remote battery sensing

[Barry Fields]

For those MidNite products that have remote Battery Bank Sensing, do they ever compare Remote vs Unit Battery voltage?

For example:  An Inverter putting out 6000watts (48v Bank) is drawing approx 125 amps. If the voltage drop between the Battery Bank and the unit is 1volt, 125watts of power is being dissipated in either the cabling or the connections. If a majority is being dissipated in one connection, that connection may overheat.

It may be a good idea to check that remote/unit voltage differential daily at start of the day (once a reasonable current is reached). Better to check before an issue occurs.

[ClassicCrazy]

Here is from the Classic which does not have remote sense but I do have -0.3v  offset set to try and get the Classic voltage to be close to what the batteries are reporting when at absorb setpoint.
The Hawkes Bay has remote sense but I can't graph that yet without combox or some way to interpret Canbus. 
This is charging 4 different lithium batteries with both Classic and Hawkes Bay on them, though the Hawkes Bay doesn't do as much in morning on this plot because it's pv are angled towards west.
Larry

[boB]

The new stuff does compare and decides not to use one or the other if it is too far away in voltage difference.   

[Barry Fields]

Correct me if I am wrong.

I am seeing a max charge rate (all 4 batteries) of about 35 amps.

If the differential really is .3v, then .3v X 55v = 16 watts dissipated over connections and cables.

Not huge unless its mostly in one connection.

[Barry Fields]

The new stuff does compare and decides not to use one or the other if it is too far away in voltage difference. 

Would be nice to give the Classic a remote BATTv. (please see BBMT  )

[ClassicCrazy]

Correct me if I am wrong.

I am seeing a max charge rate (all 4 batteries) of about 35 amps.

If the differential really is .3v, then .3v X 55v = 16 watts dissipated over connections and cables.

Not huge unless its mostly in one connection.

Barry - you have it about right .
I just played around with the offset until it is close to agreeing with what the batteries bms reports.
Notice also in the graph how the current takes a big dip as the batteries get full. The absorb time is set to about 25 minutes , then to float.
Larry

[Barry Fields]

Barry - you have it about right .
I just played around with the offset until it is close to agreeing with what the batteries bms reports.
Notice also in the graph how the current takes a big dip as the batteries get full. The absorb time is set to about 25 minutes , then to float.
Larry

Good to remember that a 6000w inverter drawing 125A (48v) 250A (24v) is more subject to this voltage drop.
125A X .5v = 62.5 watts
250A X .5v = 125 watts

[ClassicCrazy]

this is off topic Barry but thought you might enjoy this video I just watched 
"Ground is a Myth" in regards to what is ground and the benefits or detriments of grounding circuits, equipment,  or electrical systems . https://youtu.be/VvE570NPmmI?si=uFOg4l2KYYaazk-t
video from ARRL vice president.
Larry

[boB]

this is off topic Barry but thought you might enjoy this video I just watched 
"Ground is a Myth" in regards to what is ground and the benefits or detriments of grounding circuits, equipment,  or electrical systems . https://youtu.be/VvE570NPmmI?si=uFOg4l2KYYaazk-t
video from ARRL vice president.
Larry

Larry, turns out I watched this video just the other day !

[Barry Fields]

this is off topic Barry but thought you might enjoy this video I just watched 
"Ground is a Myth"

Just watched it. I feel much better grounded in the subject.

For a limited time you too can have the miraculous BBMT which will identify all your real and imaginary grounding issues and lead you to the promised land of resolution!