Is it bad practice to run the engine whilst on EHU

[Jewellbags]

Just double checking but my dealer said that you should t really run the engine whilst on EHU ... thoughts folks ?

 

[gus-lopez]

I run mine whilst on ehu + the solar is charging it as well. Never had a problem. Might be with some newer stuff though?

 

[bladerunner]

I wouldn’t/don’t.

 

[pappajohn]

In my view (others will disagree) there is one link between mains and alternator.... The battery charger, and no harm can be done by running the engine while the charger is working.
Both produce 12v (nominal) DC just like a solar panel and battery charger working together......and they get along happily.

 

[pappajohn]

I wouldn’t/don’t.

Why not?

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[Phill D]

"SOME"! motorhomes have a warning alarm if the engine is started while on EHU to warn the cable is still attached!!!

but i have never had any issues running the engine while hooked up. I would not do it for any lenghtly periods though...

 

[bladerunner]

Strikes me as too many pixies going through the electric string all at once

 

[Carolyn and Kev]

I was under the impression that if you run the engine whilst Hooked up...It can have a undesirable effect on the charger? Pappajohn...Do most motorhomes have that link you mention?
I have done it to be honest , but been told off by the dealer when mentioning it? Dont know why ...even now? Interested to know the correct way..

 

[pappajohn]

Nah... Battery will only take what it needs unless the battery has a fault then its going to overcharge on the charger anyway.

 

[eddie]

"SOME"! motorhomes have a warning alarm if the engine is started while on EHU to warn the cable is still attached!!!

but i have never had any issues running the engine while hooked up. I would not do it for any lenghtly periods though...

That’s to stop people driving off plugged in

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[pappajohn]

Do most motorhomes have that link you mention?

I don't mean a physical link but a common link.
Mains in to 230vac (primary) circuit of charger, 12vdc (secondary) circuit out to battery. The two aren't physically connected so connecting a second 12v supply (split charge from alternator) is no different to a solar panel supplying 12vdc while on hookup.

 

[WillH]

Can/do.

 

[bigtwin]

Why not?

Indeed; you beat me to it.

Ian

 

[eddie]

My built in generator is designed to run whilst driving for roof air etc

 

[CazPaul]

I was under the impression that if you run the engine whilst Hooked up...It can have a undesirable effect on the charger? Pappajohn...Do most motorhomes have that link you mention?
I have done it to be honest , but been told off by the dealer when mentioning it? Dont know why ...even now? Interested to know the correct way..

We started the engine on our 2004 Hymer S820 whilst the on board built in generator was running

It knackered all sorts, mains charger, supplementary charger, electroblock.

The countries leading Hymer expert said NEVER start the engine whilst the genny is running or on EHU as that can happen

Never would do it again. Valuable lesson learnt. So I think the answer must be on some vans, older Hymers for sure it can be disastrous, as in our case.

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[Steve and Denise]

Oh dear CazPaul, out of interest who would be the country’s leading Hymer expert ?

 

[HandyAndy]

Having the engine running whilst on EHU wouldn't make the slightest bit of difference.
The dealer talking out of his hoop as usual.

 

[dabhand]

Why would you bother to do this anyway?

 

[CazPaul]

Oh dear CazPaul, out of interest who would be the country’s leading Hymer expert ?

He's retired now, most people, in fact everyone with a Hymer will have heard of him or used him, Mr Hambleton.

 

[Steve and Denise]

He's retired now, most people, in fact everyone with a Hymer will have heard of him or used him, Mr Hambleton.

No that’s a new one to me but then again I have only been at it a few years.?

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[eddie]

We started the engine on our 2004 Hymer S820 whilst the on board built in generator was running

It knackered all sorts, mains charger, supplementary charger, electroblock.

The countries leading Hymer expert said NEVER start the engine whilst the genny is running or on EHU as that can happen

Never would do it again. Valuable lesson learnt. So I think the answer must be on some vans, older Hymers for sure it can be disastrous, as in our case.

And I wonder what possible argument he would put forward to support that?

 

[eddie]

He's retired now, most people, in fact everyone with a Hymer will have heard of him or used him, Mr Hambleton.

John Lunt started Maddison’s, and were the sole Hymer importers, from memory, Brownhills bought Maddison’s and Peter Hambleton used to work for John Lunt

 

[CazPaul]

And I wonder what possible argument he would put forward to support that?

not sure I can only say what happened and what he subsequently told us.

 

[Jonno1103]

On river cruisers it's recommended running the engine when on shore power or inverter when wanting to use an appliance such as a microwave.

 

[Cheshirecat57]

As asked elsewhere, why do you want to run it.?

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[Reallyretired]

I wouldnt see it likely to cause a problem, though I couldnt envisage a need to do it, unless to run cab aircon while stationary. Prolonged idling of engine not recommended anyway.

 

[HandyAndy]

If you want to use a high current draw 12v appliance then running the engine will use the alternator to help support the battery bank and also add in the cab battery to the the battery bank as a whole if you have a VSR / Split charger.

 

[peterc10]

Putting aside any electrical problems, as I understand it you should not allow a modern diesel engine to run on idle for long periods. I suspect Lenny HB will be along in a while to explain why.

But in reality I am struggling to understand why you would ever want to run your engine while you are on EHU. Perhaps the OP can explain that?

 

[Pausim]

If it was a serious problem it would be an easy matter for manufacturers to fit a device to prevent starting or to keep the charging circuits separated whilst on ehu. They don’t appear to do this and I think they would if it was a problem. An alarm to tell you that you have just destroyed your electrics seems pointless so presumably it is aimed only at discouraging you from driving off. Sadly I can see some dealers (not all) finding this a convenient excuse for not honouring guarantees.

I can see potential conflicts between ehu and generators or anything else that produces an AC current such as an inverter. If they are out of phase there could be a significant voltage increase and the chances of them being exactly in phase are slim. If starting the engine did anything to power up an inverter that had been isolated whilst on ehu I can see the chances of smoke signals from electrical devices increasing.

Of course I could be talking out of my exhaust pipe.

 

[DavidG58]

I had a problem running my engine while hooked up

but only because I reversed at home to get to our manhole, only about 5m

didn’t bother unhooking thought it would be OK

all would have been good if I hadn’t run over the cable and ripped it out of the socket , no harm done at all, but lucky I reckon ? just cut back and remade plug connections