Question about Xantrax diversion mode?

[snowcrow]

  I noticed that my Xantrax C-35 in diversion mode, draws down the battery bank to the float setting ?!!  I don't think I like that idea!!!

  It draws 5 amps more than the 80 watt panel was putting in, to get to the float charge set point?  Is that normal for a Xantrax unit in diversion mode?  Is there a unit out there that monitors input and diverts only input power?

  I know in charge mode the unit just shuts off the incoming power and it drops to the float charge setting by itself.

  Any suggestions?

Blessings, Snow Crow

[electronbaby]

yes, this is why I refused to use dump loads for years. I just turned the turbine off when it was not needed. The xantrex cc has a lag time (hysteresis) that was unacceptable to me. Ive found the morningstar cc are more responsive and that is a step in the right direction. They work much better as a diversion load controller. Im sure a circuit could be built or modified around your criteria.

Ghurd might want to step in here. I think he has a home brew controller kit he's been selling. From what I hear, it works well. Hugh also has some schematics on his site if your interested in building one.

[ghurd]

Not sure if this one is wind, solar, or both.

Mine responds a Lot faster.  The lag time is very small.  The voltage is stable.

Mine can be set up to divert only the solar amps away from the battery, no need for a dump load.  

The solar part can be added to a windmill using the circuit, or vice versa, but the windmill will need a dump load.

Diverting the incoming amps is easy with solar, but not such a great idea with wind.

Mine is one stage. Pick a max voltage and thats the max voltage.  Much like a SS-X solar controller.

Snow Crow could send the extra solar amps to the water heater, before they even get to the battery?  I'll have to think about that a little more.  Gotta be easier than the IGBT!

G-

[snowcrow]

  electronbaby, thanks for the input!  I did buy several of Ghurd's controllers, and its just a matter of getting them to play nice with the Xantrex.

  I still think my first idea of dumping from the AC side of the mill is my best bet.

  Ghurd, when alibro set his mill up to dump from the AC side, there was no other sources of input to the battery bank.

 alibro's post: "Dump load controller on the ac side"

 http://www.fieldlines.com/story/2007/12/18/235618/29

  If I use the Xantrex C-35 for solar, in charge mode, set my Air-X to self regulate, it should stop the constantly sharp rising and falling of the battery voltage, thus stopping the AC dump from making any analog output, true?!

Blessings, Snow Crow

[ghurd]

"If I use ..."  Sounds right.

The C-35 should simply stop the solar amps.  Air-X should take care of itself.

I'm not an expert on either, but it makes sense to me.

G-

[domeguy]

Hi Snowcrow,

I've tried the idea of using a dump load on the AC side and am not very happy with it.  My system includes about 900+ W of solar through an Outback MX60.  I also have a 10' Danbuilt wind turbine and am using a C-40 in diversion mode to feed a resistor-based dump load.  I also wired my complex with an extra 240V AC line to be used for AC dump loads (baseboard heaters).  I set it up to use an Aux relay (through some high-power solid-state relays) in the Xantrex 4024 to turn the dump load on and off based on battery set points.  The Xantrex uses actual electro-mechanical relays and it's not a good idea to make them turn on and off frequently.  Since the battery voltage sags when I hit it with the sudden extra load when the AC dump loads are activated, I needed to provide some extra hysteresis ( about 2.0V) in the voltage set points.  Since the inverter doesn't know the state of charge of the batteries (only the voltage) it would either turn on the dump load before the batteries were fully charged, or not turn on the dump load when the batteries were fully charged and should be floating, which essentially over-charges the batteries.  On top of that, it would turn on the AC dump load when charging the batteries through the generator.  Until I figure out a better way to run the system I've turned off the AC dump loads and rely on the C-40 to regulate battery voltage through the resistor dump load.

Even that doesn't work perfectly.  If the C-40 thinks the battery should be floating it will happily dump solar current supplied by the MX-60, which doesn't think the batteries should be floating.  Since the dump load is not sized to dump both solar and wind (only wind), It's quite possible to overload the dump load.  I deal with that by going to the power shed when I think that might be the case.  I can unplug the hot wire from the battery going to the C-40 to reset it (take it out of float mode) and then it stops dumping prematurely.

I'm not well educated on the latest technology in this area, so maybe somebody makes a controller that takes in to account all aspects of the system in deciding when to turn on a dump load.  So far, my system requires some human intervention to avoid too much battery abuse.

-Lee