Battery Isolation Switch Use?

[Wingeezer]

Our trailer (like most i imagine) has an "on/off" battery switch under the front sofa.

I'm not sure what make our converter/charger is, there is no mention in our AS manual, and the trailer is not at my house to check at present.


I expect it is the original, and if so, I think the charger would not be one of the intelligent three stage ones.

I keep a digital voltmeter plugged into the 12v socket in the bedroom and whenever we are on shore power, it seems to read a steady 13.8/13.9volts.

Here's what I am wondering .................

(1) Would that be the same voltage that my batteries are seeing or would it just represent what the inverter is feeding to the trailer circuits and not necessarily the voltage applied to the batteries?


(2) If my batteries are constantly seeing this voltage when we are on shore power, then I'm guessing it would not be good for the batteries if I am on 110v for a week or two at a time.

If that is so, could I just throw the battery switch to "off" after a day or two? I was thinkig that would leave everything in my trailer that needs 12 volts being fed from the inverter, but take the batteries out of the circuit and prevent them being overcharged.

Think this is right, and if so a good idea? I just put a new set of AGM batteries in the trailer and would like to ensure I get the best life out of them.

Probably I should upgrade the charger, but if this works it would seem almost as good.


Thanks .......... Brian.

[overlander63]

The 13.8 is what your batteries are getting, your converter is not a 3 stage one, and "modern" Airstreams don't have the ability to isolate the batteries when plugged in. You can pretty easily install a battery isolator like you'd find on a boat to isolate the batteries if you want. It would be a good idea anyway, so they don't get drained by parasitic loads.
Randy (68overlander here on the forums) at Bestconverter.com can help steer you to a good converter for your new batteries.

[Wingeezer]

Originally Posted by overlander63

The 13.8 is what your batteries are getting, your converter is not a 3 stage one, and "modern" Airstreams don't have the ability to isolate the batteries when plugged in. You can pretty easily install a battery isolator like you'd find on a boat to isolate the batteries if you want. It would be a good idea anyway, so they don't get drained by parasitic loads.
Randy (68overlander here on the forums) at Bestconverter.com can help steer you to a good converter for your new batteries.

Hi Terry,

Thanks, but I'm still a bit confused. I don't have the trailer here to test things out, but my manual says, quote,

"power from the battery first goes to a master or "kill" switch inside the trailer, located under the front sofa in moist models"


That was why I figured I could save my batteries just by throwing that switch to take them off the charger yet leave the trailer fed 12vdc from the converter.

Won't that work?

If not, seems o me I have een disconnects that mount right on the battery terminals and I could just get a couple of those rather than undoing the battery connectors every time.


Brian.

[Ag&Au]

Hi Brian,
I imagine that your trailer is wired the same as mine. I just went through this while checking my trailer out. I thought mine must be wired wrong, but it is intended to be this way. In my trailer the converter, solar charger, Tow Vehicle charge wire, and batteries are all connected together. Then the wiring goes through the "kill switch" to the load panel. There is no method to disconnect the batteries from the charging sources. The apparent purpose is to take all of the loads off the battery for long term storage. The only exception to this is the LPG detector which is always connected to the batteries. I am seriously thinking of doing some rewiring in that area, but am going to give it a lot of thought first.
Regards,
Ken

[Wingeezer]

Originally Posted by w7ts

Hi Brian,
I imagine that your trailer is wired the same as mine. I just went through this while checking my trailer out. I thought mine must be wired wrong, but it is intended to be this way. In my trailer the converter, solar charger, Tow Vehicle charge wire, and batteries are all connected together. Then the wiring goes through the "kill switch" to the load panel. There is no method to disconnect the batteries from the charging sources. The apparent purpose is to take all of the loads off the battery for long term storage. The only exception to this is the LPG detector which is always connected to the batteries. I am seriously thinking of doing some rewiring in that area, but am going to give it a lot of thought first.
Regards,
Ken

Thanks Ken,


After reading your post, I looked at my manual again and found a wire routing diagram which seems to confirm exactly what you said.

Wish there was a true wiring diagram rather that a wire routing diagram as I'm not sure I really understand it fully!

I wonder if one could just find a convenient place near the converter to install a double pole knife switche in the lines from the batteries to take them out of the circuit?

Maybe the simplest thing for me to do (other than replace the whole converter/charge with one containing a three stage charger) would be to just put quick disconnect knobs on top of both my batteries - just a bit more of a pain to have to open the battery doors and likely pull the batteries out to fiddle with them each time!

Perhaps a less expensive and simpler solution to changing out the whole converter/charger could be to disconnect the existing charger and wire in a standard three stage charger bought from an automotive supply place to handle the charging function.

Needs a bit more thought and a closer examination of things!

It suprises me in this day and age that AS wouldn't put in a better quality charger - since yours is a 2010 model, maybe you do have a three stage charger?


Brian.

[B25guy]

Brian,

You are correct in your assumption, turning off the store/use switch will remove them from further charging while plugged in. I learned this and proved it with a meter at both the converter output and battery input (lugs).

Note - even though you press the momentary on switch to the off position, the red light will stay lit...this is normal (albeit goofy). You should hear a click when you press the button in either direction. Best way to prove you've actually disconnected the batteries is just measure voltage at the battery lugs before and after...should see something like 13+V in the "on" position, 12.8V or less when "off". In either position, your interior lights, etc. on 12V will stay lit (assuming of course you are plugged into shore power).

I think A/S should explain this just a little better in the manual...under or over-charging batteries is occurring often and most owners have no idea what is actually going on with that switch.

Battery Disconnect Switch, Solar & AGMs

[Ag&Au]

Originally Posted by B25guy

Brian,

You are correct in your assumption, turning off the store/use switch will remove them from further charging while plugged in. I learned this and proved it with a meter at both the converter output and battery input (lugs).

Note - even though you press the momentary on switch to the off position, the red light will stay lit...this is normal (albeit goofy). You should hear a click when you press the button in either direction. Best way to prove you've actually disconnected the batteries is just measure voltage at the battery lugs before and after...should see something like 13+V in the "on" position, 12.8V or less when "off". In either position, your interior lights, etc. on 12V will stay lit (assuming of course you are plugged into shore power).

I think A/S should explain this just a little better in the manual...under or over-charging batteries is occurring often and most owners have no idea what is actually going on with that switch.

Battery Disconnect Switch, Solar & AGMs

Hi B25guy from a P2V guy
The classics (at least new ones)do not have the store/ use switch you are talking about. They have a simple manual on/off switch (in the case of mine, under the couch).
regards,
Ken

[Ag&Au]

Originally Posted by Wingeezer

Thanks Ken,


After reading your post, I looked at my manual again and found a wire routing diagram which seems to confirm exactly what you said.

Wish there was a true wiring diagram rather that a wire routing diagram as I'm not sure I really understand it fully!

I wonder if one could just find a convenient place near the converter to install a double pole knife switche in the lines from the batteries to take them out of the circuit?

Maybe the simplest thing for me to do (other than replace the whole converter/charge with one containing a three stage charger) would be to just put quick disconnect knobs on top of both my batteries - just a bit more of a pain to have to open the battery doors and likely pull the batteries out to fiddle with them each time!

Perhaps a less expensive and simpler solution to changing out the whole converter/charger could be to disconnect the existing charger and wire in a standard three stage charger bought from an automotive supply place to handle the charging function.

Needs a bit more thought and a closer examination of things!

It suprises me in this day and age that AS wouldn't put in a better quality charger - since yours is a 2010 model, maybe you do have a three stage charger?


Brian.

Hi Brian,
My converter is also 2 stage. It is a parallax 7455. There is one mistake in the 12v DC diagram in my manual. Go to Ebay and search for Perko Battery Switch. Also I would also recommend talking to Randy at Bestconverter.com. He helped me a lot on my previous trailer.
I am on the way out right now. I will elaborate more when I get back this evening.
regards,
Ken

[Ag&Au]

Hi Brian,
If I change the 12 volt system, this is what I will do:
At the point where the two batteries join together( a stud on the front wall under the couch), I would insert one of the Perko 4 position switches (off-1-all-2). I will look at mounting it on the long thin piece of wood that you see if you look over the back of the couch. I would also install a switch to allow the solar charger to feed either battery 1 or battery 2. The charger would feed both batteries if the Perko switch was in ALL. This is the way I wired my previous trailer. I like the idea of separating the two batteries when boondocking. When the first battery is depleted, you have an idea of how long you can go on the second. With the solar charger switch, you could choose to replenish the depleted battery or help the battery you are using.
Regards,
Ken

[85MH325]

Originally Posted by w7ts

Hi B25guy from a P2V guy
The classics (at least new ones)do not have the store/ use switch you are talking about. They have a simple manual on/off switch (in the case of mine, under the couch).
regards,
Ken

And Hi to B25Guy and P2V guy from a P3C guy!

I have similar issues with my B-Van... I need to figure out how to put an isolator switch in. I can't find one from the factory.

Roger

[Gene]

In my Safari I have the battery disconnect switch that drives people nutty because no one knows the purpose of the red light except to find it in the dark. My converter is a one stage. If the recent model Classics have a 2 stage converter, that may explain the difference in the switch in the Classic.

Since we have a solar system and it does have a 3 stage charger, I just leave the trailer unplugged to 120 v. when it's home—I notice the batteries use much less water since I started doing that, but the batteries are fully charged. We often run one fan during the summer to keep the trailer from getting too hot. When we are plugged into shore power, it's when the refrigerator is running and my hope, probably foolishly, is that keeps the batteries less overcharged.

I agree that many owners have no idea what's going on with their batteries or what the various switches really do. We did find out our disconnect switch was faulty and it was fixed.

Gene

[jcanavera]

I'd have to find where I read this at but I thought that if you run shore power and have the battery switch in the off position, the power converter without the battery load will have a higher voltage output which could shorten the life of your 12 volt lights and other 12 volt devices.

I did use an amp meter and tested the amp draw from the battery on my '01 Safari with the switch on and off. With all appliances turned off, but with the battery switch in the on position, I detected a .1 amp draw. With the battery switch in the off position, I detected a .01 amp draw. I attributed the draw with the switch on to the electronic brains in the fridge, furnace, water heater, and propane detector. With the switch off, the draw was from the propane detector which is wired around the switch.

Jack

[Wingeezer]

Originally Posted by w7ts

Hi Brian,
If I change the 12 volt system, this is what I will do:
At the point where the two batteries join together( a stud on the front wall under the couch), I would insert one of the Perko 4 position switches (off-1-all-2). I will look at mounting it on the long thin piece of wood that you see if you look over the back of the couch. I would also install a switch to allow the solar charger to feed either battery 1 or battery 2. The charger would feed both batteries if the Perko switch was in ALL. This is the way I wired my previous trailer. I like the idea of separating the two batteries when boondocking. When the first battery is depleted, you have an idea of how long you can go on the second. With the solar charger switch, you could choose to replenish the depleted battery or help the battery you are using.
Regards,
Ken

Thanks for the info on the Perko switch.

I don't have solar, but I assume that if I had such a switch, I could use it to select to have either battery on line on its own, both in parallel on line, or both batteries isolated so that they wouldn't get overcharged.

Am I understanding things correctly? If so, think I'll order me one of those switches!

Cheers ........ Brian.

[Ag&Au]

Originally Posted by Wingeezer

Thanks for the info on the Perko switch.

I don't have solar, but I assume that if I had such a switch, I could use it to select to have either battery on line on its own, both in parallel on line, or both batteries isolated so that they wouldn't get overcharged.

Am I understanding things correctly? If so, think I'll order me one of those switches!

Cheers ........ Brian.

Hi Brian, That is correct.
My last trailer was kept at home in the winter with AC connected to it all the time. I used the Perko switch to disconnect the batteries. Every few weeks, I connected the batteries for 24 hours to keep them charged. The new trailer is going to spend its down time in covered storage with no AC, so I am thinking I will probably have to bring the batteries home.
I googled "Perko battery switch" and found several marine supply places with prices comparable to EBay. There are probably other brands also. I attached the drawing of how I wired my other trailer. Can you tell I didn't get very good grades in drafting?
regards,
Ken

[Wingeezer]

Thanks Ken,

Diagram helps a lot and my drafting skills were no better - I remember having to work in ink! Sort of fun, but one blot or smear & that's it!

Now you won't need to refer to my profile to judge my age!


Cheers ....... Brian.