Classic aux settings for lifepo4 bms charging termination

[mahendra]

What are the aux setting that should be on a classic for charging termination.Of course the bms is determining the soc and termination voltage.
Bms has an out put relay for charge controller charge termination.

[ClassicCrazy]

I use ending amps for terminating the Absorb  charge for LiFePo4

I don't get what you mean  about the Aux  - it controls stuff but you make it sound like you want something to happen in reverse where the BMS sends signal to AUX to control Classic ?

In the Arduino section Will has code that controls the Classic various ways but he is doing it via modbus commands .

Larry

[mahendra]

Yes exactly,
Sometime ago it was mentioned that one of the aux ports can be used to receive a signal from a bms to turn off charging

[ClassicCrazy]

oh I did not know that - should be in the manual somewhere.

Larry

[ClassicCrazy]

Is this what you are looking for ?
11-28-2012
   Added Aux 2 Logic Input Function that makes Classic go to Resting when Aux 2
   is greater than approximately 6.0V (30V MAX) for 2 seconds minimum and
   lets it charge again when input drops to less than approximately 2.0 VDC

http://midniteftp.com/forum/index.php?topic=229.msg11215#msg11215

Although that won't work if you have a Whizbang on there.

Larry

[mahendra]

Yes but I don't think the settings there is practical for 48 v lifepo4. Battery bank

[mahendra]

Ok I was looking through the manual and noticed the features of aux 2 . Particularly the logic input 1 and logic input 2 .
Would someone be so kind and elaborated how this would work with a bms signal to stop charging.

[5 Minutes 2 Midnite]

Mahendra, I was just about to make a post with the same question, and there was yours at the top. I have a different trigger for the input, but beyond that I need the same result you are looking for; Classic goes to resting when input is triggered. From what ClassicCrazy has referenced you are going to need to have your BMS output relay close a 7-30v circuit that will then feed 7-30v to the Aux 2 relay contacts on the classic.

If your 7-30volt source is current limited (not sure how much current your BMS relay, or the Classic Aux 2 input maxes at) then you may be able to simply wire the source voltage through your BMS relay and to the Aux 2 inputs. When the relay closes the Classic will see the voltage on Aux 2 and stop charging.

:>

[5 Minutes 2 Midnite]

Having said that, and if Mahendra doesn't mind me piggybacking on his thread with a similar issue, My need is to also have the charge controller go to resting based on an external trigger. However, my Aux 2 is taken up with a Wizbang.

So is there a way to rig Aux 1 for INPUT? Ideally the programing would be simply IF the Aux 1 contacts are shorted THEN Classic goes to resting.

----
Just to explain the need, I need a way to stop charging my LiFePO4 pack if only ONE single cell goes over 3.6v. Fortunately the Cellogger volt meters connected to each the pack will close a relay (or open it) when any ONE cell exceeds the set voltage. This is just a way further I am attempting to accommodate Lithium Ion batteries to the Classic and keep them safe.

[mahendra]

Same here 5 minutes but I have two classics networked.
I am going to use the vacant aux two while still making use of the wbjr

[mahendra]

My bms does have a relay that would send a signal to aux 2 but I have to verify the voltage when closed

[boB]

Aux 1 doesn't accept a signal as an input.  However, a small computer like a Raspberry Pi or similar can easily be made to
tell the Classic to turn on or off with an input signal to it...

I wonder why others haven't made this happen ?  We could but don't have the time to do that right now.

boB

[5 Minutes 2 Midnite]

However, a small computer like a Raspberry Pi or similar can easily be made to
tell the Classic to turn on or off with an input signal to it

boB. Thank your for chiming in on this topic. I am relatively new to Midnite, but it's heartening that senior Midnite personnel find the time to participate here. Two questions if I might:

1) If someone was to look into using a Pi type device where would they be looking to interface with the controller in the case where Aux 2 is busy with the Wizzbang Jr? With Aux 1 being output only, where would the Pi connect to the controller?


2) Bigger picture, how big a deal would it be for future versions of the Classic to have Aux 1 take on the versatility of Aux 2? Or would it be so much re-engineering we'd be looking at an Aux 3?

I ask because as a person who just completed his first system, and employing Lithium ion batteries, I've discovered the shortcomings of virtually all charge controllers in dealing with this chemistry. Short of charge controllers being engineered with multiple channel charging (the controller having the ability to control the charging rate of each cell) 3rd party solutions such as BMS systems must be employed. I was delighted to learn recently that the inexpensive and commonly used Celllog devices that monitor individual cell voltage have the ability to close a relay if any ONE cell goes beyond a defined voltage range. Beautiful!

So I guess I'm being selfish because I would love my charge controller to be able to easily interface with the cellog device, while still providing all the joys of the Wizz bang.

And to be eve more 'selfish', ideally it would be great to have an input on the Classic whereby simply shorting the terminals on the Aux port would put the controller in [programmable] Resting mode. Why? Because that would negate the need for a separate voltage source to either provide trigger voltage to the terminals, or keep a Pi device powered! After all, it's all about mitigating energy use in an off-grid system.

boB, if you've heard this all before ad infenitum, I apologize. Thanks for reading this though.

jim

[boB]

Jim, the way the pi would connect would be through the Ethernet jack OR one of the RS-232 jacks.
Both communicate using the MODBUS protocol.  Somewhere on our site there is a document with the information on how
to do this.  It's definitely technical but can be done.

The Classic will more than likely not have an Aux 3  but not sure how hard it would be to add an input for Aux 1 ?

The issue has to do with resources (time) with too few engineers as well as too many new projects under way here.

One thing that comes to mind about making Aux 1 an input as well as an output is that another connection would have to
be made from the bottom power board up to the control board and I believe that all of the connector pins are used.

Won't hurt to take a quick look though even to satisfy my own curiosity.

boB

[5 Minutes 2 Midnite]

Won't hurt to take a quick look though even to satisfy my own curiosity.

Thanx. And It might be fun to throw the Pi idea to a MODBUS programmer on upwork.com. Those folks were cheap, and if there is sufficient documentation on how the Classic uses MODBUS perhaps they could write the code w/o actually having a Classic on hand. If I work up the energy I might iterate the idea, since so many could possibly benefit from such a solution.