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Old 03-11-2009, 09:56 PM   #1
kyleservicetech
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Default Hacker 6S2P A123 Powered Models

Take a look at these 6S2P A123 powered models.

2011 flying season, the A123 battery pack was upgraded to 7S2P A123 2300 Mah cells. Power improvement is significant, the same 16X12 prop now turns at 6700 RPM at full power.

The Electrostreak is a scratch built 150% enlargement of the original Electrostreak, with 65 inch wing span and 850 Square inch area. Weight is 8 pounds, power is a Hacker A50-12S with 14X12 APC-E propeller, 6S2P A123 batteries, Castle Creations 60 amp ESC, Spektrum radio. This model is now 7 years old, and is on its third power plant. The model flys very fast, and is fully acrobatic. Reasonable flying time is about 6 1/2 minutes.

(First was Astroflight geared 40 brush motor, 22 RC2400 Nicads. Next was Astroflight geared 40 brushless motor, new 22 RC2400 Nicads. Reasonable flying time was only 3 minutes!)

The Hanger 9 Showtime 50 weighs in at 7 1/2 pounds, is powered by a Hacker A50-16S with 16X12 APC-E prop, 6S2P A123 batteries, CC 60 Amp Phoenix ESC, Spektrum radio. The model is on its second year, flys very well and is also fully acrobatic. It will climb straight up til out of sight. Reasonable flying time is about 7 1/2 minutes.

After a flight, both the batteries and motors are only luke warm. In fact, these batteries get hotter sitting in the sun, then they do after a flight!

Neither of these models could be considered "3D", but, that is not my interest.

All we need now in Wisconsin, is for the cold weather to go away, so these models can again be put into the air.


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Old 04-12-2009, 12:35 AM   #2
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Default Showtime 50

Hi Dennis

I have a new showtime 50 hanging from my ceiling. I am new to electrics. I came across a eflight 90 and a 85 amp castle creations speed controller. Will this work? If so could you recommend an A123 configuration and should I use a BEC. Thank you
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Old 04-12-2009, 12:52 AM   #3
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Hi mofosheee
That Eflight 90 is very similar in motor charactoristics to the Hacker A50-16S. Right down to the recommended battery set up and propeller.

I'd use the same 6S2P battery setup as used on my Showtime 50 with the Hacker A50-16S and 16X12 APC-E propeller.

You can buy the 6S2P packs from places like http://www.battlepack.com/. Be certain to purchase the 2300 MaHr cells with the A123 designation.

If you've got experience in building your own battery packs, you can purchase the Dewalt DC9360 battery pack that uses 10 A123 cells. You will need to buy two more cells to make twelve cells. I had to split the 6S2P pack into 4S2P and 2S2P to get the model center of gravity in the right place. The danged wing spar is right in the way! FYI, you only need to balance these A123 cells after a day's worth of flying, if you only fly to 60 or 70% of the batteries capacity. Flying these A123 (And LiPo's) till the battery quits is hard on them. And the A123 batteries will fly at full power, and at the end of their charge, quit, like 30 seconds later. They quit like a glow engine. Therefore don't fly them beyond 60 or 70% of capacity!

http://www.nationwidetool.com/store/ has the Dewalt DC9360 packs for $115 plus shipping. Wattflyer has a thread on how to take these Dewalt battery packs apart. I've got a wiring schematic for setting this battery pack up. Let me know if you'd like a drawing.

As for the Dewalt battery packs, when taking one of them apart, absolutely do not allow the cells to short out to each other. It will sound like an arc welding machine. Personal experience. That short burned a hole right through the side of one cell, ruined it. BUT NO FIRE!

The second and third Dewalt battery packs I took apart, I wrapped a layer of fiberglass tape around the battery pack to keep it from falling apart once removed from its plastic shell.

One of my club members just did one of these packs on his own. He knows how to solder, but not much more. Just got a note today, he had sucess, and is very happy with the A123 battery performance.

I use a switching BEC on all of my models. They are made by Castle Creations, and by Common Sense. For me, both work well, but I like the Common Sense unit better electrically. They are cheaper than a 4 cell battery pack for the receiver.

Let me know how you make out!
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Old 04-12-2009, 08:34 AM   #4
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Default Showtime elec conversion

Kyleservictech

I appreciate the time you spent responding to my inquiry. You have provided me with great direction. I am ignorant with respect to electrics, yet am a very experienced with 30% acrobatic gassers and powered by A123"s (and absolutely love them!) and will never use lipo's again.

As a previous Showtime owner (nitro) I can say with authority that this is one of the best flying airplanes that I have owned. One day I got sick of the nitro mess. Sold all nitro's and switched to gas.

I intend to build my own packs as you have suggested and have down loaded a detailed tutorial that I found on one of the forums.

Next step will be obtaining A123's and a BEC. Can you suggest a charger please. THANK YOU!!!!!!!!!!!
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Old 04-12-2009, 08:53 AM   #5
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Originally Posted by kyleservicetech View Post
Hi mofosheee
That Eflight 90 is very similar in motor charactoristics to the Hacker A50-16S. Right down to the recommended battery set up and propeller.

I'd use the same 6S2P battery setup as used on my Showtime 50 with the Hacker A50-16S and 16X12 APC-E propeller.

You can buy the 6S2P packs from places like http://www.battlepack.com/. Be certain to purchase the 2300 MaHr cells with the A123 designation.

If you've got experience in building your own battery packs, you can purchase the Dewalt DC9360 battery pack that uses 10 A123 cells. You will need to buy two more cells to make twelve cells. I had to split the 6S2P pack into 4S2P and 2S2P to get the model center of gravity in the right place. The danged wing spar is right in the way! FYI, you only need to balance these A123 cells after a day's worth of flying, if you only fly to 60 or 70% of the batteries capacity. Flying these A123 (And LiPo's) till the battery quits is hard on them. And the A123 batteries will fly at full power, and at the end of their charge, quit, like 30 seconds later. They quit like a glow engine. Therefore don't fly them beyond 60 or 70% of capacity!

http://www.nationwidetool.com/store/ has the Dewalt DC9360 packs for $115 plus shipping. Wattflyer has a thread on how to take these Dewalt battery packs apart. I've got a wiring schematic for setting this battery pack up. Let me know if you'd like a drawing.

As for the Dewalt battery packs, when taking one of them apart, absolutely do not allow the cells to short out to each other. It will sound like an arc welding machine. Personal experience. That short burned a hole right through the side of one cell, ruined it. BUT NO FIRE!

The second and third Dewalt battery packs I took apart, I wrapped a layer of fiberglass tape around the battery pack to keep it from falling apart once removed from its plastic shell.

One of my club members just did one of these packs on his own. He knows how to solder, but not much more. Just got a note today, he had sucess, and is very happy with the A123 battery performance.

I use a switching BEC on all of my models. They are made by Castle Creations, and by Common Sense. For me, both work well, but I like the Common Sense unit better electrically. They are cheaper than a 4 cell battery pack for the receiver.

Let me know how you make out!
Kyleservictech

I appreciate the time you spent responding to my inquiry. You have provided me with great direction. I am ignorant with respect to electrics, yet am a very experienced with 30% acrobatic gassers and powered by A123"s (and absolutely love them!) and will never use lipo's again.

As a previous Showtime owner (nitro) I can say with authority that this is one of the best flying airplanes that I have owned. One day I got sick of the nitro mess. Sold all nitro's and switched to gas.

I intend to build my own packs as you have suggested and have down loaded a detailed tutorial that I found on one of the forums.

Next step will be obtaining A123's and a BEC. Can you suggest a charger please. THANK YOU!!!!!!!!!!!
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Old 04-12-2009, 09:01 AM   #6
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Would this be a good source for A123's? Thank you
http://cgi.ebay.com/10-A123-3-3V-230...3A1%7C294%3A50
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Old 04-12-2009, 05:31 PM   #7
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Originally Posted by kyleservicetech View Post
Hi mofosheee
That Eflight 90 is very similar in motor charactoristics to the Hacker A50-16S. Right down to the recommended battery set up and propeller.

I'd use the same 6S2P battery setup as used on my Showtime 50 with the Hacker A50-16S and 16X12 APC-E propeller.

You can buy the 6S2P packs from places like http://www.battlepack.com/. Be certain to purchase the 2300 MaHr cells with the A123 designation.

If you've got experience in building your own battery packs, you can purchase the Dewalt DC9360 battery pack that uses 10 A123 cells. You will need to buy two more cells to make twelve cells. I had to split the 6S2P pack into 4S2P and 2S2P to get the model center of gravity in the right place. The danged wing spar is right in the way! FYI, you only need to balance these A123 cells after a day's worth of flying, if you only fly to 60 or 70% of the batteries capacity. Flying these A123 (And LiPo's) till the battery quits is hard on them. And the A123 batteries will fly at full power, and at the end of their charge, quit, like 30 seconds later. They quit like a glow engine. Therefore don't fly them beyond 60 or 70% of capacity!

http://www.nationwidetool.com/store/ has the Dewalt DC9360 packs for $115 plus shipping. Wattflyer has a thread on how to take these Dewalt battery packs apart. I've got a wiring schematic for setting this battery pack up. Let me know if you'd like a drawing.

As for the Dewalt battery packs, when taking one of them apart, absolutely do not allow the cells to short out to each other. It will sound like an arc welding machine. Personal experience. That short burned a hole right through the side of one cell, ruined it. BUT NO FIRE!

The second and third Dewalt battery packs I took apart, I wrapped a layer of fiberglass tape around the battery pack to keep it from falling apart once removed from its plastic shell.

One of my club members just did one of these packs on his own. He knows how to solder, but not much more. Just got a note today, he had sucess, and is very happy with the A123 battery performance.

I use a switching BEC on all of my models. They are made by Castle Creations, and by Common Sense. For me, both work well, but I like the Common Sense unit better electrically. They are cheaper than a 4 cell battery pack for the receiver.

Let me know how you make out!
Hi Kyleservicetech
I went to: http://scriptasylum.com/rc_speed/_lipo.html entered, with a balancing circiut, 5S2P (because it is the most that the options would allow) and get the picture. That's a lot of batteries!

Another question I have is about cooling the ESC. Your thoughts and recommendations please.

Regards,

Jerry
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Old 04-12-2009, 05:57 PM   #8
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mofosheee
I'd be a little reluctant to order from this place, its located in China. As indicated, NationwideTool has the Dewalt packs, at least for the moment. As for a charger, the Astroflight company sells a charger for the A123's. Astroflight has a very good history of making good stuff. That Astroflight charger will take about 3/4 hour to recharge a 6S2P A123 pack.

Higher powered chargers are out there, but they run several hundred dollars. I built two of my own A123 chargers that will charge my 6S2P packs at 10 Amps, or about 2.2C. Could go higher, but no need to, since it recharges my packs in about 15-20 minutes.

I've included a schematic of the connections required for the A123 packs. You will need to go to the www.expresspcb.com web page to download the FREE software to read the schematic. (Expresspcb makes their money by building circuit boards from this software, they provide the software for schematics and circuit board layout program free of charge)

Note, wattflyer.com does not allow downloading a drawing.SCH file, so I changed the drawing from 6S2P A123 Drawing.sch to 6S2P A123 Drawing.TXT. If you download this file, you will need to rechange the file name back to 6S2P A123 Drawing.SCH so the expresspcb software can read it.

If you need to build up the balance cables, www.digikey.com has the connectors and pins in their inventory. They sell to anyone, and are reasonable in price. Digikeys part numbers are #WM2806-ND, and WM2510-ND. You can buy enough for 5 batteries for $10.00 or so. You need to buy the wire, about #22 gauge or so. The connector is 8 pins, just cut off the extra plastic for the unused pins if desired.
Hey, that web page for wiring A123 cells is pretty good.

You need air to enter the front of the model for cooling the motor, and you need an exit hole for the air to get out of the model at the back of the airplane. Usually I put holes in the bottom of the fuse for an air exit. That exit hole must have the same area as the enterance holes in the front of the model. As for cooling the ESC, just locate it in an area inside the fuse where air flowing through the model can hit it. These 60 Amp Castle Creations ESCs are pretty efficient, they can handle 60 Amps with air cooling all day and only get slightly luke warm.

Have a good day!


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Old 04-12-2009, 10:58 PM   #9
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Kyleservicetech..........I know what you mean about Chineese products. My employer will not order steel from this country. Anyway, Dewalt packs it will be. Thank you for the www.expressbcb.com and drawing, way cool. Gotta go to work now and will order the Dewalt packs tomorrow. Thanks again

M0f0sheee
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Old 04-13-2009, 08:37 AM   #10
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Good Morning Mr Kyleservictech:
As you recommended, I purchased the Dewalt DC9360 from http://www.nationwidetool.com/store/ today. Would you suggest that I purchase the two remainding cells from http://www.battlepack.com/ or somewhere else?

Regarding the balance cables consisting of: pins, 22 gauge and connectors. Forgive my ignorance, but this set up connects to a ________ charger.

Thank you again!

Mofosheee
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Old 04-13-2009, 03:37 PM   #11
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mofosheee
Regarding the balance cables consisting of: pins, 22 gauge and connectors. Forgive my ignorance, but this set up connects to a ________ charger.

Hi
The balance cables and such would connect to an Astroflight "Little Blinky". That would be ordered direct from Astroflight. The little blinky is used to balance your A123 cells after a days worth of flying. These A123 cells stay pretty well balanced, and do not need to be balanced after every flight.

Battlepack.com is a good a place as any to buy the two remaining cells. Be certain to order the 26650 A123 cells. The 26650 is a cell size, and Battlepack has other 26650 cells that are designed for receiver batteries, and are NOT for electric powered airplanes.

As for ignorance, ignorance is not asking questions when you are not certain of what to do.
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Old 04-13-2009, 07:12 PM   #12
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Good afternoon Kyleservictech

Everything ordered per your instructions. Since prices were comperable, one shop shopping from Battlepack.com. Waiting for shipping.

Thank you
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Old 04-18-2009, 06:56 AM   #13
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Sir:

Starting to receive the components I oprdered on line. My 36V Dewalt pack has been disassembled. In post #5 you mentioned that I will probably have to divide my packs into 2(ea) 4S2P and 2(ea) 2S2P because the wing tube will intefer with a 6S2P.

Are you able to provide pictures of your install? Am I correct to assume that the 4S2P will be in series via a handmade connector with a 2S2P? Thank you

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Old 04-19-2009, 12:56 AM   #14
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Are you able to provide pictures of your install? Am I correct to assume that the 4S2P will be in series via a handmade connector with a 2S2P? Thank you

My Pleasure:
Take a look at the attached digital photos. The LCD display in the view is my on board time/current/amphour meter covered in other areas of Wattflyer. Not necessary for flying though. (That amphour meter shows that these A123 cells have had 205 AmpHours cycled through them, with total flying time of 17 hours, 5 minutes. And, after a full flying season last year, plus 16 flights so far this year, the batteries actually turn the same 16X12 APC-E propeller 100 RPM FASTER than when the A123 cells were new.

I made the mistake of building a single pack of 6S2P A123 cells. Then stuck it into the Showtime 50, and found the model needed some 5 ounces of lead in the tail. So the perfectly good 6S2P A123 pack was hacked apart into 4S2P and 2S2P packs. The two packs were wired together with #12 wire, no connectors were used. Note the Castle Creations 5 VDC switching regulator is used, works very well with my Spektrum radios.

The 4S2P pack is held down by two pieces of one inch wide Velcro at the bottom, plus one big wire tie. The 2S2P pack is held down by two pieces of one inch wide Velcro at the bottom only.

Note the second photo that shows the individual voltage of all six cells at the same time. This thing is something I threw together last fall. Its accurate to 0.1 percent. Note all six cells are well balanced! And, I balanced these cells ten flights ago!


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Old 04-19-2009, 01:37 AM   #15
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Beautiful, the picture of the battery packs is exactly what I needed. I was inclined to build the packs as depicted in the schematics, perhaps like you initially did.

Excuse me for being dense, in my mind I intrepret that you wired the 4S2P in series to the 2S2P making it a 6S2P?

I see that you amputated the structural former that is above and parallels the wing tube. Looks like it helps when removing the batteries since they are hardwired together. I was also considering the same.

Thank you

Mofoshee
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Old 04-19-2009, 02:38 AM   #16
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Yes, forgot, I also used a Dremel with a sanding drum to remove material from the canopy so it clears the battery pack. Also placed some bracing in the front of the canopy to make it stronger. Don't need to worry about vibration on these things!

And, yes, the 4S2P is wired in series with the 2S2P making it a 6S2P pack, split down the middle.

In case I've not mentioned it, be sure to wrap some fiberglass strapping tape around your Dewalt Battery pack before you pull it apart. After you pull it out of the case, this battery pack might "fall apart" shorting it self out in the process.

That pack has considerable energy even when its not been charged for months. First pack I did, the pack kind of fell apart on me, shorting out one cell in the process. The pack burned a hole right through the side of one of the cells. Sounded like my 180 Amp Arc welder. No fire, little smoke, but that hole in the cell caused the cell to fail after a few weeks. Still flying the remaining 9 cells.:o

It's a good idea to put together two six inch by one by four lumber pieces at a 90 degree angle. When you shrink the "Pop bottles" around the A123 pack, place the whole thing into the 1 X 4 pieces of lumber to make certain everything is at a 90 degree angle. Kind of hard to fix a crooked battery pack after its shrunk down. Old Nicad battery assembly trick.
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Old 04-20-2009, 10:44 AM   #17
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Good morning Kyleservicetech
So before discecting my dewalt pac, I built a practice pack out of AA's. Observing that the dewalt is 10 in series, it is apparent that to mfg a 4S2P I need to separate (cut straps) and orientate cells so that two positive and two negitive ends match/align. Looks like the next step is to solder straps to parallel these cells. What would you recommend that I use for such material....#12 AWG copper wire flattened or something that I purchase over the counter at Radioshack?
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Old 04-20-2009, 10:45 AM   #18
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And Thank you again!
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Old 04-20-2009, 05:39 PM   #19
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mofosheee
What would you recommend that I use for such material....#12 AWG copper wire flattened or something that I purchase over the counter at Radioshack?

Hello!
The positive and negative ends of the packs need to have #12 wire for connections to your ESC. This includes the "bottom cell" and the "top cell" of both the 4S2P and 2S2P packs. So, the "bottom cell's" will have a piece of black #12 wire soldered to negative connections of both cells of the 2S2P pack. The "Top of the 2S2P pack will have a piece of blue or red #12 wire soldered to the positive connection of both cells. This piece of #12 wire will then extend to negative side of the "Bottom cells" of the 4S2P pack. Then the "top cells' of the 4S2P pack will have a red #12 wire soldered to them to lead to your ESC.

The #12 wire must be used where ever any high currents are flowing. But, in the middle of the 2S2P pack, you must solder a jumper between the pair of cells. I used a piece of #18 lamp cord material.

Same for the 4S2P packs, you must solder jumpers between the two sets of cells, again, using #18 lamp cord or similar material.

Be careful of any sharp edges of the existing battery straps. They might cut into these wire jumpers, or even the #12 wire it self. I just put pieces of 1/32 ply or balsa over any sharp corners to protect the wires. Or, just shrink extra shrink tubing over any areas that could cut through.

Please be very careful of polarity on these A123 cells. They are marked with a "+" and "-" on each cell, the case of the cell is POSITIVE!, the other end is negative. This is backwards from Nicads or Alkaline cells.

After you are all done with everything, use a multimeter to check the voltages on your balance cable, starting with the negative end. Between the negative end and the second wire, you should measure about 3.3 volts, from the negative end to the third wire should be 6.6 volts, 9.9 volts, 13.2 volts, 16.5 volts, and 19.8 volts, depending on the level of charge on your battery.

And, be certain to measure voltage between your black and red #12 wires leading to your ESC. The black should be negative, the red should be about 19 Volts DC. (If you get reverse polarity to your ESC, your 6S2P pack will win, your ESC will loose. )

Again, be careful with soldering this pack. That pack will melt just about anything in its path on an accidental short! That means take off your wedding ring, watch or any other metal on your hands!

Good luck!
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Old 04-20-2009, 07:05 PM   #20
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Hi Kyle
A fascinating thread - thank you for all the good info.

Am not a complete A123 newbie, having owned and flown a couple of packs for some time, and definitely prefer having them around the house than LiPo!

One question that's intruiged me a while - I understand about polarity on A123 being 'backwards' but I've been reading the wrong stuff or something - can these A123 cells be soldered up like dear old nicad/nimh?

I used to make up my own packs from nimh, end to end or with 'joiners' from wire or brass strip, and if I could do that with A123, that'd be it for me with lipos, for bigger packs anyway.

My present 123 packs are ready-mades - 4 in a MEC Powertube, 6 in a pre-built pack. Be great to just buy cells and make my packs up as in the good old days.

Thank you in advance

Dereck
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Old 04-20-2009, 10:12 PM   #21
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Hi Dereck
If you disassemble the Dewalt packs, they are all ready "strapped together", and if you study the pack for awhile, usually you can find an orientation that will make use of most of the existing configuration of the pack. Take care to NOT rotate the cells negative button, doing so will damage the cells internal connections.

The straps used by Dewalt readily take solder, that's not a problem. That cell I burned a hole through, tried to patch the hole with solder, that's when it was discovered that the cells have an aluminum jacket!

www.Battlecreek.com has indicated their "untabbed" cells can be soldered, but I've not done this, so can't recommend it personally.

In disassembling the Dewalt pack, I used a sharp pair of tin snips to cut through the straps, but that's when I shorted out one cell. Other folks have used a cut off wheel on a Dremel, that works OK also, but be certain not to cut into the cell casing.

On the LiPo note, one of my club members has gone electric, and has a six cell, 5000 MaHr Lipo pack. Found that one cell out of this $300 pack went South, and he has absolutely no idea why. He only had 6 flights on it. He did not overcurrent it, he did not undervoltage it.

My two sets of 6S2P of A123 packs, one A123 5S2P pack, and two 4S1P A123 packs have the same capacity and same RPM under load as when the packs were brand new at the beginning of the flying season last year. One of the 4S1P packs was run flat when it was left connected to the ESC for two weeks. That was last year. Put the charger to it, still flying it. Got away with it once, anyhow!

Dennis V
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Old 04-21-2009, 01:33 AM   #22
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Thank you Kyle, good info. Seems that there's two case types going around - the tabbed alloy ones as per the drill pack cells, and the tab-less solderable ones from Battlepack.

Better get some - Grotesque Motors have just announced a hybrid HummVee, the number of cells needed for that will clear out the marketplace real quick

Though my 6S has a balancer tap and is usually charged by my FMA charger, my 4S Powertube set usually gets refilled via my 'Daptor and old Astro or FMA nimh charger and it doesn't seem to be bothered by that old stuff. Haven't flown much, but they seem indifferent to being ignored too.

And, as you point out, the ability to swap a duff cell out of an otherwise servicable pack is, if not priceless, worth the effort. I've got LiPos, but am very loath to spend any more on larger ones than I have (still not got over the sticker shock ). LiPos are good for some things, but a little too tetchious for my liking.

For smaller models, the itty-bitty 123s seem to bear looking at too.

Next - get brave, dive into my 6S and reduce it to a 5S. It's beating my ancient Hacker B50 13S geared inrunner to a pulp, can't use my 4*40's favourite 15 x 10 on it.

Thanks again

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Old 04-21-2009, 03:06 AM   #23
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Hello kyleservicetech
How about those same dimension and green A123's that I received from robotic power solutions? Chinese?? I was trying to avoid their products as you suggested. Thank you.

Is it OK for me to solder a taylored down copper 1/2 pipe support for a battery buss bar?

Unable to find an 80 watt soldering iron. Bought a 40 watt.

Thank you

Mofo
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Old 04-21-2009, 03:15 AM   #24
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mofosheee
The true A123 cells will have "A123" on their cardboard tubes. I do believe that the original A123 cells are in fact made in China.

Don't understand copper 1/2 pipe support. Are you using 1/2 inch diameter copper pipe? I just soldered #12 wire to everything, worked fine. FYI, I stripped the #12 wire an inch or two from the end, and stripped it about 3/8 inch. Then took the extra inch or two of wire beyond the previously stripped wire, and stripped the end. Just solder the "Middle" of the #12 wire to the "Left hand" 6S1P pack, and solder the "end" of the #12 wire to the "Right hand" 6S1P pack.

I use a 40 watt temperature controlled soldering iron, works just fine. As long as you solder the wire fairly quickly to the battery, you'll be OK. I first "Tin" the #12 wire first, then tin the battery. Then place the #12 wire against the battery, hit it with the soldering iron, add more solder as needed, and you're done! Soldering to the battery should be somewhere around 5-10 seconds or less.
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Old 04-21-2009, 06:01 AM   #25
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Kyleservicetech.....Thank you for your response. Guess that I will be using the 2(ea) Green A123's that I received from Robotic Power Solutions.

The copper 1/2" pipe support are what you would find under your house or in your walls fixing a copper water pipe to wood studs. My thought was to flatten them and "taylor" them into appropriate size buss bars that would be soldered to the batteries where needed. They are not too thick and after all, they are copper.

Will start on building my pack tonight at work

Thank you again
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