Actions
Forum Thread Details
  • State Suggested Answer
  • Replies 9 replies
  • Answers 2 answers
  • Subscribers 402 subscribers
  • Views 708 views
  • Users 0 members are here
Related

A quick question on backup power

dirtdiver

Hi everyone,

im making a model house with a solar panel and a rechargable battery.I've been looking on the internet for a while, but i cant really find out if what im planning to do is correct in terms of wiring.

Idealy you will have the external power disconnected and the battery will be charged by the solar panel and drained by the consumers (servo+ a few LEDs) and when the energy is not enought the external power will charge the battery/ or if the power network is down- rely on the solar energy to charge the battery alone.

 

Is this schematic applicable?

 

Im not sure if i have to put any diods around to limit the current's direction

 

**For some reason i cant insert an image so im attaching it as a file!

 

Thans in advance!

Attachments:
image
Parents
  • 0

    Ok first you need a "deep discharge" battery. Your circuit really wont work. You will need a few things:

    1. an Inverter which will power your load. This should be about 48vdc input and 115vac output (you can geri-rig a large UPS)

    2. you need your cells on the roof, to go to your battery via a regulator. The diode that you guys where talking about is only so you don't back feed your system.

    3. you should have some sort of monitor (cpu) that looks at one cell for light/dark or a real time clock.

    4. you should also monitor the output voltage of the cells.

    5. you should also monitor the output of the system before the inverter but after the battery. (demand)

    6. you should also monitor the temperature of the battery's. (too hot is very bad and too cold you need to turn on heater.)

     

    I like your idea but you should also think of Hydrogen with fuel cells image.. (Hydrogen House on the web) very cool.

     

    enjoy my 2 cents

    Cris H.

Reply
  • 0

    Ok first you need a "deep discharge" battery. Your circuit really wont work. You will need a few things:

    1. an Inverter which will power your load. This should be about 48vdc input and 115vac output (you can geri-rig a large UPS)

    2. you need your cells on the roof, to go to your battery via a regulator. The diode that you guys where talking about is only so you don't back feed your system.

    3. you should have some sort of monitor (cpu) that looks at one cell for light/dark or a real time clock.

    4. you should also monitor the output voltage of the cells.

    5. you should also monitor the output of the system before the inverter but after the battery. (demand)

    6. you should also monitor the temperature of the battery's. (too hot is very bad and too cold you need to turn on heater.)

     

    I like your idea but you should also think of Hydrogen with fuel cells image.. (Hydrogen House on the web) very cool.

     

    enjoy my 2 cents

    Cris H.

Children
  • 0 in reply to phoenixcomm

    For a small toy house, you shouldn't need a lot.

    Your cct doesn't give you much voltage headroom to efficently control it.

     

    I would tend to try 12v and then use a regulator to drop it down to 5v for your load.

    (There are plenty of cheap switchmode 12v to 5v USB style automotive regulators that handle 2.2A.)

     

    Solar panels tend to be high source impedance (not a lot of current but can have high open circuit voltage).

    Monitor the voltage and if it rises above 13.2 lead acid, or 13.6 for gell cell, then open circuit the solar panel.

     

    If you include some hysterisis then your relay or mosfet isn't going to die of oscillation.

     

    If you set the external charger output voltage to 13v then when the battery drops below 13 it will start supplying current, which will raise the battery voltage.

    If the solar is able to hold it above 13v, then the external charger will be idle.

     

    There are some good guides around for any size installation, and if its large then going to 48v reduces the R losses in the cabling and inverter.

    (It also means it needs 4 batteries of equal performance for each 'bank')

     

    Here is a good guide for calculating the capacity

    https://nicegear.co.nz/blog/what-size-solar-panel-and-battery-do-i-need/

     

     

    mark

  • 0 in reply to mcb1

    for my project is entirely for demonstration purposes so i used the shown schematic and it seems to be working (i used a diod to prevent current going back in the cell)