Hi, I am a newbie. My goal is to use my trolling motor to power my canoe primarily using solar energy. The Trolling motor draws anywhere from 6-22 amps depending on speed I choose. I own a single 100 Watt solar panel that outputs has these specs:
- Open circuit voltage (Voc): 21.6V
- Max power voltage (Vpm): 18V
- Short circuit current (Isc): 6.11A
- Working current (Iop): 5.55A
- Output Tolerance: ±3%
I have verified the current output to be 5.5 amps in direct sun.
I bought a Victron BlueSolar PWM Controller 20amp, and connected it to my fully charged (resting voltage = 13.1V) brand new 12 V deep cycle battery from Costco that I keep fully charged using my 12amp smart charger for 12V lead acid batteries. Then I connected the solar panel as per manual and lastly I connected my battery to the trolling motor directly. When I turn on the trolling motor to max speed and panel is in direct sun, I was expecting the controller to push all 5.5 amps to the battery since motor is drawing 22 amps. Instead I only get between 0.8-1.7 amps being sent and 4.7-3.8 amps being wasted. After having my motor on max speed for 3 hours and theoretically using up 66 of its 95 AH the controller finally starts pushing out more amps but still only 4-4.8 amps! This higher amperage only occurred near the last 15 mins of the test, I didn't want to keep going because I know that discharging even a deep cycle battery past 30% remaining (70% used capacity) will not be good for its long term health. So instead of getting 16.5 amps charged back into my battery over 3 hours (5.5 *3) I only got roughly 6 to 8 amps!?? I am confused by this and think maybe I don't have the correct setup. Can anyone help me understand, my guess is that solar controller only send less amps because it is in the wrong stage of charging (not Bulk stage but maybe boost or something?). My understanding is in bulk charge stage all current is sent to battery. Please help!
1) What I did wrong or what wrong equipment I'm using?
2) Can I achieve my goal of either having all amps produced by panel get put back into the battery , OR send those amps directly to the motor so it draws less from the battery? (I just don't want to waste them)
3) Should I buy an MPPT controller and be able to program it to push all amps coming from panel at all times until battery is 100% full? It this how mppt can work?
4) interesting note, when I try connecting motor to controller load terminals and turn on motor to 1st speed (low) this draws 6 amps, the motor will spin for about 5 seconds and then then controller turns offs the power to the load terminals and screen flashes with error symbol, even though the controller is rated for 20 amps! I think this is because voltage of battery drops when motor is on and maybe it drops lower than min setting on controller. This is why I end up connecting motor directly to battery. I verified there is no spike in current drawn when motor is first turned on using an amp meter, and amps never go past 6.5 on low speed.
Note, If I can figure this out, I will buy a second 100 Watt panel and hopefully get 10-11 amps, with the plan of going on long back country trips where I use motor at max speed for a few hours a day, and then the sun charges the battery back up and next day I can do it all over again!
