question

kfergiez avatar image
kfergiez asked

MPPT 75/15 Controller draining batteries

TLDR: My batteries drain to 50% overnight. When I shut off charging on my MPPT controller, the batteries hold a charge just fine.


I've got a strange issue that I've been chasing down. I still need to do some testing, but any help would be greatly appreciated.


This controller is pulling in power from a solar array to charge a pair of group 24 deep cycle batteries on a small camping trailer. It's been running fine for 4 years.


I noticed on a recent outing that our batteries were oddly low. I took some precautions to finish our trip and brought things back home to test. Here are my findings thus far:

  1. Batteries have been load tested and are performing fine
  2. Tested the wiring for excessive draw and found none.
  3. Went through the logs of the controller and found that a week ago, my batteries would drop 50%.
  4. Turned off charging function and batteries did not drop at all overnight.

I'm going to see If I can narrow down the issue this evening. I'm curious to know if my controller is not shutting down the charging early enough.


Any thoughts?

MPPT Controllers
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2 Answers
detex avatar image
detex answered ·

Did you ever find a resolution to this? I'm also noticing the same on a number of different batteries with a 75/15. Huge drain overnight.

Battery overnight with 75/15 unplugged from it, holds voltage.. :/


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Sarah avatar image
Sarah answered ·

Hi @kfergiez , it is most likely the load connected to the MPPT that is discharging them and not the MPPT itself. Assuming you are using the load sockets. Try disabling the load in Victron connect and see what happens.
Sarah

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