Here's all you need. http://www.b737.org.uk/electrics.htm

Read it and understand it also got cockpit companion and it mentions STBY PWR and the BAT BUS doesn't show amps because its not a power source? But what does this mean...

The power source for STBY PWR and BAT BUS is the battery when no other generators/sources are available.  Shut down engines and observe your battery current at about -37A.  That current is flowing through the various busses to loads.  When the battery is charging the battery current will be positive, or too little to register on the meter.

 

A power source is a batter or generator etc.  A bus is not a power source in this context, it distributes power not create it.

Also the INV doesn't have AMPS

So how come the HOT BAT BUS has amps? Thats a BUS

Is the battery getting charged during flight because its getting used is that correct?

As far as I know Vernon, the battery is being charged during flight but not used in ordinary circumstances because the engine generators generate AC power which is then fed through transformer rectifier units into 28V DC power which powers the DC busses. So battery standby power will only come on when there is no AC power being generated and that's when the inverter will take the 28V DC power from the battery (which will last approx. 30 mins) to the AC standby bus and that's when the amperage through the inverter will be shown.

As far as I know Vernon, the battery is being charged during flight but not used in ordinary circumstances because the engine generators generate AC power which is then fed through transformer rectifier units into 28V DC power which powers the DC busses. So battery standby power will only come on when there is no AC power being generated and that's when the inverter will take the 28V DC power from the battery (which will last approx. 30 mins) to the AC standby bus and that's when the amperage through the inverter will be shown.

 

So how come placing the BAT SWITCH to OFF you loose some items? The INV doesn't show AMPS!

Depends on your configuration.  With battery off, the standby system's hot battery bus is not powered.  The inverter is not a power source and generally only power sources have the amp meter available.  Earlier you posted that you see amps on the hot battery bus, how?  My DC switch does not have a hot battery bus position.

Actually it's the same if you turn off the standby power, you lose some applications even with both AC generators. Why is that Dan?

The HOT BAT BUS is the BAT on the DC PANEL.

With battery off, the standby system's hot battery bus is not powered.

 

Thats wrong with the BAT OFF you loose the BAT BUS and SW HOT BAT BUS.

The HOT BAT BUS is the BAT on the DC PANEL.

Reference?  I would not expect that... but with a valid reference you win.

 

I forgot what the topic was.

Just at the start

 

http://www.b737.org.uk/electrics.htm

 

I'm not gaining points just correcting things incase someone picke up wrong.

 

I did mention in my topic about the electric side.

So how come placing the BAT SWITCH to OFF you loose some items? The INV doesn't show AMPS!

The battery switch position itself, rather than what is powered by it being on or off, is used in the logic of some systems. The APU, for example. If you switch the battery switch OFF the APU will shutdown

Yeh i know about the BATT being off you loose items, i was just pointing this out to rondon! My bad wording lol

 

Is the BATT constantly getting charged during flight by the TRU?

Dan when you say voltage is analogous to water pressure, could you possibly explain that a bit? I've had lots of very clever people explain the fundaments of electricity to me and they've always come up with the water analogy, but I've never quite understood it. Current and resistance I can completely understand, but even as a teenager doing school physics I never understood what exactly voltage was measuring. A bit embarrassing being an adult male and not knowing that really. Will no doubt come in useful when I start going into professional flying ^_^ .

 

I dunno if this will help but thinking about AC I just got this image of 2 syringes connected by a length of tubing filled with water. When you push one in, the other gets pushed out. Alternate between the 2 at a particular frequency with curved pressure variations to match a sin wave and you got AC voltage. The current is the volume/sec of water flowing through the tube, the voltage is the pressure that's causing it to flow. And since we are in a aviation forum, total pressure = static pressure + dynamic pressure. If the one goes up, the other must go down unless extra energy is added to increase total pressure. In electrical terms however, total pressure = total power = current * voltage. (did I get that right?)