Electrical Parasitic Drain Puzzler

[dkoldman]

Most coaches have a Booster Cable/Antenna Switch. When the Switch is on for Power to the Antenna, you get a little LED light (colors may vary but mine is green)


I was puzzled as to why that light would NOT turn off when coach was put into STORE mode

After some some thought, I assumed it was some how wired to chassis battery. Since I have a Chassis disconnect switch I turned it off, but light was still on

So I then played with all of the scenarios and learned that if BOTH are true; in STORE mode and Chassis Disconnect Switch is OFF; then the power to LED turns off.

Can someone explain why?

The Boost Switch is set to ON for all of the below scenarios.

Use/Store Switch on USE / Chassis Disconnect on ON = Boost Light Green
Use/Store Switch on USE / Chassis Disconnect on OFF = Boost Light Green
Use/Store Switch on STORE / Chassis Disconnect on ON = Boost Light Green
Use/Store Switch on STORE / Chassis Disconnect on OFF = Boost Light OFF Why?

[16ACE27]

Are you plugged in to SP during any of this testing?

How long are you waiting for the light to go out?

That LED takes a miniscule amount of power and charged filter capacitors can probably keep it lit for a long time.

Reverse your testing. Start with the light off and both batteries disconnected:
Which battery turns it back on by itself? I'm guessing house batteries.

[dkoldman]

Originally Posted by 16ACE27

Are you plugged in to SP during any of this testing?

No, we had thunderstorm come through earlier; so I had earlier disconnected the shorepower cord.

How long are you waiting for the light to go out? When I set to STORE and Turned off the Chassis battery disconnect it goes off immediately. In the other scenarios I would say 15 - 30 secs before I concluded the light would NOT go off.

That LED takes a miniscule amount of power and charged filter capacitors can probably keep it lit for a long time. Oh oh, there goes those Filter Capacitors again. What I have learned since buying an RV I may have to google and do some research on how they work.

Reverse your testing. Start with the light off and both batteries disconnected:
Which battery turns it back on by itself? I'm guessing house batteries.

With both batteries disconnected, and led light off; the LED light comes back on immediately regardless to which battery I turned on first It literally behaves as if it were a switch to turn the little green LED on/off.

It is behaving as if it wired to downstream 12vdc points from House & Chassis batteries. If either one is off it is still on, but if both are off then the LED goes off?

If true, it is just an antenna; so I don't see the need for fail safe redundancy? If no Shorepower or Genset and the House batteries are down, does no good to have antenna powered up to draw from Chassis battery.

[16ACE27]

I doubt it is engineered to work that way - they would have had to run wires to both battery busses with diode isolators to prevent cross-connecting the busses.

Do any other DC house loads have the same behavior? Like the overhead lights? If so it may be a failed isolator solenoid that is the cause.

Can you download your coach diagrams from Winnebago like we can for Thor to determine where it is supposed to get power from; and what could possibly be causing the cross-connect?

[dkoldman]

Originally Posted by 16ACE27

I doubt it is engineered to work that way - they would have had to run wires to both battery busses with diode isolators to prevent cross-connecting the busses.

Do any other DC house loads have the same behavior? Like the overhead lights? If so it may be a failed isolator solenoid that is the cause.

Can you download your coach diagrams from Winnebago like we can for Thor to determine where it is supposed to get power from; and what could possibly be causing the cross-connect?

Yes, I will work to get my electrical diagrams from Winnebago. I know I can get and I have seen, but I have been kind of avoiding I need to learn how to use it better than I do.

During interim, when my Store switch is set, there is nothing ON in coach that I can see until I stumbled on this little light. Even the carbon monoxide detector goes off.

The only none factory leads coming from battery posts is one that was installed to feed EC-30 House voltage, and the other installed to feed the EC-30 Chassis voltage. But it worth noting that EC-30 has no power when in STORE mode.

[lwmcguire]

Originally Posted by dkoldman

Yes, I will work to get my electrical diagrams from Winnebago. I know I can get and I have seen, but I have been kind of avoiding I need to learn how to use it better than I do.

During interim, when my Store switch is set, there is nothing ON in coach that I can see until I stumbled on this little light. Even the carbon monoxide detector goes off.

The only none factory leads coming from battery posts is one that was installed to feed EC-30 House voltage, and the other installed to feed the EC-30 Chassis voltage. But it worth noting that EC-30 has no power when in STORE mode.

Turn your booster off and then on while testing, results will be much faster

[dkoldman]

Originally Posted by lwmcguire

Turn your booster off and then on while testing, results will be much faster

I don't follow...?

I know if I turn the Booster OFF the green LED goes out.

The question is why is voltage still supplied to the cable / antenna switch when Shore power is OFF and in STORE mode?

Further why does the cable / antenna switch Green LED IMMEDIATELY go off ONLY when you are in STORE mode for House and Disconnected the Chassis battery?

[dkoldman]

Originally Posted by 16ACE27

I doubt it is engineered to work that way - they would have had to run wires to both battery busses with diode isolators to prevent cross-connecting the busses.

Do any other DC house loads have the same behavior? Like the overhead lights? If so it may be a failed isolator solenoid that is the cause.

Can you download your coach diagrams from Winnebago like we can for Thor to determine where it is supposed to get power from; and what could possibly be causing the cross-connect?

Attached are few electrical drawing.


The Wall Switch / Power Supply is in the AV Cabinet on right front side of coach. The only power wire I saw going into that cabinet was 110 volt?

I also noticed that on Battery Installation diagram, the two batteries come together at some solenoid, so don't know if that is related when power is shut from both batteries? Closest to a cross connect anyway that I was able to see.

[dkoldman]

Update:

I talked with Winnebago today.

They state that the power to the Cable / Antenna should be off when placed in SHORE mode.

They had me check other things and we learned that I can turn the Inverter ON when in SHORE mode.

They state I should not be able to turn on Inverter if in STORE Mode.

Of course they say I would need to take back to a Dealer to have them check. What the support person thought as possible issues was maybe backflow from the Chassis disconnect when it is ON ? If Chassis disconnect switch is OFF the Inverter nor the green light will come on.

He also mentioned it could be an issue with Battery relay connect?

Does this spring any ideas or thoughts on how to check?

[EA37TS]

Might have better luck asking for help on the Winnebago forum. More members with your model rig.

[16ACE27]

Originally Posted by dkoldman

Update:

I talked with Winnebago today.

They state that the power to the Cable / Antenna should be off when placed in SHORE mode.

They had me check other things and we learned that I can turn the Inverter ON when in SHORE mode.

They state I should not be able to turn on Inverter if in SHORE Mode.

Of course they say I would need to take back to a Dealer to have them check. What the support person thought as possible issues was maybe backflow from the Chassis disconnect when it is ON ? If Chassis disconnect switch is OFF the Inverter nor the green light will come on.

He also mentioned it could be an issue with Battery relay connect?

Does this spring any ideas or thoughts on how to check?

Define "shore mode".

[EA37TS]

Originally Posted by 16ACE27

Define "shore mode".

Winnebago not Thor. Who knows how they’re rigged, wired or plumbed.

[javelin]

Interesting issue, but I think 16ACE27 is correct in that most likely the antenna switch is powered from coach battery and the manufacturer would not duplicate power feeds to each battery bus (with isolation diodes) for a TV/antenna switch.

So if you are still getting power when coach disconnect is off (assuming the coach disconnect latch relay is actually open and you are not on shore power, gen etc) then the only way to power is from chassis battery via the “Aux start relay” as noted on your 12vdc drawing (also called battery isolation relay). I also noted that your Winnibego drawings do not show a chassis battery disconnect as factory equipped, so you must have your own chassis disconnect switch you are using in your tests (or the drawings are wrong)?
One way to test the aux start relay (isolation relay) would be to operate and release the emergency start switch and listen for the relay to operate and release. This assumes that this relay is not already held on (operated) by some other electronic control system used for normal battery charging interconnect control......but you are not charging.

I am not familiar with your coach, but a voltmeter across each battery (coach and chassis) to ground would measure the same voltage on both, if the aux start (isolation relay is on/closed) and battery loads are small (very small voltage drops on battery cabling involved). You could also disconnect a coil control wire from the Aux start relay which should prevent that relay from operating at all......unless its main contacts are fused together. Make sure you reconnect when testing is done of course.

[dkoldman]

Originally Posted by 16ACE27

Define "shore mode".

Shore mode - It is an electrical state of being term used by a challenged poster under self induced duress when conceptually thinking Store; but due to poor designs of US made keyboards; may quite often lazily type "H" versus using maximum energy required to get to the "T" key.

[dkoldman]

Originally Posted by javelin

Interesting issue, but I think 16ACE27 is correct in that most likely the antenna switch is powered from coach battery and the manufacturer would not duplicate power feeds to each battery bus (with isolation diodes) for a TV/antenna switch.

My money is on the ACE too It is confirmed that the USE/STORE switch when in STORE mode should cut off the power being supplied to the Cable/Antenna wall plate.

So if you are still getting power when coach disconnect is off (assuming the coach disconnect latch relay is actually open and you are not on shore power, gen etc) then the only way to power is from chassis battery via the “Aux start relay” as noted on your 12vdc drawing (also called battery isolation relay).
*Not on shore power as 50amp cord is not plugged in. The genset is also not running.

*Chassis power as a 2nd source is confirmed because given the House Disconnect does not stop flow to Cable / Antenna switch, when I turn off the Chassis disconnect all DC power is not ceased, including power that was going to the Inverter as well.

*I see the AUX Start Relay in the schematic but not in the actual drawing so I can tell of it is in battery compartment or not?


I also noted that your Winnebago drawings do not show a chassis battery disconnect as factory equipped, so you must have your own chassis disconnect switch you are using in your tests (or the drawings are wrong)?

When I first bought, the RV, I had the dealer install an aftermarket Disconnect switch for the Chassis. I use on my boat batteries and never had a problem. See picture. I am not sure how the switch could be an issue, because when I turn it off and if in STORE mode, there NO POWER anywhere. So when the switch is Open something else must be drawing from that chassis battery due top some other issue? Right?


One way to test the aux start relay (isolation relay) would be to operate and release the emergency start switch and listen for the relay to operate and release. This assumes that this relay is not already held on (operated) by some other electronic control system used for normal battery charging interconnect control......but you are not charging.


I am not familiar with your coach, but a voltmeter across each battery (coach and chassis) to ground would measure the same voltage on both, if the aux start (isolation relay is on/closed) and battery loads are small (very small voltage drops on battery cabling involved).

Don't follow here?

You could also disconnect a coil control wire from the Aux start relay which should prevent that relay from operating at all......unless its main contacts are fused together. Make sure you reconnect when testing is done of course.
I am not sure where the Aux start relay is?

Here is a test I did do...

With USE/STORE switch in USE mode; I put the Chassis disconnect on OFF. I tried to start and confirmed it would NOT start then I pushed the Emergency Start Button and it started right up even though Chassis battery as off.

So I am still with the fact that my Cable/Antenna wall plate and the Magnum 1000w Inverter can draw power from Chassis battery when House battery is in Store mode, that is assuming the Chassis battery had not been disconnected.

[javelin]

Good clarifying responses and your final test seems to prove that the Aux start relay (battery isolation relay) is functioning correctly for starting the coach. So under non charging conditions that relay should remain open, which gets us back to how is the ant switch LED getting power when only the chassis battery is connected? The LED is a trivial load; not sure about the antenna pre-amp, but likely small as well.......it would be nice to have a schematic for the specific wiring. At least you can either turn off the ant switch when not in use, or disconnect both battery strings to kill it as required.

[16ACE27]

Originally Posted by dkoldman

Here is a test I did do...

So I am still with the fact that my Cable/Antenna wall plate and the Magnum 1000w Inverter can draw power from Chassis battery when House battery is in Store mode, that is assuming the Chassis battery had not been disconnected.

No, the inverter draws power directly from the house battery bank through it's own fuse (per your diagrams). It is not affected by your battery disconnect switch and the Winnebago guy should have known that.

[dkoldman]

Originally Posted by javelin

Good clarifying responses and your final test seems to prove that the Aux start relay (battery isolation relay) is functioning correctly for starting the coach. So under non charging conditions that relay should remain open, which gets us back to how is the ant switch LED getting power when only the chassis battery is connected?

Remember the ant switch is getting power when either the House battery is in USE; or when Chassis Battery is ON. If either is OFF the LED light stays on. If both are OFF the LED light goes out. The same is true to turn Inverter on. If Inverter is ON then everything on Inverter circuit has power even though USE/STORE is in STORE mode.

The LED is a trivial load; not sure about the antenna pre-amp, but likely small as well.......it would be nice to have a schematic for the specific wiring. At least you can either turn off the ant switch when not in use, or disconnect both battery strings to kill it as required.

Yes both workarounds work. For kicks I was gonna try to see how low the draw was for the LED / pre amp only (using my digital readout in hundreds of KWs from inverter; so I purposely make sure Chassis is ON and USE/STORE in Store mode. And the LED light did NOT come on!!! So I press wall plate button thinking making I had the switch on cable, but it stayed dark. I then go to the Inverter remote and try to turn it on and it does not come on!!! So at that moment everything appeared to be working. I switched to USE mode and the LED came on and I was able to turn on Inverter.

However, when I turned the USE back off; the LED for ant stayed on, and I was able to turn on Inverter again This was about 2 hours after the Test above in previous post. I don't know if this is repeatable? I may try to start it again with the Chassis battery disconnected to see ?

I agree the LED & Pre amp is likely not pulling enough to worry about, but I am very curious now. I also have to account for the fact that if I do got to store mode and inadvertently left the the inverter on, I could be drawing who knows what on the inverter circuit? I don't think the latter will happen because we don't leave the inverter switch on even though it will switch automatically.

[dkoldman]

Originally Posted by 16ACE27

No, the inverter draws power directly from the house battery bank through it's own fuse (per your diagrams). It is not affected by your battery disconnect switch and the Winnebago guy should have known that.

I guess it get confusing because the chassis disconnect switch can stop the inverter from getting power from Chassis battery.

The issue is why or how can an inverter or ant switch get power from House batteries if available, and automatically switch to get it from Chassis battery if House battery is not available and Chassis battery is available?

[dkoldman]

Originally Posted by EA37TS

Might have better luck asking for help on the Winnebago forum. More members with your model rig.

I did and they got stuck too.

Last response I got was...

"When I store my RV I always turn off both - house and chassis battery. So, I've not run into anything such as this."

I don't ever store my RV to a point where I need to turn off disconnect switch for chassis battery. I just wanted the ability to do so, if I ever needed to.

I don't think I have ever left Inverter ON without AGS on Auto Mode or Driving the vehicle; so that is not a concern. Of course the Ant booster is always on, so that is small draw that I just learned I had yesterday by accident.

I may have to call Winnebago again and maybe I get a different response for different person?