a123 6.6v questions

When you gear up, it will draw more current. Going to 5S A123 with the MM shouldn't be a problem. I can't remember if I did it or not. I ran 5S A123 in my 8ight T, but can't remember if I used a MM or Monster Pro.

[ClodMaxx]

well i called a123 to see if i could change my order (didn't have confirmation that it had shipped yet) to take one of the 2s2p packs out and replace it with 2 of the 3s1p packs, but alas - they were too quick. it was shipped already. so for the time being, i'll be running 4s instead of 5s.

so, i do plan to go up to 5s2p with the a123 cells...which is still only 16.5v. it's going to be on the heavy side...10 cells total, but i'm fine with that.

my question is this: can anyone see a downside to building a deans parallel connector to connect 2 packs that are 3s1p on one side? i would think it would be fine, just wanted to make sure. i could also tear a dewalt pack apart and build a 3s2p single pack, but i hate soldering. i'm ok at it, but i hate it.

[lincpimp]

Deans parallel connectors are fine, I use my homemade one alot and it does not get hot, so I figure that it is ok. From what I have read the deans are only good for a 60 amp draw, but that must be continous, not sure what a 60 amp continuous sytem would look like, but it would be powerful!

[VintageMA]

Originally Posted by ClodMaxx

well i called a123 to see if i could change my order (didn't have confirmation that it had shipped yet) to take one of the 2s2p packs out and replace it with 2 of the 3s1p packs, but alas - they were too quick. it was shipped already. so for the time being, i'll be running 4s instead of 5s.

so, i do plan to go up to 5s2p with the a123 cells...which is still only 16.5v. it's going to be on the heavy side...10 cells total, but i'm fine with that.

my question is this: can anyone see a downside to building a deans parallel connector to connect 2 packs that are 3s1p on one side? i would think it would be fine, just wanted to make sure. i could also tear a dewalt pack apart and build a 3s2p single pack, but i hate soldering. i'm ok at it, but i hate it.

Just from my experience (which was very short lived for now) with the A123 cells, they don't hold their rated voltage under load. Granted I was using a 1P setup which didn't hold it's voltage as well as the 2P systems will, but check out the specs on a 2S2P pack here: http://www.a123racing.com/SpecSheets...te_14Aug06.pdf You will be getting about 6 volts on 2S2P @ 23Amps. @ 69Amps you are only talking 5 volts (2.5v per cell)

The packs are very heavy and very bulky. I went with the 2 of the 2S1p packs in hopes of using it in a CRT.5 project @ 13.2v. After running that and comparing it with my 3S 5000mAh Maxamps lipo packs I have to say that I am much happier with the lipo packs. The lipo pack is smaller in size than the 4S1P A123, holds more than 2X the charge and is lighter as well. The A123 cells do have a great punch, but due to the low storage capacity they seemed to dump pretty quickly.

I've never had a problem with lipo when using a decent brand (Maxamps, TP, Kokam/Orion, or TrakPower/FlightPower) so I think I will stick with them until the A123 technology matures over the next few years (which I am sure it will and am definitely looking forward to). IMO the power density (even when compared to NiMH) is too low making for a heavy pack and the cells are too cumbersome for easy placement.

[ClodMaxx]

i could give the list of reasons why i chose the a123 packs instead of lipo, but i'd rather this thread not turn into a lipo vs. a123 debate.

i'll find out about the a123 performance soon enough. i appreciate your input.

[zeropointbug]

http://picasaweb.google.com/SethHulsebosch/RCPhotos

Check out the Eagletree graphs at the top of the page there.

[VintageMA]

Originally Posted by ClodMaxx

i could give the list of reasons why i chose the a123 packs instead of lipo, but i'd rather this thread not turn into a lipo vs. a123 debate.

i'll find out about the a123 performance soon enough. i appreciate your input.

I have no intent in aiming on starting a debate on A123 vs lipo - cause that could be never ending.

Simply - I tried them and they are not for me right now.

I think in the 2P configuration in which you are going they will be much better than the 1P config I used - that will put them closer to that 5000mAh mark whichgives a nice blend of power to the motor and a decent amount of runtime.

If you are able to fit the batteries comfortably into your setup and they work for you - then I see no reason to bash them. They really do have their positive sides - the fast charge time, the safety factor, and the 1000+ rated cycles vs. about 200 or so cycles for a lipo.

It is definitely a battery technology that I will monitor closely and see how it progresses over the next few years. Once it matures to the next level - I could see it easily take the place of lipos in the car/buggy arena.

[jhautz]

Originally Posted by VintageMA

Just from my experience (which was very short lived for now) with the A123 cells, they don't hold their rated voltage under load. Granted I was using a 1P setup which didn't hold it's voltage as well as the 2P systems will, but check out the specs on a 2S2P pack here: http://www.a123racing.com/SpecSheets...te_14Aug06.pdf You will be getting about 6 volts on 2S2P @ 23Amps. @ 69Amps you are only talking 5 volts (2.5v per cell)

The packs are very heavy and very bulky. I went with the 2 of the 2S1p packs in hopes of using it in a CRT.5 project @ 13.2v. After running that and comparing it with my 3S 5000mAh Maxamps lipo packs I have to say that I am much happier with the lipo packs. The lipo pack is smaller in size than the 4S1P A123, holds more than 2X the charge and is lighter as well. The A123 cells do have a great punch, but due to the low storage capacity they seemed to dump pretty quickly.

I've never had a problem with lipo when using a decent brand (Maxamps, TP, Kokam/Orion, or TrakPower/FlightPower) so I think I will stick with them until the A123 technology matures over the next few years (which I am sure it will and am definitely looking forward to). IMO the power density (even when compared to NiMH) is too low making for a heavy pack and the cells are too cumbersome for easy placement.

I had similar results as you with did running my lightning staduim 10 on 4s1p a123. I actually found that running 3s2p gave me better acceleration and better top end witha little gearing adjustment. I'm carrying 2 extra cells around now, but they perform much better.

BTW someone mentioned a 1940/7 drawing to many amps for the a123 eariler, but I actuially think that it would be fine. I run a 1940/7 in my savage with 5s2p a123 and it rubns great. Because I didnt need a LVC with the a123 I was able to use an older style BK controller I had around. If you run a123 the 9920 and 12020 become very atractive options again.

[zeropointbug]

Originally Posted by jhautz

BTW someone mentioned a 1940/7 drawing to many amps for the a123 eariler, but I actuially think that it would be fine. I run a 1940/7 in my savage with 5s2p a123 and it rubns great. Because I didnt need a LVC with the a123 I was able to use an older style BK controller I had around. If you run a123 the 9920 and 12020 become very atractive options again.

I agree, when I ran 5s2p on a 7XL, it had awesome power, able to flip over the truck at any speed with WOT. I had it geared for 45+mph, and I think it could actually hit 50mph because of the tire ballooning on the badlands.