R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 10-07-2007, 11:18 PM   #286
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Fathead-Thanks. Should be an interesting experiment. I'll post a setup if it changes much. My car was a little nervous also at first. It would spin out on occasion on power. The problem seemed to be too much roll stiffness. I had a purple front spring on. What was happening is that it was responding to bumps poorly. Went to blue front and softened the rear with green and a standard ball front diff and the car really settled down and drove well. I could then use huge power. Then I put on the locked front diff and it settled down a little more and I could drive it harder in the corners. This required a blue rear spring. That last setup change that I made to rear toe made it easier to drive harder as well. Rear toe is about 2.75 degrees now. Interestingly it gave medium corners more traction in the rear (the car is more tight), but improved rotation of the rear on the hairpins (more loose). I wish I could have run that third heat.
The car will come around once you tinker with it enough. I am pretty pleased at the moment and running 2 year old rubber tires.
John

Last edited by John Stranahan; 10-08-2007 at 09:13 AM.
John Stranahan is offline   Reply With Quote
Old 10-08-2007, 10:32 AM   #287
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

John - you really should not be charging your FMA 4800 at 10 amps. Charging over 2C really kills the cycle life even if the manufacturer claims that the cell can handle 2C. Both capacity and internal resistance takes a bit hit and you get this odd crystal buildup when repeatedly charged at 2C. The battery actually degrades more during a 2C charge than a 20C discharge.
Attached is a pic of what happens to a lipo when subject to a 2C charge. It was dead in less than 200 cycles at 2C, but was good for over 1000 cycles at 1C.
Attached Thumbnails
Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-deceased_lipo.jpg  
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 10-08-2007, 10:48 AM   #288
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Linger-These packs measure very close to 5000 mA-h. 10 A is close to 2 C. From my testing 50 cycles is what I am going to get before I no longer find acceptable performance. I don't need to extend the battery life over 200 cycles. Now if indeed this charge rate is more harmfull than my 45 amp average discharge during the race then I should cut back a bit. I am under a time constraint while racing. It is nice to have a charged pack at the beginning of a heat. I will cut back a little and race on a 90 % charge. Glad to hear you comment on these crystals. I suspect that is what perforated a layer and caused my last battery fire.
john

Last edited by John Stranahan; 10-08-2007 at 03:43 PM.
John Stranahan is offline   Reply With Quote
Old 10-08-2007, 11:25 AM   #289
Tech Master
 
linger's Avatar
 
Join Date: Aug 2001
Location: Retired
Posts: 1,132
Trader Rating: 1 (100%+)
Default

John,
What I'm trying to say is that it's a hell of a lot cheaper to buy more packs and chargers than it is to charge at 2C. See the attached pic. The Y axis is analagous to capacity. The cells that drop in capacity very quickly are the ones charged at 2C. That chart is of Kokam cells, but I have similar data with a lot of other cell manufacturers. Compare that to the ones charged at 1C. BIG difference.

Also, I just looked up the spec sheets to the Saehan Enertech Cells (the likely cells used in the FMA revolution lineup). Their max recommended charge rate is 1C and they consider that "rapid charge".
Attached Thumbnails
Associated Factory Team TC5, Brushless, LiPo, Li-ion Nanophosphate, Tips and Tricks-kokam_1c_vs_2c.jpg  
__________________
I used to be a spitter, now I'm a swallower. I graduated.
linger is offline   Reply With Quote
Old 10-08-2007, 11:30 AM   #290
Tech Master
 
Join Date: Aug 2002
Location: Nor-Cal
Posts: 1,853
Trader Rating: 18 (100%+)
Default

Ling,

Check your PMs please.

Art
__________________
SMC ( www.smc-racing.com the only place to order your batteries online.), Awesomatix, Gonzo Paints, BN Racing

"Imitation is the sincerest form of flattery."
Advil is offline   Reply With Quote
Old 10-08-2007, 03:43 PM   #291
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Ling-The solution seem to be a third charger and use of an extra pack for practice before the race. That Scorpion charger is presently at a good price. I will see if it is still available.

Here is a note from the manual of FMA's new charger. Old LiPo's at 1 C but

For recently-manufactured lithium packs, set charge rate up to 3C. Packs in good condition
should charge without cell damage. However, use caution and donít leave the charger

unattended.

I will study your discharge data in a bit and make a post about it.
john
John Stranahan is offline   Reply With Quote
Old 10-08-2007, 04:05 PM   #292
Tech Fanatic
 
B4Bandit's Avatar
 
Join Date: Apr 2006
Location: Sydney, Australia. St Ives RC Club.
Posts: 960
Trader Rating: 10 (100%+)
Default

Hey Ling,

That looks like a good graph. Were the packs around the 40 mark the orion Platinum Edition cells by any chance? They seem to hold pretty good numbers. Or are these not specifically rc batteries?

Cheers,
Warwick.
B4Bandit is offline   Reply With Quote
Old 10-08-2007, 06:35 PM   #293
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Warwick-Those cells are made by KoKam but are not the Orion cells. They are of a smaller capacity than we use (only 750mA-h) and are produced as samples, for testing, that might be used in a custom application. I studied the graph and had some communication with Ling. On the Y axis is the energy epended on a discharge which is related to capacity. The striking result is that the cells charged at 1C are represented by the lines that don't drop very much as we go to the right. This means they have little loss in energy output with each additional cycle even at high discharge rates. They achieve upwards of 400 cycles. The lines representing cells charged at 2C drop steeply. You can see the little steps as each discharge cycle reduces the output of the cell. They tend to end at 125 cycles or so. The battery can be considered dead or unusable where the line ends. At least the testing stopped there.

1C for my roughly 5000 mA-h cells is 5 amps. 2C would be 10 A charge rate.

I have personal experience with Apoggee Lithium Manganeese cells charged at 2C which they recommended. The drop in runtime was very fast. The drop in runtime with a couple of months storage after they were no longer satisfactory in the car was exceptionally fast and complete.

Some of the other cells I have charged at 2C on occasion with much better success. If indeed the charging deteriorates the cell more than the high heat with high discharge rate then it would be worth testing this new battery at 1 C charge rate only to see if it actualy will last longer in high Drain RC car use. I have ordered a third battery charger to effect this.

Interestingly when I first tested the LiPo scorpion pack I posted that probably we would need three batteries and 3 chargers to use these cells effectively. Others proponents of LiPo said no. Is it worth this much expense is the likely question. Well the TC5 looked really good compared to the Nitro's even on the straight last race.

What we don't see on this graph is what is happening to the Voltage. It does no good to really pamper a cell so that it achieves 400 cycles if the voltage is subpar for RC car performance after 50 cycles and requires replacement. It is very possible that Average Voltage and Capacity are lost at similar rates. It is certainly worth a pampering test. These cells have only had 10 amps for about 10 minutes each just for the race.

Last edited by John Stranahan; 10-08-2007 at 06:52 PM.
John Stranahan is offline   Reply With Quote
Old 10-10-2007, 03:57 PM   #294
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

I sent a note to Paul at Titanium Racing. They have a pic of the new spool design up again on the Web site. He replied promply that it is available and would ship for the TC5 if i ordered under the old picture. I ordered one up. I requested a set of outdrives by e-mail as there does not seem to be a way to do this on the spool items page.
This new design has some advantages over the old. The outdrive cup is secured by a flange behind the outdrive bearings. This should make for a more wobble free or concentric spinning setup even after a bump on the track. Test to come.

John
John Stranahan is offline   Reply With Quote
Old 10-11-2007, 07:52 AM   #295
Tech Elite
 
yyhayyim's Avatar
 
Join Date: May 2006
Location: Weston, FL
Posts: 3,424
Trader Rating: 26 (100%+)
Default

Hi John: About the Foam tires...

I have run them on My TC's for almost 2 yrs. The car's performance will improve in handling and speed. Use 37-38 shore all around. we like the Nitro Shoes 37's all around. They wear better. The best tires are Kyosho foam tires...they are very consistant and have very nice grip and wear from the first run. They are expensive though...if you give the Kyosho foam a shot, use 35 rear and 38 fronts...

With foam tires, remember to move the rear bottom shock mount position a hole towards the inside, since the 30mm rear wheel will rub on the bottom shock ballcup and bind or grind it down quickly.

Use 6.5mm starting ride height all around- by the time you finish your 2nd pack it should be around 6mm. Check ride height every 2 or 3 runs and adjust.

Also, when you start using the foams, they are usually 63mm. Dont true them down. start them off like that wear them w/ every run...they'll work better than rubber tires even at their staring 63mm stock diameter! When they get to 58mm...oh my goodness!! The car will pick up over all speed and handling will be sharper...check your gearing- you might need to add a tooth since the rollout changes as the tires get lower.

THere's no comparison...you'll be .5 sec faster per lap, easy with the foam tires. Let us know how it goes...
yyhayyim is offline   Reply With Quote
Old 10-11-2007, 07:29 PM   #296
Tech Apprentice
 
Join Date: Feb 2007
Location: Ontario, Canada
Posts: 59
Default foam tires

We run foam 19-turn TC on a sugared asphalt track. Many run Nitro Shoes Rears on all four corners. The Nitro fronts are made of a harder different type of rubber. Electric TC donít have the weight to make them work and need more steering than nitro cars so you may want to try rears all around. Youíll likely have to narrow the rims as they are 30 mm wide. I cut mine 28 mm wide on my tire lathe with an Exacto wearing a face shield and standing off to the side. Iíve run carpet foam tires on colder days but they tended to wear very rapidly on hot days. We'll see 120ļF track temperatures. I run 38 front /35 rear or 37/35. We run carpet set-ups on the cars with a slightly higher ride height (5.5 mm).

Great thread. Iíve also enjoyed the 1/10 pan car thread. My non-RC friends are always surprised at the level of engineering that goes into these cars.
Tuner EM is offline   Reply With Quote
Old 10-12-2007, 01:04 AM   #297
Tech Elite
 
rezenclowd3's Avatar
 
Join Date: May 2006
Location: Solvang, CA
Posts: 2,367
Trader Rating: 17 (100%+)
Send a message via AIM to rezenclowd3
Default

John, I just noticed that you bought the Futaba BL451 servo. What do you think of it? I happened to buy one after Korey Harbke from Xray recommended it to me.
__________________
OOMSGFX.COM (no longer painting, but take a look for fun!), Roadrunners RC Club
"Racing drivers have balls, unfortunately, none of them are crystal" (David Coulthard)
"I believe the average IQ of a NASCAR fan is only marginally above the things that hit the windscreen during the race. "
rezenclowd3 is offline   Reply With Quote
Old 10-12-2007, 09:57 AM   #298
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

yyhayim, Tuner EM- Thanks for the tips on the foam tires. I have some 35's coming in for a test. Looks like I might need some 37's as well.

when you guys say Nitro Shoes are these Nitro Shoes made for electric cars or Nitro cars. In other words are the hex drives the same? I did notice that the width might be different and Tuner cut that down.

Futaba Brushless Servo
I am using that brushless Futaba Servo. It is working great. It is slightly lighter and more compact than the other servos I am using as well. No problems to report.

john
John Stranahan is offline   Reply With Quote
Old 10-12-2007, 12:26 PM   #299
Tech Elite
 
yyhayyim's Avatar
 
Join Date: May 2006
Location: Weston, FL
Posts: 3,424
Trader Rating: 26 (100%+)
Default

Quote:
Originally Posted by John Stranahan View Post
yyhayim, Tuner EM- Thanks for the tips on the foam tires. I have some 35's coming in for a test. Looks like I might need some 37's as well.

when you guys say Nitro Shoes are these Nitro Shoes made for electric cars or Nitro cars. In other words are the hex drives the same? I did notice that the width might be different and Tuner cut that down.

Futaba Brushless Servo
I am using that brushless Futaba Servo. It is working great. It is slightly lighter and more compact than the other servos I am using as well. No problems to report.

john
Nitro shoes are Jacos foam TC tires...the rear from tires are 30mm, the fronts are 26mm. You'll have better steering with the 26mm fronts, so dont try using 30mm fronts or cut those to 28mm; it's really unnecessary.

Nitro Foam TC tires work just fine w/ electric TCs...the only issue is the rear 30mm width...they inner wheel will rub on the rear lower shock ballcup and bind. Just move it one hole over and you'll be fine...this varies with the different cars...the JRX-s and Type R dont need to be moved at all...
yyhayyim is offline   Reply With Quote
Old 10-12-2007, 08:05 PM   #300
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

YYhayyim-Thanks. I took a look at our shop supply of tires. Quite a few brands are available but mostly in 42's. Thanks for the interchange information.

Track Report
120F track Temp, Traction Medium-Low

Only two of us on the track so traction was not as good as race day. I was able to evaluate well that increase in rear toe to 2.75 degree. This was accomplished with 2 degree Associated shims, .5 degree hubs and .025 shims added to the associated spacer. I was very pleased with the handling. Often with a locked diff it is hard to make a change that is really helpful. This was. I drove with no corner exit mistakes now. The rear end is well planted. I could drive really hard. I will add this little change to my posted setup earlier in the thread. Jeff turned on the track timing equipment. I was quickly up to race speeds even though traction was a bit off. I epect some mid 18's next race day. I am getting low 19's and an occassional 18.9 or 19 flat. I really think rubber was the tire of choice today. I will be able to compare the two better later on. Right now I can test the traction foam tires have with the pan car. Speed control and motor worked great at 120F. Front diff is chunking a pin pillow just about every run now that things have worn a little. TIR front spool on the way

John

Last edited by John Stranahan; 10-12-2007 at 08:19 PM.
John Stranahan is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks. John Stranahan Electric On-Road 2178 12-01-2010 11:26 AM
BRUSHLESS rc18t factory team with lipo dub599 R/C Items: For Sale/Trade 11 06-16-2008 12:14 AM
Factory team B4 Novak brushless with lipo PTP Racing R/C Items: For Sale/Trade 1 12-13-2007 11:36 PM
Factory Team RC18T with hopups and brushless / lipo setup! Cain R/C Items: For Sale/Trade 5 11-26-2007 05:35 PM
Xray T2R, 2100 mah 2c LiPo, and Mabuchi power: Tech tips and Tricks gacjr0 Electric On-Road 46 11-18-2007 10:09 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 10:44 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net