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Battery question 2018 T@B 400 with solar

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  • BrianZBrianZ Member Posts: 1,765
    @Deb55, if you have the same batteries as @Dutch061 discussed above, then I'd use his value for tail current, since that setting is based on your batteries' amp-hours (AH) rating, which is greater than my 150AH.  Likewise, I'm not sure if my Peukert value is transferable, since you have AGM while mine is flooded lead acid type.  You might have to do your own comparison of the State of Charge percent to the "Consumed AH" display, and if it doesn't match, then adjust SOC by changing Peukert up or down accordingly, but it won't make a huge difference.
    @Denny16, I've not seen issues or reports of WFCO overcharging, but I've seen many of undercharging.  It doesn't appear to fully charge ours (which I'm about to report on), but seems ok for a maintenance charge.
    -Brian in Chester, Virginia
    TV: 2005 Toyota Sienna LE (3.3L V6)
    RV: 2018 T@B 320S, >100 mods 
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  • Denny16Denny16 Member Posts: 5,431
    edited November 2022
    Me either Brian, but this was a possible issue pointed out by our TaB dealer during a recent presentation to TaB owners, who services a lot of the TaBs in Northern Calif., that the WFCO is not a fully regulated charger, and does not have a real float mode, it keeps a small charge current on the battery continuously whilst the TaB is not used.  if the TaB is used, than no issues leaving the WFCO charging the battery.  The issue was with storage over several months or longer.  

    This said, we have left ours on the WFCO charger over last winter without any issue.  I think it is harder to overcharge an AGM, but lead acid batteries can be over cooked with excessive charging.  But, we also have solar charging (which does go into float mode, so I am going to switch off the battery this winter, and let the solar maintain the battery, and use the WFCO (connected to shore power) power the trailer.
     Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
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  • BrianZBrianZ Member Posts: 1,765
    Thanks for that update, @Denny16.

    Yesterday I performed a battery charging test using our WFCO built-in charger with my new Victron settings shown on the previous page, but with a couple of updates shown below..

    I found that our battery spec sheet actually listed 14.8V as the charge voltage, so as described in the manual I used a slightly lower value of 14.6 for the "charged" setting.  I also returned to the default 95% efficiency setting after reading that lead acid batteries are closer to 100.
    Next, I discharged the battery to 80% SOC using the 12V frig..

    The Victron monitor graph below shows both the discharge and the charging curves for volts & amps..

    Although I'm not surprised at these results, it's not a great curve, since the charge voltage never got above 13.7V, even by the next morning after running all afternoon & night.  It left us with a less than fully charged battery..

    I think this reinforces our current practice of using the external smart charger that I reported on in the previous page, as a more reliable method for getting a full charge with our current setup.  I should note that I previously added a second 8G ground wire to our system (between Alde-Converter Ground Bus-7-way Junction Box-Battery), but have not yet added an 8G positive cable.  As far as I know, the WFCO seems to work fine as a trickle charger to keep the battery topped off.  I do test each cell's specific gravity by refractometer on a regular basis, and it's still ok after 5 years.
    -Brian in Chester, Virginia
    TV: 2005 Toyota Sienna LE (3.3L V6)
    RV: 2018 T@B 320S, >100 mods 
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  • Denny16Denny16 Member Posts: 5,431
    edited November 2022
    Good to know Brian, thanks for your update.  Whilst not an actual float charge mode, the WFCO low setting seems to work fine as a trickle charger with your batter6 setup.
    Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
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  • BrianZBrianZ Member Posts: 1,765
    Just a follow-up..  Here is the page from our WFCO8735 manual describing its operating modes..

    It describes the float mode, which does appear to agree with what I've observed.  Starting with a fully charged battery, I've tested this, and it does start out at 13.6V; but after about 24 hours or so with appliances turned off, it drops back to float mode at 13.2V and stays there unless a load is connected, as described above for Float Mode.
    -Brian in Chester, Virginia
    TV: 2005 Toyota Sienna LE (3.3L V6)
    RV: 2018 T@B 320S, >100 mods 
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