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groingo
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# Posted: 2 Nov 2014 11:29am
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Since I'm not finding any information on this I thought I'd throw it out.
The Tracer MPPT charge controller states it charges using PWM, do the all use this and just not talk about it or is this something different?
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creeky
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# Posted: 2 Nov 2014 01:55pm
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yes. mppt controllers use pwm charging. it's kinda two different things. pwm improves the charge controllers efficiency at putting the power into the batteries. mppt improves the efficiency of getting the power from the panels into the charge controller.
did I say that right?
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MtnDon
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# Posted: 2 Nov 2014 02:05pm - Edited by: MtnDon
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I can't say for certain.
MPPT controllers have to control the voltage output and as I understand it they (Outback, Midnite....) use a system of changing of DC to high frequency AC and then altering the voltage up/down and then changing that AC back to DC. The volts and amps change where if the in volts are higher than the out volts then the amps increase.
PWM alters voltage only. It does not alter current. PWM pulses the power xx number of times per second. There is a base frequency that the PWM designer selects; akin to the Hz used in transmitting AC power to the home; 60 Hz in that case. PWM operates at much high frequencies; maybe 400, maybe as high as 15,000 Hz, (cycles per second). So let's say 400 Hz. That is each second has 400 discrete time divisions. Within each of those time divisions the power is turned on and off. The greater the length of time the power output is turned on the higher the resulting voltage output. Many devices use PWM; speed controls for fans for example. The power that is not transmitted during the off part of the cycles is wasted as heat.
So maybe the Outbacks and Midnites of this world use PWM technology in their voltage changing electronics. Maybe they don't. I think maybe they don't talk about it because it doesn't matter. In other words maybe the mention of PWM in an MPPT controllers specs is just smoke and mirrors; means nothing.
Tracer has to have a reason to mention it, but why? Why? I personally don't think it means they have an advantage or benefit the others do not have. But that's just my thoughts. No proof one way or the other.
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groingo
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# Posted: 2 Nov 2014 02:14pm
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Quoting: creeky yes. mppt controllers use pwm charging. it's kinda two different things. pwm improves the charge controllers efficiency at putting the power into the batteries. mppt improves the efficiency of getting the power from the panels into the charge controller. did I say that right
Yes, it would appear you said it right you have to repeat three times quickly spin around four times counter clockwise then click you heels together.
I agree with both you and Don, this is how and why it works and the makers prefer no to talk of it.
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creeky
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# Posted: 2 Nov 2014 02:24pm
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that's what she said.
PWM uses pulse width modulation to increase power from the solar panels into the battery efficiency.
mppt uses mean point power tracking to improve panel output efficiency (which pwm puts into the battery).
so yes. all good solar controllers say they use pwm (and do) to get panel power into the batteries more efficiently. and mppt to get more power out of the panels.
hey smoke and mirrors is for magic acts. so the answer is yes. I stated that correctly and, cough cough, rather concisely.
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