Victron Limited Temp Comp Settings

Ako · May 2022

I am concerned that my Blue Solar 150/70 MPPT will damage my AGM batteries . Through the front panel buttons i have set the parameters without any problems however the Temperature compensation will not allow me to set the temperature compensation more than -35 , which is 42mv on my 24 volt bank .

I have always know temperature compensation to be a value which will be added or subtracted to the charge voltage according to the battery manifactures specifications . The scale of settings on the MPPT only go from -35 to 0 to 35 .so on my 24 volt battery bank that would be a total of 42mv which is almost 30% lower then needed which is 60mv, My Rolls flooded batteries and Triojan AGM all give 0.005mvc/cell , Morningstar products allow for this so its strange that a company as respected as Victron would sell a product that from the start would leave the end user setting the wrong charging voltages at any time other than at 25c .

The temperature here over a year is between 2c and 40c which can change during daylight hours by as much as 8c ( on my 24 volt system that's .06 per degree so less 1.9v to plus .9v .so compensation is necessary , without it my batteries would be ruined very quickly .

Has anyone any knowledge of these controllers and is it a common fault , its an expensive bit of equipment to discard but batteries cost far more .

BB. · May 2022

What brand/model of AGM batteries do you have?

Generally -5mV per Cell per degree C is for flooded cell batteries. AGM tend towards -2.7 or -2.2 mV/C/C.

If you pick an AGM charging profile--The controller defaults (max?) to -65mV/C or -2.7 mV/C/C--- However, that is for a 48 volt bank (24 cell). For a 24 volt bank (12 cell). So, you should be around -32.5 mV/C for a 24 volt bank (assuming -2.7 mV/C/C for AGM).

-0.0027 V/C/C * 12 cells (aka 24 volt) = -0.0324 V/C = -32.4 mV/C @ 24 volt bank
-0.0022 V/C/C * 12 cells = -0.0264 V/C = -26.4 mV/C @ 24 volt bank

At least that is how I understand your question and the controller setup--And the temperature offset based on 24 volt / 12 cell battery bank vs the 48 volt / 24 cell example in the manual.

https://www.victronenergy.com/upload/documents/Manual-BlueSolar-charge-controller-MPPT-150-70-EN-NL-FR-DE-ES-SE.pdf (controller manual)
https://321166-984045-raikfcquaxqncofqfm.stackpathdns.com/wp-content/uploads/2015/12/6-0101G_Lifeline_Technical_Manual.pdf (Lifetime AGM battery spec).

-Bill

Ako · May 2022

Thank you once again Bill , i did give the manufacturer of my batteries but dont think i explained the problem too well . I understood that the Defaults shown on the Manual were for 48 volt however when you Power the Charger it recognizes the system voltages and adjusts accordingly although for temperature compensation its not a problem as it displays a value for a single cell so it would multiply that by the detected system size . My batteries are Trojan L16 AGM with a temperature compensation recommendation of 0.005 volt per cell for every 1 degree C , my previous batteries were Rolls Flooded L16 which state 5mv/C/cell , ( both wrote as shown on the Batteries Manuals ) so i need 0.060 compensation for the Bank .

I did not pick a preset charging profile , i selected User so that i could be more precise on every setting , 28.8v Absorption , 27v Float , No Equalization Etc. but the one i could not set to match my Batteries profile was the temperature Compensation , the Charge Controller is limited to a maximum of 0.035 volts per cell for every 1 degree C which would be a maximum of .042 for the complete bank , thats 30% lower than both battery manufactures state which means that from the outset the charging voltage would be wrong , it would only be correct at 25 degrees , once temperature rises or falls then the voltages are out by a progressively greater degree , might as well just make a rough guess at the charges as im going to be undercharging during cold days and over charging on the hot ones .

What i cant understand is why a quality manufacturer would make such a big error , other Charge controller manufactures allow for greater offsets knowing whats required for many or the Major battery manufactures but still limit their own product in this way , i accept my knowledge is pretty basic so im wondering is there something i have overlooked or have not heard off .

BB. · May 2022

Ako,

I am not sure if I understand what you are saying--Or if it is just a typo:

the Charge Controller is limited to a maximum of 0.035 volts per cell for every 1 degree C which would be a maximum of .042 for the complete bank

0.035 V/C/C or 0.0035 V/C/C?
0.045 V per degree C / 12 cells per battery = 0.0035 V/C/C

Checking a Trojan manual, you are correct, they ask for -5mV/C/C for their AGM batteries.

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf (Table 5, page 17)

And it appears that Victron has a limit of -3.5 to +3.5 mV/C/C with -2.7 mV/C/C as the default (and note 2: only battery type 8 can this value be adjusted).

https://forum.solar-electric.com/discussion/357367/victron-limited-temp-comp-settings#latest (page 15-16 tables)

I agree--The programmable range should be to, at least allow -5 mV/C/C (pretty common spec. from what little I have read about lead acid).

Also, the temperature compensation (chart on page 21) seems to a range of 6C to 50C (battery temperature). That seems to be a pretty narrow Temp Comp range too.

Contacting Victron Tech Support?

I am not sure I would get rid of the controller because of these limits. Avoiding overcharging of AGM (and other sealed lead acid batteries) should help extend their life (at least for the catalyst used to convert H2+O2 to H2O).

-Bill

Ako · May 2022

Thanks again Bill , was typos but i see you understood what it should have read . I understood that Victron do not offer Tech support and leave that to the dealers which from my experience are not as experienced as a Manufactures Support team would be in their own product .

Victron Limited Temp Comp Settings

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