Sizing a 24V Deep-cycle Battery System for a specific application

Registered Users Posts: 2
Hi Everyone,

I have some devices that I need to connect to an OFF-GRID Power Source consisting of a;
(1) unit 500w Solar Panel
(1) unit 500w Wind Turbine
(1) unit hybrid charge controller
(1) unit pure sine wave inverter

All the devices must connect to a power strip that is connected to the inverter output.

Here are the Devices that I am going to use along with their DC-rating
*antenna - 8.5W max consumption, power supply is 24V 0.5A PoE adapter
*camera1 - 10W, 5V 2 A adapter
*sensor1 - 216mW, 12V 1A adapter
*sensor2 - 180mW, 12V 1A adapter
*RTU1 - 6W, 12V 2A Adapter
*IP Phone - 12W. 12V 2A Adapter
*Amplifier - 200W, connected directly to 220v output of the inverter

BUT I do not know how can I determine the following;
1. Ampere-Hour size of the (24v) deep-cycle battery to be used
2. how many deep cycle batteries I need to use to provide at least 72-hours of operation for my devices

I do not know how can I compute for these things given that;
*I only have the DC ratings of my devices, I do not know how long can a FULL-CHARGED (24V) Deep-cycle battery system provide for the Inverter to produce 220V for 72-Hours.

Thank you...

• Solar Expert Posts: 3,738 ✭✭✭✭
I do not know how long can a FULL-CHARGED (24V) Deep-cycle battery system provide for the Inverter to produce 220V for 72-Hours.
Welcome to the forum,

It is not hard to measure the AC load of your devices... watthour meters are cheap.  So measure the AC load of your devices, and tell us the model of your inverter.  The inverter will use a certain minimum amount of power and have a certain conversion efficiency.  If we know the AC output of the inverter, we can calculate its DC power input and that will be the critical number we need to answer your question.

--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
I guess you are in the Philippines?

For solar power systems, as vtMaps says--It starts with knowing your loads... Not only Watts or Amps (@ xx Volts), it is how many hours per day you want to run them...
• 10 Watts * 1 hour per day = 10 Watt*Hours per day
• 10 Watts * 24 hours per day = 240 Watt*Hours per day
• 1 amp (at 12 volts) * 8 hours per day = 8 AH per day
• 8 AH per day * 12 volts = 96 WH per day
Do you have a specific Inverter/Hybrid Charge controller you are thinking of using (Links)?

In general, you will need to design your loads to conserve as much energy as possible. For example, you have some 12 volt loads--If they can run from a 12 volt battery (~10.5 to 15.5 VDC). Sometimes, it is better to just put in an AC inverter (stable AC voltage) and isolate the DC loads from the very wide voltage range of a typical DC Solar Battery Bank.

For an AC inverter--If you stay with a 12 VDC battery bank, this MorningStar 300 Watt unit is pretty nice (120 VAC US, 230 VAC for other regions):

http://www.morningstarcorp.com/products/suresine/

That inverter takes ~6 Watts just being "turned on without any AC load"--If you have small devices that take a few Watts (or less) loads--Perhaps direct 12 volt connection to battery or smaller 12 volt to 12 volt buck/boost DC converters would be better for those loads and only run the inverter when needed (the Morningstar is nice, has both remote on/off input, and low power "search mode" which may help conserve power). If you have to send energy longer distances, 230 VAC may be a better choice (sending lots of 12 volt current over longer distances can be a huge problem because of voltage drop)..

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 2
vtmaps said:
I do not know how long can a FULL-CHARGED (24V) Deep-cycle battery system provide for the Inverter to produce 220V for 72-Hours.
Welcome to the forum,

It is not hard to measure the AC load of your devices... watthour meters are cheap.  So measure the AC load of your devices, and tell us the model of your inverter.  The inverter will use a certain minimum amount of power and have a certain conversion efficiency.  If we know the AC output of the inverter, we can calculate its DC power input and that will be the critical number we need to answer your question.

--vtMaps

Hello,
I attached here the datasheet of the Inverter and charge controller that I will going to use.

Inverter

Charge Controller

• Solar Expert Posts: 3,738 ✭✭✭✭
Hello,
I attached here the datasheet of the Inverter and charge controller that I will going to use.