Battery-Inverter

The 100 amp AGM is fine. Just keep an eye on the battery voltage and condition.

The microwave is you biggest draw try to use it only for a few minutes at a time.

The inverter will cut out if the voltage gets too low.

This is a basic answer and if you have more details on the amp draw I could give you a better answer but again it would depend on battery condition, sunlight and time.

Regards Derek.

Hi dj,
That's 100 amp-hour battery I assume. This will deliver 5 amps for 20 hours, 10 amps for less than 10 hours, 50 amps for a lot less than 2 hours. And that's to being fully discharged.
If it's a 240v microwave you're running, then the 850watts you're talking of is 850w output energy. These microwaves are probably no more than 70% efficient (prob more like 50%), so you are talking of (at least) about 1300w AC input to the device.
Most inverters are about 85-90% efficient, so your 12v DC input will be about 1500watts, possibly 2000w if the m/w is only 50% eff. That's about 125-160 amps at 12v, which will be a bit hard on your 100 amp-hour battery.
Gerry

Dj – the problem is not battery size, it's the inverter size. As Gerry said it is not big enough for a microwave and if you use it for the small items you listed it will be way too large.

The efficiency of an inverter is quoted at full output. Most of the power lost is the power required to run the inverter circuitry. Thus as you reduce the power output the amount of lost power does not reduce in the same proportion. If you are only using a phone charger or an electric shaver you will be wasting more power than you are consuming for useful power – not good.

For small things like phones you can get 12V chargers. They cost a little more than an inverter but are more efficient to run. Consider these first. If you do go for an inverter a 120 – 150W model should do for any portable computer and be far more efficient than your proposed 1KW one.

PeterD

Sorry I beg to differ.

Stand by current is 4 watts on a good quality unit. Almost nothing !

You only draw what you use.

The bigger units tend to work better.

I do agree that if you can get a 12v supply for the camera and laptop then it is a good option but use your inverter if you wish with confidence.

Regards Derek.

If the Microwave does in fact need 1300 watts input then it just won't run on a 1000 watt Inverter.

Running the Microwave at 50% power won't help - it doesn't wind back to 650 watts - it runs at 1300 for 5 seconds, then zero power for 5 seconds.

Mike

Hi dj,

To get the most of your battery you should not discharge it more than 50%, also if you are going to going to use appliances that draw a lot of charge (ie microwaves) you may want to consider upping the voltage of your battery bank. Taking a lot of amps out of your battery bank in a short amount of time can also shorten the life of your batteries. Higher voltage = less amps (Watts = Volts x amps)

To accurately size a system that suits your requirements try this calculator:

AC and DC solar calculators and battery sizers

Regards,

Max
Information Manager
Energy Matters - SOLAR and Battery Sales
www.energymatters.com.au