Re: Newbie with some questions
I would guess that you would be LUCKY to ~ 9 amps out of your panel if I do the calcs right. A C 60 is a pretty big controller for only 9 amps. I would guess there is a fair bit of inefficiency there. Second, # 14 is pretty small to run 75'. There is a "sticky" with a voltage drop calculator in this forum. I suggest that you look at it. Third, running your batteries down to 11.3 volts is a really bad idea! Compound this by not FULLY charging them within a matter of a couple of days will put them on the road to scrap metal. I suggest you look at the following:http://www.batteryfaq.org/ http://www.windsun.com/Batteries/Bat...of%20Batteries
The important measurement is not how many VOLTS you get our of a panel, but how many AMPS you get at WHAT VOLTAGE (watts) 17.5 volts @1 amp= 17.5 watts, same 17.5 volts @ 10 amps = 175 watts. It is also important to remember that unless you use a MPPT controller, you will never get the stated WATTAGE out of any given panel unless your battery voltage were to rise to the Vmp of the panel, which in this case would cook the battery. So lets say you were getting 9 amps @ 17 volts, you would get 153 watts. Put that same 9 amps at 12.6 volts and you would only be getting ~113 watts.
A rough rule of thumb is that flooded batteries need to be charged at a current between ~5-15% of ah capacity (11-23 amps) just to maintain charge.
At this point I wouldn't worry about float or even absorb voltages as you are unlikely to ever get there.
Finally, if you expect to run your inverter anywhere near 1500 watts you will not have nearly enough battery, except for very short term (minutes) loads.
Welcome to the forum, good luck, and read all you can here and elsewhere. There are some pretty sharp folks here who have forgotten more than most of us will ever know. Using this resource allows us not to have to re-invent the wheel each time,
Last edited by icarus; October 25th, 2009 at 16:59 PDT.
Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!