House Batteries

Consider a better way to maintain the batteries.

If these are toast, consider SiO2 chemistry. It costs more initially--but has a lower cost per cycle. They can survive an occasional total discharge (not recommended).

1 Hour of running is NOT going to fully charge your dead batteries. Doug

jkc306 wrote:
Have 2017 Thor ACE, battery dead, jumped started and let run for about an hour. Unplugged from 30amp electrical while in RV barn. Few days later went out to Thor and discovered house batteries are dead...Pretty sure they are "new" still and should be working. Any insights would be helpful (New to RVing)

Maybe the disconnect was left in the in-use position and they discharged?
Plug back in and check battery voltage. You should see 13.6+ volts within an hour. Watch for excessive gassing or heat that would indicate an internal short. I assume you have proper water levels in the battery.

Have the battery load tested - most auto stores for free. New batteries fail or they are abused.

I installed a battery disconnect switch on the battery post on both banks so that every thing is disconnected. I also fully charge the batteries every month even though they will be OK for many months disconnected.

Since your talking about the chassis battery, A 2017 motorhome was likely sold in 2016 or at least the battery was placed then. So it's likely nearing the end of it's life.
Any auto parts store can test and recommend a suitable replacement.

If your batteries are “dead,” they are not still usable.

If your batteries are "dead" (<10V) and have been sitting that way for mor than a day, don't waste your time trying to recharge them. Buy new ones.

Every RV owners should have a multi-meter with a built in "amp-clamp". While these are not prefect meters, even the cheap ones will register a draw of over 100Ma (0.100A). Anything over about 10mA when you think everything is OFF will run a battery down.

Decent one (you can spend a lot more for one also) Uni-T UT210E Current Mini Clamp - Amazon $50

Have had the same thing several times. In your and most rigs, there is enough draw on the batteries to run them down in a couple of days. CO detector, maybe a light left on, whatever... It will happen. If you have a battery disconnnect, use that when leaving it for any period without power on.

Take the battery out and have it tested - I believe Batteries plus will do this for you.