Bat Temp compensation reference

[fca]

Hi my batteries have reference working temperature of 30c .
So I need to setup the charge voltage compensation from 30c up and not 25c
Can this reference be changed ? If not please consider it  for next firmware release.

Thanks

[boB]

That should be pretty easy.

Just change the absorb and float voltage set points in the Classic up or down
by the opposite amount of voltage they would be with the 5 degree C difference.

What is your battery bank voltage ?  12V ?  24V  ?  48V ?   something else ?

boB

[fca]

Hummmm don't get it
My absorb voltage should be 2.35v/cell at 30c
At least is what I understand from these specs where nominal temp is 30c
http://www.exide.com/Media/files/Downloads/IndustEuro/Operating%20Instructions/Operating%20Instruction%20Sonnenschein_EPzV_56025017_MXSVDOEPDF00212.pdf

So at 30c I should have 2.35v*12=28,2v
And by these specs should be compensated by 0.004v/c

Please explain me better how to do it
Regards

[Vic]

Hi fca,

Have not looked at the Exide spec for your batteries,  but using the data you provided,  the temperature compensation value you noted is --0.004 V/C (4 millivolts) PER CELL per degree C for your battery.  So your 24 V battery does have 12 cells,  which yields --0.048 V per degree C,  or,  a total of 0.24 V variation for the 5 degree C difference between 25C and 30C.

So,  this 0.24V value needs to be added to both Absorb and Float values you get from the spec (when multiplied by the number of cells).  In the case of Absorb,  this is the spec value is 28.2V you noted,   or 28.44 V that will be set in the Classic.  Do the same for the Float Voltage,  and enter that into the Classic as well.

This is the way that I would do it,  anyway.    Vic

[fca]

Hi fca,

Have not looked at the Exide spec for your batteries,  but using the data you provided,  the temperature compensation value you noted is --0.004 V/C (4 millivolts) PER CELL per degree C for your battery.  So your 24 V battery does have 12 cells,  which yields --0.048 V per degree C,  or,  a total of 0.24 V variation for the 5 degree C difference between 25C and 30C.

So,  this 0.24V value needs to be added to both Absorb and Float values you get from the spec (when multiplied by the number of cells).  In the case of Absorb,  this is the spec value is 28.2V you noted,   or 28.44 V that will be set in the Classic.  Do the same for the Float Voltage,  and enter that into the Classic as well.

This is the way that I would do it,  anyway.    Vic

hi and thanks for your answer, but if i do it like this i will have my batts at 28.44 30C where they should be 28.2 at 30C ...

What i need is in fact to have the midnite with the reference voltage of 30c and not 25c (btw what comes from factory is  25c right ?) 

so i can set the voltages to 28.2 and a compensation of -0.004/C cell  above 30C  and + 0,004C cell bellow 30c..

Bob any change to have this variable  available to change by the user ?



thanks

[vtmaps]

but if i do it like this i will have my batts at 28.44 30C where they should be 28.2 at 30C ...

Vic had it correct.  If you set absorb to 28.44, the classic will put out 28.44 volts at 25°.  When the temperature climbs to 30° the Classic will reduce its output to 28.2 volts. 

--vtMaps

[fca]

Hi VIc and Vrmaps ,you are correct i'm so dumb that i didn't understand at first now i got i...
the midnite don't allow to set it at 28,44 so i set it to 28.5 my batt temperature in this hotdays (35c+ outside) are at 33c ...
thank you all for your help..
Regards

[Vic]

fca,

First,  I should have noted that it is not possible to set the Charger voltages to hundredths of a volt.

And,  my previous post was not written particularly clearly.  Should have re-done it,  but was pushed for time.

Because your batteries are Gel types,  you may also want to consider setting the Classic to 28.4 Vabs,  as Gel batteries are quite sensitive to over voltage charging.  This is probably putting too fine a point on things,  as the exact temperature of each individual battery never exactly matches its neighbors in the battery bank.

OK,  Good Luck,   Vic

[boB]

There is also a maximum and minimum compensated voltage limit adjustment in the LIMITS sub-menu.
That is for sealed VRLA batteries and can be adjusted to the absolute minimum and maximum limits
specified for that particular set of batteries.

boB