Speed kills. The gear ratio of 6:1 is too low, significantly dropping
the amount of torque to the drive shaft. At that ratio, the tank will
have problems starting from a dead stop, climbing up things and turning.
In all those cases, the EVs will bog down, draw excessive current and
basically suck your batteries to the point of permanent damage. Whoever
picked that ratio probably thought they'd be zipping around at
high-speed, but didn't consider the downsides.
You should increase the gear ratio to at least 9:1 (which has worked
well for many of our tanks). That will significantly improve starting
performance from a dead-stop, climbing and turning performance, while
being less abusive to your batteries.
Beveling the treads would also help (somewhat) in a turn, but the big
win is from changing the drive ratio.
Frank P.
On 1/5/2011 12:30 PM, HV wrote:
1) Gear ratio: 6:1
2) Drive wheel diam: 4.25 inch
3) Speed control: Robot Solutions, 160 A (I think)
4) Wire gauge: 10 AWG
5) Motor age: Don't know
And the treads are square, not beveled.
Keep in mind, I'm not the builder of the tank, nor was the previous
owner, so I'm just finding out what its quirks are. The ESC appears to
be similar or the same as the current Robot Solutions 160 Amp product,
but I haven't yet verified if it's exactly the same.
On Jan 5, 10:36 am, Frank Pittelli<[email protected]> wrote:
Yes, we ran some of tanks on EVs at 12v, at heavier weights, so let's
explore all the parameters to help diagnose the problem:
1) What gear ratio are you using between the motors and drive shaft?
2) What's the diameter of your friction drive wheels?
3) What type of speed control, if any, are you using?
4) What size wiring runs between the batteries and the motors?
5) How old are the EVs?
Frank P.
On 1/5/2011 10:22 AM, HV wrote:
Yeah, I'm definitely short of torque, but I had the impression that
others were able to run EVW's at 12V OK. Probably not the case eh?
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