Month: August 2014

A lot of you reading this note, have Inverters installed in your homes. These inverters store energy from the grid in the batteries and when the power from the grid goes out they power your appliances and lights.

They are a worthy solution if you get up to 6 hours of power everyday. It takes that long with full current to fully charge your batteries. If you get less than 6 hours a day your batteries will suffer because you never fully charge them and this significantly reduces the life of that battery. Batteries are happiest fully charged.

I had an experience with a system we installed in Nigeria that highlighted the importance of cabling. I had plugged in an iron and it ran the batteries down almost immediately. Most people assume that is because of the power draw from the iron. That is partially correct. The losses from thin cables account for more than 60% of the losses you suffer from a system. A typical battery is 200 AH. To calculate the watts you multiply by your system voltage. If you have a 12 V system that represents 2400 Watts, 4800 Watts on a 24 Volt system and 9600 watts on a 48 Volt system. Your iron draws between 1000 and 1500 watts. The battery has more than enough energy stored in them to allow you to use an iron. That is a lot of energy going through your cables.
If you have had this experience check your cables. If they get hot while your inverter is on, they are two small. The smallest cable you should use is 1 AWG (42.4mm sq) or 0 AWG (53.5mm sq) anything smaller is asking for trouble. In addition to poor system and a rapidly draining battery you can have fires. Inverter fires in Nigeria have become very common. Thicker cables reduce resistance. The thicker the cable the lower the resistance. The better the performance and the lower your chances of fires.

Conclusion; if the wiring on your system is too small, get it fixed. I have enclosed a picture of wire sizes for you to use as a reference.

Cable AWG gauge

The red is 4 AWG, the middle black cable is 1/0 AWG and the big black cable is about 0000 AWG or 4/0. If the wires are not as thick or thicker than your finger, you are inviting trouble. (if you have super big fingers, it might no apply to you.

But if you have cables that are that thick it is a good thing). If you have a 1 to 3 kw Inverter you need at least 1/0 AWG. If you plan to run your air conditioner on the Inverter go for 4/0.