No Battery Power

[khutton]

I drive a 2004 Damon Challenger 34 foot, gas class A. After driving home from AZ with no problems, I parked the rig for 3 weeks. Now, both the 2 coach and 1 engine batteries are death. I often park the unit for 6 to 8 weeks and have never had a problem with the battery power. Also, I had the battery disconnect switch on so not sure how anything could be drawing power. I have not yet tried to jump the engine battery or checked the batteries water level. The batteries were checked and water levels ok in January. Any suggestions before I go looking for the problem?

[wolfe10]

khutton,

Welcome to the FMCA Forum.

6-8 weeks with any parasitic draw will assuredly discharge batteries. 

I would recommend two things:

Fully charge the batteries and have them load tested (free at any place that sells batteries).  Make sure they are fully charged first.

Then, use an ammeter to check for draw with the salesman switch OFF (actually any battery disconnect switch turned to OFF).  On many coaches there are still things that remain "on" even with switches off.  Things like PC board for refrigerator, propane detectors, radio memory, etc.

[khutton]

Wolfe 10,

Will items still draw the coach power with the disconnect switch ON and will that draw from the coach normally draw power from the engine battery too?

[richard5933]

If the disconnect switch is 'on' then your battery is connected and power is being used.

Power may be drawn from the engine battery as well if you have a 'battery bridge' (something designed to join the house/engine batteries for charging and/or starting with a weak battery).

Do you have a manual for your coach? Perhaps there is information in the manual which would help figure this out?

[wolfe10]

And, even without a battery "'combine" switch being on, there are parasitic loads on the chassis batter. Certainly, the engine ECU and likely the radio memory are normally on the chassis battery.

[kaypsmith]

5 hours ago, khutton said:

had the battery disconnect switch on so

Not sure if this is a typo, or an actual statement, ON is not the correct position for a battery disconnect switch for long period parking, that switch should be in the OFF position to not allow drainage of your batteries. And as stated by others, there usually is some parasitic draw even in that position. You also state that it is not uncommon for your coach to sit 6 to 8 weeks without the batteries draining, is it possible that you normally plug into an electric source, and this time you didn't?

[richard5933]

If you plan to leave the coach parked and not plugged in, it might be worth it to have manual on/off switches installed immediately next to the batteries (before any loads are connected) so that you can fully and totally shut things off. This will make it much easier to avoid problems. Or course, then you'll need to reset things like radio memory unless your radio is a newer one that retains settings without power. Not sure what else will need to be reset on a newer rig, so best to check your manual on that.

[hermanmullins]

khutton,

When you have your coach stored for 4 to 6 weeks is it stored with power plugged in? If so then your inverter was helping keep everything charged.

The best way to insure that the gremlins don't drawdown you power when stored for a long time is to disconnect your battery cables. If both the house and the chassis battery are fully charged and the negative cables are off you should be OK. 

Herman

 

[khutton]

Thanks everyone for the info. My coach battery switch is marked connect and disconnect. I think disconnect turns the power off but now I am confused. Either way, before I leave the coach parked I turn the light switch on just to check the switch and if the lights don't go on, then I know the switch is set correctly.

[wolfe10]

Yes, if wired correctly, disconnect= power off.

[f301359]

Hi guys, I had a similar problem, hooked to shore power and the coach batteries would charge but the start battery would discharge. I couldn’t figure it out and considered running a charge line from my coach batts to the start battery. Well here I am at an RV park, plugged in and my start battery is charging. What I did was inadvertently turned off the auxiliary switch and when I turned it on, it energized the solenoid and it’s charging. This is on a Southwind 32 VS, and the aux and main switches are mounted above the entry door and it’s hard to tell what position the switch is in. For Fleetwood s, push the button up and you’re ON, down and it’s off or disconnected . Hope this helps. 

Edited June 18, 2018 by f301359
Misspelled word

[wolfe10]

Actually the boost/combine/auxiliary switch is not designed for constant use to charge the chassis battery.

Better to use one of the smart combiners such as Xantrex Echo Charger or a smart, low amp smart charger dedicated to the chassis battery alone.

[richard5933]

Not sure if all modern RVs have this, but we have a manual disconnect switch in the chassis battery compartment. When we get where we're going, tripping this manual disconnect is on the setup list. Nothing can draw power from the chassis batteries once this switch is tripped to the 'off' position. When switched off, the chassis batteries can hold their charge for a substantial period of time if they are well maintained and fully charged before disconnecting them.

When we're parked somewhere for an extended period of time, we also have a separate smaller charger hardwired into the system specifically for charging the chassis start batteries. To use it, we reconnect the chassis batteries and turn on the chassis battery charger. This charger can charge up to 25 amps, and it is a multi-stage charger that can act as a battery maintainer when needed.

Yes, this is a redundant system and yes it's intentionally that way. No matter the state of charge on the house batteries, we wanted to be absolutely certain that the chassis batteries would be charged and ready to start the coach's engine.

The house battery system on our coach is totally separate and distinct from the chassis batteries. We can run all of our house systems and never worry about affecting the state of charge on our chassis batteries.

If we were to ever get a modern coach, one of the things we'd add right away would be a way to manually disconnect the chassis batteries to be absolutely certain that the two battery systems can be separated when desired and to make sure that there is nothing left connected that can inadvertently run down the chassis batteries.

The only downside to this system for us is having to reset the memories on the dash radio, but they can maintain their settings for about a month or more with the battery disconnected. I'd suggest checking with the manual for a modern coach before doing this type of setup to be certain that nothing in the on-board computer(s) will have negative consequences from the disconnect.

I know that not everyone wants to have such a manual system, but I'm bringing it up here to add some ideas to the mix and perhaps spark a thought that might be helpful.

[wolfe10]

With modern computer controlled engines/transmissions, actually better to leave the chassis battery ON and use an auxiliary charger. 

[richard5933]

2 hours ago, wolfe10 said:

With modern computer controlled engines/transmissions, actually better to leave the chassis battery ON and use an auxiliary charger. 

Curious why this is so? Not saying what you stated isn't true, just curious why it is.

[kaypsmith]

Richard, you could add a switch to your radio setup to run on either house batteries or chassis batteries. My old coach had that setup from the factory, my conversion, I only wired it to the house batteries for that reason. The modern computer systems build memory of the drivers habits, which in turn returns much better fuel mileage, as well as shifting data for the transmission. Brett I'm sure can add to these couple of reasons not to disconnect. Oh yes, disconnecting the chassis batteries for a given length of time will reset the computer to factory defaults, and the driver will notice a difference in engine and transmission responses resulting in what he/she thinks is poor performance.

[manholt]

Kay, been there, done that and have several T-Shirts!  Did it on purpose, when I bought this coach used.  Had no idea, what the original drivers habit was!

It can also happen, when you lose enough charge in your chassis battery!  I have a auxiliary maintainer on mine. 

[wolfe10]

12 hours ago, richard5933 said:

Curious why this is so? Not saying what you stated isn't true, just curious why it is.

Richard,

Example: The Allison ECU has TWO 12VDC hots-- one for memory, the other only hot with ignition on.  The memory one is so you  retain all your settings and so you can instantly start the coach.

Not sure I would characterize installing a high amp disconnect switch as "bad", finding an alternate method of keeping the chassis battery charged would be considered "best practices".  And the two types of charging (combiners and small smart chargers) have been around for a long time and are not expensive.  If no shore power where you store, then a small solar panel is another option.

And, remember, even if disconnected, batteries do self-discharge.

[hermanmullins]

I may be different (no puns) but my coach is plugged in 24/7. It keep the house batteries charged by my inverter/charger. I keep the chassis batteries charged with a small smart 3 to 10 amp charger. It is connected to my block heater plug. When I plug the coach in or have the generator running the plug is hot and maintains the chassis battery. When disconnected from shore power the plug is dead.

Since I installed this setup i haven't had the parasites run my batteries down.

Works for me.

Herman