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 > Power "vampire" on coach batteries

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Land Yachters

Philadelphia

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Posted: 10/21/21 08:33am Link  |  Quote  |  Print  |  Notify Moderator

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.


Land Yachters
Griff, Ali and Coco
Philadelphia, PA
2018 Tiffin 33AA
2018 Grand Cherokee


ktmrfs

Portland, Oregon

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Posted: 10/21/21 08:44am Link  |  Quote  |  Print  |  Notify Moderator

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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MT BOB

Montana

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Posted: 10/21/21 09:52am Link  |  Quote  |  Print  |  Notify Moderator

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.

blaczero

USA

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Posted: 10/21/21 10:07am Link  |  Quote  |  Print  |  Notify Moderator

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

hughesjm21

Hoschton

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Posted: 10/21/21 07:44pm Link  |  Quote  |  Print  |  Notify Moderator

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

mobeewan

Hampton, Va

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Posted: 10/22/21 10:16am Link  |  Quote  |  Print  |  Notify Moderator

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.

Gjac

Milford, CT

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Posted: 10/22/21 07:59pm Link  |  Quote  |  Print  |  Notify Moderator

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.

ktmrfs

Portland, Oregon

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Posted: 10/22/21 10:17pm Link  |  Quote  |  Print  |  Notify Moderator

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

MEXICOWANDERER

las peƱas, michoacan, mexico

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Posted: 10/23/21 04:28am Link  |  Quote  |  Print  |  Notify Moderator

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.

Gjac

Milford, CT

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Posted: 10/23/21 08:44am Link  |  Quote  |  Print  |  Notify Moderator

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.

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