20 ah Miady Battery
- Thread starter mtngr1
- Start date
That's a teeny weeny battery. You said you wanted inexpensive. MPPT would cost 5X as much and provide 5-15% more charging over the course of the day, but a 100W panel on PWM will get you charged from empty to full 2X or more per typical day with decent solar.
MPPT is important when you need to squeeze everything out of your array and panel configuration flexibility. I have a 6kW array at 100V and 60A input with up to 5800W output to my 48V battery. I need MPPT, and it was worth the $1000 I spent. PWM would require a lower input voltage, stricter panel configuration, and it would never see the full output of my panels due to the way PWM works,
MPPT is important when you need to squeeze everything out of your array and panel configuration flexibility. I have a 6kW array at 100V and 60A input with up to 5800W output to my 48V battery. I need MPPT, and it was worth the $1000 I spent. PWM would require a lower input voltage, stricter panel configuration, and it would never see the full output of my panels due to the way PWM works,
Answered above.
LFP is essentially drop-in replacement for lead-acid with some additional requirements. The unit will either allow you to program the appropriate voltage, or it will have compatible options.
"Lithium" charging components are mostly marketing designed to add $ to the cost.
MPPT for $60. Worth it IMHO.
Will has a video on how to set it up for LiFePO4.
See here:
And here:
Will has a video on how to set it up for LiFePO4.
See here:
And here:
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,844
Typical 100W panel is 12V class, let's pick one of Renogy's. Vmp 17.9, Imp 5.72. Miady battery is 12V lifepo4, so put it at 12.8V to 14.2V. Assume the panel actually produces 100W at a given time.
MPPT, 100W in, 98% efficient conversion - may not be depends on the curves, 98W out.
PWM, 5.72A in at 12.8V, 73W; 5.72A in at 14.2V, 81W; 73W - 81W out
17.9V with a mono panel gives NCOT Vmp around 16.8V, so scraping in when it comes to MPPT voltage requirements but it would work. Some MPPT controllers have a pseudo-PWM mode and won't actually go into MPPT with Vmp this close.
Is it worth $40 extra for those 17-25 extra watts? Perhaps, if we are chasing every watt possible, but if the PWM controller satisfies the demand... ?
MPPT, 100W in, 98% efficient conversion - may not be depends on the curves, 98W out.
PWM, 5.72A in at 12.8V, 73W; 5.72A in at 14.2V, 81W; 73W - 81W out
17.9V with a mono panel gives NCOT Vmp around 16.8V, so scraping in when it comes to MPPT voltage requirements but it would work. Some MPPT controllers have a pseudo-PWM mode and won't actually go into MPPT with Vmp this close.
Is it worth $40 extra for those 17-25 extra watts? Perhaps, if we are chasing every watt possible, but if the PWM controller satisfies the demand... ?
Trust me as I have been there before.
It starts out with one little battery and then they multiply over the years.
I’m now on my eighth SCC, a Victron 250/60 and really wish I had started out with better stuff from the start. I believe @snoobler has been down this road as well.
Sometimes saving $40 costs you a lot more in my experience, just cough up the tiny extra amount now ?
It starts out with one little battery and then they multiply over the years.
I’m now on my eighth SCC, a Victron 250/60 and really wish I had started out with better stuff from the start. I believe @snoobler has been down this road as well.
Sometimes saving $40 costs you a lot more in my experience, just cough up the tiny extra amount now ?
@snoobler started with a 150/100 and finished with a 250/100 because he didn't understand the cold temperature allowance for Voc. I see it as simply adding caviar to an already luscious spread.
I have never soiled my fingers with a PWM controller, but I wouldn't hesitate if I needed a 100W panel for some dedicated application. I probably wouldn't even spring for the Renogy and would go with those cheaper models.
I have never soiled my fingers with a PWM controller, but I wouldn't hesitate if I needed a 100W panel for some dedicated application. I probably wouldn't even spring for the Renogy and would go with those cheaper models.
Similar threads
