Monitoring second Classic over wireless bridge

[TomW]

[quote ]

Im not sure I know what that would mean? My thought would be that (in fallow-me), Master and slave aren't communicating properly in this case. So the slave is seeing a charging source greater than itself causing it to rest, not a master telling what it should be doing?
[/quote]

I seem to recall that in "Follow Me" there is no actual Master Classic set, rather whichever unit reaches the set point(s) notifies the others?

Why it is so important they all are configured identically. Plus the voltage offsets are tweaked, etc.

Just from here.

Tom

[TomW]

Im not sure I know what that would mean? My thought would be that (in fallow-me), Master and slave aren't communicating properly in this case. So the slave is seeing a charging source greater than itself causing it to rest, not a master telling what it should be doing?

I seem to recall that in "Follow Me" there is no actual Master Classic set, rather whichever unit reaches the set point(s) notifies the others?

Why it is so important they all are configured identically. Plus the voltage offsets are tweaked, etc.

Just from here.

Tom

[Powerplay]

I seem to recall that in "Follow Me" there is no actual Master Classic set,

Master is just what I'm calling the one with the RTS & Wbjr.

Why it is so important they all are configured identically. Plus the voltage offsets are tweaked, etc.

It only seems to matter in certain circumstances.  Based on my limited experience they behave like this in practice:

Let's say to stay at the Absorb set point we need 1000W and both Classics can produce about 500W.  Everything should be fine but what if Classic A is T-comped to a higher set point voltage than Classic B.  B will see voltage higher than set point and drive the power down to zero to adjust down even though both are in Absorb phase as passed from Classic to Classic.  If everything was set equally and the Master is passing temperature data along the line then they should both stay at 500W and coordinate the absorb phase.  In the first case once Classic B drops power output the Classics will both fall back to bulk eventually.  Then up down up down etc.
Sp they tend to coordinate very well when fine tuned without a lot of thrashing around.  This is just what I'm observing and I could be way off base as to the cause.

[dgd]

What you are seeing with your two Classics is their normal behaviour.
No matter how you calculate the potential power into each and the power output needed there will always be a point  in the Absorb state when the power needed for charging will be taken from just one Classic and the other will go into RESTING state.

Logic would make you think that they would both provide, if each is capable, 50% or thereabouts of the needed power but that never happens.

This is because there is no communications between Classics to co-operate on providing power in the form of load or charge balancing. There will always be differences in the real voltage set point values between each Classic and no amount of tweaking will ever get them exactly equal. It probably only takes a couple of millivolts difference (on high side) to make one Classic rest while other continues making power.

This situation gets much more interesting when you have 3 or 4 Classics charging the same battery bank and can get weird enough that its necessary to use an external  controller (computer) to manage charge state and charge balancing

dgd

[Powerplay]

@dgd:  Maybe include a quote so causality can be applied.     Of course there is a point where one Classic provides all the juice but we were not talking about that.  The topic here is why is it important to keep the settings between them the same.

[dgd]

@dgd:  Maybe include a quote so causality can be applied.     Of course there is a point where one Classic provides all the juice but we were not talking about that.
  The topic here is why is it important to keep the settings between them the same.

Maybe you didn't quite see the relevance of my reply 

There will always be differences in the real voltage set point values between each Classic and no amount of tweaking will ever get them exactly equal. It probably only takes a couple of millivolts difference (on high side) to make one Classic rest while other continues making power.

So you can never make the settings the same, or same enough, or identical, to have two Classics follow each other exactly.
In many multi-Classic systems it is often an advantage to control the priority over which Classic contributes greater power by having the voltage set points differenent between Classics (or Kids, OBs etc)

dgd

[Powerplay]

So you can never make the settings the same, or same enough, or identical, to have two Classics follow each other exactly.

I'm pretty sure truncated values are used for set points after the T-comp calculation.  So the calculated Absorb set point & Float set points do match exactly.  And My classics both report they are charging to the same truncated value.  Truncated to nearest 1/10 V.  But it is true they vary in their reading of the battery voltage by a few millivolt, but this just means the one with the slightly higher reading will gradually drive down to zero first over the one with the lower reading.  It is a very stable progression and I'm reporting what I observe not conjecture.  If the T-comp calculation were based on different settings or temperature readings then you'd get the wild swings I'm talking about since the set points would then be different numbers and, therefore, totally different targets varying by as much as half a volt or more.

Maybe you didn't quite see the relevance of my reply

I disagree.

In many multi-Classic systems it is often an advantage to control the priority over which Classic contributes greater power by having the voltage set points differenent between Classics (or Kids, OBs etc)

I wouldn't do that.  But maybe I'll change my mind when I get to that point.  I'm pretty happy with the way my 2-body system is working now that I've watched it through a few cycles.  After that I would probably rather start building solenoids and combining at the Battery Bank level rather than the Charge Controller level (after more than 2 Classics are needed) though.

How many Classics are you hanging off the same Battery Bank at this point?