Emergency Start and Chassis Battery

Martythompson

Member
Joined
Nov 11, 2023
Messages
24
Location
Lake Charles
I have a 2016 Axis 25.2 I have had for a little over a year. I need some clarification on how the emergency start should work (mine doesn’t). Is there a relay somewhere that has gone bad? The house batteries are 100%. When I jump it using jumper cables it fires right up. Any thoughts and insights would be appreciated as always. Thanks!
 
A 2016 probably has a BIRD with a Trombetta relay to connect the battery banks together. The Trombetta is a frequent failure item so you should check that first.

The emergency start switch is a normal OFF, press & hold ON switch. Depending on the state of your chassis battery you may need to keep it on for several minutes to transfer enough charge to start the engine with the switch still held on.
 
Use a short jumper and your VOM to check the Trombetta, mine was bad in less than a year and the replacement has lasted since 2017 and is still working fine. They are available with silver contacts as well. Replace it with the same size/duty if needed.
 
I have a 2016 Axis 25.2 I have had for a little over a year. I need some clarification on how the emergency start should work (mine doesn’t). Is there a relay somewhere that has gone bad? The house batteries are 100%. When I jump it using jumper cables it fires right up. Any thoughts and insights would be appreciated as always. Thanks!
Your coach was built in Thor MV pant 750 so you should have a BIRD. This system uses a relay to connect both battery banks. The wiring is normally 6 awg so will carry about 50 amps. This means that proper use is to hold down the switch for a couple minutes to boos the low chassis battery before attempting to start the engine. To check for proper relay operation, simply monitor the chassis battery voltage while holding down the emergency start switch.
 
Your coach was built in Thor MV pant 750 so you should have a BIRD. This system uses a relay to connect both battery banks. The wiring is normally 6 awg so will carry about 50 amps. This means that proper use is to hold down the switch for a couple minutes to boos the low chassis battery before attempting to start the engine. To check for proper relay operation, simply monitor the chassis battery voltage while holding down the emergency start switch.
Thanks! I’ll give this a look
 
Use a short jumper and your VOM to check the Trombetta, mine was bad in less than a year and the replacement has lasted since 2017 and is still working fine. They are available with silver contacts as well. Replace it with the same size/duty if needed.
I have to replace my Trombetta frequently. Any ideas ? Is there a more durable replacement ? I have a 2016 Thor Miramar .
 
Be sure your using 100% duty cycle and the high amperage also. Silver contact models are available which some have used. Mine is almost 10 years old and is the replacement which has seen normal but continuous use. Are you cycling frequently? Life seems to vary but usually several years. You can change to an updated version of battery management as well.
 
Like the other posters, I had the same issue. A bad relay will also not allow the chasis alternator to charge the house batteries. I replaced the relay with a silver coated one and it has lasted 4 years so far. The replacement is not difficult except that the hold down screws are hard to reach on my rig.
 

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