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Old 08-02-2006, 08:27 PM   #241
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SCORPION LIPO FIRE
I'll start by saying this is NOT an Orion Lipo which is advertized to be of a fire resistant chemistry that is not divulged. This is NOT a Lithium Manganeeze LIPO that is advertized to be fire resistant, although I am not at all impressed by a simple drill test. This is a Lithium Cobalt dioxide LIPO which until January of this year was about all that was available for cars. I have used this LIPO for 6 months now. It probably had 30 runs on it. There was OPERATOR TROUBLE involved (me:short circuit). Note that J.C. won't tell us what brand of cell burned up on him.

So the battery went dead without much visible trouble. I opened the shrink and one of the thin metal leads (ribbon thin about 1/4 inch wide) that came out of the original wrap was broken right at the point where it should connect to a small printed circuit board where the leads are soldered on. The break was very clean. There was no molten solder visible. No evidence of smoke. The break might have been started by vibration damage running a high speeds on a wavy track in the touring car. After the short circuit, the break was complete. What to do with a $60 pack that is running much better than all of my NiMH that were purchased around the same time. I resoldered it. Inspected the factory case. It was perfect. No bulges. Put on New shrink wrap and a new longer lead to avoid the problem in the future.

I tested the pack in the car. It ran fine. I grabbed the front wheel and gave a 10x1 a burst of throttle to test it hard. It worked fine. Slipped the front locked diff. Put it away in a steel container on a marble top fume hood (fire proof) in the garage. Well the next morning the garage smelt like an electrical fire. Here is a pic of the remains and thus truly ends the test of the Scorpion pack which I no longer see for sale on the FMA web site.

Details in the photo. It is apparent that a fire started without a direct internal high amperage short. The fire melted the heavy shrink wrap that I put on the long lead (The white wire which used to be red silicone) attached originally to a Deans Half Plug. This created a short between this lead and the negative lead (which was also covered by heavy shrinkwrap, not the cheesy little piece that Deans ships with the very good plug). The negative lead is down lower in the pan. The pan was the conductor. You can see the burned in notch on the rim of the can. The lead wires must have incandesced red to completely powder this high temperature silicone. In other words the battery had lots of juice when the shrink on the leads melted. The Dean (female) half plug on the white wire vaporized possibly. I have not found it. The other small wire you see in the photo are the charging wires that ran to a Tamiya style plug.

Anyway I was planning to transport this cell in a 1 gallon can with a weight on the bottom so I could chunk it out the window if it caught fire in the car.

If you screw up with one of these just chunk it in salt water and throw it away.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-fried-lipo-004-cropped.jpg  

Last edited by John Stranahan; 08-02-2006 at 08:52 PM.
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Old 08-03-2006, 06:09 PM   #242
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Sorry to hear that you junked a cell John.

But more than anything, glad you had it put away safely so that your garage didn't burn down. Did you see the post on the Lipo pack left on the front car seat? Not pretty...

I've thought Of buying Lipo but the weight (or lack thereof) would upset teh car too much. Also - living in a small apartment does not engender any confidence in storing potentially hazardous Lipo batteries.

Scary thought.....

Glad that yours junked itself fairly safely..
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Old 08-03-2006, 09:13 PM   #243
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AngryAsian-Thanks for the post. I have not abandoned LiPo's completely. I have a couple of Lithium Manganeese LiPo packs ordered from
http://pfmdistribution.com/secure/sh...d=197&catid=46 I will probably store them in the garage in a can for another 6 months of testing.

If I am lucky they will fit the JRXS without modification to the car or battery. From the photos it looks like the new Orion 3200 Lipo still has the terminals too far outboard on the case to fit the JRXS without Dremmeling things up. Note that what I did was plug my speed control in backwards. The speed control survived. This is easy to do on the Orion packs as the terminals are so close and not loudly marked + and - from the photos that I have seen and the plugs are not polarized. Probably need to be careful with those to avoid damaging the cell like I did. They may not burn. Don't know if they have been tested this way or not. Mistakes happen in the heat of competition.

I saw the post on the front car seat. Now inquiring minds need to know was it one of these safer cells or not?

I add two big lead sheets to bring the weight of the LiPo equiped car up to legal minimum for the class.

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Old 08-07-2006, 08:48 PM   #244
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Apogee LiMn mods needed to fit JRXS

I received my Apogee Lithium Manganeese Polymer packs. Here is some info with respect to my LosiJRXS which is the original front motor car and as far as I know the one that is available at present although a new mor LiPo friendly chassis is in the works.

The stock apogee packs did not fit the JRXS. They have two Lexan plastic shields one on top and one on the bottom that extends the length as well as some internal assembly choices that extended the length too much.

Here are the modifications that I made which immediately voids your waranttee.

I removed the shrink and tape that is over the ends. I removed the middle small black wire from the charging plug. Just push the tab in with an X-acto knife. This is the balancing wire, save it. I Nipped off the other small red and black wires under the protective tape and discarded the little plug.

The cell is different from the scorpion. It is a 2s 1p cell (only two cells in series). The Scorpion was a 2S 2P ( four cells two in series and two in parallel) Each cell has the + and - on opposite ends rather than on the same end like the Scorpion cells. The little black balancing wire is long and is attached on the opposite end to the discharging leads. It is long enough to run along the other side of the battery and exit the same side as the discharge leads. This avoids (the entire little plug charging harness) rubbing the rear drive pulley on the JRXS. The discharge leads will exit on the right rear side of the car. Only three wires remain. Large black and Red and tiny black (the balancing port).

I soldered three leads with Dean Half Plugs to the Scorpion charger to get rid of the dependance on the plug which failed me once. I used Dean Ultra plugs cut in half.

I removed a 1/8 inch balsa wood spacer from the non lead end of the batt and cut it to 1/16 inch thick.

I took the black discharge lead solder connection which is in a taped envelope and bent it above the battery instead of toward the end. This saved about 1/8 inch in length.

New blue heavy Shrink and black tape end to end to smooth the ends. It fits nice now.

Weights
The finished pack weighed 8.1 oz compared to the LiPo from
Scorpion which weighed 7.1 oz both after a reshrink and lead change. A NiMH is about 15 ounce.

I made a small bracket to keep the battery from sliding onto the rear pulley and rubbing. Pics on request.

Apogee Li Mn First Discharge Test
First discharge test was with the charge sitting in the battery for a long while and then topped off. It was over 7 volts at 5 minutes and averaged 6.94 V over a full 3744 mA-h. I expect this voltage to improve like the Scorpion pack from a full charge discharge in rapid succesion without sitting.

Last edited by John Stranahan; 08-07-2006 at 11:21 PM.
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Old 08-07-2006, 10:05 PM   #245
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Apogee LiMn Second Discharge test.


This test was a charge and then discharge in rapid succession like I do at the track.

Average voltage at 20A discharge over a full 3838 mA-h = 7.20 Volts. This is only very slightly under the Scorpion which average 7.25 V after I shortened the leads.

This is .2 V over letting the pack sit with a charge in it and then topping it off. About the Same for the Scorpion pack which was likely a Lithium Cobalt Dioxide pack.

The voltage at 5 minutes was over 7.2 Volts.

Note that at this point my 5 month old 4200 mA-H NiMH packs are about 3400 mA-h due to degradation. One has died.

More details about this battery in the post above.

Last edited by John Stranahan; 08-07-2006 at 11:19 PM.
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Old 08-12-2006, 10:08 PM   #246
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The LiMn packs from Apogee are working well. I have made a few changes to the car to better cool the motor and to add a bit more chassis flex. My car was hooked up really well today. Traction was excellent. A small problem that I had been having was at about 3/4 point in the run the car was getting slightly loose. I suspected the tires were heating unevenly front to back. The added chassis flex cured the problem where some spring changes were unsuccsessful.

The right rear corner shot shows the three leads coming out of the battery. The silver balancing port is disconnected. Orion has a new 3200 LiPo battery coming out soon with a soft cover in their avionics line. It may fit this car as the leads are arranged the same. As soon as they are available I will test one.

I quite a while ago made a clearance cut on the center shaft support to clear the brush leads on this style of brushed motor. They need to be really free or they hang up and fry your motor.

I opened up the bottom of the chassis in front of the motor for better motor cooling. There is plenty of strength and stiffness left. If you run a top fan removing that X-brace wil really flow a lot more air on a brushless motor can. The track has been 140 F lately.

The top shot also shows a sheet of lead I run on top of the LiPo. I would run it down low, but the battery is held side to side better this way. I dremeled down the very rear of the aluminum battery tray to make it flatter on top for the LiPo. I left a very thin lip for support.

The left rear corner shot shows a little bracket to keep the battery off the pulley.

I have a Duratrax Ice charger on order to test with these LiPo's
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-balancing-port.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-jrxs-012.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-motor-cutout.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-dscf0002.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-dscf0008.jpg  


Last edited by John Stranahan; 08-12-2006 at 10:32 PM.
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Old 08-14-2006, 10:33 PM   #247
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Losi JRXS Type R
This photo is from the thread with the same title. It is larger and resampled so you can see it full screen. Still not a very clear photo. The photo had 15 views when I exchanged it for a sharpened copy.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-jrxs-type-r.jpg  

Last edited by John Stranahan; 08-15-2006 at 10:25 AM.
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Old 08-14-2006, 10:55 PM   #248
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John - What prompted Losi to release a rear motor version of the car?

To give more of a rear wheel bias to the power delivery?
I assume the shorter rear belt would deliver power more instantaneously to ther ear wheels, allowing the front to perform more "work" - Ie. leaving it more free to steer?

Or was it to reduce on-power steering?/reduce off power steering?

Just random guesses...
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Old 08-15-2006, 07:51 AM   #249
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Quote:
Originally Posted by John Stranahan
Losi JRXS Type R
This photo is from the thread with the same title. It is larger and resampled so you can see it full screen. Still not a very clear photo.
John Stranahan, you are a brilliant man!!!!! Wish i was still in Texas to take full advantage of your mind trackside, it would help me emencely!! Tito
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Old 08-15-2006, 10:07 AM   #250
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From what I can tell the rear motor car will allow a slightly better weight balance. I find that touring cars perform better with 2-3 oz more weight in the back. This is hard to achieve with the front motor car. Some weight transfers forward during corner entry giving a more even tire loading. This provides better cornering traction. Better corner speed is Losi's advertized claim on the other thread.

Some other changes from the pic. The oudrive cups are metal (possibly only in the prototype) but also seem to be shorter to allow longer drive axles. I cannot see the front drive axle, however. This allows freer movement of the supsension which probably increases cornering traction a little bit.
The battery compartment allows the use of the Orion Lipo with its terminals that are far out on the corners. The Aluminum upright are squared off instead of curved to allow the square cornered LiPo to fit. Those that hardwire will find a little space for the battery bars to stick straight up as well.

I don't see how moving the motor back improved the driveline which is already outstanding. This is a strength of the car.

I don't see changes to the sway bar links which I don't like much as they capture the hinge pin. This increase the inertia of the arm as it tries to move. They can be reamed out after tightening the screw to prevent this. I don't see major changes to the arms or shock towers, but they are not very clear in this pic.

note there is a large picture of the Losi JRXS Type R in my previous post.

Now here is an item that I invetigated previously with my home made more flexible arms that is not visible in the pic. This is a quote from Randy Caster.

"The EA3 arms have been on our cars for a few months now without any problems, it is definately stronger than graphite, and provides a bit more traction due to flexing more".

The new car will have a new one piece low top deck

tito- thanks

Better Pic of the Losi JRXS Type R

http://www.rctech.net/forum/attachme...hmentid=159165

Last edited by John Stranahan; 08-21-2006 at 08:48 AM.
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Old 08-25-2006, 05:48 PM   #251
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LiPo Chargers, Apogee Magnum Batteries

The 3800 Apogee Magnum Lithium Manganeese (LiPo) packs that I have been using are working well. They have been tested and are rated at 2C charge rate now by WJ Birmingham from Apogee. This means I can charge at 7.6 Volts. This leads to a fairly pleasant practice session with two chargers and two batteries. Probably need 3 batts to club race mod.

I have had three LiPo chargers in my hands recently the Duratrax Ice charger and an Astroflight Model 109 Charger Discharger and the FMA direct charger that I obtained with a Scorpion Pack and described previously. Here are some observations.

The Duratrax Ice charger promises 8 amps charging rate, but when you tinker with it and set it to LiPo charge you get 2amps or 4 amps depending how many cells you set it for (this is adjustable up to 8 amps see Tony's comment below). It will do NiMH as well as LiPo.

The Atrorflight 109 Charger is a LiPo only unit. If you plug in the unit it says "Waiting for Battery" on an LCD screen. When you put on the battery the computer automatically determines the number of cells. You set the amp rate with a simple knob. I like this a lot. The amp rate is displayed on the screen. This charger is a pulse charger that charges Lipos in three distinct steps. The first step is constant current. In step two, the charger pulses off every once in a while to measure the cell voltage which is an accurate measure of the state of charge. In step three it pulses more often.

If you leave a battery hooked up and then cycle the input power on and off the charger will discharge the pack at a sedate 1.25 amps and measure its capacity in milliampere-hour (mA-h)

The Astroflight charger seems ideal for LiPo's. It seems to be faster than my FMA direct Lipo charger. I'll make a test next time out. Both can be set at 7.5 ampere. The beeps are good and Loud at the change of steps and end of charge. The FMA charger is silent but has ready lights. The FMA charger is the least expensive, the Astroflight is the most expensive, but not as much as an advantage charger and definitely more foolproof. I'll test the Ice some more later.

Both the Astro flight and Ice chargers are just about an inch bigger all around than the FMA charger.

Both the FMA Direct charger and Astroflight charger will stop charging if your power supply Voltage drops too far. I had both cutout on a 30 amps supply when I goosed the variable Voltage of the Rivergate supply up to start a mod motor for breakin. I won't goose it any more. No interruption when using the lathe which has a higher wind motor.

The FMA charger will balance a two cell pack during the charge. This is rarely needed if the pack is matched to start with.

I plan to continue my LiPo tests on another thread with a different car. Not a Touring Car. Maybe next week.

Notice that the 1 C charge rate on the Astro Flight Charger is a suggestion not a limitation of the instrument.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-scorpion-chargers-cropped.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-astro-flight-chargers-lipo-cropped.jpg  

Last edited by John Stranahan; 08-26-2006 at 01:16 AM.
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Old 08-25-2006, 09:56 PM   #252
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John,

I enjoy reading your posts because they are always very informative and helpful even though I don't run the JRX-S any longer. However, I have to disagree with you on the Ice charger. I use mine to charge LiPo's and the amp rate is fully adjustable up to 8 amps. I use a 6000 Maxamps 2s2p pack. When first put into LiPo mode and you select the number of cells, it has a charge rate selected. All you have to do is scroll down to the charge amps and push in on the dial. I charge this battery at 1C as well as my transmitter LiPo. At least on my unit, the amperage is adjustable through the full range available on the charger, from .1 to 8.0 amps on any type of cell.

I really think you should reconsider the Ice as it is an excellent LiPo/LiMn charger.

Tony
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Old 08-25-2006, 10:30 PM   #253
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Tony
I have seen one of the battery suppliers also mention a 4 amp limit for this charger on Lipo's. I guess he nor I looked deep enough. I'll give it another look. I corrected my post.
John
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Old 07-02-2009, 12:56 AM   #254
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Hi, I realy enjoyed reading this thread, a lot of important info in easy to read form.
John, can you tell me if anyone produces LCD for XXX-S? This car is still very popular, in some circles even more and more.
Other question is how to equip xxx-s with spool with anti roll bars - one on front or two at both sides?
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Old 07-02-2009, 09:32 AM   #255
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Kajman- I never installed sway bars on my XXXS. Here are a couple photos I studied to help form an approach.

Making Custom Sway bars
First the JRXS sway bars attach to a molded in ball on the A-arm. You would need to find the balls size to see if a metal ballstud could be used. If yes than the links going up to the sway bar should work and the balls that attach to the sway bar wire for the links should also work. Now its a matter of finding or forming wire to reach the links and also the attachment points you select at the front and back of the car. I see a couple of handy holes in the rear. You can modify the JRXS block that holds the wire to fit. You can also use pianno wire or music spring wire found in the hobby shops to make sway bars yourself. Get a kit to help with the hardware (links and balls).

At the front you will probably be sharing the screws that hold the top middle of the bumper on.

LCDs for the XXXS
As far as I new the oldest car with LCD's is the JRXS. They will be too short for the XXXS. The X-ray LCD's would be the closest fit while using X-ray hubs, c-hubs. The X-ray axles are 150 mm long from end to end of the dogbone. You must be close here. These axles use metric bearings and wheel hex adaptors requiring the use of the X-ray parts. I succesfully installed these on my Associated TC5. There was some Dremmel work involved at the inner drive cup.


Making a spool
A friction type spool is easy to make for this car. The diff parts sizes are shared with the JRXS. Get the Losi slipper pads and remove the balls from the diff. Clamping pressure on the center pulley and pads now locks the diff. You must retension often as the pressure squeezes the pulley more narrow day by day.

Get this if the pulley is the same as your car. I think it was.
https://www.ssl-stormerhobbies.com/c...ns&pn=LOSA3324

else get these to use on your pulley

https://www.ssl-stormerhobbies.com/c...ns&pn=LOSA3250


Anti Pitch Bars
Nobody runs sway bars (anti pitch bars) on the sides that connect front and back wheels. I would not either.
Attached Thumbnails
Losi Constant Velocity Drive (LCD) vs MIP CVD-losi-xxxs-blocks-rear-view.jpg   Losi Constant Velocity Drive (LCD) vs MIP CVD-losi-xxxs-blocks-front-view-.jpg  
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Last edited by John Stranahan; 07-02-2009 at 09:50 AM.
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