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Post by jbourne84 on Mar 22, 2017 8:27:07 GMT -8
- (2) 100 watt renogy panels - wired in series
- Tracer MPPT charge controller
- (2) 230ah 6V golf cart batteries - in series for 12v
I dont think I've seen a reading yet that was much over 1 amp. I'm using a clamp meter at the solar cable going from the panels to the charge controller, in what seems like good sun it is often more like 0.6 amps. Voltage reads high, around 43-45 volts which sounds right according to the specs. Does the fact that the batteries are generally topped off contribute to this? |
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Post by rabird on Mar 22, 2017 9:58:19 GMT -8
What is battery voltage and what stage of charging is going on.
As the batts get fuller, the current tapers to maintain some voltage setpt, 14.?v absorption and then 13.?v float
If it takes very little current to maintain one of these voltages then the batts are generally FULL.
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Post by jbourne84 on Mar 22, 2017 10:47:52 GMT -8
What is battery voltage and what stage of charging is going on. As the batts get fuller, the current tapers to maintain some voltage setpt, 14.?v absorption and then 13.?v float If it takes very little current to maintain one of these voltages then the batts are generally FULL. Battery voltage varies but in the sun its usually around 13-13.5 Sorry I should have been more specific, I'm taking the reading between the panels and the charge controller, so I just figured the panels are producing power regardless of the battery state, and that the charge controller would step down the current if needed. So even at full charge the panel would still be making its normal power output. |
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Post by rabird on Mar 22, 2017 18:29:04 GMT -8
put a load on the battery @ night and drain it some! no, at full battery charge the controller turns on and off at some frequency. The on and off times change to keep the batt at whatever set pt is needed, be it 14.4v charge or 13.4v float (whatever the controller is set to do (with temp correction)). The term used is 'duty cycle'. When charging a depleted battery the duty cycle is 100% (On 100% of the time) until the batt voltage reaches 14.4v. At that time the duty cycle decreases (more and more OFF time) to maintain the set pt voltage. Usually this 14.4v is then held constant for 2 hrs (absorption) and then the controller goes to its float set pt. Producing only enough power to maintain float voltage by adjusting the duty cycle. During the off time the panel makes no power but Voc (20+v for a 12v panel), during the ON time, a MPPT controller would seek Vmp (18v for 12v panel). here is how I imagine it for PWM, ~50% duty cycle.  here's the IV (red) and power (blue watts) for my 60 watt panel made from the 3 pts on the back of the panel. Open circuit (OFF) yields zero power, zero amps, Voc of 22+/-  One can short the panels and measure amps, this should yield rated Isc (current short circuit). One can also measure the panels voltage disconnected, Voc (voltage open circuit). www.youtube.com/watch?v=HZf-sm3UXX0 |
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