyer

That depends on the resistence (wire GA and length) the discharged voltage of the A123 pack and the voltage of the source (deep cycles).

Early on I was using around 8 feet of approx. 17 GA and from memory starting amps. with 3S at 9.6V and deep cycles at approx. 12.2 (under load) charge rate was around 25 amps. I have gone to 5 1/2 feet of 16 GA and with same conditions starting amps. close to 30.

There are plenty of specs. in the Thread at RC Groups.


Charles

peskelton

Hey guys,

I've been reading the posts on a123s there's so much! I'm really excited about trying mine out. I've got a 4600 Hypersonic 2S2P off ebay for $45 new. I have a few lipo chargers and a couple NiXX chargers. I can't decide from what I've read which one to use... Here's what I have:

Novak Millenium up to 3A ( don't laugh, I know it's old )
Vortex NiCD NiMH up to 5A
LiPoly Smart Charger from Hobby-Lobby

I've seen that people use regular NiXX chargers and just monitor the pack voltage. How likely will it be to create an unbalanced pack using this method? And what voltage should I look for on a 2S2P a123 pack that will allow high performance and long life?

Thanks!
Paul

everydayflyer

The problem with using a Ni charger and watching the voltage is that the voltage shots up extremely fast near the end.

I recomend using

http://baldwincontrols.com/t_2.html

use the contact info at the bottom of the website page. Last I heard they were $40 including shipping.

They really should be balanced,especially in the beginning (first 5 -15 charges) however a 2 cell should not be a amjor problem. You can check the voltage of each cell and either charge the low one or discharge the high one till they match.

Charles

peskelton

Thanks!

So that Terminator is basically the same thing as the Dapter, right?

If you had to get by with a bare NiXX or LiPo charger temporarily, which would you choose?

Paul

everydayflyer

Same but very different IMO. Dapter limited to 8amps. max and I find it to be a pain to use. Terminator II handles 40 amps. with ease and is extremely simple to use. Terminator II also uses a higher cutoff voltage which I was responsable for developing and I find to work better.

If you have a charger with a 6 volt Pb setting it will work fine for a 2S A123.

If you have a charger with LiIon setting (3.6 charge to 4.1) per cell settings it would be safer than counting on stopping a charge in the Ni mode. SAme can be said for usin LiPoly (3.7-4.2) setting.

These A123 cells can stand being overcharged. It may reduce the total number of cycles but is really not a big deal. A single cell test was ran where a cell was charged to 4.3 volts and discharged to zero volts for 300 cycles and no damage was done.Problem with charging to higher voltages is that balance becomes a bigger issue. I have charged a 4S balanced pack to 18.25 volts (4.5625 per cell) one time after flight #44 and now 300 flights latter it is still delivering over 2000 mAh capacity. A few have left a battery unattended on a Ni charger and caused cells to vent. They are tuff but can be destroyed.


Charles

peskelton

I got my Hypersonic a123 last night. That thing is HUGE! It's the 4600 so it won't fit in my XXX buggy very well and definately won't fit in my XX4, which I knew when I bought it. I checked voltage and it was at 6.3v so I threw it on my Novak Millenium charger since I can specify cell number. I set it for NiMH at 5 cells. I can also monitor the voltage on that charger and when it got to 7.3v, I took it off. I wonder if I should go with the 4 cell setting since it overcharges...

I stuffed it in my XXX and did a bench test. It had my Mamba Maxx and a 3300kv brushless motor geared way up. I powered up and held the car in place while I gave it throttle to see what I was dealing with. Wow. It was ballooning the tires and burning my bench top while I held it down. Totally impressed. Went out to the street and ran for about 6 minutes if not more and never dumped the pack. It seemed to stutter sometimes on initial full throttle. Must be my ESC to motor connection. It also seemed to take a while to hit full speed. But other than that, I was really happy with it.

Went back to the basement, put the battery in my Clodzilla with two 17 turn motors and an old LRP speedo. At 6.xx volts, it wasn't crazy by any means but it had plenty of power and I still didn't get to the end of the pack.

Nothing got hot in either car which means I'm under geared in both? Or just that my setups are good?

Now what I really want to know is would it be a good idea to split the 4600 into two 2300 packs? Then I could use them saddle style in my XX4 and single 2300 in my XXX and race. So if I do split up the pack, I can cut the tabs in the middle and then solder to them so I don't over heat, right? Or in this config from Hypersonic, are they butted together and there are no tabs? In which case I have to heatsink the cell when I solder to it... I know there's a page with this process described but I can't remember where I've seen it. There's so much info about these batteries...it all runs together.

Thanks and sorry for running on,

Paul