I have a battery temperature sensor installed, but the Local App stubbornly denies its existence. I have lithium batteries, so I don't want temperature compensation. In the Local App, if I uncheck temperature compensation, for battery temperature, the Status panel says
BAT: Sensor Not Installed
If I check temperature compensation, but set the compensation to zero, again I get
BAT: Sensor Not Installed
So if I don't want temperature compensation but DO want to display the battery temperature, the only way seems to be to set the compensation to the minimum absolute value (-0.5mV/C) and the window to the minimum of 10C and check the Compensate Equalize Voltage Checkbox. Is there some other way to get the App to display battery temperature but do nothing with it?
I have equalize time set to zero. What will this temperature compensation profile do as a function of temperature?
Robert
First, EQ is by default, temp-comp OFF.
When you set the temp-comp to zero mV, what does the TEMP display on the Classic's MNGP display say ?
Does it also say NA (not available) ? I can't remember off hand what it does in that case but yes, you should be able to view the temperature I suppose.
This talks about lithium batteries and the temp sensor - from Midnite Knowledge base -see link below for more info than quoted here.
"The Classic now has a few new features that can be of use for Lithium Battery Systems.
Lithium batteries generally do not require temperature compensation like Lead-acid batteries do. Setting the mV/degC/cell to the lowest value without flipping the setting to DISABLE is about all we can do right now. This allows the BTS (Battery Temp Sensor) to function and this allows us to set an emergency HIGH BATTERY SHUTDOWN temperature in the LIMITS MENU under the CHARGE Menu in the Classic. When this temperature is sensed the Classic will stop charging to avoid a catastrophe."
http://www.midniteftp.com/support/kb/faq.php?id=75
Larry
Yes, but also, Lithium batteries have to stop charging when their temperature drops below some point as well.
Guess we have to eventually add that to the over-temp function as well. Of course, the BMS could also disconnect when its temperature is out of range.
Quote from: boB on July 12, 2020, 11:10:35 PM
Yes, but also, Lithium batteries have to stop charging when their temperature drops below some point as well.
Guess we have to eventually add that to the over-temp function as well. Of course, the BMS could also disconnect when its temperature is out of range.
Yes that over and under temperature feature would be a great and very useful addition for lithium batteries.
Larry
as excellent the midnite classic is. unfortunately not much work has done for them to work with lithium batteries. even american die hard lead acid fans are now turning to lithium batteries as they are getting cheaper and more available.
Quote from: australsolarier on July 23, 2020, 06:11:24 PM
as excellent the midnite classic is. unfortunately not much work has done for them to work with lithium batteries. even american die hard lead acid fans are now turning to lithium batteries as they are getting cheaper and more available.
The Classic works fine with most Lithium batteries as far as I know. I haven't heard of any that it doesn't work with ?
Lithium batteries have a BMS that makes them compatible with almost any controller.
Typically for a Lithium battery system, the Absorb time is set to a very low setting, like 1 minute or around there.
yes Bob, the midnite classic works with lithium batteries. maybe my wording can be interpreted that they do not.
"typically 1 minute setting for absorb time" : absolutely not! emphatically not. the float change is regulated by end amp and bulk V. (end amp is like 8A for an 400ah battery) it will hang around in absorption at least for 20 minutes for sure. depending how much net solar comes in. when it hits the bulk V, the current can still be very high, like 60 or more amps. as a matter of fact it can hit absorb as low as 75% with 120 amps or so. so that absorption timer will switch to float with 75% SOC . like many times stated in this forum the voltage of lithium, particularly lifepo4 are very stiff, unlike that of lead acid's which are heaps more elastic. 0.1V can make a giant different in a 48V system.
this is what i meant when i wrote "not much work has been done with lithium batteries.
my system absorb time is set to 1h. and i only set it that low, because so once or twice a year the follow me mode does not work with one of the midnites and then it keeps on cycling between float and bulk. unfortunately i am not always there to watch the status panel. so this is an added redundancy.
Quote from: australsolarier on July 23, 2020, 09:34:23 PM
yes Bob, the midnite classic works with lithium batteries. maybe my wording can be interpreted that they do not.
"typically 1 minute setting for absorb time" : absolutely not! emphatically not. the float change is regulated by end amp and bulk V. (end amp is like 8A for an 400ah battery) it will hang around in absorption at least for 20 minutes for sure. depending how much net solar comes in. when it hits the bulk V, the current can still be very high, like 60 or more amps. as a matter of fact it can hit absorb as low as 75% with 120 amps or so. so that absorption timer will switch to float with 75% SOC . like many times stated in this forum the voltage of lithium, particularly lifepo4 are very stiff, unlike that of lead acid's which are heaps more elastic. 0.1V can make a giant different in a 48V system.
this is what i meant when i wrote "not much work has been done with lithium batteries.
my system absorb time is set to 1h. and i only set it that low, because so once or twice a year the follow me mode does not work with one of the midnites and then it keeps on cycling between float and bulk. unfortunately i am not always there to watch the status panel. so this is an added redundancy.
There has been requirements for low amount of time or no time in Absorb (Bulk V). It has been many years since so thanks for the enlightenment.
The Classic's Aux 2 used as an input to turn it off from a logic signal was originally added from a request from a Lithium battery BMS manufacturer.