Just won a R-Net PM90EL!

[steves1977uk]

For £30.45! PM was £25 I needed an all-in-one PM with lighting for my Groove chair which has 6MPH 4-pole AMT motors and lights.

Steve

[Burgerman]

I wonder what would happen or if it will allow you to set max Amps to say 100, and boost current to say 120... I never tried it. It warns you not to do that. Meaning it may allow it...

[steves1977uk]

I'll try and see if it allows it BM!

Steve

[Burgerman]

If it does, and if it actually allows that, test by driving agaist a wall. Monitor M1 and M2 amps inside the PC R-Net software.

Like this, in this case a left turn in place at 0mph to show the REAL motor current required to zero turn. (the 120A PM is almost maxed out at 113A with just 7 in reserve). If you were on grass, it would max out both M1 and M2 and that may be borderline capable of turning, and certainly wouldnt be linear control. So a lower power unit would be inadequate in the stock nose heavy chair. Yet they supply is with a 90A unit and 2 pole motors as stock!

[Irving]

Don't know about the EL variant, but if I was PGDT I'd be looking to reduce my BOM & inventory costs on the PMxxx and one easy way is to make just one version of the controller, make it 120A capable with the smallest # of MOSFETs, (the latest devices can do 400A+ in a single MOSFET now, so could manage with just 8 per motor). Then do current limit setting in firmware, programmed in when you get an order. Print and stick on the appropriate label and bingo, a brand new Sunrise PM90 or Permobil PM120, etc.

It's all marketing driven now anyway...

[Burgerman]

I am sure they do that. But the firmware on the 60, 80, 90, and 120 will likely be different in just a few simple ways. Probably just in that max allowed current.

What that PM diagnostics page does show, is that with 10V you get a little over 100A per motor. So 200+A at 20V and 240+ at 24V stalled.

That means that you are only pulling about 25A at the battery stalled while both motors are taking 110 each. Due to the low motor impedance.

2 pole motors take MORE battery amps, at the same 120A stalled motor. And thats becuase they are higher impedance and need higher voltage to see that same 120A stall current. So the 4 pole motors are more efficient.

As you speed up, the battery current rises at the same motor current, and again the 4 pole uses less battery power up to a higher speed before 100% pulsewidth is needed to supply 120A.