Maximum Compensation Temperature (TS-45 Charge Controller)

Stuart

Thanks in advance.  I am programming a TS-45 Morningstar charge controller for L16 Trojan batteries and there is one parameter that I am trying to understand: Maximum Compensation Temperature (and Minimum).   They may just be the battery specification operating temperatures of -20C to +45C but the default  TS-45 values are +80C to -40C which is wide so I am trying to make sure I get this right.

The TS-45 help file defines the Maximum Compensation Temperature as "Maximum temperature at which temperature compensation is clamped".  

Any insight? Thanks

Estragon

I'm not sure about the MS specifically, but my sense as someone who has written a bit of software in a past life is that these are "sanity check" values. Without them, a sensor failure or sotware bug could theoretically send charging voltage infinitely high or low.

The controller should increase voltage at lower battery temp, and decrease voltage at higher temps. Having a wide (but finite) range shouldn't be a bad thing. If the batteries are getting to anything like 80°C, you definitely want the controller dialing back voltage. If you never see battery temps less than -20°C, it wouldn't hurt to limit voltage increase there. Some inverters and other loads get picky about voltage when compensated to really cold temps.

Stuart

Estragon, Thank you for your comment and I agree that the compensation needs to be limited.  The question now is whether to use the battery operating temperatures for the min and max or the default controller values. Thanks again for your input.

Estragon

Compensating based on a remote sensor attached to the bank is the better way to do it. Batteries are a large thermal mass.

If the bank is even getting as warm as 45°C, you likely have a problem. I would leave it at the default so it keeps reducing voltage at higher temps.

mvas

DEFAULTS:
Maximum Compensation Temperature = All temperatures above +80C, will be treated as if they were +80C
Minimum Compensation Temperature = All temperatures below -40C, will be treated as if they were -40C

If your Charge Controller will be connected to your battery bank AND
your Battery Bank's temperature will be above +45C, or will be below -20C,
then enter the temperature values for your battery.

Changing these limits is not "critical" to normal operation.

My battery bank will never be above +45C / +113F,
and won't be much below -20C / -4F,
so the DEFAULTS work just fine for me.

Many battery banks will get cold in the winter,
but are you really planning on letting the temperature of your battery bank climb above +45C / +113F ?

mcgivor

Agree with @Estragon, leave it at default, the controller will compensate both ways, hot or cold, ensuring a corrected voltage, also use the voltage sence input provided for more accurate results.

Stuart

Great information, thank you very much. I will leave the values at the default settings.  I appreciate your expertise and time.

BB.

If you are in a very cold climate (arctic)--Then setting the minimum temperature may be required. Using numbers:

• (-40C+20C nominal)*-0.005 volts per degree C per cell * 6 cells (aka 12 volt battery) + 14.75 volts nominal charging = 16.55 volts charging (@ -40C)

Many AC inverters do not like >15 or 16 volts and will shut down. So while the battery "may be happy", your attached loads may not be in cold climates "unbounded" charging voltages.

-Bill