Car losing power with Trakpower Lipos

[carlin]

Hi Guys,

Wonder if anyone can help me.

I'm currently running the following

Associated B44
Novak GTB with 4.5 motor Brushless
Trakpower 4800Mah
Ko Propo 2413ICS
PT

The problems i'm getting after 3-4 mins running the car slows right down has no power at all. It doesnt shut off all it does is goes at 1MPh then after few seconds the power is back.

I have checked the temps on my motor and that is running at 70c but when i checked my Lipos they was very warm and temp at 52.3C so they was getting warm.
Someone mentioned to me could it be the thermal cut off but the motor isnt getting hot.
The only thing i could think off is the lipos are knackered i have only had them 1month only been run about 5-6times and everytime run them i got this problem. When i run nicads the car is fine no problems at all.
Thought was the motor taking to much voltage from the lipos but how do you know if its that or what, it's just getting abit confusing now as i'm not expert on this gone bit further than what i know

Hope someone can help me out really spoiling my racing now

[mark christopher]

have you got lipo mode on or off on your speedo?
if on try it off.
lipo would not cut then come back, are all your connectors good?
are you on spektrum? is that shutting down?

[Cockerill]

Is the fan on the speedo working? It sounds like it's the speedo getting too hot and thermal cut-out kicking in.

Just out of interest, why do you need a 4.5 with lipo, that must be stupidly quick?

[carlin]

Originally Posted by mark christopher

have you got lipo mode on or off on your speedo?
if on try it off.
lipo would not cut then come back, are all your connectors good?
are you on spektrum? is that shutting down?

Hi Mark,

How do i know if the Lipo cut off is on or off it I'm not sure on that question.
All connectors are good condition.
I'm running 40Mhz no problems from that side at all.

[carlin]

Originally Posted by Cockerill

Is the fan on the speedo working? It sounds like it's the speedo getting too hot and thermal cut-out kicking in.

Just out of interest, why do you need a 4.5 with lipo, that must be stupidly quick?

Yes the fan is working fine, the speedo temp was at 90c so that werent hot to me, but i might be wrong though.

I had the 4.5 because thats all they had instock and i wasnt waiting ages for 5.5 to come in.
I no whave 5.5 so i might try that, someone just said the motor might be to much for the batteries. Voltage is dropping to low

[Cockerill]

90C is fairly hot for the speedo, especially if the fan is working. I would double check the fan is still working with the shell on, and then look at some cooling holes for the speedo. The speedo shouldn't get that hot, so there maybe something else wrong such as gearing or binding in the drivetrain.

[Rich D]

Originally Posted by carlin

Hi Mark,

How do i know if the Lipo cut off is on or off it I'm not sure on that question.
All connectors are good condition.
I'm running 40Mhz no problems from that side at all.

Refer to your speedo manual - its the low voltage lipo protection. Usually you use it to stop damage to Lipo cells from the voltage dropping too low

[carlin]

Thanks for the reply guys.

I will have look tonyt when i get home and let you know how i get on

Thanks for the quick replies

[mark christopher]

what gearing are you on? are you indoors or out?

[super__dan]

90deg C is 194 deg F!

The GTB is designed to themal at 200deg F, so I bet it's thermalling and losing a deg degrees by to time you temp gun it.

The reason for you thermaling is a 4.5 and Lipo is absolutly madness (no offense) in a buggy. The only way you could make that drivable is by deliberatley running the wrong gearing which will make it run hot. A correctly geared Lipo 4.5 will be like a cruise missile in a straight line.

In a 2wd I run a 7.5R on a tighter track like York on Nimh. I tried Lipo there for the first time tinight and the 8.5 I was running was actually a little bit faster than I wanted

[zipperfoot]

If you have an older model GTB there is no Lipo cut-off. You choose the setting while setting up the speed control. The newer models are the 171o and 1711.

I too had a similar problem as you did but mine was caused by accidentally reversing the negative and positive leads while connecting the battery with bullet connectors. (I plugged it in wrong for only a second). After that the battery acted weird not accepting a full charge. If you did not have the lipo cut-off engaged you may have run the battery below six volts thus damaging the battery. That may explain why it works for a few minutes but no longer. It is not charging completely.