Shutting down Gen with a load

[Jeff Bayley]

Dear Abby- I've heard it is bad for the generator to shut it down with a decent size load on it. Is this true ? I've started shutting the heaters or A/C off when convienient but from the bedroom I can't control that stuff and sometimes I use the remote start / kill for the gnerator (in the bedroom) to toggle the generator on or off to get heat or A/C. Is this a problem ?

[Joe Cannarozzi]

Dear Abby I always make sure that everything is off when STARTING the gen, and the inverter as well. It just seemed like a good thing to do. I know when it auto-starts with the inverter on, after it fires up the inverter dosent come on at a 40 amp charge rate but rather ramps itself up to that charge rate instead. I think I remember having this conversation with the fellow who repaired our inverter and he suggested it wasnt good for it.

[dalej]

Jeff, I haven't heard that before. I think it is logical to do it though.

Our bus like many if not all have a switcher box so when it detects volts from different sources, it can switch sources. On ours, when the generator lights up the switcher box detects proper volts and kicks over to generator power. So if you have a load on the generator and shut the generator off, the switcher box detects it and shuts power off to the house, so you don't have low volts to the system. I haven't had a problem nor think you would ever have one either.

Again it just sounds logical to shut things off. But if you watch lights they are always the first sign of bad voltage. If they are dimming and then getting brighter at start-up then check your systems.

Should be a on/off action on your switching electrial sources.

[Jon Wehrenberg]

If you cycle the generator on and off under load (there will always be some) you are exposing the switches (relays) to heavy loads and the arcing across the contacts over time will take its toll.

I do not know if it has any impact on the generator itself.

If you are using autostart you have to accept the fact that you may be switching heavy loads.

[MangoMike]

I'm pretty sure on the Liberty there is a time delay relay that allows for a smoother transisition between power sources which eases the jolting.

ElfMango

[bill&jody]

yes, this is bad. v=L(di/dt) over time it can cause insulation failure in the huge inductor that is your generator (the "L" part of the equation. as the current stops very quickly (the di/dt part), the v part gets very big.

as for the practicality of the matter, i leave stuff on that has lcd clocks, etc so i don' t have to reset 'em.

this bit of trivia brought to you from years of shipboard engineering as an indentured servant. :-)

wmm

[Jeff Bayley]

So the sharp shut off of the sudden death of power from the gen is bad on relays or switches AND also the gen itself. On start up, no load is imposed on the generator (on this bus at least) as it is set to run for 1/2 minute or so before anything kicks on. The start up portion is not as much of a sudden shock as the shut down due to that.

Jon- The relays you speak of for the roof A/C's.....where would those be generally speaking. You don't mean the breakers at the breaker box do you ? Those sound easier to consider disposable than the head unit of the generator unless they are a pain to access.

[garyde]

I think its a good idea to check with the manufacturer of your particular Generator and Transfer switch concerning use. Each Manufacturer will be different depending on what there system was intended. Transfer switches in General are designed to transfer load . The rating of your transfer switch should be designed to handle the load in you coach. The Generator being turned off under load is another matter. Although you are shutting down and therefore shedding load, the manufacturer should be consulted as the transfer switch only protects the generator when transfering load (turning on)after the generator has come up to full operating capacity.

[mike kerley]

In a perfect world (and you can forget that) you would "unload" the generator to no or minimum load and let it run for 5 or 10 minutes to cool down before shutting down.

It should not start under load and most will not, load transfers after about 30 seconds. Nothing I'm aware of to stop the shut down under load on ours, but it is not a good idea for all the reasons listed above.

Merry Christmas All!

Mike

[rfoster]

Don't know about the present Liberty, but in my previous Fiberglass Coach it was spelled out in the owners manual in big letters to unload the Gen and run for about 5 minutes to cool down before cutting it off. Sounds logical and that maybe why I had no problems with the gen.

being a creature of habit now, I cut off the Cruise Airs before shutting down the gen. Of course the Liberty has on and off buttons front, rear, and in the middle for A/C controls, As well as individual cruise air controls. My gen has 2250 hours on it and it looks and performs like new.:cool: