Sorry this took so long. I had to try a few things before reporting back.
I have connected a pair of Nidec TA600DC fans in series. These fans are
nominal 48 Volts at .42 amp. Spec sheet says they will run between 25 and 75
volts. I had mentioned before I wanted to connect them serially because 96
volts is close to my pack voltage.
Well as it has been said before. DC Brushless motors don't work well
serially connected. However, they can be made to work. The only question
will be is if you're happy with it. As Lee said, one way to operate the fans
is by hooking up the set on split off sections of the pack.
Another way would be to add a resistor to the fan to lower the voltage to
the fan. These fans can operate as high as 75 volts. In my case that means
a 35 volt drop. Connecting a 130 ohm resistor to one of the fans allows it
to run at 75 volts. The resistor is dissipating 35 volts at .27 amp or 9.45
watts. The fan draws 20 watts. Total about 30 watts per fan. I plan on 4
fans. So that is 120 watts with 40 watts being given off as heat (maybe I
could mount those resistors in the cabin for the winter?).
Adding capacitors is yet another way that this can be done. The best would
be capacitors large enough to drive the fans. I didn't have capacitors that
big. Just the same, I came up with two variations on using capacitors. I
started off with a 470mf 200V electrolytes. Each of the two fans has the
capacitor parrallel to the motor leads (make sure the polarity is correct
Positive on positive. Negative on negative.). One fan is connected to the
hot side of the pack (positive lead). The other fan is connected to the
ground side of the pack (negative lead).
The first variation. If I connect a resistor between the two fans, the fans
will level out at 35 volts. (positive fan cap lead connects to resistor
which connects to negative fan cap lead. (see drawing
http://www.lecblue.com/fans.jpg ). This leaves 40 volts going through the
resistor. For a 100 ohm resistor this is about .4 amps. Two fans would use
44 watts (110 volts x .4 amps). (88 watts for all four fans with about 32 of
those watts creating just heat.).
The second variation. If I put a lower resistor, the fans settle into their
own happy spot. With a 50 ohm resistor, one fan runs at 24 volts the other
at 72 volts. This leaves only 14 volts going through the resistor. At about
2.8 amp. Two fans would use 30.8 watts. (62 watts for all four fans with
about 8 of those watts creating heat.) I will probably use this hook up.
Operational notes:
Voltage = fan speed. The pair of fans running at different volts are running
at different speeds. I think the 24/72 pair is pushing more air than the
35/35 pair.
Capacitor value seemed to not matter (cap voltage needs to be higher than
pack voltage). 1mf 250V metalized film (non polarized) cap worked just as
well as the 470mf electrolyte cap.
I am happy with the fans. Now, on to putting them into the car.
Don
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
I have connected a pair of Nidec TA600DC fans in series. These fans are
nominal 48 Volts at .42 amp. Spec sheet says they will run between 25 and 75
volts. I had mentioned before I wanted to connect them serially because 96
volts is close to my pack voltage.
Well as it has been said before. DC Brushless motors don't work well
serially connected. However, they can be made to work. The only question
will be is if you're happy with it. As Lee said, one way to operate the fans
is by hooking up the set on split off sections of the pack.
Another way would be to add a resistor to the fan to lower the voltage to
the fan. These fans can operate as high as 75 volts. In my case that means
a 35 volt drop. Connecting a 130 ohm resistor to one of the fans allows it
to run at 75 volts. The resistor is dissipating 35 volts at .27 amp or 9.45
watts. The fan draws 20 watts. Total about 30 watts per fan. I plan on 4
fans. So that is 120 watts with 40 watts being given off as heat (maybe I
could mount those resistors in the cabin for the winter?).
Adding capacitors is yet another way that this can be done. The best would
be capacitors large enough to drive the fans. I didn't have capacitors that
big. Just the same, I came up with two variations on using capacitors. I
started off with a 470mf 200V electrolytes. Each of the two fans has the
capacitor parrallel to the motor leads (make sure the polarity is correct
Positive on positive. Negative on negative.). One fan is connected to the
hot side of the pack (positive lead). The other fan is connected to the
ground side of the pack (negative lead).
The first variation. If I connect a resistor between the two fans, the fans
will level out at 35 volts. (positive fan cap lead connects to resistor
which connects to negative fan cap lead. (see drawing
http://www.lecblue.com/fans.jpg ). This leaves 40 volts going through the
resistor. For a 100 ohm resistor this is about .4 amps. Two fans would use
44 watts (110 volts x .4 amps). (88 watts for all four fans with about 32 of
those watts creating just heat.).
The second variation. If I put a lower resistor, the fans settle into their
own happy spot. With a 50 ohm resistor, one fan runs at 24 volts the other
at 72 volts. This leaves only 14 volts going through the resistor. At about
2.8 amp. Two fans would use 30.8 watts. (62 watts for all four fans with
about 8 of those watts creating heat.) I will probably use this hook up.
Operational notes:
Voltage = fan speed. The pair of fans running at different volts are running
at different speeds. I think the 24/72 pair is pushing more air than the
35/35 pair.
Capacitor value seemed to not matter (cap voltage needs to be higher than
pack voltage). 1mf 250V metalized film (non polarized) cap worked just as
well as the 470mf electrolyte cap.
I am happy with the fans. Now, on to putting them into the car.
Don
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
