XBM Battery Monitor

[Sparky01]

Hello all, I just moved my batteries and controls into there own room because my wind turbine is 350 feet from my house. Well all went rather well, I found a small refridgerated body from a seafood company for free. And I have everything completely moved and rewired. My inverter control panel did not have a problem with the 350 foot wire run but my Xantrex Battery Monitor(XBM) is now not reading correctly. I had a feeling that it was going to be an issue scince it is reading 50mV @ 100A. So I don't know if there is a way to boost the mV signal to recalibrate my meter. Any help would be useful. Thank you all for the great info on this board.

Free RE in Unity

[Ungrounded Lightning Rod]

Can you describe more clearly where everything is?

I get the impression you have the batteries, shunt, and inverter out by the mill, the XBM in the house, and a 350 foot run of five-wire instrumentation cable between them.  (And that you're also running a similar 350 foot signal cable for the inverter control panel and 350 feet of cable for the inverter output ditto.)  Is this correct?

Does it look like it's the voltage or the current reading that's goofed up?

[Flux]

I don't know anything about your XBM monitor, but I am surprised that you are dropping 50mV to an electronic device. If you have any form of analog meter on the shunt then you will have problems.

You need to know the input impedance of the XBM to be able to deduce much.

You may be able to use a shunt with a higher volt drop but that will be expensive.

If you are real clever with electronics a high input impedance buffer amplifier between the shunt and the monitoring bit would fix it, but there is room for many problems unless you really know what you are doing. Unless it has its own supplies then you will most likely have to play with differential inputs on the buffer.

Flux

[Sparky01]

Ok I tested and found that I had a bad wire on the DC shunt. But I still have a problem with the voltage drop on the voltmeter part of the XBM. I did run 6 spare #12 AWG wires that I could connect for the meters Voltage Sensing. That is probebly the easiest way out. Thanks

[Flux]

I find it odd that any electronic voltage sensing circuit is producing significant voltage drop. I suspect that you have trouble with common mode voltages along ground lines.

Keep your metering leads completely separate from power leads, especially ground wires.

Flux

[Ungrounded Lightning Rod]

According to the instalation manuals on the company's site, the meter only has a sensing input on the plus side and apparently shares the minus side voltage sensing with either the negative power wire or one of the current sensing wires.

In the absense of a separate input, and with the shunt in the negative power cable, it SHOULD be using the I+ sensing wire for the voltage sensing.

Two things to try:

 1) Clean up and shorten as much as practical the connections between battery minus and the shunt, and between battery plus and the point where V+ sense is connected.  Also, if your bank has batteries wired in series, clean up all the jumpers.

 2) Parallel one or more of your spare wires with the one for:

    - negative

    - I+

    - I-

   If any of these improves the situation, add as many other spares as you have to it.

[Ungrounded Lightning Rod]

In the absense of a separate input, and with the shunt in the negative power cable, it SHOULD be using the I+ sensing wire for the voltage sensing.

(But what it REALLY should have is a separate V- sense wire.  Sharing the shunt wire means any voltage drop in the wiring between the battery and the shunt looks like a drop in battery voltage.)

[Sparky01]

Yes if I leave off the V+ so that it does not detect my voltage (and for some reason the light does not work this way) The amperage and AH works corectly. If I connect the Voltage sensing it throws off my amperage reading. And that thows off my AH reading so then I do not know how full my batteries are.