Jump Box Recommendations

[Lou Schneider]

Does your motorhome have an onboard generator? If it does as long as you can start it you can use that to get the chassis engine started. That is what the emergency start switch is for but the name on the switch might be different.

RV Emergency Start Switch Operation And Tricks​

Way too complicated for anything but the sustained high current demand needed to start a diesel pusher with it's high compression and glow plugs. I've always found if the house batteries have enough charge to start the generator they have enough charge to directly start a gas main engine because it usually cranks for a much shorter period than the generator before starting. Just push and hold the emergency start switch and have at it. The generator will only add the current rating of the converter, which is a factor of 10 or more smaller than the main engine's starter so you'd have to run the generator for several minutes before it makes a noticeable difference in the amount of cranking power the house batteries can deliver.

 

[House Husband]

I guess I "stand corrected" then. None of the ones I've seen/used were capable of starting from less than around 6-7 volts. Of course, much depends on the starting load of the engine - a big block V8 or a diesel takes a lot more cranking energy than a 4 cylinder compact car engine. A Chevy Tracker certainly fits the later category.

On my new Li jump start, in small size, is instructions on how to by-pass the low voltage shut down.
That would be necessary to operate things like lights.

Richard

 

[Kirk]

The generator will only add the current rating of the converter,

Which is why you may need to give it a few minutes and you can even use the emergency start switch to allow that converter to bring the chassis battery up some. It just takes a little bit longer but it works. Just like jump-starting from another vehicle with it's engine running! It is also how the converter recharges the coach batteries........