Making and using A123 packs for my Hobbico Electristar RTF

Making and using A123 packs for my Hobbico Electristar RTF
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> Making and using A123 packs for my Hobbico Electristar RTF

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Making and using A123 packs for my Hobbico Electristar RTF - 6/2/2007 8:52 PM

rick88ss

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Hi there. I'm new to flying RC airplanes but decided to start with electric RC airplanes. The Hobbico Electristar looks like a pretty good beginner plane so I ordered one and should be getting it next week.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNVC0**&P=0

Besides using the 2 7S NiMH and 2 2S LiPo battery packs has anybody used the newer A123 Dewalt batteries in this plane? How many would be needed to run the motor safely? I wanna look into this option so I can get the right battery/charger combo once.

I think running 2- 5S A123 packs run in parallel is my best option. It will still be lighter than the recommended 2- 7S NiMH packs and a little heavier than the recommended 2- 2S LiPo packs.

If I buy a Dewalt 36V pack what are the other specific items I will need to make two 5S A123 packs. I also want to be able to balance charge both packs on the same charger. I need two 5 cell packs instead of one 10 cell pack because of COG concerns.

List of needed parts ??

- Dewalt 36V pack
- Heatshrink for 2 packs (what size?)
- 2 female Deans plugs with 12 gauge pigtails
- ?? (balance harness for batteries and charger?)
- Charger??

Which balance plugs(harness)?
What charger to charge both packs at the same time?

Thanks for the help and sorry for the long post

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RE: Making and using A123 packs for my Hobbico Electris... - 6/3/2007 1:13 PM

ramboman

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quote:

ORIGINAL: rick88ss

Hi there. I'm new to flying RC airplanes but decided to start with electric RC airplanes. The Hobbico Electristar looks like a pretty good beginner plane so I ordered one and should be getting it next week.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNVC0**&P=0

Besides using the 2 7S NiMH and 2 2S LiPo battery packs has anybody used the newer A123 Dewalt batteries in this plane? How many would be needed to run the motor safely? I wanna look into this option so I can get the right battery/charger combo once.

I think running 2- 5S A123 packs run in parallel is my best option. It will still be lighter than the recommended 2- 7S NiMH packs and a little heavier than the recommended 2- 2S LiPo packs.

If I buy a Dewalt 36V pack what are the other specific items I will need to make two 5S A123 packs. I also want to be able to balance charge both packs on the same charger. I need two 5 cell packs instead of one 10 cell pack because of COG concerns.

List of needed parts ??

- Dewalt 36V pack
- Heatshrink for 2 packs (what size?)
- 2 female Deans plugs with 12 gauge pigtails
- ?? (balance harness for batteries and charger?)
- Charger??

Which balance plugs(harness)?
What charger to charge both packs at the same time?

Thanks for the help and sorry for the long post

undefined
OUPS!
For my different planes, I replaced my 12s NiMh 3300 mAh with either 4s1p LiPo 3700 mAh or 5s2p a123 2300 mAh.
In your case, it should be between 2s1p a123 and 3s1p...
My a123 cells are coming from a123 and MEC, the packs are assembled with MEC features.
Heatshrink are 47mm for cells (w/o card tube) and 80mm for a pair.
I am using 4mm plugs.
Balancing (not required, but...) is done on a FlightPower V-Balance.
Charger is a CCCV power unit set to 3.6 volts, 3 amps per cell.
Fyi, I use 10s2p packs charged at 36 volts (3 lead batteries) 20 amps in the field.
Regards

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RE: Making and using A123 packs for my Hobbico Electri... - 2/14/2008 12:31 AM

pcsketch

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Flown the Electrastar with 4 cell Dewalt batteries. Flies fine! Puzzled that the A123 battery at 2300mah last longer than 7-3500mah Nimah packs.

Above last November. Swapped Electrastar and -now- putting another togeather (Tower Hobbies $208 incl shipping). Will fly with Li-ion 4,5, and maybe 6 cell if not too much volts for motor). Find the Electrstar fine flyiner!

Still like Nimah packs! The abrupt cut off of Lith-ion needs careful watching, but great to have a battery that cost less, won't burst in flame and have a life span

Experience shows Li-poly suck after 50 charges and/or cold weather.

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RE: Making and using A123 packs for my Hobbico Electri... - 2/19/2008 11:18 PM

cwharper

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Careful with using a 6s A123 and the SS45D ESC together. That would be over the rating of the esc. It could probably be done with lots of extra cooling. The best setup with stock components is a 5s A123. If you change the prop to a 13x6.5E that would give you more thrust on take-off where it's needed most on the electristar and still keep amp draw withing the limits of the esc. It would also give you slightly better efficiency in the air. I have flown 12 minutes on a 5s A123 and 16 minutes on a 6s A123 with a higher rated ESC but with same motor and with throttle management. I have also put two 5s A123 packs in there in parallel and flown 25 minutes. This way you could easily get the 1000 cycles advertised for these batteries, because they hardly see any amp draw.

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RE: Making and using A123 packs for my Hobbico Electri... - 2/24/2008 11:26 PM

Fast Guy

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I built a couple 5s1p A123 packs for my Electristar but was planing to use just one at a time. I read that people were getting 8 to 10 min of hard flying and 12 to 15 min of slow flying on one 5s1p pack which is long enough for me. I'm using a Hyperion LBA 10-A123 to balance and my Super Brain 989 in power supply mode to charge them.

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RE: Making and using A123 packs for my Hobbico Electri... - 2/25/2008 2:02 AM

cwharper

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Looks great, I like the shrink. My 5s pack didn't have a hump, instead I put the 5th cell at the end sideways. It was a tight fit but could get two in there like this.

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RE: Making and using A123 packs for my Hobbico Electri... - 3/14/2008 3:53 AM

wrtank

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I'm another new pilot to RC flying, and am intersed in the Electristar and A123 battery packs.
I have read that the A123 packs take about 15 minutes to charge.

My question is how long does it take for the recommended battery pack and charger combinations for the Electristar to charge.

Thanks

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RE: Making and using A123 packs for my Hobbico Electri... - 3/14/2008 12:21 PM

Fast Guy

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quote:

ORIGINAL: wrtank

I'm another new pilot to RC flying, and am intersed in the Electristar and A123 battery packs.
I have read that the A123 packs take about 15 minutes to charge.

My question is how long does it take for the recommended battery pack and charger combinations for the Electristar to charge.

Thanks

About an hour.

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RE: Making and using A123 packs for my Hobbico Electri... - 3/30/2008 8:24 AM

square714

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I recently ordered an ElectriStar plane and am looking into getting A123 cells too. I am probably going to get the dewalt pack and build two 5s1p packs.

The plane hasn't arrived yet, so I have a few questions regarding fit of the pack in the aircraft. Is there space for a 5 cell flat pack (shown here) to fit inside the airframe? Or will I need to figure out a way to reconfigure the cells into a hump or other configuration?

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RE: Making and using A123 packs for my Hobbico Electri... - 3/30/2008 1:22 PM

cwharper

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The 5 cell flat pack will not fit easily in the battery space. Make your packs with two rows of two cells end to end with one cross at the end. See the drawing I made. One of these will fit nicely and will last about 12 minutes at half throttle. It is possible to get two in there, but you will need to take out the metal battery straps. With two in there it lasts about 25 minutes with good throttle management.

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RE: Making and using A123 packs for my Hobbico Electri... - 3/30/2008 2:52 PM

Fast Guy

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quote:

ORIGINAL: square714

I recently ordered an ElectriStar plane and am looking into getting A123 cells too. I am probably going to get the dewalt pack and build two 5s1p packs.

The plane hasn't arrived yet, so I have a few questions regarding fit of the pack in the aircraft. Is there space for a 5 cell flat pack (shown here) to fit inside the airframe? Or will I need to figure out a way to reconfigure the cells into a hump or other configuration?

The cells are too long to fit in the battery bay in the 5 cell side by side configuration on that site. There is a bulkhead in the battery bay that only end to end configurations will fit past. The configuration cwharper used will work only if the end to end cells are inserted into the battery bay first with the 5th side mounted cell in the middle of the bay. The 5 cell hump configuration I built works well too. The rear aluminum battery holder would have to be removed to run 2 hump packs. As it is, one pack lasts way past my attention span so one is all I need.

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RE: Making and using A123 packs for my Hobbico Electri... - 3/30/2008 6:35 PM

square714

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Thanks for the input. Looks like the battery pack construction is going to be more complicated than I thought.

How did you guys wire the 2 row with one cross and hump packs for the high current flows? Are you using heavy gauge wires or metal tabs (or both)? Did you solder directly to the tab or construct the pack some other way (spot welding)?

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RE: Making and using A123 packs for my Hobbico Electri... - 3/30/2008 10:41 PM

Fast Guy

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I used 12 gauge wire to connect the hump cell. I sodered the end to end cells with a hammer head tip along with paste and soder for sodering aluminum. At the same time I added the balance leads. I removed the original spot welded tin tabs.

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RE: Making and using A123 packs for my Hobbico Electri... - 4/3/2008 12:48 AM

square714

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Do you guys think I can squeeze in a 2s2p and a 3s2p pack into the battery bay? And will I have any problem connecting them to the ESC? My understanding is that the two connectors place the batteries in series anyway. I'm looking into using the solderless power tubes from MEC. I am either going to go with a 5s1p configuration using 1 phantom cell or the equivalent of a 5s2p pack with the two packs above if there is space.

EDIT: nevermind, I just realized that the power tubes can only do series connections.

< Message edited by square714 -- 4/3/2008 1:02 AM >

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RE: Making and using A123 packs for my Hobbico Electri... - 4/3/2008 2:44 AM

Fast Guy

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The E-Star will perform the best with the 5s1p because of the light weight and I would go with that. The 2s2p and 3s2p in series would be heavy though it would work well in strong winds. The power tubes look interesting.

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RE: Making and using A123 packs for my Hobbico Electri... - 4/6/2008 2:58 PM

Rickochet

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quote:

ORIGINAL: square714

Do you guys think I can squeeze in a 2s2p and a 3s2p pack into the battery bay? And will I have any problem connecting them to the ESC? My understanding is that the two connectors place the batteries in series anyway. I'm looking into using the solderless power tubes from MEC. I am either going to go with a 5s1p configuration using 1 phantom cell or the equivalent of a 5s2p pack with the two packs above if there is space.

EDIT: nevermind, I just realized that the power tubes can only do series connections.

How about using 2 powertube packs and connect in parallel with a "y" adapter?

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