Dual 12 volt batteries drain and are dead within 6 hrs. Everything seems to work correctly boondocking and on shore power. while boondocking the batteries will go dead within 6 hrs. I put new batteries in and drove to camp and slept over night and when i got up the batteries were dead. I ran the lights for maybe 15 minutes before going to sleep. nothing else was turned on. I cant find anything that is wrong. Any ideas????

something else IS ONyou just have to find itpossibilities whole house inverter is on..fridge is set to auto instead of LP, get power from inverter and drains batteriessame for water heater on electricshort circuit connection in battery control centerindividual components, converter and inverterboth on, converter trying to charge batteries, using inverter power from batteries equal constant drain loopbatteries NOT getting charged, you only think they are getting charged while drivingbuy a digital multi-meter, learn too how to use it, keep it in the RVmust have for all 'modern' RVs

Google battery parasitic battery draw ... should provide the basics for diagnosing. Yours sounds like something major ... the one time I had an issue it was the electric step motor which did not shut off. Providing some basic info about your rig - model, age etc might help.

I would bet you are not getting charged properly, assuming the batteries are OK. Do a few voltage checks to see what might be. Check the unit batteries with nothing connected:Check the unit batteries with the engine running:Check the unit batteries with the unit plugged in to shore power:Check the converter output right on the converter itself to see what the converter is putting out:Check the vehicle battery when off:Check the vehicle battery when running engine:Most likely, there is a very loose wire somewhere, and while you think the unit should be fully charged, you have a loose connection and the charge voltage is just causing a loose connection to heat up. In my case, everything was like you said, but I found the negative wire at the converter negative terminal to the battery was so loose it was barely connected. It had heated up and melted a bit of insulation, would not charge the batteries and worked fine with a couple of turns on the screw head.

Well, I have a multi meter and cant find any draws on the battery as of yet. obviously some thing is draining battery. But how do you check if the inverter/converter is draining the battery?

shane102.sc wrote:Well, I have a multi meter and cant find any draws on the battery as of yet. obviously some thing is draining battery. But how do you check if the inverter/converter is draining the battery?At least two people have suggested that your batteries are not being CHARGED anywhere near enough.And now I make 3.It is not "obvious" that something is draining the battery.That is only one possibility.There are several.For instance, new batteries often come 50% charged or less.....and the alternator in the chassis or tow vehicle often doesn't really provide much charge when going down the road (sometimes none). New batteries should ALWAYS be manually charged before installing.And what are you seeing that makes you think that the batteries are DEAD ??And just for curiosity, are they connected is series (6 V) or parallel (12 V) ?

dual batteries drain quickly | Good Sam Community

theoldwizard1
Explorer II
Oct 09, 2018
marcsbigfoot20b27 wrote:

For the RVC system like on my 13 Tahoe, you can simply disconnect the amperage sensor around the positive wire and it will be steady and not in different charge modes.
If you read into it, there is a lot of thinking going on by the BCM for battery charging, even "desulfation mode".
I can view and change the output of the BCM commanded alternator output volts and amps with my Tech 2 and see if everything is working.

Most "smart charging system" have the "smarts" in the PCM/ECM/ECU. (Pick one acronym - they all have the same primary function. Control the engine for better fuel economy and emissions.)

Why ? Because the PCM CAN raise the idle speed to accommodate the vehicle requirement for more voltage from the alternator/regulator.

What we call the "regulator" these days has less functionality than in the past. Someone tells the regulator to "make more voltage". The alternator does so (by changing the current going to the field) and then reports back "I am making X power". That report might be a percentage, or a voltage, depends on the manufacturer. While these messages could be passed on some kind of "data bus", they frequently are passed using pulse width modulation on dedicated wires.

You can have very weird charging systems problems when one of those computers is "lying" (passing invalid information) to the other.
theoldwizard1
Explorer II
Oct 09, 2018
shane102.sc wrote:

I am now letting the camper sit over night plugged to truck to see if problem is solved. basically all I have done is checked for draws and have found none on the truck side and/or camper side. cleaned a few connectors and thats it.

We will see in the mourning if batteries stay charged

Follow up ?
theoldwizard1
Explorer II
Oct 09, 2018
MEXICOWANDERER wrote:
Eek, to use proper vernacular drivetrain functions are derived from

Engine
Control
Unit

ECU

Recent vehicles utilize a

Body
Control
Module

BCM

Mex you have to get "up to date" !

PCM = Powertrain Control Module. They use this term because the compture chip in that box controls the engine and the transmission and sometime the AWD/4WD.

BCM, while a common term, is not universal. Ford calls it a "Smart Junction Box" (SJM). FCA calls it a "Totally Intgrated Power Module" (TIPM). Even between vehicle models of the same manufacturer some functions may or may not be in this module.
marcsbigfoot20b
Explorer
Oct 05, 2018
shane102.sc wrote:
jax mike-s marcs and red 31 stop scuffling over acronyms and Capitol letter abbreviations and put that thinking into solving my issue.

Come on boys. start at my first post and read all the posts and get to work. (please)

I am now letting the camper sit over night plugged to truck to see if problem is solved. basically all I have done is checked for draws and have found none on the truck side and/or camper side. cleaned a few connectors and thats it.

We will see in the mourning if batteries stay charged

Thanks for the help
Shane

So a recap please.....
I think you were saying that by itself, the travel trailer voltage holds its own, mostly.
If hooked up to the truck, the batteries drain quickly?

If that is correct, you need to verify that your truck 7 pin is wired correctly and the charge relay or charge wire if your truck has one is hooked up correctly.
What truck and trailer model, year?
wa8yxm
Explorer III
Oct 04, 2018
One of the things I most strongly do not like is TLA's that is Three Letter Acronyms In fact several terms and things used in these forums be they TLA's or full words mean different things.

TV Television
TV Tow vehicle
EMS.. Intelletec uses it to mean one thing. Progressive INdustires something Quite different.

Though I use A/C to mean Air Conditioning AC is used to mean both Alternating Current and Air COnditioning.

and several other terms are like that as well.. PCM (Pulse Code Modulation and Power Control Module) likewise.. I have to admit as an Electronc type I think the former and have to adjust when it is the latter. NOt complainign in the specific but in general.

Good idea. the first time you TLA to (Three Letter Acronym) Spell it out. Else confusion will ensue

Thus proclaimed the deity: "ENSUE ILLUMINATION"
And Illumination thusely ensued.

A very common phrase.. I translated it from English... to English.
Well. actually Dr. I Asimov did the translation. I just read his essay.
shane102_sc
Explorer
Oct 04, 2018
jax mike-s marcs and red 31 stop scuffling over acronyms and Capitol letter abbreviations and put that thinking into solving my issue.

Come on boys. start at my first post and read all the posts and get to work. (please)

I am now letting the camper sit over night plugged to truck to see if problem is solved. basically all I have done is checked for draws and have found none on the truck side and/or camper side. cleaned a few connectors and thats it.

We will see in the mourning if batteries stay charged

Thanks for the help
Shane
marcsbigfoot20b
Explorer
Oct 04, 2018
red31 wrote:
i watch my scan gauge have large swings in voltage! adding headlights does not keep the voltage high.

https://srs20assets.service-solutions.com/Media/OEM/GM/en-US/Generic/Downloads/Document%20Library/TL_Sept04.pdf

For the RVC system like on my 13 Tahoe, you can simply disconnect the amperage sensor around the positive wire and it will be steady and not in different charge modes.
If you read into it, there is a lot of thinking going on by the BCM for battery charging, even "desulfation mode".
I can view and change the output of the BCM commanded alternator output volts and amps with my Tech 2 and see if everything is working.
mike-s
Explorer
Oct 04, 2018
JaxDad wrote:
PCM is usually taken to mean Powertrain Control Module.
See, there's the problem with using undefined acronyms. "PCM" seems to be a Ford/GM term, not some generally accepted industry-wide one. And, in electronics, PCM is usually taken to mean Pulse Code Modulation.

My car uses an ECM (Electronic Control Module) to sense the battery. That info goes to an IPDM E/R (Intelligent Power Distribution Module Engine Room), which in turn controls an IC (Integrated Circuit) regulator using PWM (Pulse Width Modulation).

No PCM to be found anywhere, but there is a regulator.
red31
Explorer
Oct 04, 2018
i watch my scan gauge have large swings in voltage! adding headlights does not keep the voltage high.

https://srs20assets.service-solutions.com/Media/OEM/GM/en-US/Generic/Downloads/Document%20Library/TL_Sept04.pdf
JaxDad
Explorer III
Oct 04, 2018
mike-s wrote:
theoldwizard1 wrote:
On almost all light duty vehicle built in the past 10 years, alternator charging (i.e. output voltage) is controlled by the PCM, NOT the "regulator".
Define what you think is the difference between PCM and regulation, and what you thing "the PCM" is, because the normal meaning is that pulse code modulation is a method, not a thing.

PCM is usually taken to mean Powertrain Control Module.

Newer vehicles have adopted the European model of using lots of very light gauge wire as control circuits and then have relays as part of system control modules located close to the load itself.

Mine as an example has 4 such modules, one for all rear lights (including trailer wiring), one for front lights, one for the powertrain and one for all the interior and body functions.

This is in addition to the vehicles ‘brain’ itself.