Unsure why solar charge controller shows full battery charge? - Page 1
Forum section: electronics / general

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: February 28, 2025, 10:56:48 am
content: I know the battery is close to full when it flashes green light to indicate full but it seems to flash inconsistently judging by the voltage.I am trying to understand what the likely routine is to tell the charge controller it is full because it doesn't seem to be based on voltage alone.Sometimes the full charge will flash at 13.3v and go into a sort of sleep mode where it won't add more charge, or just a trickle, to the battery yet other times it will still be pushing full current from the solar panels when the voltage reads 13.4v.Btw this is for lifepo4 battery.I asked the charge controller manufacturers and they said they cannot tell me what will cause it to flash as it is a 'trade secret' or something like that.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: February 28, 2025, 02:01:36 pm
content: You did not mention the charger brand/model so we can only assume.It's possible your charger is not for Lifepo4 but normal sealed lead acid, another option could be it needs configuring to operate with this chemistry.with out models/device names etc we can only guess.darkspr1te

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 28, 2025, 02:28:10 pm
content: Is it Lead acid battery.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: February 28, 2025, 04:49:59 pm
content: ok, so you using a battery charger that is ment for lifepo4 but using it on a lead acid, well thats you issue, lifepo4 charge at higher voltage compared to lead,i would change the charger for one ment for the designed battery.if i's a universal charger (RDS-6012 or victron 30amp charger) then you nede to adjust the charging specs to match lead acid.darkspr1te

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: March 01, 2025, 08:48:38 am
content: Quote from: darkspr1te on February 28, 2025, 04:49:59 pmYou are answering based on previous reply which was not made by me.It is a lifepo4 battery.The solar charge controller is not 'made' for lifepo4 out the box however it is able to be programmed using custom profiles. I was given the settings by a more experienced person on another forum which I am no longer on for a good lifepo4 charge profile.I actually realized something I was missing.I forgot about resting and charging voltages.I am thinking that probably the reason is that the voltage is raised above resting baseline, due to solar charge, when I am looking and seeing the light flashing. Something to do with that I imagine.Anyway not a big issue really. The mppt knows what to do it seems, having worked for over a year.I don't think the specific device matters. My question is a general one in that how would mppt chargers know when a battery is full. Is it based on the voltage at the battery posts?I can tell you the mppt anyway. It is epever tracer bn 4215.Manual.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: March 02, 2025, 09:38:58 am
content: Lol, My bad,as far how does it know it's charged is based on current draw/voltage over time most often. On page 5 of the manual (section 1.5) it shows a diagram off the current draw tail off , the charger itself goes through a few stages before this happens, if these stages happen correctly (voltage right, current draw right) it assumes the battery is charged, if this "max value" stays long enough the system will set that as 100% and then stop charging unless the voltage drops (first sign of a drain)a.f.a.i.kdarkspr1te

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: March 03, 2025, 09:37:44 am
content: Quote from: darkspr1te on March 02, 2025, 09:38:58 amThanks for the explanation.Yes as you mention it, I have noticed that the PV light will turn off completely sometimes as well, so no more charging, but then come to life again for a bit on trickle charge and sometimes full charge flashing. It alternates between these states.