General Bus electrics-Solar

[T1 Terry]

No idea where the post I wrote yesterday went, but I'll try again

Hi Kappy, the Steca only has the house load wiring connected to the load terminal now? The inverter goes more or less straight from the battery? The figures you are seeing on the Steca show what comes in through the solar and out through the load port, so it is only measuring how much 24v power you are using on the house power circuit, it can't measure the load used by the inverter because it doesn't see it come in the battery positive cable and go out the load positive cable. The load side of the Steca can not carry the amount of current the inverter wants so it can't be used to measure how much is actually used from the battery.
To measure all the loads in or out of the battery you need a Victron 700BMV, this bolts in the battery negative cable with the battery on one side and the on the load side which is the other side of the shunt, the negative cable from the Steca, the negative cable from the inverter and a negative cable from the steel body to this point as well just in case any appliances are connected to the metal body work to produce a negative battery return. Now every thing in or out of the battery must pass through this shunt so the Victron BMV gauge can measuring and record what went out and what came in, this will give you an accurate reading of how much is being used from the battery, the battery voltage and how much useable is left in the battery so you can better control just how much you take out before you have to stop.

The tests did show there is no damage to the inverter and the battery did have quite a bit of capacity, you will need to put it on charge for at least 24hrs to recover the amount you took out, the voltage won't tell you, the only accurate way is to measure the current ( amps) going in, when it is at a low level and remains at that level for 2 hrs, say a few amps or maybe even 0.5 amp, but if it remains the same you will know that is the natural energy wasted by the battery through what ever recombination systems and the electrolyser action that are part of how a lead acid battery works. If they were lithium batteries it would be when the current dropped to bugger all the battery is full

T1 Terry

[Kappy]

Thank T1

I'm about to remove my solar panels and relocate to make way for my Dometic Harrier Invertor A/C.

So I will disconnect just about everything and as a matter of course, for piece of mind I get the batteries load tested.

After a little procrastination , today I decided to do some further testing before I start gutting everything.

As I'm somewhat wary of electricity took a bit of prodding for me to test the 240 side of the invertor

I discovered the AC Max output of the invertor was around 218-219V fluctuating between 189 and 205V mainly consistent at 205V.

Yesterday when running portable AC it didn't actually get cold, So I plugged into mains 240V and now is as cold as a mother in laws kiss.

Knowing very little about electrics I can't help but think this situation is part of my problem.

[BruceS]

One of my generators is like that too. Once I put a load on it, it goes up to 235V. Seems it needs a load on it to settle the output voltage.
I wonder if you plug in a little load like a hair dryer on low setting or a heatgun on low by using a double adaptor & then test in the unused socket?

[Kappy]

It went lower under load, but I'll give that a try tomorrow.

I tested the unused plug next to the A/C only hit 218 V maybe why the compressor didn't kick in.

[homeless]

My Hino is all 24v

[T1 Terry]

It went lower under load, but I'll give that a try tomorrow.

I tested the unused plug next to the A/C only hit 218 V maybe why the compressor didn't kick in.

I think you will find the problem is the type of load on a modified sinewave inverter. A purely resistive load like a jug element will probably show around the 220vac as the multimeter will have difficulty calculating the RMS of a modified sine wave as it designed to read pure sine wave. The air con compressor will not be happy with modified sine wave, if it does start up it will be rough and the motor will get hot real quick, if the modified sine wave is nothing more than a 2 step square wave I doubt it will start up at all as induction motors need the pure sine wave smooth wave form. The resistive load like a jug or heater element won't care, brush ac motor as similar as long as there is at least an attempt at making a curve.

T1 Terry

[Kappy]

Thanks Terry and Bruce,

I tested Bruce's theory with lights on, TV on and A/C on, attached a hair dryer on the spare plug as Bruce suggested and managed to reach 245 V
So running a 1400 watt A/C and a 1800 watt hairdryer at 900 achieved 245 V .

However compressor on A/C still didn't kick in, but seems the power drop off was solved.

Something tells me this is not really functional to draw over 2000 watts just to achieve 240 V .

Me thinks time to sack the MSW and head down the Pure Sine Wave Path.