Still Don't Get It (Solar)
What will charge 2 6v golf cart batteries better, a single 270 watt high voltage panel with mppt or two 135 watt 12v panels (parallel) with PWM and why???? Thanks. Gman
Forum Discussion
Gman,
First off, the numbers don't line up. 12.4Vbatt is about 66% soc. 45Ah usage would only be 22% of C. 100-22=78%. So, either the batts were not even near fully charged to begin with, or the Vbatt reading was with a load on them, and thus lower as a result of peukert effect.
If you can provide the size of wfco you have, we can estimate how many Ah's are being replaced in two hours, from 12.4v/66%soc. Clearly, it's not enough.
You're looking to go portable? In that case I recommend you save considerably on pwm over mppt, and put the money where it counts... proper wiring. Do NOT buy a kit that offers 10ga, or less. And yes, 24v panels are usually much cheaper, but there are deals to be had with 12v. I just paid $1.05 can./watt for 140w 12v panels. And I bought a 30a pwm for $35can. Subtract 15% off those prices for $$u.s.
Moreover, mppt only makes a significant difference on large solar systems. I've crunched the numbers, and an average daily increase of say 15%, using mppt only translates to about 20Ah on a really good day, and much less on a short or cloudy day. And going portable blows those numbers out of the water.
The nice thing about going with two panels vs. one is you can always use only one, if two are getting the bank charged up too quickly. Your needs will likely change with the weather, so it's nice to have options.
First off, the numbers don't line up. 12.4Vbatt is about 66% soc. 45Ah usage would only be 22% of C. 100-22=78%. So, either the batts were not even near fully charged to begin with, or the Vbatt reading was with a load on them, and thus lower as a result of peukert effect.
If you can provide the size of wfco you have, we can estimate how many Ah's are being replaced in two hours, from 12.4v/66%soc. Clearly, it's not enough.
You're looking to go portable? In that case I recommend you save considerably on pwm over mppt, and put the money where it counts... proper wiring. Do NOT buy a kit that offers 10ga, or less. And yes, 24v panels are usually much cheaper, but there are deals to be had with 12v. I just paid $1.05 can./watt for 140w 12v panels. And I bought a 30a pwm for $35can. Subtract 15% off those prices for $$u.s.
Moreover, mppt only makes a significant difference on large solar systems. I've crunched the numbers, and an average daily increase of say 15%, using mppt only translates to about 20Ah on a really good day, and much less on a short or cloudy day. And going portable blows those numbers out of the water.
The nice thing about going with two panels vs. one is you can always use only one, if two are getting the bank charged up too quickly. Your needs will likely change with the weather, so it's nice to have options.
