Q&A: Increasing system load

Since my household increased from one to three members I am finding my 1500 W renewable energy system, which was more than adequate for a frugal me, is not coping with the extra residents even though we use energy sparingly, only do washing etc on sunny days and have purchased low-energy computers and fridge.

Our system was only designed to take up to 2000 W of solar panels, so after I put on two new panels the system is still short on energy when we have two cloudy days in a row.

My battery charger will be getting regular use from now on, but only puts 10 A (300 W) into the batteries. I am looking for a battery charger that can deliver 30 amps and reduce the time I need to run my 3000 W generator.

Longer term, I may have to buy a second system, but can you suggest a suitable charger that is not too expensive please?
Jane Marriott

There are plenty of chargers around that will do that sort of current, and more, but the maximum current rate depends on the battery bank size. See www.baintech.com.au/chargers and www.inverter.com.au/category5_1.htm for examples, and there are a lot of other suppliers, but high-powered chargers like this are never really low cost. There are some cheap ones on eBay, but bear in mind that some are not well regulated and can overcharge the battery bank, and many are direct from China, so if they fail, there’s no real recourse.

Generally, if you are finding that your battery bank is struggling after the second day then you are cycling it way too deeply and it is too small for what you are drawing from it. The use of a charger will help but it is still adding cycles to the bank and the bank will degrade faster than it otherwise would.

Something to note regarding generators, they are usually rated in VA (volt-amps), not watts. They are not the same thing unless the load on the generator (battery charger or whatever) has a power factor of 1. Very few electronic loads do, especially battery chargers, so a genset rated at 3000 VA won’t be able to power a 3000 watt charger. Obviously, a 30 V, 30 A output is only 900 W and probably needs around 1200 W input at most, but it’s surprising how much some gensets struggle with battery chargers.
Lance Turner

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