LRP Sphere Problem

chris_exeter · #1 22-01-2007

Hi guys, I had a problem when practising with my car last weekend with what I assume was a speed controller problem.

I ran the car for about 15-20 minutes using 2 batteries. Halfway through the second battery the car just died. The steering servo would still work but there was no throttle. To start with I would get a small crawl for about 5 seconds and then no throttle, after a while there was nothing at all.

When I gave it some throttle, the green led on the speedo would come on which I assume means its trying to send power to the motor.

I checked all wires and they were all definitely connected.

I assumed I had a fault with the speedo. I just went to check the car this evening and it's all working fine again!

It wasn't a battery issue as the same battery used just worked in the car now with no further charging.

Has anyone encountered this problem before and does anyone know of any ideas to prevent it in the future?

My guess (which is rather weak due to being a newbie) was that the speedo cut out power to the motor for a precaution - I haven't attached the heat resistor to the speedo yet so it gets quite hot (only a 1 star motor though so I thought no resistor would be relatively safe).

Is this possible? This was the first time I had run the car for such a long period (previously the most was a 5 minute race).

I used to race 15 years ago, but have very little knowledge on brushless systems. Obviously I don't want to blow up a £200 setup.

Am I safe to run for 20 minutes solid?

Thanks in advance guys

jimmy · #2 22-01-2007

sounds like a thermal cutoff to me also. What car is it? You can overheat any brushless, doesn't really matter what wind it is - it still needs the right gearing and cool air running over it etc etc..
They do need gearing lower than normal brushed motors.

The other possibility maybe is that the cells went below a certain level and the ESC cut out to help protect the cells.. I think this is a setting for LiPo packs, and I've no experience of it, but just thought I'd throw that one out there too!

PaulRotheram · #3 22-01-2007

Sounds like you thermalled the system, Basically meaning it got quite hot and the ESC shut the system down - a self protecting mechanism.

snap jimmy!

mark christopher · #4 22-01-2007

must be thermal if you ran two packs through it and it cut on second

chris_exeter · #5 23-01-2007

Thanks guys, yeah I figured the same. I think I'll stick to one battery pack sessions from now on just to be safe. I'd be gutted to blow it so soon!

Rob · #6 23-01-2007

Are you running the heatsink on it and a power cap, that will help with the heat.

chris_exeter · #7 24-01-2007

Please excuse my stupidity, but what's a power cap?

(I fitted the heatsink tonight

)

Ron Burgundy · #8 24-01-2007

I dont know about you guys but once you thermal an LRP SPhere (the only ones I have had experience with) its basically a throw away job.. It will do it again and again and again..

Rob · #9 24-01-2007

It's an external capacitor on the speedo, not sure the the normal sphere comes witgh one as standard or not. It was definatly a thermal problem though if you were doing 15-20 minute runs without a heatsink. I'd say maximum run should be 10 mins then let evrything cool down for a short whille.

LiamD · #10 24-01-2007

Quote:

Originally Posted by Ron Burgundy

I dont know about you guys but once you thermal an LRP SPhere (the only ones I have had experience with) its basically a throw away job.. It will do it again and again and again..

Erm, strange!

Maybe it's doing it for a reason.

Roll on 2nd April, sintered rotors...