Classic 150 - Can you stop charging based on battery temperature

[ScottTENN]

I'm transitioning to lifep04 batteries and my location will put my batteries just at freezing from time to time.  I can heat the room and all that but is it possible to program the Classic 150 to not charge when a low battery temperature is sensed?  I'm not looking to compensate for the temp but to not charge at all when the battery sensor is say at 35d F.

Thanks

[ClassicCrazy]

The answer is no.
It is a feature that has been asked to be added if possible  in some future firmware update.
Larry

[boB]

It is coming.

Should have been there when high temperature cut off was added

However, the battery's BMS should stop if it is charging when too cold.

But that doesn't allow it to discharge when cold I guess which is what you would want.


boB

[ScottTENN]

My battery manufacturer specifically states that there is no temperature cut off.  There is for high temp, but not low.  I'll keep my eyes open for new firmware and just use a small heating blanket in the meantime.

[ClassicCrazy]

My battery manufacturer specifically states that there is no temperature cut off.  There is for high temp, but not low.  I'll keep my eyes open for new firmware and just use a small heating blanket in the meantime.

You could  also rig up your own low temp control . There are lots of inexpensive programmable thermostats that you can get that run on 12v, 24v , or 110 . You could use that to a relay capable and rated for shutting off the PV input or battery charging input - what ever is better.

Larry

If you had a thermostat to create or break a connection the classic does have a logic high and a logic low input you could drive with that thermostat and that will stop it from charging. The bigger issue at the moment is you cant use the BTS if temp comp is disabled.

The good news is we have an engineer that is going to tackle the classic bug fix and upgrades list so any one with any bugs or wants please email support@midnitesolar.com your list with "Classic fixes" in the subject line

[ScottTENN]

Funny you mentioned the relay because that was the route I started with.  Amazon'd the goods but have not opened the boxes yet.  I was going to temp control a relay to open and close the incoming PV.  I just hadn't decided which way to wire, fail open or fail close.  It could also be something disconnected when not needed. Which might change my fail decision.  If you fail open, because of a hardware issue, you get no voltage even if the temp is in a good range.  If you fail close, you could be charging a battery when you shouldn't.  Joys of LiFePo4.

[Steve_S]

LFP can only take Partial Charge from 0C to 10C.  Usually below 0.25C-Rate or 25A for 100AH Battery max after which you can go to full 0.5C-Rate or 50A for 100AH Battery.
LFP can safely discharge to -15C with some up to -20C.

Ideally, being able to program the SCC to manage Charge Rate relative to Temperatures would be ideal because this applies not only to LFP and now with the Sodium Cells and others coming to the Open Market this entire battery universe is going to evolve again in a huge spurt.

I heat my powerhouse with a recovered RV Furnace (12V Battery powered, LPG fuelled, direct vent) which I pulled from a new but wrecked RV, got the "Suburban NTS-20" with all fitting (including regular from RV) etc for <$300 and works the treat keeping things at 10C/50F.  I only had to extend the Direct Vent Exhaust & make a metal Thimble to go through the wall.

There are Thermostatically controlled "Warming Pads" like RV Water Tank pads and seedling matts which are encased in Silicone.  They are available for 12,24,48V models as well.  Several offer adjustable thermostats and can be fed directly from the battery terminals BUT you would have to put it all into an insulated box.  Several of our members use this method without any issues but also aware that there is a powerdraw that will affect runtime.  Have a look at this One of Many threads on it:  https://diysolarforum.com/threads/lifepo4-battery-warmer-install.14485/

BTW, I use a Samlex EVO Inverter/Charger, they have CanBus, ModBus and more comms but also they can use the Temp Sensor Input as a "Cut Off" trigger activated by a relay to stop Inverting or Charging in Lithium Mode.  Many of the higher grade tiered equipment has such capabiilities.

Option Possibility.  Using an external controller such as a RaspberryPi setup to interact with the Classic SCC & can control relays and/or opti-couplers to engage & disengage various things including the battery pack(s). 

FOR MIDNITE SUPPORT:  The method used by Samlex using the Temp Sensor as a Relay Input Signal in Lithium Mode may be an option  (depends on the hardware within our SCC's I imagine)...   It really IS time that the Classics can address life with Lithium.  One BIG PITA, is that there needs to be TWO Voltage Offset settings, they are different between Charge & when Not Charging and even 0.2V difference can result in weirdness.  Such a shame you guys never approached Volthium and arranged partnered LifePo4 battery systems branded for Midnite.   For the curious, Canadian Designed and Made with Canadian Content (hint hint) https://volthium.com/en/batteries/  and note they are all CSA/UL/ETL + Certified   Remember that the IP for LFP is up in 2022 which means more LFP Manufacturing and worldwide at that without the steep royalties etc...  Facilities are going up and some are in place already "paying the heavy fees" to be ahead of others.

Hope it helps, Good Luck