parallel charge controller intercommunication?

[silverstr8p]

If I add some more panels which requires another charge controller in parallel to handle the amperage, do the two charger controllers hooked up in parallel to the same battery bank need to inter-communicate with each other or will they both be able to sense correctly and charge the same group of batteries (12VDC in parallel)? I'm using AGM's.

[boB]

They do not need communications between each other...  Typically one charge controller may tend to take most of the absorbing power though and the other controller might go to sleep because the battery voltage is satisfied with the one CC.  This might happen because the battery voltage can be off by say, a tenth or 2 tenths of a volt from each other for their readings.   This is not a problem.   

When in bulk/MPPT though, the battery voltage will be far enough below the set point that both controllers will pull their weight trying to bring the battery voltage up to absorb or float.

Now, if you need to actually limit charge current into the battery, you can use the Whizbang Junior current monitor to do that limiting and that will satisfy however many CC's that are in place with the Follow-Me communications.  Typically there is not enough solar power to need that limit though so only necessary in the more extreme cases.  Typically.

[ClassicCrazy]

One advantage of using Follow Me to have the controllers communicate with each other is that you can just have one temperature sensor to the batteries . Also you can have one controller set up for ending amps if you want to use that  and the other controllers will follow.

Larry