Settings for mppt 100/50

DIY
1

Hi all , a newbie here just trying to get my head around some settings if anyone can help
I have 800w of solar and 4 x 120A OF LIFEPO4 batteries , what i found was at 70%charged the charger is going into float mode
I did read a couple of forums and people were saying to go into expert mode and change some settings ,
The problem is i dont want to stuff anything up so i was hoping someone could give me a few settings that might help. Batteries are 14.6v charge rate
Any tips would be great thanks
ken

2

Go to the settings and select battery, set the preset to Smart Lithium which will charge them to 14.4V which is fine. You can adjust it to 14.6v in advanced settings but not required. I find charging to 14.2V is fine for my batteries. Good luck.

3

thanks for reply , how long do you set the hours of absorption to as the preset of 2 hrs seems very short , It is in a RV so i need as much charge as i can get , thanks

4

Absorption should only start when the battery reaches 14.4V and at that point the battery should be at 95% charged so the absorption should be short, some battery makes suggest 15 minutes, Victrons are max 2 hours. Long absorption times on lithium can overcharge the batteries. I suggest you do not increase this.

5

Thanks for reply , so why would the charger start on bulk and only stay on that for a short while then go into absorption even when the battery is only at 50% and voltage around 13.6
then after 2 hours charging the bank is only at 70% and it goes into float mode only putting in around 8A when it has around 30A available thanks

6

  1. Make a screenshot of your MPPT settings and post here for confirmation as the behaviour does not sound right.

  2. Thos is often a symptom of a poor connection between the MPPT and batteries with a high resistance and voltage drop. The MPPT reads a higher voltage than the battery does so it believes the battery is fuller than reality. When charging measure the voltage at the battery and the MPPT terminals and see the difference. Then check for loose connections, crimps, frayed wire, poor isolators or fuses. The cheap resettable breakers often have poor performance.

7

Also, where is your SOC reading coming from?

8

Where are you reading 13.6V? If you are reading 13.6V at the battery and the MPPT voltage is different you might have a cable problem. A high resistance will increase the voltage and the MPPT will read a much higher voltage and go into aborbtion then float. Check the cables are not too long or too small and measure the voltage to see if it’s the same as the battery. You can also set up a Bluetooth network using a shunt or battery monitor close to the battery so the voltage reading for charging is accurate.

9

sorry for slow reply , i called away for a few days
I think JohnC might have hit the nail on the head with the resettable fuse
While watching all the settings i heard a very light ticking sound a couple of times especially when charge got up to 30A or above
It seemed to be coming from the breaker
I have replaced the breaker and it seems to be staying in bulk mode for the moment
ill keep an eye on it and see if that solves the problem , thanks

10

They are not the best to use if they keep tripping they will weld themselves closed. The best to use is a fuse. A maxi blade fuse is good for about 30amps, a midi fuse will go to about 50 amps a mega fuse or ANL is much better and will do 100amps + without getting too hot.

11

Ok if this works ill get one and replace the breaker thanks