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Old 01-18-2021, 10:24 AM   #1
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Battery - when needed.

Am new to travel trailer camping and no immediate plans to rough it in the middle of nowhere.

When at campground plugged into 30 AMP and at home with unit plugged in, can I simply just disconnect battery?
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Old 01-18-2021, 10:29 AM   #2
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I would not. Your battery operates your break away brakes incase trailer comes comes unlatched down the road.
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Old 01-18-2021, 10:32 AM   #3
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I would not. Your battery operates your break away brakes incase trailer comes comes unlatched down the road.
Disconnecting the battery may/may not be a good idea... but you don't need break away brakes when you're "at campground plugged into 30 AMP and at home with unit plugged in."
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Old 01-18-2021, 10:37 AM   #4
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Thanks. Am not sure why and if battery is needed when unit is parked and plugged in.
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Old 01-18-2021, 10:41 AM   #5
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Am new to travel trailer camping and no immediate plans to rough it in the middle of nowhere.
Hahaha, i read that as "am new to travel trailer camping and have immediate plans to rough it in the middle of nowhere." Be aware when disconnecting your battery, it will self-discharge over time, and will not be charged by your RV's converter. The converter will convert AC power to DC for your trailer stuff without the battery, as was the case when dealer gave me walk-through during PDI, there was no battery installed as I brought my own.
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Old 01-18-2021, 10:43 AM   #6
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Found a couple interesting comments here:

https://www.everything-about-rving.c...-electric.html

Having found out the expensive way; turning off your batteries can also lead to burning up your inverter/converter. If your plugged in, the converter uses the batteries as a buffer as well as charging them. If your leaving it plugged in, leave the batteries on. Even if you have to leave a bad battery in, it will save replacing the converter. If your not plugged in, than batteries can be off.

_________________________________

I had that question and I called the dealership where we purchased the RV. I was going to plug in and run our ac because my TT was going to be a guest house for a few days. My husband had previously had a knife switch installed to disconnect the batteries more easily when we weren't going to be traveling for a while.

He was out of the country on business so I couldn't ask him. The man at the dealership told me that, yes, I needed to have the batteries connected or I would, most likely burn up the converter, a very expensive thing to replace.
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Old 01-18-2021, 10:46 AM   #7
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Originally Posted by PodGeek View Post
Found a couple interesting comments here:

https://www.everything-about-rving.c...-electric.html

Having found out the expensive way; turning off your batteries can also lead to burning up your inverter/converter. If your plugged in, the converter uses the batteries as a buffer as well as charging them. If your leaving it plugged in, leave the batteries on. Even if you have to leave a bad battery in, it will save replacing the converter. If your not plugged in, than batteries can be off.

_________________________________

I had that question and I called the dealership where we purchased the RV. I was going to plug in and run our ac because my TT was going to be a guest house for a few days. My husband had previously had a knife switch installed to disconnect the batteries more easily when we weren't going to be traveling for a while.

He was out of the country on business so I couldn't ask him. The man at the dealership told me that, yes, I needed to have the batteries connected or I would, most likely burn up the converter, a very expensive thing to replace.

Ahh... thanks. I was looking for that "buffer" reference in one of our old posts but couldn't find it. Thanks for finding/posting this.
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Old 01-18-2021, 10:46 AM   #8
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You might want to consider and investigate how much the battery acts as a voltage regulator, capacitor, or buffer for the 12 volt system. It depends on your converter’s design, but without a battery connected, you should consider how well your converter can supply consistent voltage to 12 volt devices in the RV. Will the voltage spike too high at times? Will the voltage be consistent as loads instantly change due to components being turned on and off? With the battery connected, it may act to minimize spikes and variations.

Remove your battery, and monitor your 12 volt system very closely during use to see how your particular converter behaves, then you will have the answer to your question.

Frankly, I can’t think of any reason you would want to disconnect the battery, except if the charger was defective and overcharging the battery. But then you should just get the converter replaced.
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Old 01-18-2021, 11:00 AM   #9
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my 08 wildcat 5th wheel had to have a battery hooked up to complete the circuit or no 12v available in trailer.
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Old 01-18-2021, 11:30 AM   #10
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Then it was wired differently than any modern RV towable I have ever owned or worked on, or the converter failed. If the RV was plugged into shore power, the converter supplies the 12v in the absence of a battery.

As for the OP's question, with the newer multi stage converters, you shouldn't have any problems leaving the batteries connected while on shore power for extended stays.
Older converters (like 20+ years ago) could boil the batteries (over charge) so there are a few of us old timers that will use a 100% battery disconnect while on shore power because that is the way our brain works, not because we need to. Either way works just fine.
I do make sure I charge the batteries ever month or two via the converter using the disconnect switch in the connected position.
Also, I do reconnect the batteries before bringing in slides or operating anything with a lot of 12v power draw.
Of course reconnect batteries before traveling, but thats easy to remember for me as my auto level panel will complain of low power if the battery isn't connected. Plus it's just part of my routine.
As far as wearing out your converter by making it work harder in the absence of a battery, pishaw... I do it all the time and I have only had to replace one 10 year old converter.
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my 08 wildcat 5th wheel had to have a battery hooked up to complete the circuit or no 12v available in trailer.
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Old 01-18-2021, 01:44 PM   #11
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Thanks for all the replies.

It appears I should leave the battery connected.

Hopefully, the charge will not drain during inactive periods of up to 8 weeks or so.
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Old 01-18-2021, 01:50 PM   #12
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If plugged in, will not drain. If not, I would use battery disconnect.
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Old 01-18-2021, 02:22 PM   #13
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Thanks for all the replies.

It appears I should leave the battery connected.

Hopefully, the charge will not drain during inactive periods of up to 8 weeks or so.
If left plugged in, the battery will remain charged.
If you are going to be inactive and unplug it for 8 weeks, DEFINATELY disconnect the battery or the parasitic draws on the 12v system will drain it deader than a doornail.
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Old 01-18-2021, 02:30 PM   #14
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Thanks for all the replies.

It appears I should leave the battery connected.

Hopefully, the charge will not drain during inactive periods of up to 8 weeks or so.
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If plugged in, will not drain. If not, I would use battery disconnect.

If your 8 week inactive period is in a not on shore power state, make sure the battery disconnect disconnects everything. I've read some posts where the battery disconnect left the propane sensor and some other stuff live. Even small drains will kill your battery quicker than you may think.
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Old 01-18-2021, 02:31 PM   #15
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with 30years of trailer camping I have never disconnected nor turned of battery except to work on or replace. I keep my trailer plugged in at home and usually use plugin site. Also have good record of batteries lasting several years.
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Old 01-18-2021, 02:41 PM   #16
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Thanks for all the replies.

It appears I should leave the battery connected.

Hopefully, the charge will not drain during inactive periods of up to 8 weeks or so.
Apples and oranges comment here:

Apples: Leave your battery connected because it is an important part of the feedback circuit your converter/charger relies on for information, and because a battery is a valuable "spring" or "shock absorber" (pun intended) in the overall operation of your 120 volt and 12 volt systems. 12 volt items WILL function without it if connected to shore power, but if shore power goes out, your furnace, fridge, and so on will then have NO source of power to make things function. And park power is often taxed to the limits, offering low voltage, surges and dips as neighbors' AC units and so on tap into limited amounts of power. The battery soaks up that shock for at least the 12 volt loads in your rig.

Oranges: Leaving your rig "disconnected" from shore power for weeks on end while parasitic loads drain your battery is NOT a good idea...on its own. In this case, the best thing you can do to protect the battery is to disconnect the negative terminal (all wires) while disconnected from shore power, otherwise the parasitic loads will drain your battery dead over the course of 8 weeks.

Hypothetical math. Your numbers will vary...and probably be higher.
Assumption: you are a newbie who likely told the sales person you have no boondocking aspirations, so I expect you have a single group 24 or group 27 12 volt FCLA (flooded cell lead acid) marine battery on the tongue. Assuming that:
A group 24 has about 35 USABLE amp hours (AH) before you start harming the battery by draining it too low.
A group 27 might have 40 usable AH.
These are round number estimates, and they will decline as your battery ages.

Your parasitic loads include the CO/propane detector, standby circuits in your stereo/DVD system, standby circuits in your TV, and possibly miscellaneous other stuff. For the sake of illustration, let's assume they consume 0.3 amps/hour (3/10 of an amp per hour). That load is relentless, 24/7. The fancier your rig, and the more toys onboard, the higher the parasitic loads. Some people see as much as 1.5 amps per hour.

Quick math reveals how that 0.3 AH consumption adds up over time:
24 Hours: 7.2 AH/day
1 Week: 50.4 AH/week
In one week you've drained both batteries well beyond what's recommended.
8 Weeks: 403.2 AH - There basically isn't an RV battery bank extant that can handle that...even with LiFePo4s at about a kilobuck a piece.

So the Oranges part of the answer is that you either disconnect the negative terminal on the battery, or second best, turn off the battery disconnect (which still may allow some parasitic loads to drain your battery), or you remain plugged in to shore power, or you add a substantial amount of solar to the rig to offset the parasitic loads.

How much solar is enough? Again some easy math.
A 100 watt solar panel will deliver as much a 7.5 amps in perfect conditions. Under normal conditions, it will deliver about 5 amps. Over the course of the solar day, a 100 watt panel might deliver an average of about 2.5 amps per hour for roughly 12 hours (during the summer). That comes to an estimated 30 AH over the course of a full day in the sun. That's more than enough to keep up with 7.5 AH per day and allow for bad weather and so on.

Many rigs will offer a 50 watt panel and simple solar charge controller to sustain the rig when shore power is not available. If the 50 watt panel can reliably produce about 15 AH/day on good days, as things average out for bad weather, it should be able to keep up with the relentless 7.5 AH/day drain from parasitic loads.

But, if you don't have solar, you absolutely must either stay connected to shore power at least intermittently, or disconnect the negative terminal on your battery.

A really good routine, assuming you can manage this properly, would be to:
A) Know what your battery capacity is in USABLE AH (about 50% of its RATED capacity) and the sum total of your parasitic loads.
B) Disconnect from shore power for, say, 3 to 5 days to let the parasitic loads drain/exercise your battery, then plug in for 24 hours to charge it up again.
That's a whole lot of trouble compared to just disconnecting the cables from the negative terminal and leaving the rig unplugged. When you go to use it again in 8 weeks, connect the battery, plug in the shore power, turn on the fridge to get it cold, exercise the slides, etc. to make sure everything is working as it should, pack the camper for the trip, and drive away with a full, healthy battery.

The really good news is that most RV electrical converters/chargers will drop down to a "float" mode charge to the battery. This is comparable to a "battery tender" charger that you might connect to any battery just to keep it topped off.

One can "overcharge" a battery...and cause sulfation. This is a problem in its own right. Sulfation is something that can be corrected, but it is a concern. I'll leave it to you to Google sulfation.

This is why the best option for leaving your rig parked for 8 weeks unused is to disconnect the negative terminal on the battery bank. Left to their own devices, the typical FCLA battery will hold charge nicely for months on end...certainly for 8 weeks. It is important to know, however, self discharge rates are higher in warm weather than cold weather. If you're in Sacramento, CA where summer daytime temps often go to 115 degrees F, you'll need to charge up much more often than leaving your battery disconnected at freezing temps.

Apples and Oranges. When using the rig, leave the battery connected. When storing the rig for extended periods, disconnect the negative terminal. Better yet, install a switch for this purpose.

WHEN TOWING, ALWAYS HAVE A GOOD BATTERY CONNECTED, BECAUSE IT'S WHAT OPERATES THE SAFETY BRAKES IF THE RIG COMES ADRIFT OF THE TOW VEHICLE.
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Old 01-18-2021, 03:41 PM   #17
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Apples and oranges comment here:

Apples: Leave your battery connected because it is an important part of the feedback circuit your converter/charger relies on for information, and because a battery is a valuable "spring" or "shock absorber" (pun intended) in the overall operation of your 120 volt and 12 volt systems. 12 volt items WILL function without it if connected to shore power, but if shore power goes out, your furnace, fridge, and so on will then have NO source of power to make things function. And park power is often taxed to the limits, offering low voltage, surges and dips as neighbors' AC units and so on tap into limited amounts of power. The battery soaks up that shock for at least the 12 volt loads in your rig.

Oranges: Leaving your rig "disconnected" from shore power for weeks on end while parasitic loads drain your battery is NOT a good idea...on its own. In this case, the best thing you can do to protect the battery is to disconnect the negative terminal (all wires) while disconnected from shore power, otherwise the parasitic loads will drain your battery dead over the course of 8 weeks.

Hypothetical math. Your numbers will vary...and probably be higher.
Assumption: you are a newbie who likely told the sales person you have no boondocking aspirations, so I expect you have a single group 24 or group 27 12 volt FCLA (flooded cell lead acid) marine battery on the tongue. Assuming that:
A group 24 has about 35 USABLE amp hours (AH) before you start harming the battery by draining it too low.
A group 27 might have 40 usable AH.
These are round number estimates, and they will decline as your battery ages.

Your parasitic loads include the CO/propane detector, standby circuits in your stereo/DVD system, standby circuits in your TV, and possibly miscellaneous other stuff. For the sake of illustration, let's assume they consume 0.3 amps/hour (3/10 of an amp per hour). That load is relentless, 24/7. The fancier your rig, and the more toys onboard, the higher the parasitic loads. Some people see as much as 1.5 amps per hour.

Quick math reveals how that 0.3 AH consumption adds up over time:
24 Hours: 7.2 AH/day
1 Week: 50.4 AH/week
In one week you've drained both batteries well beyond what's recommended.
8 Weeks: 403.2 AH - There basically isn't an RV battery bank extant that can handle that...even with LiFePo4s at about a kilobuck a piece.

So the Oranges part of the answer is that you either disconnect the negative terminal on the battery, or second best, turn off the battery disconnect (which still may allow some parasitic loads to drain your battery), or you remain plugged in to shore power, or you add a substantial amount of solar to the rig to offset the parasitic loads.

How much solar is enough? Again some easy math.
A 100 watt solar panel will deliver as much a 7.5 amps in perfect conditions. Under normal conditions, it will deliver about 5 amps. Over the course of the solar day, a 100 watt panel might deliver an average of about 2.5 amps per hour for roughly 12 hours (during the summer). That comes to an estimated 30 AH over the course of a full day in the sun. That's more than enough to keep up with 7.5 AH per day and allow for bad weather and so on.

Many rigs will offer a 50 watt panel and simple solar charge controller to sustain the rig when shore power is not available. If the 50 watt panel can reliably produce about 15 AH/day on good days, as things average out for bad weather, it should be able to keep up with the relentless 7.5 AH/day drain from parasitic loads.

But, if you don't have solar, you absolutely must either stay connected to shore power at least intermittently, or disconnect the negative terminal on your battery.

A really good routine, assuming you can manage this properly, would be to:
A) Know what your battery capacity is in USABLE AH (about 50% of its RATED capacity) and the sum total of your parasitic loads.
B) Disconnect from shore power for, say, 3 to 5 days to let the parasitic loads drain/exercise your battery, then plug in for 24 hours to charge it up again.
That's a whole lot of trouble compared to just disconnecting the cables from the negative terminal and leaving the rig unplugged. When you go to use it again in 8 weeks, connect the battery, plug in the shore power, turn on the fridge to get it cold, exercise the slides, etc. to make sure everything is working as it should, pack the camper for the trip, and drive away with a full, healthy battery.

The really good news is that most RV electrical converters/chargers will drop down to a "float" mode charge to the battery. This is comparable to a "battery tender" charger that you might connect to any battery just to keep it topped off.

One can "overcharge" a battery...and cause sulfation. This is a problem in its own right. Sulfation is something that can be corrected, but it is a concern. I'll leave it to you to Google sulfation.

This is why the best option for leaving your rig parked for 8 weeks unused is to disconnect the negative terminal on the battery bank. Left to their own devices, the typical FCLA battery will hold charge nicely for months on end...certainly for 8 weeks. It is important to know, however, self discharge rates are higher in warm weather than cold weather. If you're in Sacramento, CA where summer daytime temps often go to 115 degrees F, you'll need to charge up much more often than leaving your battery disconnected at freezing temps.

Apples and Oranges. When using the rig, leave the battery connected. When storing the rig for extended periods, disconnect the negative terminal. Better yet, install a switch for this purpose.

WHEN TOWING, ALWAYS HAVE A GOOD BATTERY CONNECTED, BECAUSE IT'S WHAT OPERATES THE SAFETY BRAKES IF THE RIG COMES ADRIFT OF THE TOW VEHICLE.
Lots of great information. Thanks a bunch.

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Old 01-18-2021, 04:23 PM   #18
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A little sidelight to this discussion, that I discovered recently. I have started removing my batteries & LP tanks when the camper is in storage. My pleasant surprise discovery is that when the TT is plugged into my truck the lights and slide work even though the batteries are not there.
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Old 01-18-2021, 04:47 PM   #19
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A little sidelight to this discussion, that I discovered recently. I have started removing my batteries & LP tanks when the camper is in storage. My pleasant surprise discovery is that when the TT is plugged into my truck the lights and slide work even though the batteries are not there.
Many dealers use their 'lot truck' with the umbilical cord urged in tobopen/clise slides when showing units for sale since most do not have batteries at that point
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Old 01-18-2021, 04:54 PM   #20
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As for running a converter without a battery connected, most newer, quality, converters can be used without a battery (breakaway function for brakes aside) and their manufacturers state this in their literature.

"Back in the day" when converters were merely DC power supplies that put out a fixed Float charge of 13.2 volts the battery was required as a "filter" (it acts like a giant capacitor) or buffer for when loads exceeded the converter's capability.

Newer converters don't need filtering and if overloaded they just shut down until load is back in it's capability.

There are a lot of "Bloggers" who are only familiar with the old type like the Magnatek's etc.
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