House batteries

[Joec]

I’m trying to find out what is correct way to maintain house batteries during winter. I was just starting RV and run motor 30 mins weekly. I found out that just running engine will only charge house batteries if voltage drops below 12.5.
Now I’m plugging in 120 volts , is this the correct way?? Also do I disconnect the battery switch? Thanks for your input on this issue trying to keep batteries in top shape
Joe C

 

[ghnl]

If you select 'store' on the Use/Store switch the batteries are disconnected. If you are plugged in to 120V (aka Shore Power) turn the switch to 'use' and the converter should keep the batteries charged. Older RVs may have a 'dumb' charger that might keep charging them and thus over-charge them. Most newer RVs will have a smart charger that charges the batteries then switched to a 'float' mode to keep them charged without over-charging.

Do you have a generator in your RV? It should be run - with an electrical load - for 60 - 90 minutes every 1 to 3 months. The electrical load (120V heater or A/C) is needed to work the generator parts and drive off moisture (condensation).

 

[Joec]

Yes, it’s a 5500 generator I ran it 45 minutes last week. Today I plugged rv in (120) and with battery switch on was charging 13.5 according to the display on the solar panel and the inverter. When I first plugged it in battery voltage was 12.5 volts charged a couple hours and was 13.5 volts on both displays. Turned battery switch off and immediately displays read 12.8 volts charged. I left RV plugged in but turned off battery switch. Is this correct?? I was told by the guy that I bought it from to plug in and turn battery switch off . Or do I even need to plug it in during the winter if battery voltage is above 12.5 volts charged??
Thanks for your input
Joe C

 

[ghnl]

Once the batteries are fully charged you can switch to 'store'. But if your converter has smart circuitry you can leave the switch on 'use'.

 

[16ACE27]

I was told by the guy that I bought it from to plug in and turn battery switch off . Or do I even need to plug it in during the winter if battery voltage is above 12.5 volts charged??

You were told wrong. Leave the battery switch ON at all times unless storing the RV for more than a few days NOT plugged in.

12.6 to 12.7 VDC on the batteries is fully charged. Anything above that is a temporary capacitive surface charge unless connected to a charger.

 

[tomah]

Howdy, and thanks for the information. We are new to having a camper and pretty lost.

I was hoping to clarify a few things regarding winter care. We store our 2021 Scope covered in our driveway. It gets winterized with an air compressor. Regarding batteries/power, am I understanding correctly that the following should be done:
-- leave it plugged in with the house battery in on/use mode - this will keep the the house (coach) and engine (chassis) batteries charged up.
-- run the generator 60-90 min every 1-3 month with the furnace or AC running
-- drive or run the motor 30 min every month
Is that all correct and am I missing anything major?

I also want to clarify from 16ACE27's post "12.6 to 12.7 VDC on the batteries is fully charged. Anything above that is a temporary capacitive surface charge unless connected to a charger."
-- how long does it take to fully charge the battery when plugged in?
-- what does it mean if I charge to 13.0 and within hours it drops to 12.0 for both the coach and chassis batteries? I had the chassis battery assessed by the dealership and they report the battery life is at 70% but it needs " a good charge."

Thank you for being patient with me, I am new to this. I appreciate any help.

 

[16ACE27]

I also want to clarify from 16ACE27's post "12.6 to 12.7 VDC on the batteries is fully charged. Anything above that is a temporary capacitive surface charge unless connected to a charger."
-- how long does it take to fully charge the battery when plugged in?
-- what does it mean if I charge to 13.0 and within hours it drops to 12.0 for both the coach and chassis batteries? I had the chassis battery assessed by the dealership and they report the battery life is at 70% but it needs " a good charge."

Time to fully charge a battery depends on many factors - too many to guess - it can take as little as 15 minutes if it was fully charged before starting an engine (for the chassis battery) or as long as 24 hours with really dead, old, cold house batteries.

There is not "charging to 13.0 VDC". Batteries need to have over 13 volts applied to just start charging. While charging the voltage should rise to 14 volts or above as the battery becomes charged.

If your batteries read 13.0 VDC after you've stopped charging and withing hours it is down to 12.0 VDC then it was not fully charged, or it is bad, or you have a draw on the battery.

 

[ghnl]

I would assume (with all that means...) that your 2021 model would have a "smart charger". Smart charging boosts the batteries to fully charged then cuts back to a maintenance charge. This avoids over-charging which can be just as bad for battery life as leaving them discharged. Thus, if I assume correctly, you can safely leave the RV plugged in with the Use/Store switch on Use.

As mentioned above, the batteries will likely not charge at 13V. It usually takes 13.8 to 14.4 volts to charge up the batteries. And 12V is, at best, 1/2 charged. If measured immediately after charging the batteries may show a higher voltage. That is known as a surface charge and will quickly dissipate. Better is to wait a few hours (with everything off) and see what the battery voltage is then. Fully charged is ~ 12.6V