Emergency Start Switch

[ekomalley]

We have an emergency start switch which was shown as an option installed by the manufacturer. There is nothing in the Owners manual so have no clue what it is for. Thanks for any info.

[jayme]

If your vehicle battery is inoperable (dead), you can use the emergency switch, which uses your house battery(s) to start your vehicle

[THenne1713]

I have also used it to start the generator, when the coach battery was going bad. :-) HANDY, but you do not need to leave it on all the time, it bypasses the diodes that prevent undesired discharge :-)

[miataroadster]

I know you could turn on this emergency start switch to jump start the engine battery. BUT is it good idea to leave it on for a few hours from time to time in order to trickle charge the truck(engine) battery?

[THenne1713]

I DO EXACTLY THAT WITH MINE OCCASIONALLY, to occasionally top off my chassis battery, and it is Continuous Duty RATED. I did replace my SOLENOID last year, as it wud CLUNK but not connect, however, it was 22-yo. It can also be the Other way at 5am to start GEN when the furnace ran your coach battery down :-)

[miataroadster]

I DO EXACTLY THAT WITH MINE OCCASIONALLY, to occasionally top off my chassis battery, and it is Continuous Duty RATED. I did replace my SOLENOID last year, as it wud CLUNK but not connect, however, it was 22-yo. It can also be the Other way at 5am to start GEN when the furnace ran your coach battery down :-)
That's good to know! Mine is old too and I hope I wont have to hear that clunk anytime soon.Thanks.

[BPeschka]

My switch is spring loaded (wrong term) so I have to hold it down to start. It hadn’t occurred to me that you could use it to start the generator when the coach battery is low.

2004 BT Cruiser 2051

The switch is quite a clever function.

[Chuck v]

Yes the emergency start switch is a momentary function requiring it to be pressed to work, and returning to OFF when you stop pressing. This is as it should be, because connecting batteries of different ages, types and manufacturers in parallel long term is detrimental to performance, cell life and charging response.


The emergency start switch is a relay/solenoid implemented equivalent to jumper cables...and as such should be used only when needed and for short duration.


Chuck

[Darbgnik]

It can also be the Other way at 5am to start GEN when the furnace ran your coach battery down :-)
Unless at 5am your batteries were completely toasted by the furnace to the point the generator wouldn't stay running without the switch held or a booster pack on the house batteries....... doh!

[THenne1713]

Sounds like CONVERTER OFF/ TRIPPED? (because e.g.) my old, old Magna says it can put the full 45a into battery when needed, so once GEN started & online, CONVERTER SHOULD take over all 12vdc FUNCTIONS NEEDED. Even if you have the smaller 25a max?

[RY469]

I agree with "Chuck V" the E-start switch engages the solenoid that connects house to chassis batteries AND it is an >INTERMITANT< duty solenoid, not a continuous duty solenoid. Used to start your coach when the chassis is low, using the house batteries. You can burn it out prematurely using it long term to charge both banks. Better to get a DC-to-DC battery charger and connect it to charge chassis batteries (from house side) while plugged into shore power.

[Chuck v]

Manual use of the 'emergency start switch' should be limited to short duration as noted several places above and for those RVs that do not have a shore power means to charge the chassis battery can be added as I did.


There is another battery interconnect system that exists in most rigs however that allows the engine alternator to charge all battery banks when the engine is running, and this system has a controller to ensure that the connection is only present when charge conditions are appropriate for the various banks. This capability is usually called a "BIRD" which is an acronym for Bidirectional Isolator Relay Delay and the controller has both delay times and threshold voltages to actuate and stay actuated. This is far different than the 'unattended' or manual emergency start switch.


Chuck