I parked the RV after 10 months on the road and full service at the dealer which included checking all batteries. I parked it for 10 days with no shore power and the coach batteries (4 6 volt) were down to 11.7 v. I had the inverter off, and both battery banks shut off. This has happened before, but I had forgotten about it. I have power to run charger thru the winter, but would like the option of disconnecting if we have power outage etc. I understand some coaches have things wired directly to battery bank, but would like to know best way to figure out what is drawing power when everything is shutoff.Thanks.

first thing I'd check is your audio system. Many of the radio's in RV's draw current in the "off" mode which is really standby. Enough to drain a single 12V in a few days, Also often the CO and propane detectors along with smoke detectors are wired to 12V.Check those out first. Now when you say you had the battery banks "shut off" if they truely were disconnected the only load is the battery self discharge which is very very low.

The best way to check for parasitic drain is use a quality meter and check for amps, at the battery. Plenty of youtube vids to show you how.Also,if your batts were quite low on electrolyte,then topped off, but not fully charged before parking, this can happen.

I would test each battery individually and make sure you don't have one that's going bad.

I installed a disconnect switch at coach batteries. They hold charge for weeks.

Some radios draw power to keep the memory for favorite stations and other owner set features.Another draw could be forgetting to turn the antenna power button off. I include it in my packing up to return home checklist.

Power "vampire" on coach batteries | Good Sam Community

ktmrfs
Explorer II
Oct 23, 2021
Gjac wrote:
ktmrfs wrote:
Gjac wrote:
I would disconnect the neg battery terminal and set your muti meter to 10 amps with one lead on the post and one lead on the cable. This will tell you what your parasitic draw is. If over a couple of amps something is left on . If you do this simple test first and post what your draw is you will solve your problem. As a data point my parasitic draw on my chassis battery is .4amps. If less than 1 amp I would check the cells in your battery.

couple of amps is WAY to high. if everything is off, draw should be on the order of 0.01A or less. Even 0.4A is going to discharge a battery bank faster than you want. That's about 10Ah/day
As I said in my post if you have a couple of amps draw something is left on. However I misplaced a decimal on my parasitic draw, it should read .04 amps or 40 milliamps. On a newer MH with radio, satellite ,GPS systems, Wifi and other electrical stuff the draw will be higher. For OP's batteries to go dead in 10 days something is left on or batteries are bad. If after you check the draw and find it more than an amp or two you can then go to your 12v fuse box and start pulling fuses one at a time to see which one reduces the draw.

Lots of vehicles from the last 15 years or so will go through a shutdown process over around 20 minutes or so. But to get to that state it requires doors shut, ignition off, hood closed, no kefob nearby, etc. making it hard to actually measure standby current. But it will drop to the 10-40ma range.
Gjac
Explorer III
Oct 23, 2021
ktmrfs wrote:
Gjac wrote:
I would disconnect the neg battery terminal and set your muti meter to 10 amps with one lead on the post and one lead on the cable. This will tell you what your parasitic draw is. If over a couple of amps something is left on . If you do this simple test first and post what your draw is you will solve your problem. As a data point my parasitic draw on my chassis battery is .4amps. If less than 1 amp I would check the cells in your battery.

couple of amps is WAY to high. if everything is off, draw should be on the order of 0.01A or less. Even 0.4A is going to discharge a battery bank faster than you want. That's about 10Ah/day
As I said in my post if you have a couple of amps draw something is left on. However I misplaced a decimal on my parasitic draw, it should read .04 amps or 40 milliamps. On a newer MH with radio, satellite ,GPS systems, Wifi and other electrical stuff the draw will be higher. For OP's batteries to go dead in 10 days something is left on or batteries are bad. If after you check the draw and find it more than an amp or two you can then go to your 12v fuse box and start pulling fuses one at a time to see which one reduces the draw.
MEXICOWANDERER
Explorer
Oct 23, 2021
A favorite robber is a power amplifier for a stereo sound system. A hidden light left on in some remote compartment is another drain.

An unprofessionally installed constant duty power relay's coil can draw amperage.
ktmrfs
Explorer II
Oct 23, 2021
Gjac wrote:
I would disconnect the neg battery terminal and set your muti meter to 10 amps with one lead on the post and one lead on the cable. This will tell you what your parasitic draw is. If over a couple of amps something is left on . If you do this simple test first and post what your draw is you will solve your problem. As a data point my parasitic draw on my chassis battery is .4amps. If less than 1 amp I would check the cells in your battery.

couple of amps is WAY to high. if everything is off, draw should be on the order of 0.01A or less. Even 0.4A is going to discharge a battery bank faster than you want. That's about 10Ah/day
Gjac
Explorer III
Oct 23, 2021
I would disconnect the neg battery terminal and set your muti meter to 10 amps with one lead on the post and one lead on the cable. This will tell you what your parasitic draw is. If over a couple of amps something is left on . If you do this simple test first and post what your draw is you will solve your problem. As a data point my parasitic draw on my chassis battery is .4amps. If less than 1 amp I would check the cells in your battery.
mobeewan
Explorer
Oct 22, 2021
Some radios draw power to keep the memory for favorite stations and other owner set features.

Another draw could be forgetting to turn the antenna power button off. I include it in my packing up to return home checklist.
hughesjm21
Explorer
Oct 22, 2021
I installed a disconnect switch at coach batteries. They hold charge for weeks.
blaczero
Explorer
Oct 21, 2021
I would test each battery individually and make sure you don't have one that's going bad.
MT_BOB
Explorer
Oct 21, 2021
The best way to check for parasitic drain is use a quality meter and check for amps, at the battery. Plenty of youtube vids to show you how.
Also,if your batts were quite low on electrolyte,then topped off, but not fully charged before parking, this can happen.
ktmrfs
Explorer II
Oct 21, 2021
first thing I'd check is your audio system. Many of the radio's in RV's draw current in the "off" mode which is really standby. Enough to drain a single 12V in a few days, Also often the CO and propane detectors along with smoke detectors are wired to 12V.

Check those out first. Now when you say you had the battery banks "shut off" if they truely were disconnected the only load is the battery self discharge which is very very low.

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