Never assume anything. Welp im a newb to solar. I bought the Midnite Solar classic 150. One problem. I cant hook an inverter to it? If not, what inverter could I use. I have an inverter but it shuts off at 10.5 volts. So what am I missing here?
The classic 150 is a battery charge controller. That means it needs a charged battery connected to it, so it can boot up and control the solar.
An inverter would connect to the battery, not the classic
The battery would need to be sized to never get so low, that the classic shuts down from under voltage.
Quote from: mike90045 on January 22, 2020, 02:09:54 AM
The classic 150 is a battery charge controller. That means it needs a charged battery connected to it, so it can boot up and control the solar.
An inverter would connect to the battery, not the classic
The battery would need to be sized to never get so low, that the classic shuts down from under voltage.
Yup It maintains the charge to the battery from the PV. Yup I get all that. Yup it needs power to run. I agree. But my inverter shuts off at 10.5 volts. So with a 12 volt battery bank your saying I have 1.5 volts to work with? THis cant be right. I keep thinking I have the wrong kind of inverter. How do people run solar banks over night? Or long cloudy weeks? Why is there all kinds of warnings not to drop your deep cycle battery below 50%. I guess I dont have to worry about that because my inverter wont let it drop below what 88 to 90%. So what your saying is Im only allowed to use 11% of the energy I store? THis doesnt sound right to me.
Ryun,
Your 12-volt lead-acid battery charges near 14.5 volts. At rest with a full charge the battery voltage will be about 12.7 volts. At whatever load is placed on the battery, it is fully discharged at 10.5 volts. In that 2.2 volt range you use up 100% of the battery's rated capacity. With a large load pulling the battery voltage down, it doesn't deliver as many amphours - that is why the battery different ratings for, 8 hour discharge rate, 20 hour discharge rate, 100 hour ...
holy cow. So I got a @*#& ton more batteries to buy right. Right now I have two 12 volt 80 amp batteries. I just gotta stack the @*#& out of batteries with high amperage until im satisfied it seems.
I know I sound like an idiot, but that actually why im doing this. THis has been a slow incremental project for me to learn and keep phasing myself off the grid. I have a cheap one for my rv and that cheap little charge controller plugs right into power. It does both. Not a problem, Now I buy this expensive one, and yay.
Oh well I guess all I have left to do now is just keep buying batteries as I can afford them. THankx for your help.
I think you are going about designing your system in the wrong way.
First you determine how much power you want to use.
Then you determine what size inverter you need to run those loads.
Then you figure out how many days of battery storage capacity you would want to be able to run loads for with no sun and also a battery pack that will run the surge of above loads.
Next you size a solar array to be able to charge the size battery pack you have .
And then you size controller to handle the solar pv input .
Add in a generator to charge batteries since there will be days with no sun in most places
A couple rules of thumb .
You want all the batteries to be same type and age .
You don't want too many parallel strings of batteries because they are hard to balance charge/load
If you want your lead acid batteries to have a longer life span you don't discharge them more than 20% from full which is helpful in your design above ( the deeper you discharge them the less cycles you get )
For your present system it sounds like you have too big of an inverter and the load on it drops the battery voltage . So less load or smaller inverter would help.
If you can't fill up the batteries soon after you discharge them you will sulfate batteries and have shorter life span - so that is why you need enough pv or generator.
Watch some how to videos about solar on youtube
Alt E has some good intro ones.
There is another guy who makes lots of beginner videos
https://www.youtube.com/user/errolprowse
Larry
and to sizing for the batteries
don't go with 8 parallel 12v batteries for 800ah
build a bank with the same batteries, but with 48V configuration. Same storage, but way less amps needed in the wires.
read this about parallel batteries http://www.smartgauge.co.uk/batt_con.html
I agree on both counts 48-volts is a better choice if you need lots of energy stored and connecting a bunch of 80-amphour batteries in parallel is a terrible solution. It is a pain to maintain them - just count the number of cells you end up with. And remember the probability of a problem is proportional to the square of the number of cells. Use larger batteries. Six-volt golf-cart batteries are 225 amphours. Six-volt L16 batteries are 350 to 400 amphours. Better yet use an industrial battery that is 12-volts and 1800 amphours.