Roadrunner2 Report post Posted October 2, 2019 Neighbor who is unfamiliar with RVs has a 2017 Thor Tuscany. Failed to plug back in after a trip. Sat unplugged for 3 weeks. Discovered and all batteries are 2 volts or less including the start batteries. We plugged in but they are not charging. I can't locate any tripped breakers and see the power is getting to the line monitor. Assume the batts may be bad now but shouldn't they take some kind of charge? I thought the inverter would drop out and protect the batteries if they dropped to 11 volts. Why did the start batts go down as the key was not left on. As you can see I am only a little better informed than neighbor. I guess I am seeking help on where to start isolating the problem. Thanks for help. Share this post Link to post Share on other sites
wolfe10 Report post Posted October 2, 2019 Most smart chargers/smart inverter-chargers will NOT try to charge a severely discharged battery, This is a safety issue. You will need to use a "stupid" charger to begin the process. Once they are charged past extremely deeply discharged, the smart charger should take over. Share this post Link to post Share on other sites
Roadrunner2 Report post Posted October 2, 2019 Thanks Wolfe10. Any guess on why the start batts went dead or why the inverter let the house kept discharging all the way down? Is there an option I need to set on the Magnum? Share this post Link to post Share on other sites
desertdeals69 Report post Posted October 2, 2019 There are several reasons that batteries go dead. A current draw or moisture on the top of the batteries or bad battery. Batteries should be kept clean and dry. Share this post Link to post Share on other sites
rayin Report post Posted October 4, 2019 The inverter, when on, draws power from the batteries, as you know, then there are several phantom/parasitic loads that are also on all the time, some are on even when the main battery disconnect switch is activated. The sure way to disconnect MH battery banks is to disconnect the negative cables. At this point I would have the batteries de-sulfated, re-charging is part of that, and load tested 2 hrs after being removed from the charger. Then you/he knows the real condition of the batteries. As Brett said, one must use an old-fashioned stand-alone battery charger to kick battery voltage up to the point a smart charger will recognize they are batteries. ref: https://www.chargingchargers.com/tutorials/battery-recognition.html Share this post Link to post Share on other sites
