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Old 10-25-2007, 04:03 PM   #1
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Default a123 battery packs

These packs run through more cycles and are less dangerous then lipos. They don't go up in flames either. They are rated at a 30c discharge and you can charge them at a factory recomended 2c rate.
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Old 10-25-2007, 04:03 PM   #2
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You can find most of this info w/ google and a little common sense.

I purchased a dewalt 36volt pack, made out of 10 a123 cells for like $80 and used 6 of them to make my pack.
You can find them on ebay for around that price. Anything under $100 shipped is normally a decent price. If you are looking for a
2s2p pack for 4wd buggy then you could just split the cost w/ a friend.
Be sure to do your research on these cells before you take apart the pack. There are sites on breaking them down. The two pieces of information you will need though are to leave the tabs that come w/ the cells on them, just cut them if you want to take them apart or leave them togather instead of using battery bars, because you can't solder directly to the cells so you solder to the tabs & do not twist the tab, twisting it can cause the cells to dead short. Do not cover the little blimish w/ solder, that is how the cells vent.

How to build a saddle pack:
required
*4cells,3 long pieces of wire, two battery bars, plug,shrink rap
All soldering will be done on the tabs & will not be over the small blemish in the middle of the cells.
1.take two cells and solder the + to the - using a battery bar(this will be side 1, repeat w/ the other two cells.(side 2)(the more you wire + to - the greater your voltage)
2. take a piece of wire that reaches across the chasis and connect the wire to the + of (side 2) to the + of (side1).
3. repeat this process for the neg.
4. repeat this process again, you can use a lighter piece of wire for this(balancing plug), with the side the battery bars on on. Run it from battery bar to battery bar.
5. Now remove the rubber off the + wire in the middle for your plug. and solder the plug to it there.
6. repeat step 5 for the neg.
(don't let the + and - wires touch, these are just like any other +&- wires on a 6cell stick.)
Now take the 3rd wire and stick a FEMALE PLUG ON IT(you want to make sure that the wires are not going to dead short when they touch since you have an extra wire. Often times I zip tie the two plugs away from each other on the car.
7. shrink wrap the cells if you want too.

For building 3p2s pack(perfect for 2wd truck or buggy), you will have to lower the sides of the battery trey just use a cheap solding iron and melt the sides down, much easier then dremeling them down. You can see what i'm talking about at
thedunemaster.com (more of those expensive packs)
1. zip tie 3 cells togather w/ the + ends all facing the same way.
2. strip down a nice thick wire and use it as a battery bar to connect the 3 cells + side.
3. repeat for the - side.
4. repeat steps 1,2,&3 w/ the other 3 cells.
5. take a wire and solder the + side of pack 1 to the -side of pack two.(short wire) and another longer wire from any of the cells in the middle(balancing plug).
then bend the wire connecting the sides so that the cells make a straight line.
6. run a wire from the free sides to your plug.
7. Now shrink rap it.
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Old 10-26-2007, 12:16 AM   #3
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i dunno, but is 30C discharge a bit low? i mean my 4400mah 2s lipo pack is 66C recommended. thats more than double the discharge rate available.

isnt that a concern? they gotta make the discharge rate that high for sum reason otherwise all packs would have a low C
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Old 10-26-2007, 01:00 AM   #4
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There are no packs that discharge at a 66c constant rate. Odds are your pack discharges at around a 20c rate. A 30c constant rate is very high. Not even the high end orions have a 30c constant discharge rate. Can you please get your facts straight before you make another false comment about these cells. A 4600mah 30c pack can discharge at over 130amps. Your max amps pack discharges at around 80 amps. If your worried about 30c providing enough current then you should probly stop running lipos all togather.
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Old 10-26-2007, 02:27 AM   #5
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notice my question marks and how i was unsure about the stuff?

btw, i didnt post any facts other than that my lipo has a sticker on it saying 66C discharge on it.

so please, dont go accusing me of saying i am making false claims.

EDIT
yep, i think they miss labelled the pack, ugh, lol

also, got any pics of your setup?

EDIT again:

exploding a123 cell http://www.rcgroups.com/forums/showthread.php?t=759304
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Last edited by d4_racer; 10-26-2007 at 02:46 AM.
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Old 10-26-2007, 05:49 AM   #6
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I've got three 4 cell packs. Two 4s and one 2s2p. All three are equipped with MEC SPT .(no soldering) I charge them at 8 amps with a Dapter connected to my Astro Flight 110D charger. Nice cells! Don
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Old 10-26-2007, 08:08 AM   #7
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Odds are he covered the little blemish where the cells release pressure. As stated earlier this is why they don't explode when you over charge them. Not to mention if you actually read the thread everyone is talking about how much safer they are then other cells in a worste case scenario.
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Old 10-26-2007, 08:29 AM   #8
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Quote:
Originally Posted by party_wagon View Post
Odds are he covered the little blemish where the cells release pressure. As stated earlier this is why they don't explode when you over charge them. Not to mention if you actually read the thread everyone is talking about how much safer they are then other cells in a worste case scenario.
yeah, i agree and i know.

but when cells DO explode IMHO it is more physically dangerous than a lipo. lipo is a just like thin bags with the stuff in it while normal sub c cells are decent thickness metal. from all the nimh explosions i've come across they really do turn into like a shrapnel grenade. after an explosion i can easily find metal bits and the internals scattered across my whole area, like what, 20m radius?

i aint saying lipos arent dangerous, they just have a less BANG explosion, more like a BURST explosion as they seem to just swell up and pop while nimh just leak acid and explode.

i understand where your coming from about the a123 cells and they seem fairly good and safe, but until they fit a lil better, by being not as long, i'll stay with lipos. i'll try them one day
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Old 10-26-2007, 08:34 AM   #9
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Just a bit of info. The length of one a123 cells is about the length of 3 cub cs side by side. However two a123s side by are is a little wider then a sub c is long. When I run them in 1/10th 2wd I have to lower the sides of the battery slot a little so that they will fit & use zip ties to keep them in place. I have heard of numerous people making saddle packs that fit effortlessly into many 4wd buggies.
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Old 10-26-2007, 08:42 AM   #10
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ahh, kk. i just seem to see more 2wd/truck drivers using the a123's then 4wd drivers.

i know they have more punch so u can gear up, but dont that make a bit more motor heat? i agree n all with what your saying but u too gotta agree that lipo is pretty good considering you have more voltage than sub c, more run time than sub c and more punch than sub c and also a heck lot lighter than sub c is.

not bad for something so dangerous in the wrong hands

eg. i saw a guy purposely stab a lipo pack just to make it explode. he stabbed it himself with a short handled screw driver.
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Old 10-26-2007, 09:02 AM   #11
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Yeah, it will make more heat, but people have been doing it without any issues. I went w/ a mamba 7700 and have had too much power in all the aplications I have run thus far. lipos are good and all, but I just prefer these cells because they are already durable, don't cause a fire hazard, and you can build a pack w/ specs better then the high end kokam cells for less then half the price. You can build an a123 4600 mah 6.6volt pack for under $50 a pack. That lipo pack will set you back $100+ and is still more vulnerable to side impact damage. I feal like any product that will allow people to run longer w/ less maintanance & long term cost is good for the hobby.
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Old 10-26-2007, 06:08 PM   #12
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Quote:
Originally Posted by party_wagon View Post
You can find most of this info w/ google and a little common sense.

I purchased a dewalt 36volt pack, made out of 10 a123 cells for like $80 and used 6 of them to make my pack.
You can find them on ebay for around that price. Anything under $100 shipped is normally a decent price. If you are looking for a
2s2p pack for 4wd buggy then you could just split the cost w/ a friend.
Be sure to do your research on these cells before you take apart the pack. There are sites on breaking them down. The two pieces of information you will need though are to leave the tabs that come w/ the cells on them, just cut them if you want to take them apart or leave them togather instead of using battery bars, because you can't solder directly to the cells so you solder to the tabs & do not twist the tab, twisting it can cause the cells to dead short. Do not cover the little blimish w/ solder, that is how the cells vent.

How to build a saddle pack:
required
*4cells,3 long pieces of wire, two battery bars, plug,shrink rap
All soldering will be done on the tabs & will not be over the small blemish in the middle of the cells.
1.take two cells and solder the + to the - using a battery bar(this will be side 1, repeat w/ the other two cells.(side 2)(the more you wire + to - the greater your voltage)
2. take a piece of wire that reaches across the chasis and connect the wire to the + of (side 2) to the + of (side1).
3. repeat this process for the neg.
4. repeat this process again, you can use a lighter piece of wire for this(balancing plug), with the side the battery bars on on. Run it from battery bar to battery bar.
5. Now remove the rubber off the + wire in the middle for your plug. and solder the plug to it there.
6. repeat step 5 for the neg.
(don't let the + and - wires touch, these are just like any other +&- wires on a 6cell stick.)
Now take the 3rd wire and stick a FEMALE PLUG ON IT(you want to make sure that the wires are not going to dead short when they touch since you have an extra wire. Often times I zip tie the two plugs away from each other on the car.
7. shrink wrap the cells if you want too.

For building 3p2s pack(perfect for 2wd truck or buggy), you will have to lower the sides of the battery trey just use a cheap solding iron and melt the sides down, much easier then dremeling them down. You can see what i'm talking about at
thedunemaster.com (more of those expensive packs)
1. zip tie 3 cells togather w/ the + ends all facing the same way.
2. strip down a nice thick wire and use it as a battery bar to connect the 3 cells + side.
3. repeat for the - side.
4. repeat steps 1,2,&3 w/ the other 3 cells.
5. take a wire and solder the + side of pack 1 to the -side of pack two.(short wire) and another longer wire from any of the cells in the middle(balancing plug).
then bend the wire connecting the sides so that the cells make a straight line.
6. run a wire from the free sides to your plug.
7. Now shrink rap it.
Got any pics????
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Old 10-26-2007, 06:15 PM   #13
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nah, no pics. You can probly find wiring diagrams and such on how to break them down if you google the 36volt packs and such.
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Old 10-27-2007, 05:01 AM   #14
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did you say these things are 6.6v ???
if so your still a nearly a hole volt down on power this is =top end speed.?

if this is true a 7.4v nicd will kick its ass......over 5 min race.
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Old 10-27-2007, 06:51 AM   #15
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Quote:
Originally Posted by ROV View Post
did you say these things are 6.6v ???
if so your still a nearly a hole volt down on power this is =top end speed.?

if this is true a 7.4v nicd will kick its ass......over 5 min race.

I would disagree unless you're talking about running stock class.

6.6v is plenty of juice, you just might have to motor up a bit.

Example: A guy at my track runs an X-6 which is set up with a 4x2 battery pack. Since the chassis is so tight he runs 4 cells (4.8v) and he puts his GTB in the spot where the other 2 cells go. Really clean installation, and with a 5.5 motor he isn't giving up anything to anyone. He says the car is still over min weight too.
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