Brushless Revo + A123 and ICE

[Purplefade]

OK, I know there have been a ton of questions regarding A123 cells and how best to charge them... Not wanting to lose the CC\CV charging ability (and to get a full charge vs just 90%) I've been considering modifying my original pack plans and still using my ICE.

Originally I was going to run dual 6S1P packs for a cumulative 19.8 volts at 4600 mah, my problem, the ICE won't charge 6S or A123s for that matter...

My solution and the lead in to my crazy question: I've modified my pack design to dual 3S2P packs since the ICE can do 3S :-) MY question, 3S works out to 9.9 volts aprox, can I simply set my ICE to 2S (Li-Po) and my charge limit to 110%? I realize voltage and amperage aren't the same thing, hence the "crazy question"...

I know that as the A123s approach 3.65 volts that they "stop" accepting a charge, wouldn't the 10% "overcharge" allow the packs to climb up to their full capacity, or there abouts?

And if not with the ICE I guess I'm going to have to resolve myelf to getting an A123 Sonic charger or two..., though that may not be all bad. I like the Dapter+ and the DualDapter+, the only downside and I don't know that it is, I lose the CV and can't ever get a fully charged pack... Can I use the Dapter+ to get my 90% charge and simply hit the packs again for another 10 minutes to top them off?

Thoughts??

Thanks!!

[ClodMaxx]

i have 2 Ice's, and have been right on the verge of pulling the trigger and building my own m1 packs to charge on them. problem is, the cost of the lipodapter and if you want to do it right, a balancer on top of that.

a guy i work with is going the m1 route and just bought the cellpro 4s 4 amp charger/balancer. it'll fully charge m1 cells. you sure can't beat the price at $75. could be worth checking out.

[zeropointbug]

Purplefade: The A123's have a max charge voltage of 3.8volts, and 3.6v standard, so anywhere in that range will give full charge. Like you said, the A123's don't accept much charge at all after 3.6v, so charging them is fairly straight forward.

To answer your question, the only way to get a 100% charge with the A123's is to buy a switching mode power supply (lab type) that has the CC/CV function, most do though. I have a 5s2p setup for my truck and I am charging them using a BK PRECISION power supply (20volt/10Amp), it's very good quality, charges them in <30mins, and I can completely program it if I want to. It is ~$240 though, but can charge any battery type you hook up to it, and would most likely be your last.

-So I would either just stick with the Dapter+, or Dual...+, I am not sure if putting them on again will top them up though.

-Or solder on the proper balancer plug, and use A123's charger they sell.

-Or buy a good power supply with CC/CV programmable, very nice.

[BrianG]

The TME Xtrema also has a programmable CC/CV threshold from 3.6v/cell to 4.2v/cell in 0.5v increments. But it's around $190 and you need a 12v DC power supply (around 25A for full capability).

[zeropointbug]

That is another good option too BrianG, I just searched for it and it shows 3.7v - 4.2v.

How much for a good 12v power supply then?

Also, you would need to get the 40v/5Amp version of my switching power supply in order to charge 6s M1, but you only have 5 Amps charge, so 1 hour charge.

The charger BrianG might be the same price and you have the same voltage range, but 8 Amps charge rate, which is nice.

[jhautz]

The Extrema is what I use. The website says its 3.7 -4.2 but the new ones have an update to the software that alows it to charge to 3.6V. It works great as long as you have a power supply big enough. I fried a power supply using it once. Now I'm using a 30A PS from a big computer server that I converted for use as a charger PS.

[BrianG]

Yup, it is 3.6v. At first, I wasn't sure I liked it, but it's pretty nice. I emailed the designer and we had a little chat about how it worked and I like the algorithm it uses.

To figure out what size PS you need, you can use this page as a guide. The table below is for the Xtrema:

Input V   Min A    Safe A 
 11.0V    20.5A    25.6A   
 11.5V    19.6A    24.5A   
 12.0V    18.8A    23.4A   
 12.5V    18.0A    22.5A   
 13.0V    17.3A    21.6A   
 13.5V    16.7A    20.8A   
 14.0V    16.1A    20.1A   
 14.5V    15.5A    19.4A   
 15.0V    15.0A    18.8A

It's obvious that a higher input voltage will require lower current so try to find a PS with a solid voltage. Most dip down once you start drawing some heavy current...

[zeropointbug]

This is just a thought, you could also get a computer 12v PSU and tap the switching ON wire and just use the 12v Rail on it, they should provide a very solid 12v volts, if you get the right one. Contact me if you want to go that route.

[BrianG]

I already wrote a tutorial on that topic. But, for the higher power chargers, only a really powerful PC supply will work. And most of the high 12v current supplies out now are either comprised of dual smaller 12v outputs, or are just as expensive as getting a power supply specifically made for this application.

[zeropointbug]

Originally Posted by BrianG

I already wrote a tutorial on that topic. But, for the higher power chargers, only a really powerful PC supply will work. And most of the high 12v current supplies out now are either comprised of dual smaller 12v outputs, or are just as expensive as getting a power supply specifically made for this application.

That's true, I forgot to mention that. But I do know of inexpensive psu's that have dual 35 amp rails.

How much is a charger PS for this then?

[BrianG]

What inexpensive PSUs do you know of that supply a single 35A rail?? The ones I made work well for smaller chargers (my EOS 7i), but the Xtrema needed 180w + losses. I ended up getting an Astron 30A supply off ebay for like $80. I then tweaked the voltage up to 14.5 (from 13.5).

[zeropointbug]

Sorry, I meant 35 amps through two rails (18A rails).

You can combine the rails as well.

Here is one as an example. Actually, it has quad 18A rails. $85 CAD


http://www.ncix.com/products/index.p...y&promoid=1060

What regulated PS would you recommend for that charger then?

[jhautz]

This is the power supply I use. I bought it from MetalMan almost a year ago for $25 I think. He said he bought 2 of them for a deal and didnt need the 2nd one. Dont know where he got it, but it seems to be very solid. No major mods were needed to make it work.

http://i66.photobucket.com/albums/h2...z/CIMG1892.jpg

I just soldered some 4mm gold plugs to the output and can just plug in to them of use aligator clips on them.
http://i66.photobucket.com/albums/h2...z/CIMG1893.jpg

Here is the specs and model number if anyone wants to hunt one down.
http://i66.photobucket.com/albums/h2...z/CIMG1897.jpg

[zeropointbug]

Nice, it looks like that is a modular server power supply.

30A on a single 12v rail is very good.

[MetalMan]

Yeah, they are excellent power supplies. This is where they were bought:
http://www.allelectronics.com/cgi-bi...A,_5_35A_.html
Unfortunately they aren't sold anymore, otherwise I'd buy them up, mod them, and sell them on Ebay for a profit :). They come as two in an enclosure, and can do 60amps for the entire enclosure, for only $40!

jhautz, I didn't remember that you were the one who had bought the power supply from me. It's good to know it's working well for you still!

Right now I'm charging A123s using a modified Astroflight 109. It can charge 1-10s A123, and is selectable between A123 and Lipo with a small toggle switch. The mod is completely removable, and works very well. What's nice is that the AF 109 charger can do 170watts, and it costs only $120:
http://www2.towerhobbies.com/cgi-bin...&I=LXFWW2&P=ML
Astroflight also makes an A123 version, but it can only do A123, and I've heard of some issues with it choosing the proper cell count.
http://battlepack.com/chargers.asp (about 2/3 down)

I used to charge my A123 packs with the ICE, and I just did a manual CV phase. I charged the pack until the cells got to 3.6v/cell, and then manually decreased the charge current to maintain the 3.6v/cell overall voltage.