Kid aux +- functionality

[daklein]

I have wired up a Kid in a van, per the attached diagram. I'm happy to be making use of the Kid again! We used it in a previous camper trailer for about 5 years and I kept when selling that trailer.  I'm happy the Kid has the Load terminal functionality, and the shunt input that I'm using so far.  And I would like to use the aux terminal.  It's great that the Kid alone can be a brain to control the system, without having to add some other device. I still might add something to get the Kid serial data, and that would allow other controls or features.  I have second to last f/w (1797?), I'll update that, IIRC there's a change for the serial data since then.

In the system so far, the Kid Load terminal disables the inverter & DCDC loads, using the Load low battery disconnect.  It does that all at the same voltage threshold, about 32v, as everything is linked to the Load terminal, and that will keep the batteries away from BMS disconnect.

Ideally I would like to have some loads still run as long voltage > say 35, still pretty full battery. (Want to add a microinverter to discharge to shore power, as long as battery is over half or so).  But run other loads, the 12v DCDC down to another low voltage, say 32v, a bit lower which I like to not normally get to.   And not trip the battery BMSs in either case.

Questions: 
I'm not sure what the aux port functionality is.  What's the difference between the Aux port LBD High, and LBD Low functions? See p.39 of the manual attached, it doesn't seem to say, or there's a typo?  Does LBD High trigger the aux +- relay contacts on when _over_ the thresholds, effectively high battery voltage trigger?  And LBD Low do the opposite?

Playing with the menus on the Kid, it seems like only the LBD High allows changing its voltage thresholds, do both LBD High and LBD Low use the same thresholds, set only under the LBD High setup menu?  It seems these voltage thresholds are separate from what I have set under the Load terminal Low Battery Disconnect.  Is that correct, are they separate?  Or do the Load & Aux functions share the same voltage thresholds?

These are relay dry contacts?  I see the manual says only use 12v & 100mA through the aux/gen port terminals.  How should this be wired, I guess +- direction should be observed, but are they isolated otherwise?  Or should the aux - be tied to same neg as the Kid sees, and sink +12v through an external relay coil to the aux +.  I ask because my 12v is isolated from the solar / Kid 36v system.  Maybe I need to have a 12v DCDC non-isolated with the Kid just for that?

If I haven't written too much already, there is more about the van electrical system here, pictures, etc.
https://diysolarforum.com/threads/van-36v-9s-nmc-system.111470/#post-1637950

Thanks!

[ClassicCrazy]

You sure make some nice pictorial schematics !
No way I would have understood your system without those.
If I had a system like yours with battery safety in mind , I would want to put the Kid on the bench with a variable power supply and be able to change the voltages and confirm the Aux settings behavior.
I don't know the answer to your wiring questions for the negative connections from load or Aux. . I do know that it is important on the Kid to not tie the PV input negative together with the battery negative.
I didn't know what nmc lithium was but just looked it up, and now it makes sense to me what you  were talking about keeping battery voltages at certain levels.
Larry

[daklein]

Yes, the Kid negatives are all isolated.   

I could have said, NMC = Nissan Leaf battery, 2 modules from 2019+MY 62kwh pack. It's an odd voltage, 9s lithium. May as well use them, I primarily got them as spares to have for two of the full 62kwh battery packs I have. Of the two spare modules in the van, one has a cell that drifted .1-.2v lower than the rest while sitting for a couple years. The BMS balanced that cell and module within a couple days of being hooked up, so it should be fine.

[daklein]

Maybe a more basic question I should ask about the Kid Whizbang / Aux port:

Are the three pins (+ - WBjr) all one port?   Can the WBjr input be used at the same time as the Aux port functions (AGS,LBD Hi/Lo)?   I think so, the manual shows an example of shunt and AGS together.

https://midniteftp.com/forum/index.php?topic=2579.msg24541#msg24541            (Maybe not?)   I bought my Kid in late 2015, I guess it's later hardware, the aux port has the 3 pin push terminal shown in the latest manual.

Thanks!

[ClassicCrazy]

I haven't messed around with a Midnite Kid in a very long time that I don't remember much about it. Seems like it had some odd behavior sometimes charging lithiums - like it didn't get to the set voltage. That is documented on the forum here . They talked about a firmware update to address that but don't think there ever was one. And it might not have happened all the time with that issue.
I had an original Kid but it was sent in an internals updated at some point. I mostly used Classics , and now am using a Hawkes Bay.
Glad you have your lithium pack working. I use LiFePo4 lithium and know the technical points of those well.
Larry