question

Bill avatar image
Bill asked

Two SS charge controllers and one battery bank

I am using a SS 100/50 for 640w of panels on my RV roof and a SS 75/15 for a portable 200w suitcase. They are all on the same victron BT network but I see vastly different times for Bulk/Absorb and Float when looking at them. Depending on when I look at them I can see one controller is a couple hours into Absorb and the other controller still in Bulk mode. Is there some incompatibility there? They are all on the most current firmware offered. They are both talking to a Smart Battery Sense for temp and voltages.

I thought they used voltage to determine what stage they should be in, but that doesn't appear to be the case. Maybe I don't understand exactly how the controllers use my custom battery voltage settings? I have verified the voltage settings are exactly the same on both.


520 AH LA batteries, Float 13.5v, Absorb 14.5v and the unused Equilize 15.5v all provided by my Battery Manufacturers support team (Crown).


-Bill


PS is there a document explaining what the controllers are supposed to be doing based on the battery voltages? What setting tells the controller to switch to Absord, is it when it hits my 14.5v Absorb setting? If so, is it just time that tells it to go into Float or is it another voltage.. I know it cannot be it seeing 13.5 as it was already above that. :)







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1 Answer
Paul B avatar image
Paul B answered ·

Its just Time thats sends it to float,

it goes from Bulk to Absorption once the absorption voltage is reached then after 4 hrs or whatever the absorption time you have set it goes to float.

however this time period depends on how long ago it was in absorption before, there are some other discussions about this in the fomun so look them up as well.

and I think Victron is going to do some changes in the next firmware upgrade or two as well

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Bill avatar image Bill commented ·

Ok, that says that both the controllers should have switched to Absorb at 14.5v as they should be getting the battery voltage reading from the Smart Battery Sense. But I regularly see the 75/15 still in bulk hours after the 100/50 has been in float. Victron Connect shows both are on the same network and both Temp and Voltage boxes have a green check on each controller. The way I normally tell if the SBS is communicating is the main VC screen shows the Tempature field, its not there on that screen if that controller isn't talking to it for some reason, although that is very rare since the last firmware updates. -Bill

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Paul B avatar image Paul B Bill commented ·

keep in mind that the75/15 unit is way smaller than the 100/50 in output.

Maybe there are differences there, anyway I suspect that it will be no big deal to the batteries as the 75/15 wont be affecting the batteries by much.

There will be lots and lots of reasons for it,

dont get to picky over it

and as I said before,

I think Victron is going to do some changes in the next firmware upgrade or two as well

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Related Resources

Additional resources still need to be added for this topic

Additional resources still need to be added for this topic

Smart Battery Sense Product Page

Smart Battery Sense Manual