I have a lithium system installed in my motorhome along with a Multiplus and just added a CCGX to it, is it possible to limit the SOC to say 80% as lithium batteries don’t like to be held at full charge.
Thanks
asked
CCGX limiting SOC
I don't think that there is any 'formal' way to do this yet...
But you could possibly get it working by using the CCGX generator start/stop function to trigger the relay (open it) at 80% SOC.
The CCGX relay output can be connected to the MPPT remote terminals and it would stop the MPPT charging whenever the circuit is opened.
To enable a full charge / balance when desired you could also wire in a simple switch to keep the MPPT remote terminals closed. You may also be able automate this say once a week using the more advamced CCGX generator start/stop functionality/options.
Edit: Sorry I just read your post again & see that you want to limit charging with a Multi & not a MPPT... You may be able to achieve the same by wiring the CCGX relay into the Multi 'Aux In' terminals and using / creating an assistant to stop charging or disconnect AC In. The Multi also tracks SOC % itself & that can also be used directly (without the CCGX).
I see that @Boekel has just replied - he is quite good with programming of Multi assistants & Lithium batteries so should be able to advise further.
What kind of lithium batteries do you use?
Even if the BMS shows 100% SOC for the batteries, it should not normally keep the batteries above the voltage for safe "long-term battery endurance". If you do not fully charge Lithium Batteries, the Battery BMS may never get a chance to "balance" the under-charged cells. So only charging your batteries to 80% may do much more long-term damage!
I recommend that you use the "Absorption" and "Float" voltage settings specified by the battery/BMS supplier for use with the Multiplus.
IMHO don't micro manage your Lithums. They don't like it.
Just let it run and only worry about full depletion. Even then an occasional bottoming is good. Lithium isn't lead acid where all this micro management is useful.
Think about it. Your phone is lithium -- how many times have you only charged it to 80%? How many times have you charged to 100% and let it sink to 0%. How long have you had your phone?
I have had mine for 4+ years and it takes the abuse just fine. I even monitor to see if there has been degradation and their hasn't been a bit. In contract, I have a friend who keeps it on charge as much as possible and never let's it die. The battery has been replaced twice.
Lithium are the baddies of the battery world. They like it rough.
I’m using Victron 12v 2x90ah
Than just use the recommended charge voltages, the 'float' voltage is a safe level where you can keep the batteries all the time.
80% charge to increase cycle-life is not applicable for LiFePO4 batteries. If you want to keep 'm healthy just don't discharge too much, below 12V (under no or light load) the battery is pretty empty, and below 11V really empty. Low voltage events (a cell below 2.5V) are really damaging and should be avoided at all times.
