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Old 12-18-2005, 04:14 PM   #61
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Well, they are really fast and can have huge capacity and light weight. You will just probably need more than two packs, maybe three packs and two chargers or 3 chargers. Just to note, I have 3 NiMH chargers so this is not that unusual. It is inevitable that all the electric racing will eventually use these packs. Probably be a month or two before the regular RC suppliers start stocking the Orion Packs.

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Old 12-18-2005, 07:53 PM   #62
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Here are some claims about the parent Kokam cells that make up my Scorpion LiPo pack. Maybe the cells are available separately somewhere.

"EaglePicher Kokam SLPB has Superior advantage to any other type of batteries.
1) Low material cost and low production cost
2) Ultra thin battery can be made up to the thickness of 0.4mm
3) No limit of high and larger capacity cell production
4) Very easy to change the size
5) Easy operation due to the simplified process
6) High quality at high temperature"

This backs up my claims, so why are they killing us with a $200 suggested retail price for the Orion LiPo Pack. Because it's new, I guess.

http://www.kokam.com/english/biz/rc.html

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Old 12-18-2005, 08:26 PM   #63
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One thing I noticed on that link was how the Lipo is affected by ambient temps with capacity and voltage during discharge, how doe the temp affect that charging of these batteries. I know that not every track is indoor, climate controlled. So they will be used in all temperature ranges, from freezing point up to 45 degrees C(approx 105 F).
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Old 12-18-2005, 09:51 PM   #64
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T.- I charged it up outside at 50 F it seemed to take the same 1.5 hours that it took inside at 70 F. I did not time it, though. It was plenty fast in the car. Felt just like the Turbothirty numbers predicted it would be. It might be a little colder tomorrow. I'll take another look at that web site for this data and report it on this post.

I took a look at the graphs. There is a discharge graph that plots the voltage of the discharge at different temperatures. This is after the cell has been unused for 2 hours after the charge and has stabilized at the lower temperature. I have found with a couple of test after a 15 minute wait that the voltage is .4 volts less just sitting. That's pretty unusable for racing. We are not going to let this cell sit for racing. I do notice that the voltage at 0C, 32 F, is quite a bit lower. The pack is warm after you charge it though, so I don't think we will see this lowering in the car. They waited 2 hours for the cells to cool down completely.
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Old 12-19-2005, 12:09 AM   #65
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John is a great example of American ingenuity...and insanity.


Keep it up John!
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Old 12-19-2005, 03:40 PM   #66
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Quote:
Originally Posted by Soviet
...and insanity.
How did you know. LOL.

I ran the Lipo again. I had a failure to charge, both the yellow and green lights were blinking. The red light was continuous and indicated the charger had power. It is hard to see that yellow light in the bright sun so I actually ran 4 NiMH packs before I tended to the charger. From now on I will tilt the charger when I check it to view the LED's better. I imagine that cheesy plug the scorpion charger uses for charging is the problem. I had a similar problem with a Tekin charger false peaking that I resolved by replacing the plug with Dean's connectors. The charger lost contact sometime during the slow constant voltage charge. I will probably eliminate that plug from the charger and put on a longer pigtail with a Dean Plug to charge the pack. I will put the white wire on its own Dean Half plug and eliminate two more wires from the pack. It will fit the TC3 Battery tray better this way. Did not get times due to the difficulty. I am getting consistent lap times now.

Here is some more detail from the KoKam site. The battery will undergo an irreversible chemical reaction (and die) if brought below 5.4 V per 2 cell pack. They stop their discharge at 6.0 V for their tests. The rate of self discharge is slow compared to NiMH. Long term storage is accomplished by charging it half way and then 3 - 6 months of storage is possible without the cell discharging below its 5.4 V threshold.
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Old 12-20-2005, 12:35 AM   #67
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Default Lightweight Locked Diff

Here is a picture of my lightweight locked diff prototype. It might be useful for stock motor racing. A manufacturer could make it quite a bit neater from Losi Parts with screws that do not perforate the flange. 22 gram. No thrust bearing drive rings or Diff screw. 3 Losi Locked diff shims (sandpaper) per side on the pulley. The one-way is a very nice light piece as well at only 23 grams.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-locked-diff-80%25.jpg  

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Old 12-20-2005, 08:24 AM   #68
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i just took the diff. balls out of my spool and added sandpaper...its worked great for the last couple months...watch out though it'll wear out your LCD's like crazy!
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Old 12-20-2005, 08:52 AM   #69
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R/CAnonymous. Thanks for the report.

I am told slipping is not a problem with the Sandpaper shims, then the only advantage is losing a few grams of rotating weight.


X-ray has a nice front diff unit that will work as either a one-way, locked one way or completely locked diff.

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Old 12-22-2005, 08:53 AM   #70
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Spektrum Module

I got my new Spektrum Module for the M8/M11 Airtronics Radio. The antenna on the receiver is only 8.5 inches long. According to the instructions it can be mounted inside the body without losing range. I removed the factory antenna from the Airtronics radio. The spektrum module uses a technology similar to cell phones. It searches for an available channel and also uses several channels at once. It is on the 27 Mhz band so it should not interfere or be intefered by anyone using crystals on the 75 Mhz band or anyone else using a Spectrum Module up to about 70 racers. This should be really handy at the races and at informal tracks where guys usually pickup their radio turn it on and check for interference by seeing if anybody crashes. I plan to test it this afternoon. I have reduced my glitching (without the Spektrum)to only a few times per outing, but I ended my last outing with a big glitch that crashed and broke the car. I am getting interference from the neighbors huge AC box service entry at M&M in Houston.
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Losi Constant Velocity Drive (LCD) vs MIP CVD-spectrum-receiver-module-installed.jpg  

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Old 12-22-2005, 09:17 AM   #71
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Quote:
Originally Posted by John Stranahan
Spectrum Module

I got my new Spectrum Module for the M8/M11 Airtronics Radio. The antenna on the receiver is only 8.5 inches long. According to the instructions it can be mounted inside the body without losing range. I removed the factory antenna from Airtronics radio. The spectrum module uses a technology similar to cell phones. It searches for an available channel and also uses several channels at once. It is on the 27 Mhz band so it should not interfere or be intefered by anyone using crystals on the 75 Mhz band or anyone else using a Spectrum Module up to about 70 racers. This should be really handy at the races and at informal tracks where guys usually pickup their radio turn it on and check for interference by seeing if anybody crashes. I plan to test it this afternoon. I have reduced my glitching to only a few times per outing, but I ended my last outing with a big glitch that crashed amd broke the car. I am getting interference from the Neighbors Huge AC box entry at M&M in Houston.
There is an accessory capacitor that plugs inot the Spektrum reciever. Be sure to get that or you will have problems with loss of signal (seemd like glitching but it not).
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Old 12-22-2005, 09:37 AM   #72
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John - it's been interesting reading this thread even though I don't have any Losi cars. Your reports and pictures would be perfect for a personal RC site, or possibly added to an already existing site that you could update and get comments on the articles. Have you thought of that? Just wondering, because the topic has ranged far and wide and the topic title doesn't really reflect the content Keep it up, good stuff!
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Old 12-22-2005, 03:25 PM   #73
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Spread Spectrum Road Test
The spread spectrum Module worked great at M&M in Houston today. Not a single glitch from the neighbors Electric Utility Box. In my previous test I had changed to a receiver fresh from being checked out by airtronics (new antenna) and a new servo. I had moved the receiver farther from the power capacitor. All of this improved the situation, but I still had an occasional big glitch. Some heavy electrical equipment is probably powering up when this happens. I did not need the auxilliary capacitor that Adrian mentioned for the Spread Spectrum receiver. This particular track does not have the best traction so you are never pulling the really big amps that might lower the Batterry Eliminator circuit's voltage to a level that the receiver would momentarily be weak.

The short antenna inside the body worked great. I am quite happy with this product.

I tested the Lipo and a GP 3700 NiMH pack back to back. I'll make another post after I cycle the GP 3700 pack again.

Frank- I listed the topics to be covered at the top of the first post in black boldface. I cannot change the title of the thread. I am including some auxilliary items that are essential for me to give the listed items a good test. I have a personal website, as well as a personal Journal, but this is not a good way to get feedback and additional information. That is the purpose of this thread. It is not likely that any of this information stuck in the middle of the million page JRXS thread would be well taken. I have a hard enough time here. I prefer the stealth-tech thread approach for now. I paid a small fee for storage of the TC3 thread and will do so for this thread if it gets bigger.

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Old 12-22-2005, 04:20 PM   #74
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Scorpion LiPo vs GP 3700 NiMH

Might as well tell you the whole story. I ordered a sale priced GP 3600 for this test, but received a GP 3700. They must have run out of the old ones.

Orion GP 3700 Racer Pack Numbers
I cycled the pack a few times on the turbothirty. The third test was 607 seconds at 20 amps (3372 mA-h) with a very nice 7.21 Voltage. I have no additional sneaky tricks to raise this voltage as I used them all when I assembled the pack. This is not the best pack Orion sells of this type nor is the Scorpion a selected pack with exceptional numbers. The capacity of this NiMH is less than advertized but may improve slightly with use. I have 5 cycles on the pack.

Scorpion Numbers
The Scorpion LiPo with all my sneaky tricks tested 7.25 Volts at a 20 Amp discharge for 3188mA-h (or 3.2 Ampere-hour). The capacity is right on the money as advertized.

Voltage loss on storage
The Scorpion pack loses .4 V on the average after a 15 minute wait or overnight wait and repeak from charging to use. Capacity was not affected much.

I made a similar test on the NiMH pack and it lost .14 Volts from a 15 minute wait and also lost 32 seconds of run time at 20 A.

Both packs need to be raced right after the charge for the best performance.

Charging time at 7 Amps and 70 F
I charged both packs at 7 amps today at the track. The NiMH took 34 minutes. The LiPo pack 1 hour and 28 minutes at about 70 F.

The Lipo pack can be charged at 3 C which is 3 times the capacity in Ampere-hour, or 3 x 3.2 or 9.6 amps. (Don't these battery manufacturers now that that letter, C, is already used up for Celcius Temperature) This faster rate will speed up the charge only a little as the constant voltage, slow part of the charge, will be unnaffected.

Track Results
On the track, the Lipo had a slight edge in top speed. Both batts were pulling a 7.20 overall ratio well. This top speed is unnafected by the lighter weight of the LiPo. The Lipo had better punch but only a little better. Probably would end up being 1/2 lap or so better on a high grip track, though (with 12 second laps). I did not add ballast to the LiPo.

Run time on a loose oudoor track with 12 second lap times

I got 7 minutes of good runtime on the NiMH pack followed by 3 minutes of pathetic run time for a total of 10 minutes.

I got 8 minutes of good runtime on the LiPo followed by me taking the car off the track to avoid overdischarge.

The Lipo is supposed to keep its performance longer. I'll see.

Last edited by John Stranahan; 12-22-2005 at 07:45 PM.
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Old 12-23-2005, 07:31 PM   #75
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Default Battery Weights

Here are the weights of the two packs.

GP 3700 with Deans Bars and short pigtails, and homemade Dean Half Plugs -14.4 oz

Scorpion Lipo pack ,with new short leads and thick shrink wrap - 7.1 oz
(LESS THAN HALF THE WEIGHT).

The photo shows a piece of 1/2 inch square solid steel stock that brings the LiPo batterries weight up to that of the NiMH. Lead would require a smaller but still huge piece.

The TC3 handles poorly with both of these batteries due to very poor side to side balance. One is heavier than the car is setup for, One is much lighter. I plan to mill the TC3 chassis to run the heavier battery closer to the center line. I will run ballast with the LiPo to have a more fair test. The Losi Side to side balance is unnafected.

Second Photo Mission Accomplished. Center Rib milled inward .230 inch. Note the TC4 and TC4 pro don't need this mod.

I used two sheets of lead .090 thick, the same length and width as the LiPo pack to add ballast under the battery pack. That's a lot of lead. Side to side weights are good now with both batteries. I left the car with the LiPo pack at legal race weight (1 ounce heavier on the left). With the NiMH the car is 2 ounces over, but the side to side balance is perfect. The car should handle much better now. It was accelerating in an arc previous to this mod. This is no good on a slippery track.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-battery-weights-lipo-vs-gp-3700-002.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-battery-weights-lipo-vs-gp-3700.jpg  

Last edited by John Stranahan; 02-05-2006 at 09:36 AM.
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