Maker Pro
Maker Pro

Solar cell power

colum

Jul 25, 2013
175
Joined
Jul 25, 2013
Messages
175
I have 2 x 7v Solar cells in driving a small 6v DC motor at 7v it will not start until I push the shaft and then it runs with good speed and powers a music box easily
Without using a relay capacitor booster is there anyway a capacitor would work on a 2 wire DC motor or is there another way...Thanks..colum
 

bertus

Moderator
Nov 8, 2019
3,302
Joined
Nov 8, 2019
Messages
3,302
Hello,

It sounds as if the solar cells can not manage the inrush current of the motor.
The inrush current can be much higher as the running current.
From the wiki:
Motors
When an electric motor, AC or DC, is first energized, the rotor is not moving, and a current equivalent to the stalled current will flow, reducing as the motor picks up speed and develops a back EMF to oppose the supply. AC induction motors behave as transformers with a shorted secondary until the rotor begins to move, while brushed motors present essentially the winding resistance. The duration of the starting transient is less if the mechanical load on the motor is relieved until it has picked up speed.

For high-power motors, the winding configuration may be changed (wye at start and then delta) during start-up to reduce the current drawn.

https://en.wikipedia.org/wiki/Inrush_current

bertus
 

Audioguru

Sep 24, 2016
3,656
Joined
Sep 24, 2016
Messages
3,656
Are your soar cells connected in series (wrong) or in parallel (correct)?
Are the solar cells in bright sunlight (correct) or in the shade (wrong)?
 

colum

Jul 25, 2013
175
Joined
Jul 25, 2013
Messages
175
Hello,

It sounds as if the solar cells can not manage the inrush current of the motor.
The inrush current can be much higher as the running current.
From the wiki:
Motors
When an electric motor, AC or DC, is first energized, the rotor is not moving, and a current equivalent to the stalled current will flow, reducing as the motor picks up speed and develops a back EMF to oppose the supply. AC induction motors behave as transformers with a shorted secondary until the rotor begins to move, while brushed motors present essentially the winding resistance. The duration of the starting transient is less if the mechanical load on the motor is relieved until it has picked up speed.

For high-power motors, the winding configuration may be changed (wye at start and then delta) during start-up to reduce the current drawn.

https://en.wikipedia.org/wiki/Inrush_current

bertus
 

colum

Jul 25, 2013
175
Joined
Jul 25, 2013
Messages
175
Thanks bertus its back to the drawing board...colum
 

Bluejets

Oct 5, 2014
6,901
Joined
Oct 5, 2014
Messages
6,901
Thanks bertus its back to the drawing board...colum

An option here might be to run the motor from say 4 or 5 NiMh rechargable cells in series and then use the panels in series to charge the battery.
Some form of regulator or isolating diode may be necessary betweem the panel and battery.
 

colum

Jul 25, 2013
175
Joined
Jul 25, 2013
Messages
175
Thanks Bluejets Thats probably my best option and one I would never have thought of...colum
 

colum

Jul 25, 2013
175
Joined
Jul 25, 2013
Messages
175
The battery system will not work, the voltage applied to the motor goes to zero on startup
I think it will need a timer and relay to give the rechargable battery time to powerup...colum
 
Top