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Old 11-11-2019, 03:29 PM   #1
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Brand: Thor Motor Coach
Model: Chateau 31L
State: South Carolina
Posts: 20
THOR #3217
2016 Chateau 31L - battery issues

I am hoping someone can help me understand the relationship between the truck battery (Class C RV) and house batteries. We have had issues with both since we purchased this new in 2016. let's start with the truck battery - what should we do with it when we will be leaving the rig parked in the driveway for a couple of months at a time? I bought a black and decker 12v battery tender and that doesn't seem to help it from getting run down. Just this morning I had AAA replace it as it was dead dead. Also the house batteries are dead at this time - not sure what i will be doing for that situation yet. And, can't start the generator - push button and absolutely no sound or attempt to start - and this is with the newly replaced truck battery - so assuming the generator gets started from the house batteries? my question - how can i charge up the house batteries? there is a use/store button for the house batteries. when we get home from a trip we usually plug in the battery tender attached to the truck battery and leave the house batteries on use. and to add - i have the unit plugged into a regular house plug (30amp to house plug adapter) all the time when parked in driveway. any insight and intelligence on this topic would be greatly appreciated - not sure why - but i just can't get my head wrapped around the battery situation. thank you for any assist and guidance.
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Old 11-11-2019, 06:49 PM   #2
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Brand: Thor Motor Coach
Model: 2013 ACE 30.1
State: Alberta
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THOR #2631
Well typically the house batteries provide 12vdc for your coach DC loads but they also power the generator starter motor (as you found out) and hydraulic leveling jack pump motor if equipped. Batteries fail for many reasons and one of them is plate sulphation from inadequate or not getting regular appropriate charging voltages.



The best procedure is to buy a multi-meter (voltmeter) and check your battery string voltages (coach and chassis) to make sure they are charging under normal conditions (on shore; on gen and when engine is running). Some coaches don’t necessarily charge both strings at the same time so you will have to determine if that applies to you. If the battery strings are receiving at least 13vdc or more they are charging at least.



When parked in your driveway plug into shore power....even if you only have a standard 15 amp house connection (use the appropriate 30 amp adapter on your shore cord). Note the use/store must be on to charge house batteries (and chassis batteries in many coaches) when on shore power. If your house batteries are dead/discharged the use/store latching relay will not work to allow charging from shore (unless it failed in the on position), so you will either have to charge them with a car battery charger first (some new car chargers wont work with dead batteries either); or you may have to boost them from a known good 12 vdc battery (tow car?) just enough to get the latch relay to turn on so shore power can start charging. Check it is with your new voltmeter.



Many folks on this forum use auxiliary battery disconnect switches on the battery terminals to completely disconnect batteries when the coach is stored (log on and do a search). Note though wet cell batteries require regular charging at high enough voltages to remove sulphates from the battery plates, so leaving them disconnected for very long storage times can result in shorter battery life.
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Old 11-11-2019, 08:13 PM   #3
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Brand: Thor Motor Coach
Model: Chateau 31L
State: South Carolina
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THOR #3217
thank you for the response, javelin. i still have to reread this a few times LOL but what i think i understand your point about the house batteries being so dead now that being plugged into shore power (even if just 115) the use/store button is stuck in store - so even though i am plugged in - the house batteries can't get charged. wondering - could i use a regular car jumper cable from the new truck battery to one of the house batteries to charge it for a bit to get it so the use/store switch will work? and if so - what configuration of red/black on each end should i use - red black on the truck battery and red/black on one of the house batteries? and - an aside - should i bother with the 12V battery tender on the new truck battery - or should i disconnect the positive instead - (for when the truck is just sitting in the driveway? thank you!!!!!
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Old 11-11-2019, 10:23 PM   #4
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Model: 2013 ACE 30.1
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THOR #2631
Hi, yes, your new and charged chassis (truck) battery can be used to boost the house batteries with proper jumper cables connected in parallel (+ to + and - to -) to get enough voltage to operate the use/store house latch relay. I would personally remove the chassis battery from the engine bay first though (a PIA) or even attempt a temporary boost from your Toad. This is just like boosting a discharged car battery but you are placing a single good battery in parallel with (I assume) two 12vdc discharged house batteries which are already connected to each other in parallel. If you have two 6vdc house batteries they will be wired in series (to make 12vdc).......so be careful to connect the new battery across the 12vdc connection points only and in correct polarity. Also 12vdc batteries can cause serious damage if you are not careful with jumper cables and where you connect them. If you are not comfortable doing this get a mobile tech to assist.

Note that in most coaches you could try operating the “emergency start” switch by the driver seat somewhere, which basically connects the two battery strings (coach and chassis) together via a different relay, without using any jumper cables. But, there is one problem though; this “other” emergency interconnect relay usually gets its power to operate from good house batteries also. Since yours are discharged, the emergency start method will also likely not work. So manual connection or a stand alone car battery charger are required. If you knew your coach well and could identify the emergency interconnect relay you could manually bypass its main terminals to simulate the emergency contact closure......but this might be too dangerous if you are not careful and depending on your experience. I am attaching a basic typical schematic showing the connections of a 12vdc battery system for reference only.....it may not be what you actually have.


Assuming all else in your battery charge system is functioning correctly, once the new battery is correctly connected you should be able to operate your use/store switch and hear the latching relay operate. Plug in shore power and your converter (coach battery charger) should start charging your discharged house batteries (plus the temporarily connected chassis battery). A voltmeter across the three parallel batteries should measure the charging voltage (approx 13vdc or higher depending on how badly discharged the house batteries are and other coach DC loads that may be on. Once the old house batteries begin charging you should be able to disconnect the chassis battery and reconnect it for the engine function.


Regarding the last question, after you fix your current porblem, if you find that plugging into shore power only charges your house batteries and not the chassis battery at the same time (and it is designed to be like that), then it is wise to use a battery tender as a minimum on the chassis battery. Again your voltmeter will show you if both battery strings will charge off shore power/coach converter. Take measurements across both strings when charging. If both strings charge on shore power then you should not need the tender.
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Old 11-12-2019, 11:41 AM   #5
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Model: Vegas 24.1
State: Florida
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THOR #5313
The first week we brought our e450 based unit home the chassis battery drained.. Emergency start would not work due to being so low. I was not plugged in used the use/store button in store position. I since learned on our unit we always keep it plugged in and never use store position. If we did not have option to plug in I would add battery disconnects. There are parasitic draws on both battery banks. Our unit is always stored at either of our houses and plugged in. It also never sits more than 2 weeks at a time, usually less.

On a warning note, a few months back on a trip the chassis battery died while fueling. Running lights left on while fueling drew it down. I was able to start internal generator and use racecar charger to boost and continued. I now check battery capacity every quarter by unplugging and running inverter to power tv. When I first installed inverter it took 6 hours of tv to drop panel to 3 lights. Last week it only took 2. Time for new house batteries. I check chassis battery with cigarelle lighter display. When plugged in it goes from 12.4 to 13.2.
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Old 11-12-2019, 12:09 PM   #6
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Model: Chateau 31L
State: South Carolina
Posts: 20
THOR #3217
Muggs, Javelin - thank you for your responses. i am going to do some more research based on your comments/guidance and will come back here with our plan - or - most likely more questions. really appreciate the time it takes to write out these responses - and willingness to help a completely battery/electric ignorant fellow camper. believe it or not - i am a computer/technical person but for some reason electric and battery concepts are just beyond me. even the terms just confuse me. and my brother was an electrician on a submarine for 13 years - i guess he got all the electric brain cells. thanks again. chat soon.
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Old 11-12-2019, 01:08 PM   #7
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THOR #2631
Quote:
Originally Posted by Muggs View Post
The first week we brought our e450 based unit home the chassis battery drained.. Emergency start would not work due to being so low. I was not plugged in used the use/store button in store position. I since learned on our unit we always keep it plugged in and never use store position. If we did not have option to plug in I would add battery disconnects. There are parasitic draws on both battery banks. Our unit is always stored at either of our houses and plugged in. It also never sits more than 2 weeks at a time, usually less.

On a warning note, a few months back on a trip the chassis battery died while fueling. Running lights left on while fueling drew it down. I was able to start internal generator and use racecar charger to boost and continued. I now check battery capacity every quarter by unplugging and running inverter to power tv. When I first installed inverter it took 6 hours of tv to drop panel to 3 lights. Last week it only took 2. Time for new house batteries. I check chassis battery with cigarelle lighter display. When plugged in it goes from 12.4 to 13.2.

Just a comment regarding a wet cell battery state of charge. Your 12.4vdc measurement represents about 75% of full charge only. The voltage measurement to estimate state of charge should be taken at least several hours after battery charging has been stopped; and while battery is kept unloaded. When charging, your cigar lighter voltage monitor is confirming that you are at least "float" charging the battery, but it is showing you the converter output voltage across the battery. To get the last 25% charge and remove plate sulphation, your converter should probably be running over 14vdc (Absorption mode) holding that voltage while letting the charge current fall as the battery voltage rises. Some after market converters (like Progressive Industries) allow you to manually force this stage and also have an automatic mode as well if you leave it on shore power. There is lots of info on line about the "care and feeding" of wet cell batteries.
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Old 11-12-2019, 06:55 PM   #8
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THOR #5313
Yes the 12.4 to 13+ is nominal while unit sitting I may not see actual charge rate. I got a little over 5 years total life on battery. So based on life of my SUV and Altima batteries I will likely replace arbitrarily every 4 years. Overall performance leads me to think existing converter is adequate.

Is rare when I actually depend on chassis batteries. Sometimes overnight in cool weather they run heat overnight. I do not use onboard generator much as we are either plugged in or running chalpion RV ready generator on trailer. At this point it likely has 10 times the 417 hours on Onan. We just came back from 4 day race where I would fill up, check oil and use continuosly. 3.5 gal gets me 9 to 16 hours of run time.
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Old 11-14-2019, 12:24 PM   #9
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THOR #5837
As a data point, the house batteries in my 2018 Chateau 31E lasted less than 2 years before they would no longer hold a charge. I replaced them a couple of months ago with AGM batteries, which hopefully will last longer. The original batteries also needed water added quite often, and I don't have to hassle with that anymore.


I have had no issues with the truck battery, even after winter storage.
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Old 11-16-2019, 06:32 PM   #10
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Model: Chateau 31L
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THOR #12189
Mine died in April of last year. I grab an adjustable wrench and remove the + clamp fro the terminal. Not a fancy solution and works like a disconnect switch, just takes 15 seconds instead of 5. Haven't had a problem since and I can park for month+ at times.

House batteries are a whole 'nother animal (almost). They take a little more abuse than the chassis battery, constantly up and down. Darn, charge, drain, charge, on and on. Drain doesn't mean wipe out here. It means drawing juice. Your chassis battery most like only sees a draw at startup. Even if you run a lot of 'accessories' while driving, the alternator is replacing it as fast as it's consumed so the draw-down is significantly less. Your house batteries will only get that treatment when plugged in and the converter sees they need a charge.
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Old 11-23-2019, 09:56 PM   #11
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THOR #15410
Quote:
Originally Posted by jbrophy View Post
I am hoping someone can help me understand the relationship between the truck battery (Class C RV) and house batteries. We have had issues with both since we purchased this new in 2016. let's start with the truck battery - what should we do with it when we will be leaving the rig parked in the driveway for a couple of months at a time? I bought a black and decker 12v battery tender and that doesn't seem to help it from getting run down. Just this morning I had AAA replace it as it was dead dead. Also the house batteries are dead at this time - not sure what i will be doing for that situation yet. And, can't start the generator - push button and absolutely no sound or attempt to start - and this is with the newly replaced truck battery - so assuming the generator gets started from the house batteries? my question - how can i charge up the house batteries? there is a use/store button for the house batteries. when we get home from a trip we usually plug in the battery tender attached to the truck battery and leave the house batteries on use. and to add - i have the unit plugged into a regular house plug (30amp to house plug adapter) all the time when parked in driveway. any insight and intelligence on this topic would be greatly appreciated - not sure why - but i just can't get my head wrapped around the battery situation. thank you for any assist and guidance.
We have a battery tender on truck battery with no issues. Make sure everything is off. The house batteries have a store switch, which I use and make sure the inverter is off . We have had no issues. Something must be draining them . Our truck radio, camera runs off the inverter. The unit also has a auto gen start that I make sure is off. Sorry, I can't help more good luck
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Old 11-23-2019, 09:57 PM   #12
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THOR #15410
Quote:
Originally Posted by jbrophy View Post
I am hoping someone can help me understand the relationship between the truck battery (Class C RV) and house batteries. We have had issues with both since we purchased this new in 2016. let's start with the truck battery - what should we do with it when we will be leaving the rig parked in the driveway for a couple of months at a time? I bought a black and decker 12v battery tender and that doesn't seem to help it from getting run down. Just this morning I had AAA replace it as it was dead dead. Also the house batteries are dead at this time - not sure what i will be doing for that situation yet. And, can't start the generator - push button and absolutely no sound or attempt to start - and this is with the newly replaced truck battery - so assuming the generator gets started from the house batteries? my question - how can i charge up the house batteries? there is a use/store button for the house batteries. when we get home from a trip we usually plug in the battery tender attached to the truck battery and leave the house batteries on use. and to add - i have the unit plugged into a regular house plug (30amp to house plug adapter) all the time when parked in driveway. any insight and intelligence on this topic would be greatly appreciated - not sure why - but i just can't get my head wrapped around the battery situation. thank you for any assist and guidance.
We don't leave our unit plugged in either
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Old 11-24-2019, 03:07 PM   #13
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Brand: Thor Motor Coach
Model: Windsport 32R
State: South Carolina
Posts: 21
THOR #17209
Battery Issues

If you plug in a battery tender or charger to the engine battery while not in use, the BIM (battery Isolation Module) will not be energized and you won't charge the house battery. I have just gone through this for a neighbor and found that a LOT of BIMs are bad. Hers failed in the ON position so that you never really disconnect the engine battery which draws it down. The BIM is energized when the key is turned to the ON position. It is deenergized in the off position. Also, if you are plugged in to shore power, the converter/inverter should be charging the house batteries as long as the use/store switch is in use position. If it doesn't charge the batteries, there is a problem with the wiring or the converter. Just because it's relatively new does not mean that it works. The emergency start relay in my neighbor's unit was wired improperly from the factory and Camping World did not honor the warranty charging them almost a grand to fix it.
Just sayin'.
As a sidebar, my Windsport has TWO disconnect switches, one for the engine battery and one for the house batteries. Works like a charm and I have never had a problem. I also don't trust the bar graph idiot lights for the charge state so I removed my panel and wired in a voltage monitor. When I'm plugged in, the converter supplies 13.5 volts. When the generator is running, it supplies 13.5 volts. When the engine is running, the alternator supplies 14.4 volts which gives a full charge. It also lets me know what voltage is left in the house batteries any time the batteries are in USE mode.
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Old 11-24-2019, 05:04 PM   #14
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Brand: Thor Motor Coach
Model: Four Winds 31W
State: Michigan
Posts: 452
THOR #9522
My 31W class C does not charge the chassis battery when plugged in ( confirmed with Thor that is how it is designed). Coach yes but chassis no.

My solution is a 0.75 amp battery minder plugged in inside the coach with the output plugged into the cigarette lighter on the dash. Works great to keep the chassis battery charged since that outlet is always live. Without the minder it takes a month or two to run down the chassis battery.
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2018 Four Winds 31W
1999 Aero Cub F-21 trailer
1977 Tioga 24 foot RV
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Old 11-24-2019, 05:06 PM   #15
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Brand: Thor Motor Coach
Model: Four Winds 31W
State: Michigan
Posts: 452
THOR #9522
Quote:
Originally Posted by TLeenhouts View Post
If you plug in a battery tender or charger to the engine battery while not in use, the BIM (battery Isolation Module) will not be energized and you won't charge the house battery. I have just gone through this for a neighbor and found that a LOT of BIMs are bad. Hers failed in the ON position so that you never really disconnect the engine battery which draws it down. The BIM is energized when the key is turned to the ON position. It is deenergized in the off position. Also, if you are plugged in to shore power, the converter/inverter should be charging the house batteries as long as the use/store switch is in use position. If it doesn't charge the batteries, there is a problem with the wiring or the converter. Just because it's relatively new does not mean that it works. The emergency start relay in my neighbor's unit was wired improperly from the factory and Camping World did not honor the warranty charging them almost a grand to fix it.
Just sayin'.
As a sidebar, my Windsport has TWO disconnect switches, one for the engine battery and one for the house batteries. Works like a charm and I have never had a problem. I also don't trust the bar graph idiot lights for the charge state so I removed my panel and wired in a voltage monitor. When I'm plugged in, the converter supplies 13.5 volts. When the generator is running, it supplies 13.5 volts. When the engine is running, the alternator supplies 14.4 volts which gives a full charge. It also lets me know what voltage is left in the house batteries any time the batteries are in USE mode.
If you have an inverter, it's display works fine to display the coach battery voltage. Just remember to not leave it on if you are not plugged in.
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2018 Four Winds 31W
1999 Aero Cub F-21 trailer
1977 Tioga 24 foot RV
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