Chassis Battery Drain

[Tuna Can]

I have a 2017 Grand Tour. Recently (one year old now with 15,000), my M-B chassis battery drains overnight. Took it to the M-B Dealer and they confirmed battery is okay as well as the starter cable (known to be a problem).

M-B stated they have seen a problem before on the house-side with a faulty relay. If I engage battery disconnect switch, the charge holds.

Can anyone confirm or have experienced otherwise? I have no problem taking it back to the Airstream dealer, but my experience is that you need to point them in a specific direction and not just give a symptom or it doesn't go well.

[uncle_bob]

Hi

Do your house batteries work ok? ( = they don't drain overnight)

Does everything charge ok? (house *and* chassis)

Bob

[FlyFishinRVr]

Originally Posted by Green Flash

M-B stated they have seen a problem before on the house-side with a faulty relay. If I engage battery disconnect switch, the charge holds.

Not sure what you mean here, so let's get specific. Are you saying that when you turn off the Main Disconnect by the sliding door (i.e. little red LED next to the switch is OFF), you have no problem with your chassis battery, but if you leave the switch on (i.e. little red LED is ON), your chassis battery dies overnight? If the latter is true, a number of questions follow:
- What do you have "on" inside your coach. Fridge? Propane? Inverter? etc.
- What does the tank panel show as your Aux Batt (i.e. coach batteries) voltage and Main Batt (i.e. chassis battery) voltage?
- Have you left your Fusion radio on (screen may be off, but radio still on...press and hold power icon to actually turn it off)?
- Staying with the Fusion for a moment, in the settings, have you enabled the WiFi to stay active even during sleep? Have you enabled Battery Saver mode?

[Tuna Can]

Originally Posted by uncle_bob

Hi

Do your house batteries work ok? ( = they don't drain overnight)

Does everything charge ok? (house *and* chassis)

Bob

House batteries are fine. Charge when both plugged in and by solar. No drain noted. Chassis charges fine too. It holds when battery disconnect is engaged (light off). It drains down to 11 volts when not plugged in and battery disconnect switch is off (light on). All other systems off.

[Tuna Can]

Originally Posted by FlyFishinRVr

Not sure what you mean here, so let's get specific. Are you saying that when you turn off the Main Disconnect by the sliding door (i.e. little red LED next to the switch is OFF), you have no problem with your chassis battery, but if you leave the switch on (i.e. little red LED is ON), your chassis battery dies overnight?

CORRECT

If the latter is true, a number of questions follow:
- What do you have "on" inside your coach. Fridge? Propane? Inverter? etc.

ALL OFF

- What does the tank panel show as your Aux Batt (i.e. coach batteries) voltage and Main Batt (i.e. chassis battery) voltage?

AUX = 12.6 after day in sun
Main = 11.8 down from 12.6
- Have you left your Fusion radio on (screen may be off, but radio still on...press and hold power icon to actually turn it off)?

Has been OFF

- Staying with the Fusion for a moment, in the settings, have you enabled the WiFi to stay active even during sleep? Have you enabled Battery Saver mode?

Wifi has been OFF. I was under impression that Fusion runs off House batteries. Not having problem with them.

[FlyFishinRVr]

Originally Posted by Green Flash

Not sure what you mean here, so let's get specific. Are you saying that when you turn off the Main Disconnect by the sliding door (i.e. little red LED next to the switch is OFF), you have no problem with your chassis battery, but if you leave the switch on (i.e. little red LED is ON), your chassis battery dies overnight?

CORRECT

If the latter is true, a number of questions follow:
- What do you have "on" inside your coach. Fridge? Propane? Inverter? etc.

ALL OFF

- What does the tank panel show as your Aux Batt (i.e. coach batteries) voltage and Main Batt (i.e. chassis battery) voltage?

AUX = 12.6 after day in sun
Main = 11.8 down from 12.6
- Have you left your Fusion radio on (screen may be off, but radio still on...press and hold power icon to actually turn it off)?

Has been OFF

I was under impression that Fusion runs off House batteries.

What battery bank the Fusion is running off of is a current source of debate, so I'll leave that for the other threads where it's being discussed.

For this thread, what is your Aux level at in the morning before the solar kicks in? You say your chassis is down to 11.8v in the morning (very bad BTW, that's 70-80% discharged), but what's the house at? I'm trying to figure out if your BIM has died and is "stuck closed" such that your chassis battery may be "back draining" into your house bank. If it is, in the morning your house bank (Aux) will likely be near where it was when you shut everything down at night. The BIM might be the "relay" the M/B tech was referring to because in essence, it is just a relay, and they have been known to fail.

[Tuna Can]

Originally Posted by uncle_bob

Hi

Do your house batteries work ok? ( = they don't drain overnight)

Does everything charge ok? (house *and* chassis)

Bob

House batteries seem fine and both charge ok. It's just the chassis battery draining overnight. This morning it was down to 11.4.

Gary.

[Tuna Can]

Chassis battery was down to 11.4 this morning and house were at 12.4.

Gary

[Tuna Can]

Originally Posted by FlyFishinRVr

What battery bank the Fusion is running off of is a current source of debate, so I'll leave that for the other threads where it's being discussed.

For this thread, what is your Aux level at in the morning before the solar kicks in? You say your chassis is down to 11.8v in the morning (very bad BTW, that's 70-80% discharged), but what's the house at? I'm trying to figure out if your BIM has died and is "stuck closed" such that your chassis battery may be "back draining" into your house bank. If it is, in the morning your house bank (Aux) will likely be near where it was when you shut everything down at night. The BIM might be the "relay" the M/B tech was referring to because in essence, it is just a relay, and they have been known to fail.

Chassis battery was down to 11.4 this morning and house were at 12.4.

Gary

[FlyFishinRVr]

Disconnect the chassis battery via the quick connect by the accelerator and get a charger on it pronto before it's ruined.

My guess is your BIM is bad. Check its operation via the instructions found here: http://www.precisioncircuitsinc.com/...e-Shooting.pdf

[Tuna Can]

Originally Posted by FlyFishinRVr

Disconnect the chassis battery via the quick connect by the accelerator and get a charger on it pronto before it's ruined.

My guess is your BIM is bad. Check its operation via the instructions found here: http://www.precisioncircuitsinc.com/...e-Shooting.pdf

Will do. Thanks for all your help!
Gary.