WBjr with a 1000A/50mV

[Lou]

Aloha All,

I have a 3-phase Sunny Island system with 2 Classics on it and I want to read the SOC on both the SI and the Classic (using the WBjr). Because of the size of the system I am using a 1000A/50mV shunt. The SI can be programmed for this shunt and reports SOC correctly. The WBjr obviously wants a 500A/50mV shunt.

Is there a way to get the WBjr to report correctly in this instances? Is there a Modbus register to change?  Or is there another way with different equipment to make this work?

Thanks!

[ClassicCrazy]

What does the Whizbang read the current as compared to what your Sunny Island is reading it ?
I never heard about any way of changing shunt types.

Larry

[boB]

Hey Lou !

Well dang !   Too bad you didn't have a 1000A/100mV shunt !   That would have worked right off the bat except for the larger spacing between the sense screws.   BTW, with 500A/50mV  or 1000A/100mV  or 3000A/300mV, the WB Jr. works up to just above +/- 3000A

I will look and see though...    You need the gain of that to go up by a factor of two (2).   I think the WB Jr. itself is programmed for its highest gain right now for use at 500A/50mV

boB

[boB]

What does the Whizbang read the current as compared to what your Sunny Island is reading it ?
I never heard about any way of changing shunt types.

Larry

There  IS a wee bit of change possible but I do not think it is capable of changing to twice the gain.

Right now, I believe that Lou's 1000A/50mV  will read half what it should read.

[boB]

Sorry Lou...   It doesn't look like there is an easy way other than updating the Classic software somehow to multiply that number by two (2)

There is a command that can be changed to the WB Jr.  (AS I REMEMBER !)  but it is all the way up to 16X internally.

This was all done in 2013 as I just looked at the code.

Can you get a 1000A/100mV  shunt to replace that 1000A/50mV  one with ?

What is the spacing of the 1000A/50mV shunt ?   Did you have to modify the connection to the WB Jr. to make it connect up the the shunt ?

Just remember  when adapting the WB Jr. to a larger spaced shunt to keep the adapter wires as short as possible.  Best thing to do is to use some kind of short bent conductive clip or piece of copper so that it is short as possible and rigid/rugged.

The issue as far as I know would be that the current draw of the WB Jr. iteslf, if run through a long-ish piece of wire to the shunt terminal, will act as an increased resistance and then the small amount of WB Jr. operational current will be added to the actual shunt measurement.   This is why a short adapter wire or clip conductor should be used to adapt it to the larger and increased space between those sense screws.

boB

[Lou]

Aloha Bob!

Thanks for the info. Super informative as usual!

I try a 1000A/100mV  shunt with some bent copper.

[boB]

Aloha Bob!

Thanks for the info. Super informative as usual!

I try a 1000A/100mV  shunt with some bent copper.

THAT should work just fine !