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Old 03-11-2009, 03:46 PM   #826
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Originally Posted by jrrc View Post
Anybody that has run 1c lipo have a good starting rollout for a 17.5?
medium track is near 98.17mm... ymmv

edit: Tekin 1.89, sensored, full boost, speed passion motor.
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Old 03-11-2009, 05:07 PM   #827
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Interesting thread here.
Only got to page 13 so long way to go yet.
I am looking at Gen-X10 with 10.5 outdoors
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Old 03-12-2009, 07:06 AM   #828
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Hey, guys. I need a little help on getting the SMC 3.7v pack to work in my WGT car. I tried running without a rx pack and the servo would "lock" after about 2 minutes of run time. So, I tried a 2s lipo rx pack and the same thing would happen. Last night, I finally got a 6v regulator (Losi LOSB9608) for the lipo rx pack and the problem was worse. I tried leaving the GTB switch off and just using the switch on the regulator...didn't work. Then I tried both switches turned on and still no luck. I then threw some AA alkaline batteries together to make a 6v pack and it worked for one 5-minute heat then the locking feeling came back in the main......uuuugggghhhh (Charlie Brown style!!)!!! So, here I am pleading for assistance. Here is my set up:

Speed Merchant Speed Spec II
Novak GTB (tried it with switch off and switch on and had same results)
Airtronics FM micro receiver
700mah 2s lipo pack with Losi LOSB9608 regulator
Mulitplex Polo Digi 4 servo (baciscally a digital HS-85MG servo)

I'm going to swap out the servo to a larger servo with more torque. Anyone have any other suggestions? Thanks!!

Troy.
I swapped out the servo and the problem was fixed!! I'm kicking myself for not trying that sooner as I didn't even need a rx pack to make 6 minutes in WGT with a 10.5 motor!! Doh!!!! Anyway, thanks to all those that offered suggestions.

Troy.
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Old 03-12-2009, 03:01 PM   #829
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Ok, Im hoping to run mod this fri. I have an orion 6.5 race motor. Think I will have any problem with run time on a 75x36 sticky carpet track? I have a booster so I know the radio is fine but dumping a lipo doesnt sit well with me.

Any advise would be great.

DK
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Old 03-14-2009, 04:16 PM   #830
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Still catching up slowly with this section

I tried my GT3 spec Gen-X10 today with its cheap Ansman ESC and HPI Saturn 20T motor with a 3.7v LiPo, it normally runs with a 7.4v LiPo, and apart from the slower speed all the electrics worked fine for the 10 laps I ran (got bored at the slow speed).
Once the other Gen-X10 arrive it will be set up for 3.7v use hopefully fast enough with the 10.5 to run in GT1.
Now to go back to page 19 and carry on reading.
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Old 03-14-2009, 09:41 PM   #831
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EDIT: I've added a set of diodes to the parts list, and I've updated the schematic to show where they go. This is in response to Team Tekin posting his concerns regarding the rather high voltage of two LiPO cells as input to the receiver and ESC. Thanks sharing your concern.

Okay, I've had my SMC 3.7 Lipo for a while now, but so far I've still been running 4 cell NIMH. I'd been having a hard time finding a suitable receiver pack that didn't cost an arm and a leg, and the Novak booster is yet to be available.

I decided I'd run the Lipo this weekend, and I came up with a pretty low cost, lightweight solution. I bought a couple of E-Flite single cell 110mah Lipos (the ones they sell for their Blade CX Micro helicopter). THese cells are TINY and weigh almost nothing. My original plan was to put two together in series to make a tiny 7.4v receiver pack. I took one of the cells out of the package, and tried to get the molded plastic end fitting with the integral plug off it (the tiny plug on this cell is incompatible with any connectors we normally use) I wound up shorting the contacts and that cell went poof.

So now I had only one cell left, when the idea hit me... We already have 3.7 volts from the SMC battery, why not just add the ONE tiny cell in series to give 7.4 to the receiver... I picked up a couple of servo extensions, and in about a half hour it was wired up and working...

Here's how to do it... but first...

WARNING!!! DO NOT ATTEMPT THIS UNLESS YOU ARE SUPREMELY CONFIDENT IN YOUR SOLDERING ABILITY AND HAVE EXCELLENT EYESIGHT FOR CLOSE-UP WORK ON TINY OBJECTS. DO NOT ATTEMPT THIS WITHOUT PROPER EYE PROTECTION AND PROPER FLAMING LIPO BATTERY PROTECTION.

I used a bucket of sand with a metal lid next to the bench... if I heard any hissing or saw any sign at all of the battery going to get weird, I'd just throw it in the bucket and close the lid.

You'll need one E-flite 110mah LiPO cell (or other suitable small LiPO cell), and two 6" servo extensions to do this. Here are links to the parts:

Battery

Servo extensions
Diodes

First step is to remove the white wire from both extensions, you won't be needing them so shave the weight... Now cut each extension in half, and strip a bit of insulation from the red and black ends. tin the ends neatly.

Now, VERY carefully, attach one lead with a male lug to the E-flite battery. This is VERY close work, and it'll be VERY easy to inadvertently short out the battery, so BE CAREFUL here. Put some heatshrink on the lead and shrink it after you're CERTAIN that you have made good solder connections. I'm not kidding about being certain... if one of thise wires comes off after the heatshrink is in place, that cell is going up in smoke, so BE SURE. with the cell on the bench, label side UP, red dot side DOWN, and the little connector pointing LEFT, the BOTTOM of the two contacts is the positive. double check if you have a multimeter with fine point tips. If you have one of those illumina1ted magnifiers to work under, it make this step quite a bit easier. Once again, if you're at all doubtful of your ability to produce good clean solder joints in VERY close quarters without shorting anything, don't attempt this!!

Now take the other lead with the MALE plug, and solder the BLACK wire to the NEGATIVE side of the deans plug that plugs into your SMC pack's deans socket. Splice the RED wire from this to the RED wire from one of the servo extension FEMALE sockets. Connect the BLACK wire from this female socket to the POSITIVE side of the Deans plug that goes into the SMC pack (yes this black wire DOES go to the POSITIVE, trust me) Now cut this black wire in the middle and splice the two diodes inline, with the striped ends pointing AWAY from the Deans plug. All your connections should have heatshrink on them, so go back and unsolder and reconnect if you forgot the heatshrink.

Now, before you plug this all together, grab your voltmeter... plug the little Eflite battery into the female socket, and check that the receiver plug is showing 7.4 volts, red wire should be POSITIVE. consult the diagram and find the problem if it isn't.


Now UNPLUG the Eflite battery, and plug the receiver plug into the battery slot of the receiver. When you plug the Eflite battery into the extension socket, your receiver and speed control should power up. Do NOT turn your speed control on when you power the receiver this way. IN fact, it's probably a good idea to move the ESC switch to an out of the way place where it can't be turned on by mistake.

Unplug the Eflite battery from the socket to recharge it (or just to turn the car off)

Oh... that extra half a servo lead left over... use it to make an adapter socket for your charger to charge the tiny eflite LiPO. Charge at 1/10 of an amp... it should only take a few minutes to top off after a run.

Here's the wiring diagram:
Attached Thumbnails
SMC 4000/25C/3.7V single cell Hardcase pack.-schema.jpg  
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Last edited by Trips; 03-16-2009 at 06:01 PM.
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Old 03-14-2009, 09:49 PM   #832
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Sounds like a nice solution trips, but I dont trust my soldering skills so I'll wait for the booster
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Old 03-14-2009, 09:49 PM   #833
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And here's a pic of it installed in the GenX. You can see just how small that Eflite battery is, hiding there next to the left front suspension arm.

IF you look carefully, you can see I added a switch to the circuit on the chassis. I did this primarily for the benefit of the turn marshals... if my car goes dead or breaks during a run, I wanted to make it easy for the marshal to turn the car off rather than have to pull the body and unplug the connection.

If you decide to add a switch to yours, the most logical place is in the BLACK wire going from the POSITIVE side of the Deans plug to the Socket for the EFLite battery. Anywhere between the Positive side of the Deans plug and the reciever plug will work. Don't pout the switch in the wire from the receiver plug to the NEGATIVE side of the Deans connector... if you put it there it will be useless.

Another thing you'll notice is the pair of battery bars I servo taped to the top of the SMC pack... the reason for this is so that if I need to run my NIMH packs for whatever reason, I can just pop the SMC pack out of the car and pop the NIMH in without having to re-wire the car. LiPO 1/12th's aren't allowed everywhere yet...
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Old 03-15-2009, 11:20 AM   #834
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I have some comments on this setup as the speedo manufacturer…

First we really do not like getting 8.4V from the receiver. It appears to work so far, but it is on the edge for us to deal with. We like 5V to 6V and we can deal with7V, but a full lipo supplying over 8V is a concern. A lot of people are using a 2s lipo for a receiver pack and it seems to be working, but it is not something we are in favor of.

Here is another solution that is easy, safe and works pretty good with the spec motors.

Just put a servo plug from the speedo battery post or the 1S lipo to the receiver. This gives the receiver the full voltage of the single cell lipo and adds a few tenths of voltage from a normal config. The BEC output in a normal setup is typically .3 to .5V less than the battery.

This setup does need our new 1S software ( not released yet) to ensure you have full throttle for the entire run. It works pretty good with the current software, except 189, with the slower motors. The harder you pull on the battery the sooner the throttle reductions kick in late in the run.

With the new software you be able to to leave the red wire in the receiver plug and turn the speedo switch on. The VC will work correctly and can be set for 3V in the hotwire. If you are willing to have 4v or less for the servo this may be the best setup overall in the end. Our favorite is still a booster that supplies 5V or 6V to the receiver.

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Last edited by Tekin Prez; 03-17-2009 at 04:09 PM.
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Old 03-16-2009, 05:13 AM   #835
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Thanks for posting that info... While I did get away with running that much voltage into the receiver this weekend, I wasn't aware that it might be an issue... So many people I know are ruhnning two cell LiPO receiver packs that I made ther assumption that it was safe. Best not to make assumptions...

Also, for anyone thinking of trying this, bear in mind I've only tried with ONE speed control... I have absolutely NO idea if it will work with any others.

I'm now of the belief that it's probably best to NOT run that much voltage into the receiver/speedo. I would prefer to run a booster, but they';re a bot difficult to get right now. I AM thinking of using a couple of diodes to drop the voltage of the LiPOs for now until I can get a booster.
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Old 03-16-2009, 09:04 AM   #836
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We (Colorado On Road RC Club)just finished our annual Carpet Challenge.
SMC was kind enough to donate 1s batteries for a Demo class of 1/12 scale 1s lipos with 10.5 motors.


We had almost all speedos in the class. We got some die hard round cell users say they would not go back.


Thank you SMC, we have some converts

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Old 03-16-2009, 06:07 PM   #837
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I've edited my previous post by adding some diodes to the parts list and updating the schematic... anyone who was interested in trying this should follow the updated directions.

The diodes reduce the input voltage to the receiver and ESC by around 1.4 volts.

I just want to mention something else... I thought I could make good solder joints in small spaces... Twice yesterday the lead came off my little E-Flite battery and my car switched off during a run. I started further back on the grid in the main because of this, and I DNF'd in the main. I've been soldering for the better part of forty years, and this was a humbling experience. Thankfully the little celll didn't short out when the wire came disconnected, but I'm starting to think this whole thing was an exercise in futility...
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Old 03-17-2009, 12:30 PM   #838
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I was a VERY pleased participant in the Colorado Carpet Challenge 1s demo class. I ran the SMC pack (THANKS DANNY!!) in the car through a GTB 4-cell esc and a Spektrum 3500 micro with one of the voltage boosters from Hobby King. The class was spec'd to run 10.5 motors. The car ran flawlessly, power-wise, and I couldn't have been happier. ESC observations:

The Novak GTB is truly plug-n-play with this combo. Too bad it's been discontinued by Novak. I ran the voltage booster to keep voltage to the servo up but will run a back-to-back experiment to determine if this gained me anything or not.

The Tekin RS seemed to work well with a switch between the esc and receiver as described above by CeeDee. I have NO earthly idea why this should be necessary and nobody was able to satisfactorily explain this to me, but one can't argue with the results.

All three guys who ran LRP/Nosram esc's had problems with the battery feeling like it was "dumping" after 2 or 3 minutes. Sounds like this is something that might be cured with a workaround similar to that with the Tekin.

I will be trying this combo with one of my KO BMC brushless speedos soon. I'm hoping it's plug-and-play like my Novak was.

I found that for the 1s-10.5 that pink rear and double pink fronts worked very nicely once I got some other issues with the car sorted out.

I was putting 2200-2300mah back into the packs after each heat so a single pack would probably work if you have an hour between rounds. Using my GFX/LiPo it took about 45 minutes to complete the charge using the CC/CV method at 4000 (1C) charge rate. I was actually using two packs and alternating them so I could have one charging while I had the "ready" pack in the car so I could complete tuning, etc. with the pack in-situ.

I REALLY liked the lighter feel of the car compared to my 4-cell NiMH rides. The car feels like a sportscar compared to a garbage truck and impacts were FAR less brutal with the reduced mass.

JP and I talked about this class a fair bit as we trudged our way back across Wyoming. We are VERY hesitant to fool around with proposing alternate specs for our 1/12 Stock class, but I think a 1s class that might find legs here would be an open class where we spec the SMC 1s pack and the ROAR 1/12 dimensions re: track width, etc in place but leave everything else (motor, weight, etc) wide open and see what we find. I'd be delighted with this as it would give me an opportunity to test my Mongoose 380 sensored system in a competitive environment.
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Old 03-17-2009, 12:59 PM   #839
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Originally Posted by Scottrik View Post
The Novak GTB is truly plug-n-play with this combo. Too bad it's been discontinued by Novak. I ran the voltage booster to keep voltage to the servo up but will run a back-to-back experiment to determine if this gained me anything or not.
My buddy Alex (the VOICE of 360 Speedway) has been running the 1S with the GTB straight up and mentioned he wants to try an rx pack or booster... hje also feels there might be some loss of servo authority late in the run and wants to see if he can notice a difference. Please let us know what you find when you do the comparison...

Quote:
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The Tekin RS seemed to work well with a switch between the esc and receiver as described above by CeeDee. I have NO earthly idea why this should be necessary and nobody was able to satisfactorily explain this to me, but one can't argue with the results.

All three guys who ran LRP/Nosram esc's had problems with the battery feeling like it was "dumping" after 2 or 3 minutes. Sounds like this is something that might be cured with a workaround similar to that with the Tekin.
I must have missed that post... gonna go back and find it... Tekin has mentioned that they're on the verge of releasing a new revision to the RS firmware that could let us run our RS's without any rx pack or booster... I'm running 1.89 with my own unique "booster cell" setup to get the voltage up for the electronics... I posted details a couple of days ago.

Quote:
Originally Posted by Scottrik View Post
I found that for the 1s-10.5 that pink rear and double pink fronts worked very nicely once I got some other issues with the car sorted out.
I ran CRC yellow rear/magenta front this weekend, same exact setup as my 4 cell setup, only backed off a bit on the shock spring collar to let the chassis sit down level. We're running 13.5 with the SMC 3.7 here. Exact same fast lap times for me as with 4 cell/17.5, and exact same best 5 and best 10 times, but MUCH more consistent through the 8 minutes.

Quote:
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I was putting 2200-2300mah back into the packs after each heat so a single pack would probably work if you have an hour between rounds. Using my GFX/LiPo it took about 45 minutes to complete the charge using the CC/CV method at 4000 (1C) charge rate. I was actually using two packs and alternating them so I could have one charging while I had the "ready" pack in the car so I could complete tuning, etc. with the pack in-situ.
I'm noticing it takes quite a while to get the 1S pack topped off between runs... much longer than my 2S packs form touring car. Charger seems to go at 4 amps for a VERY short while then stays in the CV portion forever. Thunder Power 610 charger here... My buddy Alex got topped up much quicker with his Losi LiPO charger... not sure why.

Quote:
Originally Posted by Scottrik View Post
I REALLY liked the lighter feel of the car compared to my 4-cell NiMH rides. The car feels like a sportscar compared to a garbage truck and impacts were FAR less brutal with the reduced mass.
YES... it felt like a fast mod car from 1995... edgy, quick, almost a little nervous feeling, but FUN to drive and easy to make a bunch of quick laps. I wasn't expecting to like it as much as I did...

And YES, I was pretty pleased to see that some UNBELIEVABLY LOUD "smack" sounds I made when the wire came off my "boost cell" caused NO damage...

Quote:
Originally Posted by Scottrik View Post
JP and I talked about this class a fair bit as we trudged our way back across Wyoming. We are VERY hesitant to fool around with proposing alternate specs for our 1/12 Stock class, but I think a 1s class that might find legs here would be an open class where we spec the SMC 1s pack and the ROAR 1/12 dimensions re: track width, etc in place but leave everything else (motor, weight, etc) wide open and see what we find. I'd be delighted with this as it would give me an opportunity to test my Mongoose 380 sensored system in a competitive environment.
I'm really liking the 3.7/13.5 format a LOT, but I think a 3.7 "open" class like you describe would be HELLA fun... And I can also see a 3.7/17.5 class as a VERY approachable entry point for would-be 1/12 drivers who want something a little less intimidating...
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Old 03-17-2009, 02:11 PM   #840
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With the tekin RS, you have to wire in another mini switch off the + and - on the esc into the booster and than the booster into the reciever. Long story short you are suppling the reciever with 5v, and anything else down stream from there, ie servo and transponder. With the tekin you leave the speedo switch off and tuck it away somewhere. Also used the 189 software/profile.
I'm not sure why you need that extra switch... mine seems to work just fine without it. I just unplug the rx pack to turn the car off, and plug it in to turn the car on. ESC switch always off and tucked away. No issues so far. IS this an issue for the booster only? Have you tried it without the extra switch, and just plug in and unplug to turn on and off? I'm not running a true receiver pack, I'm using a single little lipo in series with the SMC pack to boost the voltage, but my circuit is more like a booster setup than an rx pack...

Quote:
Originally Posted by Scottrik View Post
The Tekin RS seemed to work well with a switch between the esc and receiver as described above by CeeDee. I have NO earthly idea why this should be necessary and nobody was able to satisfactorily explain this to me, but one can't argue with the results.

All three guys who ran LRP/Nosram esc's had problems with the battery feeling like it was "dumping" after 2 or 3 minutes. Sounds like this is something that might be cured with a workaround similar to that with the Tekin.
Scottrik...

Your RS didn't work without the extra switch? HAve you triedr just plugging the booster output into the receiver and unplugging to turn on and off? I don't have a booster yet, but no extra switch needed...
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