Permanent Magnet DC Motor wiring question

Mark Hartford
11 Posts
Jan 28, 2009 01:09 pm
Permanent Magnet DC Motor wiring question

I now have my DC motor hooked up properly to my batteries.  My DC motor is run by pedaling an exercise bike.  I am using a 15A solar controller.  When I pedal I get an amp or 2 showing on my amp meter I hooked up between my motor and controller.  My solar controller also shows it charging.  When I turn on my inverter hooked up to the batteries for the purpose of running a light everything works great.  Light is on, pedaling continues at same resistance, light is bright.  All of a sudden my DC motor resistance jumps way up and the bike is hard to pedal.  If I turn off the inverter to the light the pedaling goes back to normal as stated above.  The resistance feels very similar to when I had the amp meter hooked up incorrectly and set up a closed loop between the motor and the meter.

Any ideas as to why the resistance jumps up under these conditions?  Any way to corrected it if it is a problem?  Is it possible that the controller is shutting off the amps to the battery and creating a closed loop back to the motor?

TIA for help and advice.

Newbie Mark


 
 
John Hassell
28 Posts
Jan 28, 2009 02:23 pm
Re: Permanent Magnet DC Motor wiring question

Mark,

send me a drawing of how you have everything connected (wiring diagram). Maybe I can answer your question.

John
 
 
Ken Hall
351 Posts
Jan 28, 2009 03:47 pm
Re: Permanent Magnet DC Motor wiring question

If I understand your post correctly, you are probably pedaling the bike and trickle charging a full battery (how big?) at 1-2 amps. You then turn on the inverter with light bulb (how many watts ?).  Sometime later, the pedaling resistance jumps.   Does the amp meter jump at the same time ?

I think your inverter/bulb are initially running off of the battery, while you are seeing the trickle charge load.  When the battery voltage drops down below “full”, your charge controller is kicking from “trickle charge” to “bulk charge”, so you are attempting to run the light bulb/inverter and charge the battery simultaneously.

If you want to test this, try running the battery down a ways with the inverter/bulb.  Then shut it off and start pedaling.  See if you get more resistance and higher amp readings than your current 1-2.
 
 
Thomas Allen Schmidt
679 Posts
Jan 28, 2009 08:46 pm
Re: Permanent Magnet DC Motor wiring question

I second Mr. Halls assessment.
Certain wind genny's can be turned off simply by putting a switch in series with - and +, effectively "locking" the rotor. Of course the batteries have to be disconected first.

PV modules will put out closer to short circuit amperage when powering a large load as opposed to just recharging batteries.

This reminds me of that story about the guy who, from a young age, picked up his young calf every day, and as his calf grew, the man was able to pick up his full grown cow. Believe it or not!
 
 
Mark Hartford
11 Posts
Jan 29, 2009 01:19 pm
Re: Permanent Magnet DC Motor wiring question

John, how do I send a jpeg of the wiring diagram?  I can also save it as a PDF file.  Mark
 
 
John Hassell
28 Posts
Jan 29, 2009 01:48 pm
Re: Permanent Magnet DC Motor wiring question

Mark,

email to: johnwhass @ aol.com. A jpg or pdf is OK.

John
 
 
Mark Hartford
11 Posts
Jan 29, 2009 05:38 pm
Re: Permanent Magnet DC Motor wiring question

>>If I understand your post correctly, you are probably pedaling the bike and trickle charging a full battery (how big?) at 1-2 amps. You then turn on the inverter with light bulb (how many watts ?).  Sometime later, the pedaling resistance jumps.   Does the amp meter jump at the same time ?<<

KEN, HERE ARE THE SPECIFICS:
 I have 2, 12 volt deep cycle batteries hooked up to act as one 12 volt battery (negative to negative, positive to positive).  3ach 12v battery: 105 AH @20 hrs.; min. 25 @amps 185.  I have my positive and negative wires from the controller hooked to the same positive and negative posts on the batteries as I do the converter.  I have the positive for each hooked up to battery A and the negative for each hooked up to battery B.  I have a 60 watt light hooked up to inverter. My inverter is 1500w.  The amp meter jumped when the pedaling resistance jumped.  My load light on the controller is on even though the light is not on.  The load light goes off when the easy pedaling starts.

>>I think your inverter/bulb are initially running off of the battery, while you are seeing the trickle charge load.  When the battery voltage drops down below “full”, your charge controller is kicking from “trickle charge” to “bulk charge”, so you are attempting to run the light bulb/inverter and charge the battery simultaneously.<<

Would it change this if I hooked the controller to the opposite posts (still neg. to neg. and pos. to pos.) as I have the inverter hooked up?  I hope that made sense!


>>If you want to test this, try running the battery down a ways with the inverter/bulb.  Then shut it off and start pedaling.  See if you get more resistance and higher amp readings than your current 1-2.<<

Resistance remains light after turning off the light.

Mark
 
 
Ken Hall
351 Posts
Jan 31, 2009 02:02 am
Re: Permanent Magnet DC Motor wiring question

Mark:

You probably didn't run the battery down far enough.  You have a much bigger battery than I expected.

But the bottom line here is that you really should not be trying to use a solar charge controller on a generator.  A solar charge controller is made for a passive source like PV, not an active source such as a wind (or pedal powered) generator.

I would take it out, and install a blocking diode.
Look for a wind generator blocking diode in the 40-50 amp range.

Ken
 
 

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