How does the emergency start circuit work when your engine battery is dead and

you use your coach/house battery to supply power? We had sat at a site for 4 days and I had the the experience of a dead battery and the emergency power switch did  nothing.  I'm not sure why my battery went dead either.  House batteries were fine.  Is there a control relay somewhere that the switch actuates? I take it some unit failed to keep my engine battery charged? I wish we had diagrams on the systems. 

2008 Fleetwood Tioga 31M

Did you push in the button and hold it for one minute?

SeilerBird said:

Did you push in the button and hold it for one minute?

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I pushed it in but can't say I held it in for a minute.  What does holding in for a minute do?

On some RV's, the relay that ties the house and engine batteries together for emergency starting is powered by the engine battery, and won't pull in with a totally dead battery. Our previous Coachmen was wired like that, so I added a couple of isolation diodes and a feed from the house batteries as well, so the relay would pick as long as either battery had enough juice. I also have a battery charger and jumper cables on board, "just in case". The battery charger can also be handy in the event of a converter failure.

NY_Dutch said:

On some RV's, the relay that ties the house and engine batteries together for emergency starting is powered by the engine battery, and won't pull in with a totally dead battery. Our previous Coachmen was wired like that, so I added a couple of isolation diodes and a feed from the house batteries as well, so the relay would pick as long as either battery had enough juice. I also have a battery charger and jumper cables on board, "just in case". The battery charger can also be handy in the event of a converter failure.

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been carrying jumper cables with me for nearly 50 years...so I was able to jump my Tioga with our tow car.  I do have a small trickle charger I use on toad that I can put on RV battery for overnight.  I'm concern about the engine battery was dead (5.65v).  Nearly 2 years of owning and first time we had a dead battery.  It charge up fine on 75 mile trip to Orlando and its been holding 12.4v overnight but that tells me its not getting trickle charge from shore power?  Thanks for responding.

How does it work...
Well since Motor homes have two sometimes independcent, sometimes not, 12 volt systems (more on that later) you have two batteries. So if you need a JUMP START.. You got it. Right there in the house (WOW.. I have two Jump Start systems in this coach but one i sluggable and has been used on OTHER things).

Pressing the EMERGENCY START or BOOST button (Same button different names) closes a solenoid and in effect that is the same as hooking up the jumper cables (you only need on to do this).

Now. Holding it for 30 seconds (I do not recommend a minute) allows some power to transfer from HOUSE to Chassis.. Then release and do it again, then release and do it again this time turning the key at the same time.. Hopefully VAROOM results.

Always has for me. Even when the problem was a bad connection on the chassis battery.

NOW: Why did the chassis battery fail?
FOr one thing it's a 2008, so batteries (IF OEM) are 10 years old.> Time to replace.

For another I said I would explain the "Sometimes independent" on all motor homes. far as I know starting the engine connects the two so the alternator charges all batteries (Save the luggable but that is not a factory system)

On some coaches when you plug into shore power.. Same thing happens. and the house converter charges ALL batteries.. But not on all.. So if you are plugged in you may need to add something like a Trick-L-Start

The bad connection comment:
On my coach which is the one I know best, the factory, instead of using a proper battery terminal type connection, since there are 3 wires hooked to the positive post. used crimp on Ring connectors. These are simply the WRONG METAL so they reacted with the lead post on the battery and corrorded, bad connection, Lasted about 3 years between cleanings..

When I put in the new DEKA at 9 years of age.. I made a few engineering type changes so I now have a p;rop;er battery terminal.. IT was cleaned last year but as part of "other" work that required removal and replacement. .but now I have a single lug that hooks to the battery and the wires come together or divide depending on your direction of travel a few inches away  Have not had a bad connection since.

engine battery is 4 years old and hasn't been an issue before.  I'm looking at this problem 2-fold.

1. what caused my engine battery to drain in 3 days.
2. why didn't shore power "trickle charge" the engine battery

I think I got a way better understanding on the emergency start power now.  Now I got to figure out how shore power "charges" the engine battery.

thanks for the replies

I don't know if Fleetwood uses a "BIRD" (Bi-Directional Isolator Relay Delay) system to maintain the engine battery or not, but if so, it may have failed. Neither my current or previous Class A's had a BIRD setup, so I installed an aftermarket "Trik-L-Start" device that uses the house converter/charger to charge the engine battery as needed while parked.

Neither my 2016 Thor, or my 2017 Jayco, would charge the chassis battery when plugged in. One of my little projects is to install a permanent trickle charger for the chassis battery. I have 120V available at my storage location, so just having a trickle charger plugged in will work for me.

NY_Dutch said:

I don't know if Fleetwood uses a "BIRD" (Bi-Directional Isolator Relay Delay) system to maintain the engine battery or not, but if so, it may have failed. Neither my current or previous Class A's had a BIRD setup, so I installed an aftermarket "Trik-L-Start" device that uses the house converter/charger to charge the engine battery as needed while parked.

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thanks Dutch, I'm going to get a hold of fleetwood once we are back from our near 4 months in florida. So far my engine battery is holding charge and may even be "charging" by what I saw with my meter this morning.  I never did like being ignorant of anything so this is like a sliver to me.

I had the same indications as you did with a dead engine battery.  The problem was the Battery Isolation Solenoid which most motorhomes have.  It is what allows the house batteries to jump to the engine battery for a start when you press the Emergency Start switch.  The house batteries are kept charged on shore power.  Like a previous poster I also use a Trik-L-Start to allow the house batteries (only when on shore power) to trickle a charge to the engine battery.  KEY POINT:  Battery Isolation Solenoids are famous for failing - mine did and I just went to the local auto store and got a continuous power solenoid to match the one that had failed. Took about 30 minutes to replace but I recommend disconnecting the batteries to avoid a lot of sparking when doing the replacement.  Why your engine battery went dead - I don't  have a clue.

Bill

I'm not real familiar with the battery charge control in the Class C Fleetwoods, but to the best of my knowledge, all Fleetwood coaches are designed to charge the chassis battery from shore power, once the house battery has reached an adequate state of charge.  Some of the coach models are more sophisticated than others, but basically they close a relay to cross-connect the house & chassis system after the house battery reaches a steady state of 13.3v or more.  That means the relay will not close if the house battery is weak and never reaches that charge level.

The battery boost (Aux/Emergency Start) switch activates the isolation relay to connect the two systems. The relay stays engaged only as long as the switch is held down, so you have to push and hold it. Hold it for 30-60 seconds to allow time for current to flow into the chassis (starter) battery and bring its voltage up, then try cranking the engine again while continuing to hold the switch down.

Your chassis battery may simply be old & getting weak, or you may have something draining power from it while parked. Over the years there may have been minor changes in the coach wiring or accessories that inadvertently created bridges that can drain the chassis battery while parked. If the house battery is also a bit weak, there may be no charging of the chassis battery from shore power and it runs down.

My Fleetwood built-on generator is supposed to charge the chassis battery when it is dead--in other words act as a jump start while it charges the house batteries. I have used this function a couple of times.  However, I once had a battery so dead, it would not do this.  Per instructions from CoachNet, I even let the generator run for 20 minutes before trying the emergency start button.  No luck starting my motorhome, however. 

At this point, CoachNet's only solution was to tow me somewhere to a repair facility for the night, but that did not sound good to me.  Luckily, I had all this happen in a shopping center parking lot, literally 300' from a Firestone Center.  (Excellent planning, don't you think?)  I walked over to Firestone, and a mechanic accompanied me back to check my battery and inform me it was dead dead and would not take a charge.  So, i purchased a new battery and they installed it in the parking lot.  Voila!  Started right away and I drove back to campground. 

So, it should work, but not if your chassis battery is too far gone.  And I am pretty sure shore power does not charge my chassis battery.

JudyJB: For future reference, your onboard generator doesn't actually charge anything.  It is merely a substitute for shore power and provides the electric power to the same onboard converter/charger that does the job on shore power.  20 minutes of charging from shore or genset doesn't put much juice back into a totally dead battery, so if both house and chassis batteries were dead, a little bit of genset time won't do much.

John From Detroit: " Pressing the EMERGENCY START or BOOST button (Same button different names) closes a solenoid and in effect that is the same as hooking up the jumper cables (you only need on to do this.

Now. Holding it for 30 seconds (I do not recommend a minute) allows some power to transfer from HOUSE to Chassis.. Then release and do it again, then release and do it again this time turning the key at the same time.. Hopefully VAROOM results."


I only recently learned that the best way to "give someone a jump" is to wait approx 5 minutes for the host car (at idle or fast idle) to partially charge the dead battery. ..... then, hopefully VAROOM.  Hadn't really considered that the same principle applies to the "boost" switch.  Never had to use the boost, but now I know the best way to do it.  Thanks, John. 

ed s ..... (86 and still learnin' )

Is  there any water in the battery?

So what is your point, Gary?  I start the generator and it charges my batteries, even if that is via a converter.  As far as I am concerned, my generator charges my batteries.  The technical fine points of how it does it is really not relevant to this discussion about starting an engine.

So what is your point, Gary?  I start the generator and it charges my batteries, even if that is via a converter.

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You appeared to be saying that the generator had some special capability for charging the chassis battery when needed and I wanted to point out that is not the case.  If you had been at a campsite, you could have plugged in the shore cord for similar results (or lack thereof).  It's a common misconception that I merely wished to clear up. If you are aware of that, perhaps others were not.