Battery disconnects ... do they really?

WrkdbfGuy · 03-20-2021, 11:10 AM

Our 2018 Dynamax Force HD 37TS has 2 battery disconnects - one in the basement battery compartment for the house batteries and one under the drivers seat for the starter batteries. When I put the RV in storage at the end of the season, I always turn the disconnects to the Off position.

But when I went to take the RV back out of storage a few days ago ... you guessed it, dead as a doornail. Both systems. We were able to jump and get the coach started. And now we're plugged in so everything is charging back up.

But why don't the disconnects keep things from discharging? Isn't that the whole idea behind having them? And, if I doing things wrong, what can I do better to keep this from happening?

Thanks, Bill

railroaderone · 03-20-2021, 11:19 AM

batteries naturally lose charge in storage no way around it

CHICKDOE · 03-20-2021, 11:31 AM

The terminology of battery disconnect because my on or off drives me crazy! When you have your switches I the on position does that mean the batteries are ‘online’ (connected) or the the disconnect is on, which disconnects the batteries? Then there are the parasitic loads that stay connected to the battery regardless of the position of the factory installed disconnect switch. A fully charged battery should make it many months if all loads are truly disconnected.

I had similar problems until I installed my own disconnect switch right at the battery that disconnects all loads.

Webefine · 03-20-2021, 12:21 PM

Quote:

Originally Posted by railroaderone

batteries naturally lose charge in storage no way around it

I use the same two disconnects as the op and my batteries only lose about .2 to.3 volts in three months of storage.

rskeans · 03-20-2021, 03:03 PM

I had the same problem as the OP. My Guess is that I had the entry stairs out while stored even while plugged in!. Came back and the stairs were partially retracted with dead batteries. I don't believe that the BIRD had closed the relay allowing the chassis batteries to be all by themselves.

I replaced the BIRD and solenoid and things still were not correct. Then I happened to do a fast idle on the engine to use the air tanks to air up the tires. The solenoid closed and all is normal. The BIRD needed fully charged chassis batteries to close the solenoid. After that the house batteries kept the chassis batteries charged.

Now my observations and conclusions could be wrong! Wouldn't be the first time. So, FWIW. BTW, the stairs are directly connected to the chassis batteries all the time.

**bclemens** · 03-20-2021, 03:14 PM

By code not all items can be disconnected. Steps being one...they need to be able to extend and retract no matter what.

Webefine · 03-20-2021, 04:21 PM

I just pulled my DX3 out of storage today. It has been in storage since the middle of December unplugged with the disconnect in the battery compartment off and the disconnect inside the drivers door off, temperatures as low as 0 through the winter. I checked the voltage of the chassis and coach batteries before trying to start and both were at 12.4 volts.

rskeans · 03-20-2021, 04:32 PM

Were the steps retracted during storage?

Webefine · 03-20-2021, 04:49 PM

Yes

Webefine · 03-20-2021, 05:30 PM

It doesn’t seem right to me that the steps would need power to stay out but maybe so.
I am going check this while mine is sitting at the house. I’m going to leave it unplugged with the steps out and both disconnects off, I will then check the voltage every few days to see if there is any noticeable voltage drop.

chriscowles · 03-20-2021, 05:34 PM

Quote:

Originally Posted by bclemens

By code not all items can be disconnected. Steps being one...they need to be able to extend and retract no matter what.

CO/LP sensor being another?

Webefine · 03-20-2021, 06:15 PM

Those go off with the main disconnect on my RV

Bob2019 · 03-21-2021, 01:18 PM

The only and I mean ONLY was to insure all loads on the batteries are disconnected is to install a battery slide blade switch on the negative cable side of the battery. Have one on the coach battery for the winter and also on the house batteries. The battery voltage is slightly lower than when put away in the fall, but everything works and can be started. Ck Amazon for slide blade switches. They don't cost that much and sure beats a dead or ruined battery.

chriscowles · 03-21-2021, 02:08 PM

Quote:

Originally Posted by Bob2019

The only and I mean ONLY was to insure all loads on the batteries are disconnected is to install a battery slide blade switch on the negative cable side of the battery. ...

If proximate to the battery, connections to the existing cutoff switch can be rearranged to accomplish the same thing for the house bank, at least. I did that on my Mini-Lite by moving a couple of wires from the hot side to the switched side.

CHICKDOE · 03-21-2021, 02:10 PM

Mr Clemens, you say some devices must stay connected to the batteries. You mention steps. Also the emergency brake circuit is usually wired directly to the battery bypassing any disconnect switch. I don’t have an issue with these as long as there is a make or break switch (on / off) in their power circuits. By breaking these power circuits there will be no current flow thus no battery drain from these on / off devices.

But I think I found 5 devices on our trailer that were always on. Devices such an propane sensor, co sensor, stereo, slide out controller (it has a remote and must always be listening for the remote), and I believe the inverter still draws some power even when it is off.

So with all these always on devices, what is the purpose of installing a factory disconnect that doesn’t truly disconnect the batteries? And for all of us that have installed our own true disconnects, are we going to go to disconnect jail when the weight police stop us and discover the supposedly illegal disconnect?

rskeans · 03-21-2021, 04:41 PM

Quote:

Originally Posted by CHICKDOE

are we going to go to disconnect jail when the weight police stop us and discover the supposedly illegal disconnect?

Now you are really in a heap of trouble. LOL

chriscowles · 03-21-2021, 05:00 PM

Quote:

Originally Posted by CHICKDOE

Mr Clemens, you say some devices must stay connected to the batteries. You mention steps. Also the emergency brake circuit is usually wired directly to the battery bypassing any disconnect switch. I don’t have an issue with these as long as there is a make or break switch (on / off) in their power circuits. By breaking these power circuits there will be no current flow thus no battery drain from these on / off devices.

But I think I found 5 devices on our trailer that were always on. Devices such an propane sensor, co sensor, stereo, slide out controller (it has a remote and must always be listening for the remote), and I believe the inverter still draws some power even when it is off.

So with all these always on devices, what is the purpose of installing a factory disconnect that doesn’t truly disconnect the batteries? And for all of us that have installed our own true disconnects, are we going to go to disconnect jail when the weight police stop us and discover the supposedly illegal disconnect?

Are you suggesting a manufacturer should ignore building codes?

Cold Lake Kid · 03-21-2021, 06:33 PM

I always lost a lot of power in my house batteries.
I found it better to physically disconnect them if I wasn't going to use the motor home in more than a week.
I take them right out for the winter, here in Canada, store them in the basement and give them a slow charge every month or so, until I re-install them.

Nomore9-5 · 03-21-2021, 08:08 PM

Quote:

Originally Posted by WrkdbfGuy

Our 2018 Dynamax Force HD 37TS has 2 battery disconnects - one in the basement battery compartment for the house batteries and one under the drivers seat for the starter batteries. When I put the RV in storage at the end of the season, I always turn the disconnects to the Off position.

But when I went to take the RV back out of storage a few days ago ... you guessed it, dead as a doornail. Both systems. We were able to jump and get the coach started. And now we're plugged in so everything is charging back up.

But why don't the disconnects keep things from discharging? Isn't that the whole idea behind having them? And, if I doing things wrong, what can I do better to keep this from happening?

Thanks, Bill

By bitter experience I've learned the best thing I can do is take the batteries out and put them on battery chargers/ maintainers over the winter. I tried solar charging but the lack of full sun wasn't enough to keep them from discharging to critical level. I yanked them out ,brought them home and put them on chargers that brought them up to full and then maintained them

My suggestion is you do the same

TitanMike · 03-21-2021, 08:50 PM

Quote:

Originally Posted by CHICKDOE

Mr Clemens, you say some devices must stay connected to the batteries. You mention steps. Also the emergency brake circuit is usually wired directly to the battery bypassing any disconnect switch. I don’t have an issue with these as long as there is a make or break switch (on / off) in their power circuits. By breaking these power circuits there will be no current flow thus no battery drain from these on / off devices.

But I think I found 5 devices on our trailer that were always on. Devices such an propane sensor, co sensor, stereo, slide out controller (it has a remote and must always be listening for the remote), and I believe the inverter still draws some power even when it is off.

So with all these always on devices, what is the purpose of installing a factory disconnect that doesn’t truly disconnect the batteries? And for all of us that have installed our own true disconnects, are we going to go to disconnect jail when the weight police stop us and discover the supposedly illegal disconnect?

There is a special police force checking for battery disconnects that shut off everything. A branch of the force that looks for people who cut off the "do not remove under penalty of law tags).[emoji41][emoji16]

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