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jondrew55 · 07-31-2021, 09:55 AM

Our new to us 2021 25’ Globetrotter has 2 standard Interstate batteries. For the 2 weeks we’ve had it so far it’s mostly been plugged in at home or at a campground. I dropped it off at our storage facility on Tuesday and just picked it up today on Saturday. I turned the shore power switch to off, but did not disconnect the battery. When I picked it up and flipped the shore power switch on the power panel said “low batt” and the meter said 11.6V. That seemed a bit low. I plugged the trailer in and checked the battery water. One battery was full to the rings the other was a bit low, but not uncovering the cells.

Should the battery drain that fast (4 days)? Should I disconnect the battery whenever I store it?

ROBERT CROSS · 07-31-2021, 10:16 AM

Disconnecting is the quickest solution.
Finding and eliminating the parasitic draw is the other.
On our '03 Classic it was fairly easy,(not a lot of 'letric gizmos), remove Sony faceplate, and switch on LP detector.

Owners of late model AS's can help with the new 'gizmo's.

POI...I do not remove the batteries for Winter storage

Bob
🇺🇸

uncle_bob · 07-31-2021, 10:53 AM

Hi

Four days is a bit quick, but a lot depends on just what state the batteries were in when it went into storage. We run the fridge most of the time, that pulls down the batteries.

Anything below 12V is past the normal "stop using / time to charge" level. It's not to the point of major damage, but past the "good idea to stop" level.

Trying to figure out battery usage from a voltage reading is tough. There are simply to many variables. It will fake you out as often as it will help. You. Below 12V is indeed a problem. 12.6 / 13.2 may or may not be fully charged. Indeed, at low temperatures 12.6 might be the "stop using" point.

The only way most of us deal with battery "fullness" is to install a shunt based monitor. The Victron BMV 712 is one. Another alternative would be a clamp amp meter with a 40A DC clamp on it. Then measure every load everywhere in the trailer. The BMV is about $200 that meter is above $300 for a good one ....

A couple of quick hints:

1) Never leave the inverter on. Turn it off unless it is in use. It will flatten your batteries in no time at all.

2) It's amazingly easy to bump a light switch in a storage bin ... I have data on this ....

3) The battery disconnect is a different gizmo than the use/store switch. Understand what each does and when to use them.

4) It takes 24 hours on shore power to get a battery back "up to full". Yes, it can happen quicker. If all you have is a voltage reading, there is no way to really know....

Indeed this list could go on and on. There are lots of threads here with more hints.

Fun !!

Bob

field & stream · 07-31-2021, 11:09 AM

Another source is the internal discharge rate of the batteries; that is, power loss while there is zero demand on the batteries.

Standard lead- acid perform the worst (a few percent a week), AGM’s are significantly better (a few percent a month), and lithium’s are the best.

jondrew55 · 07-31-2021, 02:40 PM

After about 6 hours of charge the battery was 12.7-12.8v. We’ll see how long it lasts after charging all nigh. There must have been something besides the propane detector drawing power after I turned the coach switch off.

field & stream · 07-31-2021, 04:30 PM

I am not an expert on this, but my research on “mysterious” power drains has suggested:
- LP detector (add switch)
- radio (remove face plate)
- sub-woofer (disconnect and/or add switch)
- if the water pump is turned on, there is a pressure sensor
- tv antenna amplifier (it has its own switch, turn off)

As suggested above, you can add a real disconnect switch at the battery ( I have done this) which will stop everything.

Maybe I’m being paranoid, but depending on how/where you store the trailer disconnecting the LP detector may not be wise. A self-powered (battery) LP detector could cover those periods.

Daquenzer · 07-31-2021, 06:28 PM

Has the Airstream ever sat on a lot for a period of time such that the batteries drained down completely? The thing about Interstate Wet cells is they have to be maintained at nearly full charge while in storage. If you let them deplete and stay depleted for a long time the batteries can become toast very fast. I never store mine without a battery maintainer on all the time. But I store it at home. Learned the hard way. If you have a storage place without a plug-in I would take the batteries out, store at home, on a battery maintainer. It’s a pain. But it’s either that or get AGM’s.

StuartsDad · 07-31-2021, 07:07 PM

Install a battery disconnect switch and your problem should be solved. Right after I bought our AS new, batteries wouldn't operate jack after three days of sitting. One battery was bad. Dealer replaced both with new Interstates, but even then, after a week, jack would struggle. Installed disconnect switch and I know it will hold a charge for at least 6 months because I had it in storage from last Thanksgiving until May.

jondrew55 · 07-31-2021, 09:04 PM

I see a disconnect switch in my future

Quote:

Originally Posted by StuartsDad

Install a battery disconnect switch and your problem should be solved. Right after I bought our AS new, batteries wouldn't operate jack after three days of sitting. One battery was bad. Dealer replaced both with new Interstates, but even then, after a week, jack would struggle. Installed disconnect switch and I know it will hold a charge for at least 6 months because I had it in storage from last Thanksgiving until May.

field & stream · 07-31-2021, 09:41 PM

Quote:

Originally Posted by jondrew55

I see a disconnect switch in my future

Good idea.

Correction to my earlier statement that a disconnect switch “will stop everything”: everything except the battery’s internal discharge. With lead-acid this might still be a problem, with AGM’s (modest additional cost) you are good for many months, and with lithium (significant cost) good for even longer plus other benefits.

Mollysdad · 08-01-2021, 06:37 AM

Quote:

Originally Posted by jondrew55

After about 6 hours of charge the battery was 12.7-12.8v. We’ll see how long it lasts after charging all nigh. There must have been something besides the propane detector drawing power after I turned the coach switch off.

First, I don't think of the USE/STORE switch as a battery disconnect.
Other than the propane detector, there could be parasitic draws from a subwoofer standby, radio memory, TV standby. The only real disconnect is to install a battery disconnect or remove the leads from one side of the batteries.
There's all kinds of disconnects, here's mine. (no compromise)
https://www.airforums.com/forums/blo...sconnect-3036/

Kawboy01 · 08-01-2021, 09:08 AM

The propane detector I believe draws even with switch in store mode. Also make sure you.dudnt bump the tongue jack light switch or the dump valve light switch before storing.disconnecting a terminal would be the simplest.

jnm30327 · 08-01-2021, 09:21 AM

It is pretty hopeless to find all the loads after you put switch in store mode. Learning this cost me a set of original batteries. The only solution is to install a kill switch on the battery when storing. It is too bad Airstream does not tell you this.

Note: this will disable the propane detector. I always thought an active propane detector when stored was pretty silly. Who is going to hear it? Nevertheless, I always close the valves on propane tanks as well when storing.

thewarden · 08-01-2021, 09:39 AM

Quote:

Originally Posted by StuartsDad

Install a battery disconnect switch and your problem should be solved. Right after I bought our AS new, batteries wouldn't operate jack after three days of sitting. One battery was bad. Dealer replaced both with new Interstates, but even then, after a week, jack would struggle. Installed disconnect switch and I know it will hold a charge for at least 6 months because I had it in storage from last Thanksgiving until May.

A battery disconnect switch is the simplest way to ensure nothing is drawing power from your batteries while in storage. Or you can just disconnect one of the terminals, but a disconnect switch is the cleanest way to go.

missaviatrix · 08-01-2021, 12:20 PM

How and where would one install a battery disconnect. I have a 23' FC front bed and my lithium batteries are under the bed. Is there an easier place to put a disconnect switch so I don't have to tear my bed apart?

Mollysdad · 08-01-2021, 02:56 PM

Quote:

Originally Posted by missaviatrix

How and where would one install a battery disconnect. I have a 23' FC front bed and my lithium batteries are under the bed. Is there an easier place to put a disconnect switch so I don't have to tear my bed apart?

Sure. It would involve running some extra cable from the battery to the switch and back. Mount the switch through the panel that supports the bed.
Or, it looks like there's a couple of drawers, maybe under those? In the locker next to the bed?

rmkrum · 08-01-2021, 03:51 PM

My battery boxes are external, but here’s what I did. Short length of cable from an 80 amp MRBF fuse and fuse holder on the positive battery terminal. A BlueSea Systems battery switch with a weather/tamper cover put over it, then the original feed into the Airstream. Split loom over the cables to keep the sun damage down.

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uncle_bob · 08-02-2021, 08:34 AM

Hi

If you want to really make the disconnect easy to mount, use a Blue Sea 7000 series latching solenoid. The gizmo goes near the batteries and does what it needs to do. You run light weight wire to the control switch. It has a nice LED on it (if you wish) to tell you the battery is not disconnected. "Isn't that light supposed to be out" *might* be something I've herd while exiting the trailer ... maybe ...

https://shop.pkys.com/Blue-Sea-7700-...2V_p_1691.html

Is one. They have a *lot* of different models with a range of features. Yes, they cost more than a simple switch. No they don't isolate the battery any better than that simple switch.

Bob

jondrew55 · 08-03-2021, 07:57 AM

I’m guessing the remote control switch works suck that it is never drawing power except when you turn it on?

Quote:

Originally Posted by uncle_bob

Hi

If you want to really make the disconnect easy to mount, use a Blue Sea 7000 series latching solenoid. The gizmo goes near the batteries and does what it needs to do. You run light weight wire to the control switch. It has a nice LED on it (if you wish) to tell you the battery is not disconnected. "Isn't that light supposed to be out" *might* be something I've herd while exiting the trailer ... maybe ...

https://shop.pkys.com/Blue-Sea-7700-...2V_p_1691.html

Is one. They have a *lot* of different models with a range of features. Yes, they cost more than a simple switch. No they don't isolate the battery any better than that simple switch.

Bob

66Overlander · 08-03-2021, 12:02 PM

The main power feed to the inverter is not disconnected with the shutoff switch. A "leaky capacitor" in the inverter can draw the batteries down over a few days. We had to install a physical shut off switch in the line to the inverter after my buddy discovered this issue on his Airstream. The inverter work fine, it just sucked down the battery when parked and not plugged in. We diagnosed this issue to the inverter with an ammeter to measure the leakage current.