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View Full Version : a123 High Voltage Swift!


litespeed
01-01-2007, 10:07 PM
Hey all,

Me again fab-in the Swift to run a123's on them since I keep sucking the juice out of the emoli's too quick since I've gone to the 550 blades. I custom made my emoli's to sit up high on top of the cf battery tray and removed the radio tray. This worked well till the first crash which snapped the cf plate right off the front with the nearly 1 1/2 lbs of batteries on it. I made a custom (don't laugh!) aluminum battery plate and never looked back. Having the batteries up high made the roll rate better and honestly flew better than them hangin underneath the heli. Kinda similar to a TREX 600 set up. I was running 8s on my Neu 1910-1.5Y with an 11 tooth pinion. Since the soldering issues and for pure simplicity with the a123 cells I decided to try and run a "brick" pack instead of my custom made packs, this way I could use shrink wrap also. I played and played with design idea's and this one seemed most logical and kept the weight up as high as possible while still being able to use the canopy. I dropped to a 10 tooth pinion since the headspeed seemed really high with the 11 tooth. I'm not for sure what it was but with these plastic main grips and 550 blades it kinda scared the crap out of me. I'm not for sure what voltage I should figure on while figuring headspeed on one of the online calculators, I've read anywhere from 2.6v to 3.2v under load.

The results were great. Bogging is quite non-exsistant although I can still feel the weight of the heli. I may need to design a lighter version of my battery shelf/holder but fear it won't be as crash worthy as the current set-up. I will find out, trust me! I got about 5 to 6 min of hovering and fast climbouts while trimming it. I hope to get atleast 6 mins when done. If not I may go to a 12 cell since my Shulze will go that high but then the battery tray will need to be redesigned, who knows. The whole battery tray/holder really tightened the frame up, it seems the cyclics are faster but I may have increased the headspeed with the battery/pinion change I'm not for sure. It feels fast though.

After adding the whole set-up the Swift was slightly nose heavy so I pushed the rudder servo back to staticly balance the heli and shortend the control rod (I said "rod!" hehe) and it balanced perfect. I haven't weighed the heli yet, I only have a postage scale that goes up to 4 lbs so that will have to wait till next time.

One comment on charging, I have a Shulze 6-330D with the new eprom v8.51 (or something like that!) anyway when I charge the 10s a123 at 5.5 amps it keeps giving me a low voltage warning. I have an 06 Dodge 1500 and the battery just can't keep up with this charger. It works fine if the motor is running but that doesn't work well with the garage closed up. Is there any el cheapo suggestions on a power supply that will work ok? I'll prolly get my Thunder Power charger upgrade as well so I'm sure it will do the same thing?

Any thoughts or comments?

Wifes a calling, time to take the Christmas tree down, Happy New year to all of you.

Tom

Below is the results.

litespeed
01-03-2007, 06:24 PM
Well I got a few more flights in and I'm happy so far. I'm getting about 7 mins of flight which includes fff, flips, rolls and some major climbouts then I come in and hover another 30 seconds or so and then I can hear the power start to fade. As I start getting more agressive I'll run 6 1/2 mins and keep checking it out. I have 3 packs so far and with 30 min or less charging I should be ok after I get another pack and my TP charger upgraded.

I'm really, really happy so far.

Tom

P.S. Man is this place dead or what? Hope you all are out flying.

t-rexn8
02-18-2007, 04:52 AM
Nice work. Keep us posted.

TomC
02-18-2007, 05:09 AM
Sounds like a few too many 'New Years Cheers' to me!

You do the math's!

My Swift with 6s 4400 Lipos (old Trex 600 packs @ 750g) and a +600 motor, 8t Mikado pinion, and 550mm CF blades gives very good 8 min runs and the heli weighs 2.7 kg. I got these packs used @ ~$60 each. Check with Trex600 guys and you might get a bargin like this as well as they move to better and/or 8-10s cells.

Cheers,

Tom C

RAV50
02-18-2007, 09:59 PM
Tom C,

I too like the light "power to weight" available from the Lipos. Your 2.7 kilos is almost 6 lbs. (5.95 lbs.)

I run a bit lighter at 5.6 lbs with my 6S1P - 3700 FP packs. I easily get 6.5 minutes of pretty hard 3D flying, with NO soft hover at the end. When my TX beeps at 6min 15sec., I bring it in and land (that usually takes the 15 seconds to the 6 1/2 minute mark). After the 6.5 minutes I usually end up putting only 3080mah back into the packs. So I can see you easily getting 8 minutes from the 4300 packs. All of this, with a motor/pinion combo that gives me a 2100 head speed.

So it is also verified with what the EagleTree says - about 480mah per minute. But I use 515 and 520 mainblades. The 550's may well load more and give less flight time.

Lightspeed,

Have you had a chance to get an all up weight fo your Swift with the 10 x A123 cells?

litespeed
02-19-2007, 07:32 AM
Lightspeed,

Have you had a chance to get an all up weight fo your Swift with the 10 x A123 cells?

Nope! I need to buy a larger postage scale but haven't. Mine only goes to 3 lbs. I really would like to know how much it weighs.

Tom