Oops, sorry... have no help for you at this point

Increase the voltage to the motors but use PWM to limit the speed, the traction should increase. Use better tyres for more grip too, there's no point in increasing torque if you can't transfer the power from the motor to the surface you are driving on. Believe it or not, weight distribution can play a huge part in helping get the power down.

Hi myerson,

No the batteries are 1500 watts each in parallel. Panels are 225 Sharps. I have 43 on roofs.

I may try the tractor base I have.

It is snowing now here in NJ and I tried again and he slide almost off the roof.

Hi Rich,

Tried different setting with PWM.. no success... the biggest problem is the traction.

I need to be careful.. don't want to break the panels.

Were talking batteries not solar panels now, right? Batteries would be measured in amps not watts.... 1500 watts would be around 125ah battery .... assuming we are talking about a 12v battery

If they are decent panels they will be hard wearing, or at least should be.

Throw some decent tyres on that thing and improve grip. Distribute the weight over the drive wheels to get the power to transfer from motor to surface. You could increase the torque but if it can't get the power down it'll sit there spinning it's wheels. If it already spins it's wheels start with weight distribution and tyres. If it doesn't then increase the torque with either better motors or more volts.

I am using 2 of these in parallel.

@jackphillips1953 in this case speed and batteries are not the prime factors. The tractor base will provide better traction. I have both a rover 5 track base and the wild Thumper base, the Thumper base exceed in rough terrain travel with speed and awesome chassis. The rover 5 chassis exceed in rough terrain hill climb, awesome traction's. I say give the tractor chassis a goes .

Those are 1800mah batteries... So they would, (assuming they are charged and in good condition) should drive your wild thumper no problem... As mentioned, your problem is probably traction... Rubber gets hard and looses it's grip as temperature drops so your slipping on the panel's smooth surface... Also as mentioned, tank treads would work better for this...

Thanks.. I do not have another motor controller handy. I will have strip off Thumper.

Rubber is soft because i place outside and start right away.

Is there a way to adjust the spring tension on the suspension?

If were flatter it may get more traction also.