Long Recharge Issue

I've done a quick search...but was a bit overwhelmed with all of the posts so I decided to start a new discussion.
We were dry camping last week and for the first two days my rooftop solar did very well...restoring the batteries from 90% to 100% in 4-5 hours (very good, direct sun).  
The last few days were a bit overcast so, as expected, it didn't recover fully.  I was only down to about 84% battery when I packed up, so I wasn't concerned.  I drove all the way home hooked up to my TV.  I would have thought that after a 4 hour drive, it would have been recharged...but I didn't think much of it.  I don't get a lot of direct sunlight in my parking spot, so I wasn't too suprised when, after a few days, I was still less than 90%.  I plugged into shore power two days ago and I am still only at 95%.  This seems very strange.  It seems that, in the past, it always reached 100% overnight when connected to shore power. 
I will start digging into details, but any advice would be appreciated!


  • JilongJilong Member Posts: 85
    You'll need to post a few more details about your electrical system. What year and model T@B? What type and size of battery? What size solar panels? What type of controller and shunt?
    2018 Tab 400 × 2013 Toyota Highlander Limited AWD
  • Basil48192Basil48192 Member Posts: 251
    @Jilong.  Thank you!  Makes sense.  I thought my post might be a common issue that others have run into and a quick 'check this'!
    I may be over-reacting as well....it just seems to be taking much longer than it has in the past....though I've never really timed it.
    Here are my details:
    -2021 T@B 320S
    -Upgraded batteries (2 years ago):  2, 6V, 235 AH AGM wired in series
    -Victron shunt style battery monitor
    -105 watt factory roof solar panel with Victron MPPT 75/10 controller
    -200 watt Renogy suitcase panel with Victron MPPT 100/30 controller (not used for this trip)

    On Monday, I noticed that I was still around 88% battery.  I just assumed that it was slow because, at this time of the year, I get very little direct sunlight on my rooftop panel.  So, I plugged into shore power.  Almost 2 days later, I'm still only at 95% and virtually nothing is running in the camper except typical parasitic draws from various panels.  Below is a screen shot from my battery controller as of a few minute ago.

    Maybe it's just in the slow, 'trickle' charge phase of the converter, but it still seems like it should have been 100% charged by now.

    Thanks again for the help!

  • Basil48192Basil48192 Member Posts: 251
    OK...apologies....but a good lesson!

    I checked all of my fuses and breakers...all good.  
    Next, I turned off all power, then disconnected the positive leads to my battery.
    Then I turned shore power back on to make sure I was getting power from the converter to the battery lead...and I was. 
    Although they didn't look bad, I cleaned the terminals and connectors to make sure I had good contact.  I also made sure my shore power plug was tight...though it only took 1/4 turn.  When I put everything back together and restored power, I was at 100%!
    Maybe just a marginal connection..maybe on the battery monitor...but it seems fine now.  
    Thanks again!
  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 9,426
    I would charge via a smart charger, then reset the Victron BMV.  It can require calibration when exposed to multiple charging methods.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
  • Basil48192Basil48192 Member Posts: 251
    @Sharon_is_SAM.  Thank you...I will look into a smart charger.  I wonder if, by unplugging everything, I ended up resetting the BMV...and thats why it jumped from 95 to 100% when I reconnected?  Still not sure how it got corrupted.  I have been charging with shore power and two solar controllers for over two years and this is the first time I've had any issues.  Thanks again!
  • manyman297manyman297 Member Posts: 1,185
    @Basil48192 I had kind of a similar experience this year. My batteries charge to 100% but it can take a while to get there. I documented it here:


    I’m not sure if my issue is the battery or solar. I’m leaning towards batteries as they seem to be discharging faster than normal. Also because I was hooked to a generator for hours and my batteries still weren’t getting topped off. 

    I need to maybe do a hard reset like you did.
    2021 400 BD
    2020 Tacoma TRD Off-Road 
  • AnOldURAnOldUR Member Posts: 1,263
    The voltage on my batteries had dropped to 13.4V after sitting for over a month with the battery switch and solar charging off. My shunt's SOC was still at 100% even though the voltage had dropped. No current had gone in either direction. A firmware update cleared the shunts SOC yesterday so that there was no percentage reading in the app. After attaching my NOCO and the voltage going up to the 13.8 "charged voltage" it went back to 100%.

    Wondering if @Basil48192 unplugging had the same result as my update reset?
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler

  • Basil48192Basil48192 Member Posts: 251
    @manyman297.  Thank you for the link!  It seems this is a more common issue than I thought.  I really think (and hope) that this is a battery monitor issue (as it seems with @AnOldUR).
    Again, I haven't really monitored the discharge/recharge rate closely, but the change to my system was definitely not linear.  It went from a very quick recovery to a painfully slow recovery....virtually overnight.  I will do some testing in the next few days as I have a 5 day boondocking trip scheduled for the end of the month.  

    I almost exclusively 'boondock' and usually just use shore power at home to maintain a charge.  For the past 2 1/2 years, my discharge/recharge cycle has been very consistent.  With my fridge running, lights, fan, heat, etc., my 235 AH (6V) batteries drop down to ~88-90% in a typical 24 hour period (consuming around 26 AH).  With good sun, I can usually get back to 100% charge on the following day (often using my rooftop and 200W suitcase panel).  I have a 2021 320S...but I'm guessing power consumption is relatively the same on a 400.  
    Thank you again for all of the replies.  I'll let you know how my testing goes.  
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