4 replies to this topic

[buckland]

I have 2 BB LiFePo4 batteries (200 ah), Victron: DC to DC charger, MPPT 100 I 20 controller, (200 W Renogy panel + 100 W portable), Smart Battery Shunt. 

 

Since I updated the firmware on all of the above I scrolled through the App pages of each blue toothed unit above (3).

 

I have a few questions as it seems 'things' are different. 

 

* Instead of Lithium Battery it states 'user decided' which very well maybe as I have tweaked a few settings... but I know I had 'Lithium' chosen before. (there is a Smart Lithium now listed as an option). Perhaps the questions below will help determine if this should stay as is?

 

*Not sure my settings for the DC/DC Charger settings. If anyone sees incorrect settings in the photos below please let me know. I just have a nagging feeling it is not charging over 13 V when the battery could easily take up to 14.2?

 

 

 

 

 

 

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[Vic Harder]

Rob, first off, the resting voltage on the opening page of the app is 12.5V in my settup, with dual Optima Yellow Top AGM starting batteries.

 

Under Battery Settings, I also have:

 

-  "user defined"

- Absorbtion voltage = 14.4V

- Float voltate = 13.4

 

Unlike you I have

- Bulk = Disabled (so no time limit)

 

And like you I have

- Adaptive absorption time OFF

 

And unlike you my 

- Fixed absorption time is 1h (I wonder if this needs to be bumped up or turned to ON above so it stays in Absorb longer?  BB says 2 hours, so you are closer to "correct" than I am)

 

The BIG differences are in the Engine Shutdown Detection section

 

- Alternator type = user defined

- Start Voltage = 13.2

- Delayed start voltage = 13.1

- Delayed start voltage delay = 20s

- Shutdown voltage = 12.8

 

I also have Input Voltage Lock-out disabled.

[buckland]

Thanks Vic. Correct me if I'm wrong but the settings for AGM and LiFePo4 would not be the same as the charging profile is different. My question was if the alternator charging is being stopped at a too low a voltage, i.e at 13V when it could be charged to 14.2. I Thought you had lithium batteries? 

I have a smart alternator and sometimes see my truck battery voltage at 15.5 V (actually the voltage jumps all over the place at times). 

I just want to be sure that I am using the DC/DC charger appropriately for Lithium. 

Edited by buckland, 29 May 2023 - 04:26 PM.

[Vic Harder]

Same as you, lithium in the camper and AGM starting batteries.  The DCDC is looking at the AGM side to determine when to start sending charge over to the camper batteries, especially in the  "engine shutdown detection" section of the settings.  The Lithium part of the setup is in your "user defined" battery voltages for absorb and float. 

 

Yes, your "Start" voltage is way to high.  This is my logic....

-  At rest, my healthy AGM batteries will be sitting at 12.7.  I do NOT want the DCDC to engage at that voltage.

-  When running, my "smart" alternator drops to 13.7 when the truck batteries are fully charged... I DO want the DCDC to be running then

- So set the "Start Voltage" at higher than 12.7 and lower than 13.7

- Set the "Shutdown voltage" at lower than the start voltage, and just above resting voltage.

 

Make sense?

 

Caveat, I have 2 AWG cables from alternator to camper, so voltage drop is not much of an issue for me.  With smaller wires, you may have to tweek these settings... 

[buckland]

Thanks Doc, That does make sense and will make the adjustment when I get back home. Currently on the road. Appreciate your knowledge.