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-   -   Tamiya mini cooper (https://www.rctech.net/forum/electric-road/20068-tamiya-mini-cooper.html)

mekios 11-25-2013 02:16 AM


Originally Posted by sosidge (Post 12755729)
It sounds like a bad pack to me. Have you been balance charging? How long do you suppose they may have been sitting on the shop shelf before you bought them?

Charging within 40 minutes shows that the packs are no way near empty when the car stops running, probably less than 2000mAh has been taken out. The LiPo's may well be struggling to give the voltage your ESC and receiver is expecting when they are under load, even though they seem OK voltage when resting.

I'd also check the connectors (make sure they have a good contact, standard Tamiya plugs are always poor and should be replaced), and the servo you might be using (some cheap servos and the Savox brand in particular are very inefficient and cause heavy current draw). Also, check your radio, Spektrum brand is very sensitive to low voltage (personally I would avoid their technology like the plague!)

My general experience with very low capacity cheap packs is that they are not really up to racing, there is a dip in quality at the bottom end of the market.

I bought them the day they arrived at the shop, cuz they were a back order straight from Absima/Germany.
Connection is a brand new Deans (original) plug and all wires are 14awg. My radio is a Sanwa/Airtronics M11X and the servo is actually a cheap Power HD.
What i found after posting here is traces of water (stains) on the car. Could it be that water entered the speedo? But it's working fine before dying and then it works again. I mean if it was a short circuit we would see firecrackers! :)
The car is performing flawlessly while it works. I got good power, braking, reverse, doing gonuts and stuff. It's really good. Then suddenly dies.

marcos graveyar 11-25-2013 04:33 AM


Originally Posted by Boons (Post 12755596)
Hello Sir!

Which ones do you use?

I use the Tech Racing ones, MR0090 and MR0100.

Granpa 11-25-2013 08:29 AM


Originally Posted by mekios (Post 12755737)
I bought them the day they arrived at the shop, cuz they were a back order straight from Absima/Germany.
Connection is a brand new Deans (original) plug and all wires are 14awg. My radio is a Sanwa/Airtronics M11X and the servo is actually a cheap Power HD.
What i found after posting here is traces of water (stains) on the car. Could it be that water entered the speedo? But it's working fine before dying and then it works again. I mean if it was a short circuit we would see firecrackers! :)
The car is performing flawlessly while it works. I got good power, braking, reverse, doing gonuts and stuff. It's really good. Then suddenly dies.

Unfortunately, for most of us who aren't electronically gifted, the best way do trace out problems like these is to switch out components. It seems to me tho, that a battery problem wouldn't manifest itself with the symptoms you describe. If I were to guess, it's probably your esc. Will not argue with those who think otherwise.

I've seen situations where the problem was the receiver. There was one situation where switching models in the Tx cleared up the problem. Don't ask, I don't know the answer to that. All of us who have been around R/C for awhile have had some weird electronic problems.

KA2AEV 11-25-2013 02:02 PM

There is definatly something going on in the Power area of your car
whether its a bad battery pack or a short someplace in either the servo/esc
area
If you have access to another battery, not your Buds because you said previously
that he is developing the same symptoms, try swaping batteries and run if you see that
the problem is not there, then that was your trouble, but if it still exists
and wait
You say that you have water in your car???
Where are you running this and how much water are you running thru?
You could be getting moisture into either the Motor/ESC or the Servo that
is causing a short condition which would drain your batteries faster giving you the
LOV Cutoff.
I would start with a different battery and move onto the different components that
I listed above one by one going after the ESC like Granpa said above
And I would really keep the car out of water!!!

mekios 11-25-2013 03:13 PM

First of all, thank you all for your answers. You got a nice thread here, lot's of info!

To get things straight.:
-battery comes out at 7.9 (have 2 packs of them), so nothing drains them
-speedo is TEU 105BK
-speedo is flashing red (not mentioned in the manual what this stands for,LVC was my guess)
-there is steering even after "cut off"
-car was not supposed to run in water, i ran the car in my basement-parking-area which had some hidden puddles obviously. Not much, just stains of water on the chassis. The car will be racing on carpet track from now on (that's what it was bought for)
-actually both cars ran in the same basement. Could be coincidence that both of them run into water?

monkeyracing 11-25-2013 03:22 PM

If two cars are exhibiting the same symptoms, then the problem lies in a common area between the two cars. Same speedo, same batteries. These are the two commonalities we know about. Are they using the same type of receiver?

First thing to try is a different type of battery, owned/charged/maintained by someone else. If the same thing happens, then it's not your battery.

If you're running a power hungry servo (Blue Bird, Savox, etc) that could be causing "brown outs" where the ESC temporarily shuts down, due to a sudden voltage drop. Spektrum receivers are prone to this when combined with a weak BEC circuit like that found in Tamiya ESCs. The way to test this is either swap out the servo for a cheap standard model (like a Futaba S3003) or attach a "glitch buster" capacitor to the rx to smooth out the voltage. If the problem remains, then it's not the servo.

I completely trust Spektrum, btw. They make really good stuff, but it is sensitive to voltage drop outs.

So, if you've made it this far and all else is equal, you're left with (in order of descending likelihood)

- low voltage cutoff being set wrong on both ESCs
- improper charging
- two bad batteries

sosidge 11-25-2013 10:49 PM


Originally Posted by mekios (Post 12757659)
-actually both cars ran in the same basement. Could be coincidence that both of them run into water?

I suspect in that case that it is the unexpected water. Make sure the car is kept in a nice warm place until your next race it to help all that water evaporate out of the electrics. If you still have problems on the dry carpet track, report back. Water and electrics don't mix.

monkeyracing 11-25-2013 11:41 PM

Ah. Looks like posted pretty close to the same time. Yes. Water bad.

Boons 11-26-2013 01:30 AM

Regarding servos, I've just ordered a low profile Futaba s9551 digital type (same as the one on the M05 on RC Mini.net:cool:) for my M05 and am now concerned about browing out after reading the above posts.

My car is running the Tamiya TEU 105BK esc, kit silvercan, nimh cells and Core Code TX & RX.

Should I be concerned, or a case of just trying it?!

Cheers

Boons

sosidge 11-26-2013 01:41 AM


Originally Posted by Boons (Post 12759018)
Regarding servos, I've just ordered a low profile Futaba s9551 digital type (same as the one on the M05 on RC Mini.net:cool:) for my M05 and am now concerned about browing out after reading the above posts.

My car is running the Tamiya TEU 105BK esc, kit silvercan, nimh cells and Core Code TX & RX.

Should I be concerned, or a case of just trying it?!

Cheers

Boons

Futaba is top quality, as good as you'll get. You'll have no problems whatsoever with it.

The NiMH and the Core radio are more likely to cause problems, but as long as they are working reliably for you now, they should stay reliable after the servo change.

Boons 11-26-2013 01:51 AM


Originally Posted by sosidge (Post 12759028)
Futaba is top quality, as good as you'll get. You'll have no problems whatsoever with it.

The NiMH and the Core radio are more likely to cause problems, but as long as they are working reliably for you now, they should stay reliable after the servo change.

Brilliant thank you, that has put my mind at rest!

Boons 11-26-2013 01:55 AM

I've received my new hop up front upper arms for my M05, I'll be fitting the -1 degree items later.

My logic is telling me that in doing this, the steering toe out will be decreased? I know it's a case a re adjustment on the steering arms, but am I correct in assuming that?

Cheers

Phoenix82 11-26-2013 02:23 PM

Hey guys, if anybody is looking for a M06 Pro/orca combo. comes with MX6 body and NIP Civic Type R body, I have one for sale.

Nick K

mekios 11-27-2013 08:47 AM

Hey guys i am back

Been doing some testing and i found that there is no problem with a Nimh pack but the problem still occurs on other brand Lipo's (reedy ones that i am using on my competition buggy).
So i am guessing that there is an overcurrent problem that kicks protection in.
I have to mention that i rewired everything (both mine and my buddy's) to 14 awg cable and soldered motor directly to the speedo, so we don't have those awefull bullets. Could this decrease in resistance cause overcurrent issues?

I think there might be a resetable fuse in the speedo that braks the circuit when power exeeds a limit of Amperes. So i got 2 options. Either reinstall the bullets or deans or som sort of connector to increase resistance. Or try to find the fuse in the speedo board and bypass it...
After all if it doesn't work with lipos i am gonna ditch it and buy something aftermarket.

KA2AEV 11-27-2013 10:06 AM


Originally Posted by mekios (Post 12762941)
Hey guys i am back

Been doing some testing and i found that there is no problem with a Nimh pack but the problem still occurs on other brand Lipo's (reedy ones that i am using on my competition buggy).
So i am guessing that there is an overcurrent problem that kicks protection in.
I have to mention that i rewired everything (both mine and my buddy's) to 14 awg cable and soldered motor directly to the speedo, so we don't have those awefull bullets. Could this decrease in resistance cause overcurrent issues?

I think there might be a resetable fuse in the speedo that braks the circuit when power exeeds a limit of Amperes. So i got 2 options. Either reinstall the bullets or deans or som sort of connector to increase resistance. Or try to find the fuse in the speedo board and bypass it...
After all if it doesn't work with lipos i am gonna ditch it and buy something aftermarket.


I really doubt that you are dealing with an overcurrent issue like you think.
How is your soldering skills?
If you have a cold solder joint someplace in there that could be the cause
of all your ailments.
Did you do the same modifications to your Buds car too?
Any other modifications that your not telling us about, like upping the gearing
maybe???


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