setting charging output limits

[kauaisolarman]

hello

I have a battery bank that can only handle a max amperage of 48 amps.

if i am running 2 Classic controllers in follow me with 2 big arrays connected to each controller and i set the charging limit on the master will it limit both controllers to only put out 48 amps combined?

is this possible with 2 classics in follow me?

or do i need to run KID controllers in twin mode for this to happen.

i basically need to know how i can run 2 controllers and have the max amps out set point followed by both simultaneously.

thanks again for all the help 

[Vic]

Hi Kauai..,

From memory,  there is a Global Current Limit for Classics,  with FW Version 2096 and above.  Each Classic needs its own Wbjr,  and believe Follow Me is needed,  as well.

Will try to search this site,  later,  ...   not much time right now ...  others probably know much more than I.

EDIT:  Here is a Link that  Halfcrazy Ryan posted in the Make Output Current Dependent ..  Thread, in the Classic Topic:
Use the Link in reply #52 in this Thread:
http://kb1uas.com/mnsforum/index.php?topic=2696.45
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FWIW,    Vic

[Halfcrazy]

Correct, 2 WBjrs and set global current limit on both classics

[kauaisolarman]

Correct, 2 WBjrs and set global current limit on both classics

so i need firmware version 2096

2 classics each with their own WBj and both in follow-me with global current limit set per instructions on reply #52 from this topic http://kb1uas.com/mnsforum/index.php?PHPSESSID=4916b0ac69237c43109971a2d6e55400&topic=2696.45

Do i just hook the WBjs in parallel?

and just to clear things up; by doing it this way only the current going into the battery is limited v.s.  limiting the output current of each separate charge controller.  this way the controller can put its max set charging amps to the battery and still provide more if needed to run loads during the charging process?


please correct me if im wrong

and tanks for the help

[Vic]

Hi Kauai..,

So,  each Classic needs its own,  independent,  WBjr.  Classic #1 needs its Aux 2 wired to WBjr #1.   Classic #2 needs its WBjr wired to wired separately to its own independent Aux 2.

A single Shunt in the negative lead of the battery should suffice,  and,  in that case,  the Classics should Limit the current into the battery.

I have not looked at that White Paper ...   and have not thought about how one stacks two WBjrs on a single Shunt.  Probably one of the WBs needs to be connected to the shunt with fly leads ...   Will read the white paper now ...

The Classics should limit the battery charge current,  but provide maximum available current to the loads.

Will study that doc,  now ...  more later.   Vic

[kauaisolarman]

thanks again Vic,

i was thinking of how to get 2 WBjr's on 1 battery bank and i though that you had to run 2 shunts in parallel off the battery bank each with their own WBjr?

please advise of the best way to get 2 WBjr on 1 shunt because that seems like the better way to go.

the shunt i have only has holes on 1 side for the WBjr is there another shunt option with mounting points on both sides?

its slowly coming together!

[Vic]

Hi kauaisolarman,

Know of two major 500 A  Shunts  --  the Deltec,  and the MidNite.   The MN Shunt has an additional set of holes on one end of the shunt,  for a Negative Busbar,  but this will not be any benefit for an additional WB.

I DO believe that you can stack two WBs on that one set of two holes,  by carefully stacking a number of standoff spacers.  There might be a need to use two screws that are a bit longer than those included with the WBs.

The second option would be to just add two wires,  one from each of the WB mounting holes.  This would be just like the example of Sharing the Shunt terminals with another monitoring device.   The second WB could be stowed in some out-of-the-way spot,  perhaps in a small length of tubing,  plastic,   or even a plastic bag (perhaps).

A single Shunt should be the best.  If you were to use a second Shunt,  it would need to be in SERIES with the existing one.  If it was in Parallel,  you would need to change the Scale Factor.   A single Shunt is really the most direct,  and reasonable approach,   IMO.

FWIW,   Vic

[Westbranch]

Yes, the WBjr can be mounted on the shunt with another sensor of same or different manufacturer...
See page 2 of the installation manual for a good picture and page 1 for some text about same..

[dgd]

..solarman,

Just looking at your setup for the 24v battery bank you have 5*190=950w of pv plus the 8*140=1120w of pv
so if you had full output from both arrays then that would be near 2Kw. With an absorb voltage of 29v that would be about 72amps.
However this would be unlikely since your two arrays are pointing in different directions to optimise morning then afternoon power generation.
Other pv power losses mean you would likely max abour 75% power from one array and much much less from the other array
This probably means you would be lucky to get a sustained 49Amps from the combined controllers at any time.
There is also the fact that battery charging is not an exact science and that 48A figure for your interstates is probably, in practice, quite flexible. Even if you went above that by 10 to 20 percent I doubt the bank would be seriously damaged.

So, my point is that all this concern and need for two WBjr to get exact CC output current set,  is probably not necessary.
All just MHO of course, others may have different views :-)

dgd

[kauaisolarman]

thanks everyone for the input.  currently i have the 5-190 watt SANYO running the battery bank and at solar noon on a clear no cloud day the classic can pull 1120 watts from the 950watt array (don't ask me how i guess were really close to the sun here in hawaii).  this results in about 40-46A with just the 5 190 watt panels.

the reason for adding the additional 8x 140 watt solar panels is i have them just laying around with an extra charge controller laying around and i want to be able to produce more power on the cloudy days.  problem is i would probably go over my charge limits on clear days.

anyway back to topic.   

so just to clear up i can stack 2 WBjr's on top of each other ion the 1 shunt i just need to space them out and use longer screws because now there will be 2 wBjr's sticking off the side of the shunt.


if this proves to be too difficult i just may sell the panels and controller and get panels close to the same Vmp as the 190W sanyo and just run everything off 1 charge controller with the global current setting on that 1 controller running all the panels.

[CDN-VT]

Correct, 2 WBjrs and set global current limit on both classics

so i need firmware version 2096

2 classics each with their own WBj and both in follow-me with global current limit set per instructions on reply #52 from this topic http://kb1uas.com/mnsforum/index.php?PHPSESSID=4916b0ac69237c43109971a2d6e55400&topic=2696.45

Do i just hook the WBjs in parallel?



please correct me if im wrong

and tanks for the help

Yes two WBjrs & SHUNTS  that create a Y , both shunts have battery - and are joined , here is a 3 feed !
Pigging backing I can NOT see it work successful, I could be wrong 

Edit ADD :

Doing more digging into the two  WBjrs on one shunt with longer screws & the longer spacers I can see how that would work if you also were in follow me with Global current set .. Last night I couldn't see it , till I viewed it physically..

VT

[kauaisolarman]

are all the negatives from the other side (non battery side) connected together somewhere or are they all going to separate places?

will 2 controllers in follow me work well with this type of current limiting or will they be competing against each other to provide the required loads and charging current?  like when the maximum battery current is sensed which controller will decide to "let back" on the amps.

good input again thanks people

[dgd]

will 2 controllers in follow me work well with this type of current limiting or will they be competing against each other to provide the required loads and charging current?  like when the maximum battery current is sensed which controller will decide to "let back" on the amps.

I have never seen this level of charging control (output current balancing/limiting) implemented in Classic firmware releases AND using the follow-me connection to have CCs cooperate to manage this.
Follow me appears to be simple charge state alignment with sharing or temp sensor as an addition.
It would be good if sharing WBjr data was possible over follow-me to allow EA absorb finishing over multiple CCs.

dgd

[Vic]

will 2 controllers in follow me work well with this type of current limiting or will they be competing against each other to provide the required loads and charging current?  like when the maximum battery current is sensed which controller will decide to "let back" on the amps.

I have never seen this level of charging control (output current balancing/limiting) implemented in Classic firmware releases AND using the follow-me connection to have CCs cooperate to manage this.
Follow me appears to be simple charge state alignment with sharing or temp sensor as an addition.
It would be good if sharing WBjr data was possible over follow-me to allow EA absorb finishing over multiple CCs.
dgd

Thanks dgd,  for the clarification.   I muddied the water,  by saying that I "believed" that FollowMe was needed.   That White Paper said nothing about FollowMe.

Appreciate your input,   as you really do know the inner workings of the MN CCs.

At some point,  that White Paper will probably contain a bit more information.

Thanks,   Vic

[CDN-VT]

So since I have a few spare classics & was playing in the fun room (Raining Cats & dogs ) Im doing a mock up and will see. This was one though I also had on my split array that's coming next year.


Bolt size is 8-32 X1.25" all the spacers are from the WBjr units .
It goes thin ,WB -2 tall-WB -thin ,lock washer bolt .


VT