[lucas]

I can't find a real datasheet for these motors.
Looks like the current setting is to high for series connection.
It would be better to use the half-coil connection and keep the 1.5Amp current setting, this will also increase the torque at higher speeds .

Using slow decay should reduce the motor heat a bit, the current ripple is lower and this reduces the losses in the motor.

Hope this helps,
Luc.

[bogdanalex]

thank you very much!
Not finding a proper datasheet bother me a lot too....I looked everywhere....but I'll certainly try those changes you said.
By slow decay what do you mean? I have 20% - 40% - 60% and 80% setting

[lucas]

Sorry for the late reply.

The motor heat is caused by the incorrect current setting for the series connection,
20% decay will generate less heat than 80% but this will be marginal.
Did you try the half coil connection as recommended?
This is the best configuration considering the relatively low 28V supply.

[bogdanalex]

I've not tried the half coil connection yet but I did lowered the current at aprox 1.1A and it works. Although it's only 0.4A lower the motors are dead cold and still have a reasonable torque.
My PSU can go as far as 36V. Should I push it beyond 28V or leave it there if it does not skip steps ?
I'll also try the half coil connection when some connectors that I've ordered will arrive. Now I have to re-solder the motor wires which is not quite convenient.

[James Newton]

Great to hear it's working. Higher voltage gives higher speed (but may cause mid band resonance). If it works, I wouldn't change it. Good motor connections are critical. A motor lead coming loose while running can fry a driver.