MPPT controller - voltage sensing without separate wires?

I seriously doubt that the new model will ever do that function.
My belief is that it will simply output the voltage desired at it's terminals and hope that there is not too much loss when the current arrives at the battery.

Ok, so when exactly the MPPT will be able to use power cable as a battery sense cable - only when it falls into sleep mode at night?

Guess I read this a bit differently than others
The way I read it is that the new controller has optional voltage sense capability, while the older model required the user to connect the sense wires

From my perspective voltage sense is a very nice feature
Easily compensating for a few hunderd milli volt losses experienced in larger cables with high currents - small systems say 15amp and below might not need it

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February 25, 2013 - Someone on another forum asked what the differences are between the new MPT-3048 controller and the older 3024 models. Here's a summary of the highlights:

•Will support 12/24/36/48v battery banks
•100v max Voc PV limit
•Battery sense wires are now optional (the 2nd gen 3024 required them)
•Auto fault resolution (faults will not require the user to restart the controller)
•Reverse battery and input short protection
•User-upgradable firmware
•Auto pass-thru on startup after initial setup (will power down/up and start charging without any user interaction after initial setup)
•More extensive data logging and more real-time data accessible with the PC connection and software utility
•Historical data log accessible via PC
•Master-slave option for two controllers
•Modified MPP tracking algorithm with new triggers for sweep and user-adjustable options
•Real-time data always remains on display now, even during sleep
•Adjustable battery temperature compensation
•Adjustable current limiting
•User-adjustable calibration
•Slightly larger and heavier physically, more robust thermal design
I'll have a full spec sheet out on the 3048 controller soon ... it's on the long list of things to do, but not toward the top quite yet. I'll post a link to it here as soon as it's available.

•Battery sense wires are now optional (the 2nd gen 3024 required them)

I see nothing fancy here. 3048 will just read what is available on the main feed wire. If you have a long run to the battery I think you will use the sense wire option.

This is what Morningstar does.

http://www.roguepowertech.com/blog.htm

IMO 3048 will just use the the higher voltage number between sense terminals and output terminals.

Rogue Power Technologies MPPT 3048. The info is from their blog.

Sal, your explanation makes sense. Now I wish I could understand when and why one might need those additional sensing wires offered as an option.

But how do it know its line losses?

That looks like a good approach. When controller disables charging current, the power cables look just like sense lines. The mppt algorithm may measure PV open circuit. At that time charging current is also disabled. That's a good time to sense battery voltage.

To make this work, a dedicated line to batteries is required that's not shared with other loads. That's usually the case anyways.

Iota converter does something similar. It senses battery voltage when ac power is off. When power gets turned on, converter knows exactly which mode is required.

Who builds 3048?

Sal

Are we discussing the Blue Sky MPPT 3048 controller?
Or as I assume we are discussing the yet to be released aka delayed several months Rouge Technologies MPPT controller

Might be possible to remote sense the battery voltage without dedicated small wires but is not something I have ever heard of. Just guessing I would say since there is a cost involved with the feature and most folks use a short run of heavy wire from the controller to the battery a design change was incorporated removing the feature.

Tell us more where did you get this info?