Using Generator to start RV Motor

[lorance el]

This morning my car wouldn't start - battery was dead! It got me to thinking about how I would go about starting my RV if its battery died. Has anyone used their genny to start their vehicle by jumping from the genny? How would i go about it? thanks for your help!
-lorance el

 

[B and C]

I had to do that once this summer.  I used the generator to power my automotive battery charger that I connjected to my engine battery.  Let the generator run about an hour with the charger cranked to maximum. Started up and drove to a shop to get the alternator replaced.  My alternator was not working at the time.  Otherwise I would have used the boost charge to provide a jump.

 

[highdesertranger]

no you can't directly jump it but you could plug a battery charger into it or you could jump from your house batteries to your start battery. highdesertranger

 

[John61CT]

Cranking a starter takes a lot of amps, even if just a short time.

The 12V output on little gennies is very low amps, I would think you'd have to charge a flat batt for at least a few hours, assuming the battery is healthy.

If you have a high-amp mains charger plugged into the genny's AC current output, depending on how healthy / flat the battery is, 20-40 min may be enough, but of course longer is better, up to say 3 hours.

Keep the charger going while cranking to help support the voltage, as long as it is a good one with overcurrent protection.

But you're really needing to crank off the battery, not the batter charger itself.

So if the batt is truly flat, that may just suck up all incoming power without releasing enough to crank the engine. If it's at EOL or shorted internally forget it.

There are pocket sized lithium jumper powerpacks that are great for this, just need to keep one charged if you also use it for charging phones too, they make bigger ones (like a VHS tape) that'll start a big diesel truck. just FFR.

All this is made much more difficult if the battery is very cold.

 

[lorance el]

Thanks so much for the useful info.
So the short answer is - Kind a sort a, but not directly, use a charger that I could charge from the genny.

 

[John61CT]

Yes, key concept is

> you're really needing to crank off the battery, not the batter charger

 

[MikeRuth]

My RV at the time had a Emergency Switch that connected the house batteries to the starting battery, fire it up and return the switch to normal.

Yours might as well. Investigate!

 

[speedhighway46]

Powering your battery charger with a generator: My suggestion is you try it to see if it works before you actually depend on it to start your vehicle. Using my cheap "automatic" charger powered by my Honda generator works fine. But powering my Xantrex 40 amp charger using my Carrier APU on my Peterbilt motorhome does not work. Checked the AC wave form output on the APU with a scope, and its right on 60 cycles, but the Xantrex must be sensitive to minute variations, and won't work.

In my case, I can start my APU from either my "starting" battery bank or from my "house" battery bank, so if my starting batteries are dead (which has never happened) I can start my APU from the house batteries and it will charge the starting bank to get the motor started.

Try it before you need it . . . just my opinion.

 

[John61CT]

Yes running a mains charger off your genny can take a bit of research, but this is something you have setup beforehand for routine use if you boondock, even if you have solar.

Many good ACRs have a "self-jumping" switch or button for exactly this purpose. There are also 1/2/both switches as common on boats, but too easy to forget and leave in the wrong position.

Jumper cables will work in a pinch.

 

[user 13167]

Simple answer... carry a battery charger. When out on the road I always carry a good charger. Have even used it to charge my house batteries when a problem occurred. Genius chargers are popular with some.


Sent from my iPhone using Tapatalk

 

[bullfrog]

I have started my 7,000 watt generator to charge my house batteries before using the house batteries to jump via cables my automotive battery in the RV's engine compartment. The reason for this is to use the converter powered by generator to charge both the house batteries and the automotive battery and insure I don't run down the house batteries.

 

[John61CT]

Yes if a charge source is available, it is always a good idea to support the jump.
But even though cranking does require high amps, it is for such short duration, any healthy House bank at high SoC should have no trouble at all.

Like a 2-sec crank attempt might use .01% of a 200AH House bank.

The danger of depleting House would only come from

the Starter batt being shorted or so otherwise shot, it is absorbing high amps as a bottomless load dump

repeatedly trying to crank dozens of times without addressing the root cause of the vehicle's problem, or

House starting off already very depleted, or not large or not healthy or a poor quality batt to start with

Any lead batts being below freezing temps will also cripple their performance.