Battery drain while disconnect is off

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Joined
Jan 9, 2021
Messages
5
I just put a simple electrical system in my cargo trailer. I have two AGM 12 volt batteries. The positive lead goes through a disconnect before connecting to the inverter. I fully charged the batteries to 100% and left them with the disconnect off. It shouldn’t matter but the inverter was off too. In one week the batteries dropped to 53% just sitting. Everything is mounted to a wood shelving system I built. Is this normal? I can do a test by fully charging and removing the battery cable to the disconnect. I don’t think it will matter as the only thing on the system is the inverter and it was off.
any ideas? Thanks
 
Joined
Nov 2, 2019
Messages
3,020
Location
WA, MT or somewhere else!
RV Year
2018
RV Make
Newmar
RV Model
Mountain Aire 4047
RV Length
40'
TOW/TOAD
2014 Honda CR-V
Are the batteries new? How did you determine that they were charged "100%?"

Batteries do lose charge, even when they are disconnected, but I would expect a battery in good condition and charged to 100% to last more than three days before dropping to 53%.

TJ
 
Joined
Jan 9, 2021
Messages
5
Are the batteries new? How did you determine that they were charged "100%?"

Batteries do lose charge, even when they are disconnected, but I would expect a battery in good condition and charged to 100% to last more than three days before dropping to 53%.

TJ
The batteries are new. I bought them and brought them home and put them on my charger. I built the rest of the system and then connected the batteries. Ran a heater for 30 minutes. I then turned off the inverter and disconnect switch. I recharged the batteries and parked the trailer for a week. When I went in this morning I put my charger back on to see where it was at (it shows current % of charge) it said 53%.
 
Joined
Jan 9, 2021
Messages
5
The batteries are new. I bought them and brought them home and put them on my charger. I built the rest of the system and then connected the batteries. Ran a heater for 30 minutes. I then turned off the inverter and disconnect switch. I recharged the batteries and parked the trailer for a week. When I went in this morning I put my charger back on to see where it was at (it shows current % of charge) it said 53%.
I just bought a Renogy battery monitor and connected it this morning. I am recharging now to calibrate the monitor.
 
Joined
Nov 13, 2019
Messages
324
Location
Where ever I park it
RV Year
2017
RV Make
Salem
RV Model
Hemisphere 346RK
RV Length
38'
So, what you are saying is that the positive from the battery goes directly to the disconnect? If so, there should be no load on the battery UNLESS you have something hooked to the positive before the disconnect.
 
Joined
Jan 9, 2021
Messages
5
So, what you are saying is that the positive from the battery goes directly to the disconnect? If so, there should be no load on the battery UNLESS you have something hooked to the positive before the disconnect.
So I found the issue today. My wife plugged in a 1500 watt 120v heater and ran it. The inverter went into alarm and she didn’t tell me. 😂 I recharged the batteries and everything is working right now. My fault I didn’t tell her she could not use that thing. Our old trailer had a generator so she thought she could use it in this set up. I ordered a bunk heater so that issue will be solved soon.
 
Joined
Nov 13, 2019
Messages
324
Location
Where ever I park it
RV Year
2017
RV Make
Salem
RV Model
Hemisphere 346RK
RV Length
38'
Well, thank you for letting us know what the problem was! At least it was an easy fix.
 
Joined
Jan 9, 2021
Messages
5
Well, thank you for letting us know what the problem was! At least it was an easy fix.
Thank you for your time looking at the post. Wish my wife had told me she plugged the heater in. Could have saved everybody some time. Thanks anyway for your time.
 
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