# charge controllers disagree with each other



## Sparticle (Nov 1, 2004)

We have 2 C-40's and a MX60(3 different sets of panels). One of the 40's shows one green blink and the other shows constant green. How can this be? What's wrong?


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## ace admirer (Oct 5, 2005)

you have more than one controller on the same battery bank?

anyway. tolerances of components, charge curves, tolerances of assemblies, wiring. i would be surprised if two controllers agreed with each much more than 2 or 3 percent.


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## Jim-mi (May 15, 2002)

You need something more sophisticated than blinking led's for your answers.

The least of which would be to put a Tri-Metric in the circuit.


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## Sparticle (Nov 1, 2004)

Yeppers, we have the Trimetric. I was wondering why the 2 C-40's would be different. I thought the green blinking lights indicated state of charge for the batteries. Solid green meant fully charged, one blink means a lower charge than full. Why would the battery charge measure differently to each controller? I might not understand it correctly. I appreciate any and all advice and suggestions.


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## 12vman (Feb 17, 2004)

I would disconnect the MX60 and work on the 2 C-40's. Are they set at the same charge voltage? (12, 24, 48) Are the bulk/float adjustments set at the same levels? 

The voltage settings must be set exactly the same on the C-40's. (Bulk and Float) If one is solid green and the other is still flashing, they could be fighting each other. The one that is solid green is holding the voltage down and the flashing one will never achieve the voltage that it's set at and hold for ~ an hour to switch to float. 

Lower the bulk voltage setting on the one that's flashing just a touch and see if they align. Adjust and wait for an hour and see if they both go to solid green. It may take you a week or so to get them right. Be careful.. This level setting will be very touchy and it must be flashing 5 times in a row.

The one that is flashing only once could have a problem or the one that goes solid green may be set at the wrong charge voltage. Is one set to diversion load mode and one not? Check your jumpers on the PC board.

The green LED should flash once to let you know everythingis OK. Once the battery voltage starts to rise, the LED will flash in "sequences".. 2 flashes, 3 flashes, 4 flashes, 5 flashes in a row. When it's flashing 5 times, the battery has achieved the bulk voltage setting. It will hold that voltage and flash 5 times for ~ an hour and flip to the float setting and turn solid green and remain there until a load pulls the voltage lower than the float setting. If this happens, the controller will kick back into the bulk mode and build the voltage back up again.

Just some food for thought..


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## Harry Chickpea (Dec 19, 2008)

ace is right. One controller will become dominant in a situation like that. Put Donald Trump and Bill Clinton in the same room and try to get them to agree. Same situation here. Each expects to be in charge.


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## Cyngbaeld (May 20, 2004)

Why do you have two controllers on one bank?


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## Jim-mi (May 15, 2002)

I would place no faith what so ever in blinking led's..

Get a top of the line DMM and start measureing voltages........
One of my main 'tools' is a Fluke DMM

The C40 is an ok unit, but remember what you paid for it . . .??
It is far far away from good lab equipment.......
Therefore many sutle differences between each unit.....


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## Sparticle (Nov 1, 2004)

We have 3 charge controllers on the same battery bank. This is because we have 3 different sets of 4 panels. Today, the C-40's are all matched up. Same number of blinks.

I've got to check all the panels to make sure they're doing what they should. 

Thanks very much for the help.


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## nadja (May 22, 2011)

Cyngbaeld said:


> Why do you have two controllers on one bank?


I have three C-60's on my battery bank. Two for my two racks of solar panels and one for my wind generator. They all read the same. First of all, I never pay much attention to the green blinkie thingies, as I bought the led read out covers for each. They are seperated between the two racks as then I can still add more solar panels to each without any trouble at all. I am 12 volt and the amperage can spike no and then, especially on the snowy just right days. I also have two spares brand new and in my new faraday box/cage


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## nadja (May 22, 2011)

Another thing about any of The C- Series charge controllers. My friend who is a solar guy had me reset with my fluke test meter and there is no comparasin to just looking at the little printed numbers. They need to be the exact same set points to work correctly


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## ace admirer (Oct 5, 2005)

perhaps we need an understanding of terms like. precision, graduations, repeatability, accuracy and balance these against tolerance need to properly maintain the bank.


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## mightybooboo (Feb 10, 2004)

My little Mornigstars work together on same bank without a problem,FWIW


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## ace admirer (Oct 5, 2005)

so understand, that i only have one controller for my system..so i'm asking more than telling....

if two controller are used on one bank, i can see one taking the lead in charging perhaps a little higher final voltage or charging at a slightly higher c rate. two different charger, two different charge curves (but both within tolerance of correctly maintaining the banks). so each will show a different bank condition, but again within tolerance of reasonable actual bank condition.. so if you don't mind the slight differences of the readouts, it don't matter. am i correct?

usually when comparing measuring devices a "master" is used. the master is usually a measuring device ten times more accurate than the device to be tested or calibrated. 

but anyway, it seems that perhaps, one controller would change what the other controller is sensing, that one controller would always cause the other controller to perhaps under charge? or am i way off base on my thinking?


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## 12vman (Feb 17, 2004)

If you use 2 controllers on one battery, they need to be set *exactly* at the same voltage points or they will fight each other. There is no master or slave. They are all totally seperate units trying to do the same thing, as they were designed to do. The variables are the voltage settings. It could take months to get 2 or three controllers to work in harmony connected to one battery.


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## sisterpine (May 9, 2004)

We also have two charge controllers in our set up. One always goes to solid green shortly before the other one. We also have the meter thing and they seem to be working just fine. sis


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## nadja (May 22, 2011)

12vman said:


> If you use 2 controllers on one battery, they need to be set *exactly* at the same voltage points or they will fight each other. There is no master or slave. They are all totally seperate units trying to do the same thing, as they were designed to do. The variables are the voltage settings. It could take months to get 2 or three controllers to work in harmony connected to one battery.


12vman I set mine by the little 'wheels' when I first got them and still did not experience any real problems. However when I set the settings via my fluke, it made all three go to the same setting. Each of my three c-60's are for 3 different sources of 12v power coming in. 12 panels on one , 8 panels on the second one and my 12v wind gennie on the third. Once all three have reached the 14.4 and held for about an hour , they drop down to about 13.4 from then on. What they then do (one at a time ususally) is to start regulating the amount of power coming in by divirting the excess to the heat sinks at the top of each unit. If you place your hand on the heat sinks , you can tell that they are doing what they were designed to do from the start and that is to prevent over-charging your batteries. I do however have the all set to manual equalization so that they don't come on at seperate times etc. I prefer the manual equal. over automatic. That way, I can control the equalization process for the best possible days , especially when my wife drives into town, which is always at least a 4 hour day for her.


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## ace admirer (Oct 5, 2005)

there is no "exact" no "perfect" in the scientific world there is only with in tolerance, outside tolerance....thats the point i trying to question....only God is perfect and exact...us mortal humans have errors and our equipment has errors which we can tolerate or not...


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