ellisaudio

Gents,

My basic question is... Will 3s or 4s provide longer run time when puttering around the yard in the grass? - Assuming the same net electrical potential from the two batteries (i.e. 3s at 4000mah / 4s at 3000mah ).

I am relatively new to RC, and recently purchased a Losi TEN SCTE. The previous owner used 2s batteries, and they were puffy. I managed to reconfigure the MMP slightly and experienced good success (I think) with 2 x series 2s batteries (4s total). This worked well and I am seeking a long term solution. I don't care if it's ROAR approved.

Related thoughts:

On 4s I have experimented with different pinion gears 20, 16, 13, and think I prefer the 13 in the grass. The 16 is faster on pavement, but I prefer to remain in the grass.

The Casle link for the MMP is terrific . When running 4s I set the forward power to 75% and the punch control to 80%. This keeps traction under control and I haven't broke anything - yet . I am very pleased in this regard. Using these settings, my 4s battery probably performs like a 3s.

After puttering around the yard, motors temps are perhaps 120-130 degrees F. The batteries are barely warm. The Castle ESC doesn't even feel warm - even when the fan gets stuffed with grass. Run time on 4s 4300mah is 22-25 minutes.

I think the 4s setup should push more volts and less amps than a 3s in the same environment provided proper gearing. Therefore, the 4s should run cooler - right?

The top speed in the grass using 13 tooth pinion is perhaps 20mph and this is perfectly fine. On pavement using a 16 tooth pinion, the truck is extremely fast - IMO - even with the MMP limiting.

Thanks in advance for any insight you might have regarding my question above. I welcome any links or further reading.

Sincerely,

Dave

ta_man

iTrader: (168)

If you are setting your max throttle to 75% running 4S, I think you would be better off running 3S and 100% throttle.

That way when you are giving it full throttle, the ESC will turn the FETs on and leave them on for the full power cycle for each phase of the motor. Less switching means higher efficiency.

Of course it is quite possible, the difference will be so small you won't notice it.

theblitzkidd

iTrader: (11)

I think its good to have the higher bat and the throttle set back, then u are not draining the batts as fast by using full capacity of the throttle, just my opinion

ellisaudio

Thanks for reading gents. It appears I am thinking in sane fashion about these matters. I really apprecaite your time and expertise.

I am going to experiment with an 11 tooth pinion this afternoon. I read a very good article about motors conveying that current draw under load DECREASES at higher RPM. Hopefully my run time will be slightly longer and cooler too.

I also experimented with a nifty program called ecalc for aircraft RC guys. It was very useful when trying to understand the dynamics of motors, current and heat.

Dave