Emergency start switch did not work

lucky55616 · 03-20-2018, 12:47 PM

I have a Sunseeker 3010DS on the Ford chassis with the V10 engine. I normally start the engine and let it run for a while once a month during the winter months while in storage. This has always worked fine in the past 3 winters that I have had the RV. When I tried a few days ago, it seemed that the starting battery was totally dead, I only got a slight clicking sound when trying to start the engine. I then tried using the emergency start switch which is supposed to engage the house batteries to start the engine, I still only got the slight clicking sound that I got before. The house battery disconnect switch was set so that the house batteries were not disconnected. The house batteries measured 12.71 volts on my voltmeter, I never did measure the chassis battery. Finally, I started the gen set and let it run for about 5 minutes and then tried starting the engine and it fired right up. I don't understand why the emergency start switch did not allow the engine to start using the house batteries.

bubbles · 03-20-2018, 01:22 PM

The interconnect relay for the emergency start is controlled by the coach batteries. Sounds as though the coach batteries were to low also.

270S · 03-20-2018, 01:25 PM

The house battery bank needs to be nearly fully charged or there is not enough voltage to close the relay. It is a false hope if not monitored 100% of the time. That is why I have redone my RV to work correctly,

From the attached 12Vdc Battery control center PDF.

Interconnect Relay
Control electronics on the circuit board parallels the coach and chassis batteries with the interconnect relay. In addition, the batteries can be paralleled with a momentary pushbutton switch on the driver's console that applies +12vdc to P3-1. For the purpose of charging the coach and chassis batteries, power for the control
electronics is obtained from the ignition switch and coach battery through diodes D1 and D2. Underway, when the charging source is the engine generator, +l3.2vdc on the
ignition line triggers the electronics. After a lSsec. delay, the interconnect relay closes, paralleling the batteries. Should the battery voltage go below 12.7vdc, the interconnect relay will open after around a 15sec. delay. When the vehicle is parked and on shore power, when the converter brings the coach battery up to +13.2vdc, the interconnect relay will close after the 15sec delay, charging the chassis battery as well. As before, the relay
will open when the battery voltage goes below 12.7vdc.

Ignition Relay
The ignition relay closes when the vehicle ignition switch is turned on (P3-2 goes to +12vdc). This provides chassis battery power to P3-3, P3-4 and P3-5 through fuses. P3-
6 is hot when the ignition switch is off and dead when the key is on. Optionally, P3-6 can be hot all the time if jumpers are installed which circumvent the NC contacts of the ignition relay.

lucky55616 · 03-20-2018, 02:19 PM

As I mentioned, the house batteries were at 12.71 volts which I consider in the fully charged range so they should have had the capacity to start the engine. Do I need to hold the emergency start (battery boost) switch in for several seconds or a minute before trying to start the engine ?

mbtelguy · 03-21-2018, 01:13 PM

Check Fuse F5 (5amp) in the Battery Control Centre it is in line with EM start circuit

rickkey2 · 03-21-2018, 02:36 PM

Never needed to use mine but if I understand it right you need to hold down the boost switch while trying to start the engine and then release the switch when the engine starts.

270S · 03-21-2018, 06:44 PM

Quote:

Originally Posted by lucky55616

As I mentioned, the house batteries were at 12.71 volts which I consider in the fully charged range so they should have had the capacity to start the engine. Do I need to hold the emergency start (battery boost) switch in for several seconds or a minute before trying to start the engine ?

Voltage alone tells you nothing about condition. The only true way to tell is with a battery load tester. If in good health, 100% fully charged is 13.2 Vdc. Depending on condition, 12.7 is apx 75-80%.

Bodiedog · 03-21-2018, 10:56 PM

Rickkey2 is correct. You have to hold the switch in while turning the ignition, and release after it starts. Feature came in handy on a couple of occasions on my previous rig.

JLeising · 03-21-2018, 11:30 PM

No experience- my Solera doesn't have the emergency start switch- but some thoughts. If your chassis battery is that low, I believe you would need to hold the switch "on" for several minutes to "recharge" your chassis battery sufficiently to start the Motorhome. I don't believe the emergency start wiring and relay can conduct enough current to directly start the vehicle engine from the house batteries. Think of the size/diameter of vehicle jumper cables. Even with heavy duty jumper cables, I usually have to wait a while before trying to start a vehicle with a dead battery. What the "emergency start" switch/circuit can do, I believe, is supply enough current over time to recharge the chassis battery sufficiently to start the vehicle engine.
I believe your house batteries were in decent shape, or you would not have been able to start the generator. At least on my Solera, the generator starter gets its power from the house batteries.

Wolverine 1945 · 03-22-2018, 10:35 AM

Quote:

Originally Posted by bubbles

The interconnect relay for the emergency start is controlled by the coach batteries. Sounds as though the coach batteries were to low also.

X2 !!!

bubbles · 03-22-2018, 10:48 AM

Quote:

Originally Posted by Wolverine 1945

X2 !!!

I didn't pick up on the starting of the genny so my guess would be operator error. The interconnect relay would energize with the genny running. One other possibility is a blown fuse in the BCC (the feed to the emergency start switch) and the BCC is a typical BCC. This is predicated upon no wiring issues.

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