Utility Battery Maintenance and Management

[oconnpe]

I am new to RV's and recently purchased a 2015 Mercedes Airstream Interstate Grand Tour EXT about 18 month's old. My utilities batteries seem to go flat in about 2 days after use and/or after charging. However, they charge up very quickly when I next used the vehicle.

Is this normal? Are my batteries bad? Should I be doing something?

Other than this everything is in excellent working order.

Regards, Patrick (oconnpe)

[Rich W]

Hi Patrick, welcome to the forum, greetings from central Kentucky. Congratulations on your Interstate acquisition.

How long batteries last depends on several factors; usage, size, amp-hours, age and condition. 2-4 days, without a recharge or solar panel(s) I would say is probably about right, if you aren't connected to external AC power.

You can take the batteries to just about any parts store and they can put them on a load tester to determine their condition.

I'm assuming you're boon docking, not connected to AC power at a campground. If this is an incorrect assumption, let us know.

[Boxster1971]

Welcome Patrick. There is a lot of discussion about Interstate battery life on the "Sprinter and B-van Forum". It is a sub forum to Airstream Motorhomes Forums. The response from richw46 above is about right on a couple of days use being all you can get with the stock setup.

It not really well understood by most new owners of Interstates that they are really designed by Airstream to spend most of their time plugged into shore power. That is why a lot of us owners have modified our Interstates with better solar capability and more batteries. I have four 100 watt solar panels on my roof with a Blue Sky MPPT controller feeding four 6V AGM batteries hanging under my van behind the rear wheels. That gives me over four times the capacity of the stock set-up. Now my only boondocking limit is the water supply as long as I don't need the Air Conditioner.

[oconnpe]

Originally Posted by oconnpe

I am new to RV's and recently purchased a 2015 Mercedes Airstream Interstate Grand Tour EXT about 18 month's old. My utilities batteries seem to go flat in about 2 days after use and/or after charging. However, they charge up very quickly when I next used the vehicle.

Is this normal? Are my batteries bad? Should I be doing something?

Other than this everything is in excellent working order.

Regards, Patrick (oconnpe)

I think I may have been a bit unclear about my concern. I have only camped out once to date and plugged in as normal with no issues. All batery monitoring information looked good.
At Home: I plug in and then disconnect with a full charge. I then park the RV in my garage. Without using anything or having the utility power switch on my batteries seem to loose charge in 2 days. i.e. no lights etc., until I start engine of plug back in.

However, everything seems to be ok within a few hours of re-charging. So if I go on a trip all seems ok since I am driving or plugged in.

My concern is that the batteries go flat when just parked with no pwer demand on them. Is there something else I should be switch off when parked in my garage for a few weeks? or am I worrying about nothing? i.e. everything charges up again very quickly when in use. Thanks Pat and Carol (oconnpe)

[Rich W]

Sounds like your house batteries are bad, not holding a charge, perhaps a dead cell in one is dragging down the other one. I think you should have them checked. If you can, pull them out and take them to an auto parts place to have them load tested. Otherwise, take your Interstate to an RV repair shop and have them checked in the vehicle. (If we knew your level of repair/tool ability we could offer better options. Are you a DIY person with some knowledge of tools and electric repair?)

If you have to replace them, replace both, it's always best to have batteries of the same age when running in parallel.

[Boxster1971]

Originally Posted by oconnpe

I think I may have been a bit unclear about my concern. I have only camped out once to date and plugged in as normal with no issues. All batery monitoring information looked good.
At Home: I plug in and then disconnect with a full charge. I then park the RV in my garage. Without using anything or having the utility power switch on my batteries seem to loose charge in 2 days. i.e. no lights etc., until I start engine of plug back in.

However, everything seems to be ok within a few hours of re-charging. So if I go on a trip all seems ok since I am driving or plugged in.

My concern is that the batteries go flat when just parked with no pwer demand on them. Is there something else I should be switch off when parked in my garage for a few weeks? or am I worrying about nothing? i.e. everything charges up again very quickly when in use. Thanks Pat and Carol (oconnpe)

OK - thanks for clarification. Now that I better understand your issue you need to give us a bit more information.

Since you purchased your 2015 Interstate GT used you don't know the history of how those house batteries were used or abused. Then richw46 could be correct - your batteries are bad.

You say you give the batteries a full charge and then park the van in a garage. Couple of things to think about. When you say the batteries get a full charge how do you tell? If you have had the van plugged in for less than 48 hours I suggest they are not getting fully charged. When plugged in does the Magnum display indicate the batteries are at Float? If not they are not fully charged.

By parking the van in the garage you are eliminating any solar charging that will keep the batteries topped off.

You say you park it without using anything. Have you used the battery disconnect to isolate the house batteries? If not there is a sizable parasitic drain on those batteries from the parasitic load of the inverter and other 12V systems. This is especially true if your Interstate has the notorious SB-164 installed, which adds even more drain for a relay they added. This SB-164 was one of Airstream's attempts to improve battery life that they introduced about 2015. It was a total disaster and actually made things worse. Airstream no longer uses this SB-164 approach and now just adds a second disconnect switch to isolate the inverter parasitic load.

Go over to the "Sprinter and B-van" sub-forum and search on the term "SB-164" to get the details on this issue.

Under normal conditions with battery disconnect in ON position the parasitic drain is a constant 0.75 amps or more with SB-164. That means your house batteries are loosing at least 18 amp-hours (AH) each day. See page 9-8 of your Interstate Owners Manual for more details on battery maintenance. Without solar charging a set of weak batteries will be drained in a few days. Even good batteries will be under 50% State-of-Charge (SOC) in 5 days without solar charging. Every time your batteries are drained to below 50% SOC they loose capacity. If drained to less than 10.5 Volts they are damaged.

Hope this helps,

[Tronadora]

My used 2015 AI GT was showing similar results so the coach is getting new batteries installed as we speak.

I presume you are turning off the Main Disconnect switch near the side entrance?

If your garage has 110v you can use an adapter to get the coach juiced while out of the sun. Two ways to do this... order one of these and use your big electrical cord:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

OR:
Use this attached to the coach and use a standard 110V heavy duty extension cord.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Mark

[oconnpe]

Mike,
Thanks for your comments: I have 2 questions (which highlight my lack of experience)
1.0. How do I disconnect the house batteries. Currently I turn off the switch at the sliding door entry. I thought this was sufficient.
2.0. I have never seen any reference to battery float. Will check this out.

Also, how difficult is it to remove the house batteries to get them checked - where are they?

Thanks

[Titus]

Question about having a auto parts store do a load test: My understanding is that the auto parts store test will be a high load test, to determine if there is a dead cell. I understand that the capacity test is much more complicated. I am not sure where to have that done. (I could do it myself if I had a controllable 25 A load.)
My understanding of the capacity test is as follows:
1) Batteries have to be fully charged per normal charging cycle
2) Discharge batteries using a 25A load
3) Record time it takes for battery voltage to drop to 10.5 V
4) Compare this time to the specification (149 minutes for GPL 24T)
5) If the time to reach 10.5 V is less than 80% of specs (<119 minutes for GPL 24T), then the battery needs to be conditioned (equalized).
6) Conditioning is a normal charge followed by an 8 hour charge at 15.5 V. This desulfates the battery (hopefully). Some literature recommends routine conditioning (every 2-4 weeks), other suggests doing it only when a discharge test shows it to be necessary.

Is the above correct? Has anybody had a capacity test done? Where? Do others routinely run a conditioning cycle? How frequently?

(I hope that Lewster reads this and chimes in with his professional advice.)

[amirm]

Originally Posted by oconnpe

Mike,
Thanks for your comments: I have 2 questions (which highlight my lack of experience)
1.0. How do I disconnect the house batteries. Currently I turn off the switch at the sliding door entry. I thought this was sufficient.

That doesn't turn off all the circuits unfortunately as Boxter explained. A number of "phantom" loads remain which suck power. A current clamp meter at the battery terminal would show how much.

Also, how difficult is it to remove the house batteries to get them checked - where are they?

Thanks

It is a big pain to remove them as they are underneath, mounted sideways and there are a lot of cables attached to them.

They can be checked where they are though with an electric load tester. So I would either buy one or take it to some place to have them checked.

Net, net, you can't leave the unit without a charge source.

[Boxster1971]

Originally Posted by oconnpe

Mike,
Thanks for your comments: I have 2 questions (which highlight my lack of experience)
1.0. How do I disconnect the house batteries. Currently I turn off the switch at the sliding door entry. I thought this was sufficient.
2.0. I have never seen any reference to battery float. Will check this out.

Also, how difficult is it to remove the house batteries to get them checked - where are they?

Thanks

1.0 – The switch by sliding door is how you disconnect the batteries. But as amirm said above it does not get rid of all the loads.

2.0 – Your Interstate has a Magnum Inverter/Charger that has a remote control/display panel. It is a model ME-MR on your Interstate and a copy of the user manual can be downloaded at this site:
http://www.magnum-dimensions.com/me-...-64-0031-rev-e

The remote is also discussed in section 5 of your Interstate owner’s manual. If you don’t have a copy it can be downloaded at this link:
https://www.airstream.com/service/ma...ear_select=326

The batteries are being automatically charged when plugged into shore power. The Magnum display will display the message “ STATUS Float” when they have reached the final stage of charging and are fully charged. Image of manual description attached.

3.0 – As amirm noted removing the batteries is a challenge unless you have DIY skills. I’m attaching a few photos I took at an RV show in 2015 of the battery location on your Interstate, under the van behind the driver side rear wheels.

[oconnpe]

You guys are great (and the forum). Thanks

I now have a plann. I will get my batteryes checkked, then satrt paying more attentionntion to battery charging managementent and maintenancence. I feel I understandnd the issues much better now, which takes a bit of stress away.

I purchased from a friend - in excellent conditionition (15 months old). However, he did not understandnd "many" of the workings, particularly the power requirements / issues for TV and utilities. He just drove it to a site, plugged in when on a trip, and had a great time. I think he did not plug in at his home for relatively long periods and then drove to RV sites, so he was not aware of any potential battery issues.

I canot thank you enough for your responses.

Regards, Pat. (oconnpe)

[oconnpe]

Originally Posted by oconnpe

You guys are great (and the forum). Thanks

I now have a plan. I will get my batteryes checked, then start paying more attention to battery charging management and maintenanc. I feel I understand the issues much better now, which takes a bit of stress away.

I purchased from a friend - in excellent conditionition (15 months old). However, he did not understand "many" of the workings, particularly the power requirements / issues for TV and utilities. He just drove it to a site, plugged in when on a trip, and had a great time. I think he did not plug in at his home for relatively long periods and then drove to RV sites, so he was not aware of any potential battery issues.

I canot thank you enough for your responses.

Regards, Pat. (oconnpe)

I tried to book in my RV in with local dealer (I am still under waranty) to have my battery and charging system checked, but earliest appointment is one month away. I have looked at the location and can get access to remove batteries. Do I need to turn stuff off before I do this i.e. breakers (or remove fuse), battery disconnect switch etc. I can then get my batteries checked locally.

I have now confirmed my RV is 2016 model (grand tour ext), not 2015 as I originally thought (purchased in Oct. 2015).

I have not found airstream website, documents, or dealers very helpful.

Regards Pat

[Boxster1971]

If your rig is still under warranty I'd just wait for dealer to check it out. You can still use it with weak batteries. But do make sure you plug in for charging for at least 48 hours to get a really full charge.

[oconnpe]

Originally Posted by Boxster1971

If your rig is still under warranty I'd just wait for dealer to check it out. You can still use it with weak batteries. But do make sure you plug in for charging for at least 48 hours to get a really full charge.

Mike,

Ok. Thanks. Good advice. I have a garage and am well set up for charging.

Regards, Pat

[TheHoff]

I solved my battery issues by installing a total of 250 watts of solar and getting two new 100 amp hour AGM batteries. With the main disc off and with the vehicle parked outside in a partly sunny area, the batteries are mostly 100% all the time. With my next battery purchase, I will probably get 4 6 volt batteries, in a few years. That seems to be even better according to folks who know more about this than I do.

[fourjean]

We purchased a brand new 2018 Airstream Estate Grand Tour about 3 months ago - have taken 2-3 weekend trips and now are about halfway through a 6 week western trip (currently at Zion NP). We're very disappointed with our battery performance (unless we're plugged in). We generally drive 3-4 hours/day and/or run the generator an hour/day - then turn everything off and cannot plug in for the night. The next day the house batteries are showing red. We have 300 watt solar panels and its typically sunny and 90F. The only thing I haven't been doing is turning off the battery switch at the side door (because I didn't understand what that does exactly) - I'll try that tonight.
I'm wondering if the magnum converter settings are messed up as I did push some of those buttons without knowing what I was doing. Should I reset that unit back to factory settings? Sure seems to me with 2 house batteries and 3 solar cells and everything turned off the vehicle should be able to make it through the night without its batteries going red??? Any help out there? Thanks Brian

[Boxster1971]

fourjean - you need to get your rig back to the dealer and let them check it out. Something is definitely wrong if your batteries die that soon. I was going to suggest that it might have sat uncharged on dealers lot that caused damage to the batteries, but since it is so new that is not likely.

Some things to consider on your current trip - limit the use of inverter when not plugged in because it will drain your batteries. Also don't leave the Propane (LP) valve turned on - it draws a lot of power. Plus be sure to turn off the TV antenna booster when not using it for over the air TV.