Running out of power?

OddJoe82
OddJoe82 Registered Users Posts: 4
Ok so I have 4 75watt panals connected together, hooked up to a load controlar ( setup for 12 volts ), 2 12v batters hooked up ( + to + - to - ) and a 12v 410 watt power converter. During sunny days, it works fine, but on cloudy days and and night I run out of power. I run 2 12v rv lights, cellphone charger, laptop and dsl internet modem. On days its sunny then everything is powered up and charged then run out of power at about midnight. How can I fix this to run all day and night. The solar panals are set facing the south to get the max ammount of sun each day. The setup is all for 12 volts and I have 2 extra batterys I can hook up with the others ( pos to pos, neg to neg ) but am not sure that it will provide whats needed. The battertys are all 12v marine and about a year old. The power converter has 2 120v ac plugin's that let me connect a surge protector to plug in the laptop and dsl router/modem, the lights and cellphone charger are connected directly to the batterys. In the long run want to be able to power 2 laptops, about 10 12v rv lights, dsl modem/router, 12v air pump, 12v coffee maker, 12v water heating eleament, and have a single 120v ac plug for extra use. Am living in a trailer house and would like to have it all setup on solar.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Running out of power?

    Welcome to the forum.

    We'll try to analyze and see what's wrong.

    First up, the heart of any off-grid system is the batteries. You have two Marine/RV batteries in parallel. Okay, so wrong type of battery even though they say "deep cycle" on them; they tend not to work well in a renewable energy system. Also, they are usually about 90 Amp hours each (Group 27 size). This makes a difference for two things: loads and charging.

    Loads in your case is largely unknown. You know what you're running but not how much it is using. You can plug the 120 VAC things in through a Kill-A-Watt meter and find out. The inverter will also use power just to run, and the AC Watt hours it supplies will be more on the DC side due to its conversion efficiency. This is probably an MSW type inverter: uses less power for itself but does not supply best power for the loads.

    Then there's the charging. Four 75 Watt panels, probably around 4 Amps each, using probably a PWM type charge controller so 16 Amps peak charge current. That's for 180 Amp hours (probably) of battery. It would work fine were it not for the loads drawing at the same time.

    Off hand it seems your panels are supplying enough during the day to run things but not enough to fully recharge the batteries, resulting in them running out of power before you run out of things you want to run. :D

    What to do:

    Step #1: These batteries are no doubt flooded cells you can take the caps off from, right? So get a hydrometer and take the specific gravity reading of each and every cell. Don't be surprised if they are low and/or uneven. If this has been going on for a year the batteries are probably well on their way to sulphation.

    Step #2: Get the Kill-A-Watt and measure your loads under actual usage conditions. You can come up with a number that is the amount of Watt hours you need to supply. Divide it by 12 and multiple by 2 (for 50% depth of discharge) or 4 (for 25% depth of discharge which is better) and you have about the amount of Amp hours you need. What you have now would (if they were good shape and fully charged) supply about 1kW hour, not including inverter consumption and conversion losses. You'd be amazed how fast those 'little' items run up the Watt hours.

    Step #3: Change the equipment as needed to meet the power requirements. Most likely this will involve new batteries (like golf cart deep cycle) and more panels.
  • OddJoe82
    OddJoe82 Registered Users Posts: 4
    Re: Running out of power?

    Thanks for the help. I will start saving up to replace the batteries as soon as possible. The average wats anytime I check the load controler is about 96 watts. Took a picture just now showing the load controler readings. The load controlar amp hours was reset last week. current amps 07.0 watts 0090 volts 12.8 amp hours 330.5 total amp hours 01587.0. Will get the items suggested and start testing everything.

    Attachment not found.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Running out of power?

    Just looking at those numbers you can see trouble. 90 Watts could be used for 10-12 hours before the batteries go dead. The panels will alleviate this somewhat, but not against the loads drawing roughly half the current they can provide. As such you end up with putting only about 8 Amps into the batteries which is a meager 4% charge rate.

    If that 90 Watts is average over 24 hours that would be more than 2 kW hours per day, about double what the batteries could supply.

    Remember that if you increase the battery bank capacity you have to increase the array (panel) size as well. Your 300 Watts just manages during daylight hours but doesn't have enough to fully recharge the batteries and supply loads.
  • OddJoe82
    OddJoe82 Registered Users Posts: 4
    Re: Running out of power?

    The times I have checked the watts and stuff has been durning the day. Usually around 3 to 4 pm.

    So are you saying I need to upgrade the panals and the batteries? Am on a tight budget and trying to figure out how to make everything work. But also need to have around the clock power as well.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Running out of power?

    That's why you need to figure out just what the daily Watt hour number is. If the batteries can supply that and the panels can recharge the batteries all will be well.

    Being able to really shut off loads when not in use helps; plug things in through a power bar that can be switched off. So many things use tiny amounts of power when "off" and that adds up.

    My satellite modem & VOIP phone set-up consumes as much as the refrigerator even though the running Watts are less. Why? Because it draws those Watts all the time it is on whereas the 'frige only runs about 1/3 of the time.
  • Timinator
    Timinator Solar Expert Posts: 32
    Re: Running out of power?

    First off, the guys that have replied know way more than me. By chance, are you unplugging or turning off the power to the inverter when not in use? Also, are the batteries ever fully charging and going to float mode? I know I run pretty much the same stuff you do in my Lance truck camper off just a single 12V battery with an inverter and I don't draw down nearly as much as you seem to be. I can run my chargers, lights, phones, HDTV with DVD player most of the evening for a couple of nights before voltage gets below 12.3 volts or so.
  • OddJoe82
    OddJoe82 Registered Users Posts: 4
    Re: Running out of power?

    I think alot of it is the laptop. Becouse it drains power alot.

    When the laptop is not pluged in things last alot longer and the lights are brighter.

    However the laptop battery only last 2 hours when fully charged, and takes about 2 hours to recharge. I could unplug it when charged, but then would have to plug it back in son, and thought by just leaving it pluged in it wouldent drain as much power, becouse the start power vs running power. They do make a car charger for this laptop and maybe thats a option I need to do.

    The laptop is a must for me though as I have a radio talk show online and lots of other stuff the laptop is needed for.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Running out of power?

    Laptops are the "light choice" for battery systems. Desktops are murder. About 35 Watts versus 150 Watts.

    You are correct that recharging the laptop's battery will use somewhat more energy than just running it on AC. It always takes a bit more power to recharge a battery than you can get back out of it. Some laptops are better than others, but really it isn't worth it to buy a new one to save 5 Watts (no matter how much you want that new one ;) ).

    Back to 1, 2, 3. Check the battery's state of charge with a hydrometer, get firm numbers on your power usage, adjust the system to meet the needs.
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Running out of power?

    Back to 1, 2, 3. Check the battery's state of charge with a hydrometer, get firm numbers on your power usage, adjust the system to meet the needs.

    The ONLY way to go without a lot of guessing, trial and error, frustration, and wasted money