firstrc

My Feedback: (1)

So I got my TsuMamba out today and decided to try out my new lipo batt's.
It ran awesome for about 10 minutes then started acting up.
It would lose all power just like I completely let off the throttle and would just sit unresponsive for 10 seconds. Then it would be fine for a little bit then cut off again. This would happen over and over again untill i finally gave up
Any ideas?
Motor is R.C. Brushless
Radio and electronics are factory.
Battery was true rc 7.4v 2cell 6400mah fully charged. (first use)
Also had a true rc low voltage alarm plugged into the batt. I removed it and the problem was still there.
Nothing else crazy in my set up. I went over the whole car all all seems to be well.
Suggestions please?

ehroof

what brushless system are you running? i dont remember.

firstrc

My Feedback: (1)

Still have the redcat system in it

joeyhatch11

Try and reset your low voltage cutoff again on the ESC. Did you have these problems before using a nimh battery? When you first got the truck, did you have to program the ESC before use?

ehroof

Thats the problem, they are not very reliable, they dont like regular nimh or nicd batteries, they dont like too high of a mah lipo, lol.... They are worse than having a 2nd wife. lol

Its cutting out, then coming back on, either overheating, too much mah for it to handle, etc. etc. etc. I swapped them all to the himoto setup.

firstrc

My Feedback: (1)

I don't think this esc has low voltage cutoff.
Nope never had this problem with any other battery.
No no programing out of the box

firstrc

My Feedback: (1)

Anything I can try?
No way I can swing the cost of a new brushless right now.

Redharris

Try it with the original Battery.....
If it doesnt act up, that will be a clue that the new battery may be pushing to much power through the esc or the motor.(most likely an ESC problem I would guess).
If it DOES act up then you will Know it has nothing to do with the battery. Then you are left with the motor OR the ESC as the problem.

It COULD be that the motor bearings are dry or stiff, or the drivetrain could be Binding somewhere.That would cause the motor to draw more Amps and the ESC might Shut Down due to overheating.
Disassemble the Motor (if its possible) and clean/lube everything. Free up the drive train and lube the axle bearings, then try again.

airoscar

this is interesting, i'd like to stay in tune and see what is really causing the problem.

(i dont think the new battery is pushing to much power through the esc though, because: 1. the battery is 7.2v; 2. he says he can run for ten minutes with no problem, and then the problem happens after that.

maybe the battery is defective, and that it is not actually the 4600mah high current as it is supposed to. my ESC even with the low power cut off switched off, it'd still cut the power if the voltage drops low enough. but then just at that threshold, if u leave it there for a bit, like for ten seconds, the battery valtage comes back up just slightly and exceeds your esc's cut-off threshold, your esc will run the motor again....

Redharris

Airoscar.....Thats a good point you make.....

I guess what I was trying to get at is This.....

When you Change something and incur a Problem, and you are not sure what is Causing the Problem, it is a good idea to revert to what you know worked before, to see if it STILL works.....(Did you damage something that was working fine before?)

By swapping (CAREFULLY AND CAUTIOUSLY) parts back and forth, from Known Good to UNKOWN, we can often deduce the Problem. Or, at least Narrow it Down some.....

Electronic problems can be difficult to solve, because SO many things can go wrong. His problem MIGHT anything from a Cold solder joint to a bad connection or frayed cable to a worn out Motor.

Thats why your trouble shooting technique needs to be methodical and Cautious.
You dont want to miss something Simple,,,,OR damage something ELSE while trying to fix the problem.

firstrc

My Feedback: (1)

Well unfortionately I don't have any orig batts... I sold them to partially pay for the new ones. (money is tight) So that's out. However the last time I ran it with the old batt it ran great for the whole battery charge (25-30 min or so)

I am anal about keeping it nice so it is all in all in excellent shape.... the drive train all turns very freely and doesn't bind up at all. The motor and esc are in like new condition... I never had it wet or even dirty enough that just blowing the dirt off didn't make it look new again.

Just not sure... Maybe esc overheating???

firstrc

My Feedback: (1)

Hmmm. Yeah it ran great for about 10 minutes...
I dont thing the redcat esc has a low voltage cutoff (does it?) so I dont think that could possibly be the problem.
Tha batts are 6400mah (not 4600 ) could it be defective??? yeah I guess so... It is brand new and this was the first use. I will charge up the other new one (I baught 2 of them) and see what happens. I didn't have time to yesterday.

firstrc

My Feedback: (1)

Crap.. sorry for the additional post... just realized there were some other things I didn't answer.....

What did I change since last time it worked great?
- New battery ( Lipo 2 cell 6400mah with deans pre-installed frome trueRc)
- replaced gears in front diff. (whole drivetrain is clean and turns freely and easily - no binding at all)
- had my wheels / tires from my volcano on it (practically the same over all diameter)

What I am thinking I should try,
- charge up the second new battery I have ( I bought 2 and have only tried one due to time constraints) and try it to see if the first one might have been defective.
- maybe try a fan on the esc to cool it ( good idea??? )
- I have no idea after that.

I really can't afford a new brushless system especially considering I have 2 trucks using this system so I would have to replace both.

joeyhatch11

If the Lipo was bad I think you'd know when you plug it in. It probably wouldnt charge right. The mah on the battery wouldnt make any difference. Only if the new battery offer more power (voltage) and the ESC couldn't handle it. I dont know of any brushless systems that dont offer a low-voltage cut off. Even the EZ-Run systems found on Nitrorcx.com offer that. But that shouldnt matter either. I run my micro mamba with no cut off and just watch close when I see a drop in performance. I've been doing this for a better part of a year and all is fine. If your able to run for 10 minutes or so then she shuts off, maybe it's over heating and shutting down. Check your temps at that point and she where she's at. The big mah battery is offering a longer run time and could be getting the ESC too hot.

Lastly, If all else fails, I think it's time for a new ESC. You can get one off Nitrorcx.com or even ebay. You shouldnt need a whole new setup, just a ESC. Also check on Ebay, you can always find a good deal on there.

joeyhatch11

What kind of truck is this? Can you post a link so I can check it out?

Nitrorcx.com has the EZ-Run Brushless system on sale for $89 incase you do need a replacement.

ehroof

first, check the temp of the motor and esc when it starts to cut out and let me know, that EZ run system is not the greatest and will have more problems then the novatech system, I wouldnt reccomend it.

firstrc

My Feedback: (1)

I don't have a temp gauge but I can tell you that after those first 10 min when it started acting up it was VERY hot. Could not hold my fingers on the EEC. The motor was hot but not more than normal ( I don't think)

Doesn't seem low a low voltage cut prob. The low voltage alarm I had pluged in showed the voltage to be between 7.4 and 6.8. Also... No way I could have killed a full charge in 10 minutes right?

Eddie, does the redcat system have low voltage cutoff?

Thanks so far guys... Please keep suggestions coming

ehroof

thats too hot, you need to try using a smaller pinion gear, the esc cant handle the extra power of the new lipo your using and is overheating.

Also, be sure not to run the battery too low, stop using at the first sign of performance drop when your using a lipo

firstrc

My Feedback: (1)

Eddie please see my edit ony prev post I think I must have neen posting at the same time as you LOL
What will the new pinion do for torque and speed ( curious) and should iI try a fan on the esc?

ehroof

I honestly dont know, most esc's are programable but there isnt much info about that esc, even when i was "part" of redcat I didnt have that much info about that esc.

A new pinion will make the motor work less by making it easier to turn but you will loose top end and gain low end power. Smaller pinion=more low end power, larger pinion=more high end speed but less take off and more stress on the engine/esc during acceleration. its the opposite for the spur gears.

firstrc

My Feedback: (1)

okay well I might give a dif pinion and an esc fan a try and see what happens.

Can you recommend a pinion for me?

In the meantime I will try to get full specs on the brushless system to see if it is a programing thing.

I have the second batt charging now (to officially rule out the bad battery possiblility)

ehroof

pede kid has been running that brushless with his truck, I will let him chime in and let you know what pinion he is running and what he has done and found out.

pede_187

I would definitely try a smaller pinion. The mamba uses 0.7 module pitch (I tried 0.6/48p and it stripped the spur out every time). I never ran a lipo but when I would run 10 or 12 cells it would do the exact same thing that you are describing and the esc would basically go into failsafe mode. When I would use a smaller pinion, it would allow me to run longer before it got too hot or went back into failsafe mode (because the motor is demanding less amps from the esc).

firstrc

My Feedback: (1)

Thanks Tom.
So even with the smaller pinion it still eventually went into safe mode.

Tom, Do you know if the esc is programable? And do you think a fan would help?

pede_187

Yes it did but it took longer to go into failsafe mode. When I was having that trouble it would last 4-5 minutes if I was lucky so I think that if you are getting 10 minutes now that you would probably be fine getting a smaller pinion gear.

That I Know of the ESC is not programmable