Auxillary output to control contactor

[asdex]

Hi, I have designed a system and have all the equipment except for contactors. I have attached the diagram which looks like it will all work except for one thing. When the hot water is hot and the thermostat open, the wind generator dumps to a separate load resistor. If the battery bank isn't fully charged that's a waste. Could the Midnite controller also control the dump contactor in parallel with the thermostat to keep it charging the batteries? The dump contactor is a CDS24 - 24 to 30 Volt Solenoid.
Thanks,

[kitestrings]

You might consider using the Classic's "Waste-Not" (aka use it or lose it) function off one the aux relays to run the diversion (water heater) load.  Waste not allows you to set a voltage relative to your charge set-points.  We've been doing this for a few years now, most recently using aux2 (pwm) output from the Classic.  In this application it would be "waste-not hi".  I think ours is set with an offset of -1.0 V or a little better, and a width 3V (I'll check this).  It works great and we're getting much higher 'harvest' of opportunity load.

If you search the board on this there's quite a few articles.  Good luck, ks

[asdex]

Hi, thanks for your info. I also have the Wizbang Jr which I think uses the Aux 1. If I use the Aux 2 to hold in the contactor, can I use a 24 vdc coil ? eg is it a clean contact or does it supply a voltage?
I'll check on the forum as well for the answer. My manual is up at our farm with the controller.
Thanks.

[Vic]

Hi adex,

The WBjr uses Aux 2.

Also,  you might need a Coil Driver for the Contactor,  as many Contactors have fairly high coil currents.

Read the Classic manual regarding the capabilities of the Classic Aux ports.

Vic

[kitestrings]

Vic,

I'm admittedly not very familiar with the Wbjr, but my understanding is that it just a current sensing module that let's you connect to your shunt for monitoring your system.  And, the only connection is the 'purple wire' to the aux2+ IIRC.  I assume this means if you are using the Wbjr that aux2 cannot be used for anything else - like output to a relay for diversion.  Is that correct?  If so, I guess you still have aux1, but this seems like a real disadvantage to me simply to get load monitoring.  The PWM output is really nice for opportunity diversion.

asdex, I believe the aux output can be either a dry contact or a 12V source to a relay.  If you use a SS relay you can avoid the coil current issue that Vic is talking about.

[Vic]

Hi Kitestrings,

Well,  we do get to CHOOSE how we use Aux 2 --  more is always better,  but there will always be some limit on what will be included in any product.   A number of CCs have absolutely NO Auxes at all,  and others have a very stunted single Aux output.

At this point,  Aux 2 cannot be shared with any other function,  when it is committed to the WBjr.   This could change,  but seems not too likely (to me).

And,  IMO,  the WBjr is not just a Monitoring function,  it is a monitoring/control function.  The WB allows using Shunt EA,  which permits termination of Absorption based on real battery Finishing Current  --  a huge advantage on systems with reasonable changes in DOD from one day to the next,  etc.

And,  kite..,  you are correct about the Aux output,  it either is a Dry contact,  or a current source,  which is limited to approximately 200 mA by a PTC device (self-resetting current limiter) ...  all from distant memory.

Opinions,  FWIW,   Vic

[asdex]

Hi, Aux 1 sounds fine to me. I'll use it to drive a 12v slave relay for the contactor.
Cheers,

[kitestrings]

Good luck and keep us posted.

Vic, thanks for the explanation.  I clearly need to read up more on the Wbjr, I think I have the concept though.  To be clear I'm not knocking the product, or it's limitations in an way.  On the contrary, I think it is a well designed, function-packed unit.

kindly, ~ks

[asdex]

My system is working well now. I have used aux 1 to activate a 24 volt relay which turns on a SSR and puts battery power directly onto a 24 volt 900 watt element for heating the water. The water takes about 9 hours of daylight to heat and is 40 gal. I have tried SOC and waste not high to switch the aux but are not sure as yet which gives me more heating. I’ll need to fit an hour meter on the element. The SOC setting seems to work well and is straight forward to setup with % and time delays.
The Wbjr is on Aux 2 but I haven’t use it much as yet.
I have attached a picture of my setup so far. Have a 1kw wind generator to add yet.

[kitestrings]

asdex,

Very slick.  This is pretty similar to what we're doing only our system and elements(2) are 48V.

Looking at you drawing I think you may have the Aux 1 & 2 reversed.  BTW what software are you using for the drawing.  I'd love to have something like that - most of my flow/illustrations are cut & paste, and my attempts at schematics are usually on Excel, or poor-man's CAD as I think of it.

~ks

[asdex]

Yes your right there. I'll fix it in version 16. I have it attached to the correct aux onsite.
I use Libre Office which is a free alternative to Micro$oft Office. It has a drawing program called LibreOffice Draw which is very flexible.
Cheers,

[kitestrings]

Thanks for the information.  I'll spend a bit more time on the site when I get a minute.

A follow up question:  I notice that you have both a Wzbjr and a Bogart battery monitor (is that right?).  I assume they share the same shunt, but I was just curious why you have both, and if one serves needs the other doesn't.  The Bogart allows for remote monitoring IIRC, so that could be part of it?

~ks