Engine start on EHU.

Apologies if this is a silly question , but is it okay to start your engine while still connected to the mains power ? In other words could it damage any of the on board electrickery?

Good question, never thought of that, what made you ask?
I should imagine there will be safeguards to prevent any problems but couldn't say for sure.
I look forward to finding out.

Firstly, it's my belief that the only silly questions are the ones you DON'T ask!

I am not aware of any reason why starting your engine with the EHU connected would cause any damage. Depending on your model and set-up, once you have started the ignition you may find that the 12V in the habitation area is cut off. Many if not all reasonably recent models have a relay which controls this, supposedly to prevent any problems with the electronic engine management system. However, we have bypassed this on our 2002 Peugeot based Pollensa, so that travellers in the rear seats can use the reading lights, laptop PSUs, etc.
Note also that a similar relay operates the other way round, only connecting 12V to the refrigerator when the engine is running so as not to flatten the engine battery.

Hope this helps.

PS edit: on my original post, when it appeared it had inserted in it the following when I used the common abbreviation for refrigerator:
* Inappropriate Word *
- what's that all about???

I've started ours up while still on EHU without any problems, but our '95 van doesn't have any of the fancy circuitry that Roger mentions.

Frank

It's a very good question.

During a tour this year I made a fairly long stop on a site in Bulgaria. The site was good.....and the weather was boiling....so I fancied a long break from driving! I was on EHU as the fridge really struggled with the weather when on gas or 12v. As the van had stood a while, one day I decided to turn the engine over just to give the starter battery a bit of a boost. And yes the EHU was still connected whilst I did this.

After a fortnight on site I decided it was time to move on, but when i'd packed everything away and fired up the engine I noticed the Fridge had not switched in. When I looked under the bonnet (where my habitation fuses are), the fuse to the fridge had literally melted. So bad that it proved a heck of a job to remove!

With fuse replaced it was sorted and I was eventually on my way, but i've often thought back 'how on earth did that fuse fry itself when I was on EHU'?

You ~should~ be fine, because you have the vehicle battery effectively acting as a buffer on the vehicle electrics - it should under normal circumstances absorb any voltage spikes from either starter or alternator.

-mojo- wrote:You ~should~ be fine, because you have the vehicle battery effectively acting as a buffer on the vehicle electrics - it should under normal circumstances absorb any voltage spikes from either starter or alternator.

Interesting point - when the engine is running, does the charge to the leisure battery come via the engine battery or direct from the alternator?

Also, when the engine is running AND the EHU is connected, presumably the leisure battery is being charged by both the engine and the 240V/12V charger simultaneously? Does that simply mean it would charge more quickly??

We also have a BatteryMaster fitted to charge the engine battery via the leisure battery charging circuit when on EHU - not sure how that might be affected by the engine and EHU powering simultaneously???

It's too late at night for my brain to get around this stuff . . .

rogerblack wrote:Interesting point - when the engine is running, does the charge to the leisure battery come via the engine battery or direct from the alternator?

Also, when the engine is running AND the EHU is connected, presumably the leisure battery is being charged by both the engine and the 240V/12V charger simultaneously? Does that simply mean it would charge more quickly??

We also have a BatteryMaster fitted to charge the engine battery via the leisure battery charging circuit when on EHU - not sure how that might be affected by the engine and EHU powering simultaneously???

It's too late at night for my brain to get around this stuff . . .

On the first one: charging current will come from the alternator, though how much goes to the vehicle battery and how much to the second one probably depends on how sophisticated the split charge system is.

Regarding having multiple chargers on a battery at once - generally it seems that (having done it inadvertently myself before I fully understood my van's wiring) it does no harm, and they don't have any tendency to fight with one another. Seems that if the battery is low and they are both in "bulk charge" mode then both will probably be adding charging current. I think that fairly quickly one will dominate and the other will drop back to trickle charge mode - it depends on their design and the threshold voltages for the various modes on each.

Bulletguy wrote:After a fortnight on site I decided it was time to move on, but when i'd packed everything away and fired up the engine I noticed the Fridge had not switched in. When I looked under the bonnet (where my habitation fuses are), the fuse to the fridge had literally melted. So bad that it proved a heck of a job to remove!

With fuse replaced it was sorted and I was eventually on my way, but i've often thought back 'how on earth did that fuse fry itself when I was on EHU'?

I've had the fridge fuse blow twice and melt as you describe. I've never thought about it before but I think I may also have started the engine while still on hook-up. So perhaps that's why the fuses blew. You learn something evrey day!

Hi.

I start my 1995 Smyphony every day with EHU connected and run up to 70degrees and" refridger" switched on and have done for 18 months with no problems whatsoever checked fuse today and found ok.
I also have small solo panel connected full time via cig lighter and battery always fully charged .#
John

johndean wrote:
I start my 1995 Smyphony every day with EHU connected and run up to 70degrees and" refridger" switched on and have done for 18 months with no problems whatsoever checked fuse today and found ok.
I also have small solo panel connected full time via cig lighter and battery always fully charged .#
John

If the van gets driven every day there doesn't seem a lot of point in putting it on EHU! The alternator should keep everything nicely topped up.

Just a word of warning, If you don't need it do it then avoid it. It could be easy to forget that you are connected and drive off , then the fun wil really start
John

hoopman wrote:Just a word of warning, If you don't need it do it then avoid it. It could be easy to forget that you are connected and drive off , then the fun wil really start
John

Sensible warning! We never remove our Stoplock steering lock until the EHU cable is disconnected, that acts as a reminder.

hoopman wrote:Just a word of warning, If you don't need it do it then avoid it. It could be easy to forget that you are connected and drive off , then the fun wil really start
John

When mine goes on permanent EHU (in the garage) I'm going to fit a pull-free connector a couple of feet from the connection on the van, so that when I finally do forget it will simply leave a short "tail" attached to the van.

Paulmold wrote:

Bulletguy wrote:After a fortnight on site I decided it was time to move on, but when i'd packed everything away and fired up the engine I noticed the Fridge had not switched in. When I looked under the bonnet (where my habitation fuses are), the fuse to the fridge had literally melted. So bad that it proved a heck of a job to remove!

With fuse replaced it was sorted and I was eventually on my way, but i've often thought back 'how on earth did that fuse fry itself when I was on EHU'?

I've had the fridge fuse blow twice and melt as you describe. I've never thought about it before but I think I may also have started the engine while still on hook-up. So perhaps that's why the fuses blew. You learn something every day!

Good to know someone else shares my suspicions then! It was the only thing I could think of as prior to going static for a couple of weeks the 12v supply to the fridge had worked exactly as it should.

As I was about to suggest someone 'experimenting' by kicking the engine in whilst on EHU to see what happens......the post below then confounds the issue which leaves my 'theory' inexplicable!!

johndean wrote:Hi.

I start my 1995 Smyphony every day with EHU connected and run up to 70degrees and" refridger" switched on and have done for 18 months with no problems whatsoever checked fuse today and found ok.
I also have small solo panel connected full time via cig lighter and battery always fully charged .#
John

-mojo- wrote:
If the van gets driven every day there doesn't seem a lot of point in putting it on EHU! The alternator should keep everything nicely topped up.

That's true John but my van goes on SORN over winter as I no longer have any desire to venture off to Spain and get robbed! I use my car and just occasionally hook the van up to mains to keep the Leisure battery topped up. As it is, my starter battery had seen better days anyway so decided to remove it and will replace with a new one next year.

Bit 'off topic' but I should mention something here which applies to all Duetto or Transit owners where the batteries are sited over each inner wheel arch.

When I removed the starter battery I found the tray had badly rusted and was rotting away in parts, so have removed that as well (already have a genuine Ford replacement which I picked up for a fiver ready to go on).

Not sure about other base vehicle models but before fitting anything in the engine bay, Ford cover the entire area with a plastic backed rubberised foam sound proofing. This stuff is even underneath the battery trays, ie over the inner wheel arches. This sound proofing acts like a sponge and even though your engine bay may look nicely clean and dry, what you cannot see is lurking hidden underneath the battery trays. This stuff is the perfect built in panel rotter and needs ripping out....ASAP!!

I did this 'job' last year on my leisure battery tray (the n/s arch) and removed the proofing from over the inner arch, then coated it with a liberal amount of Waxoyl before fitting a new tray which was also given a few coats of Hammerite and Waxoyl.

hoopman wrote:Just a word of warning......It could be easy to forget that you are connected and drive off , then the fun wil really start
John

Met a French couple while I was away with a very expensive MH (they were fulltiming). His wife had done this and needless to say it was quite expensive to sort the damage! So now they have a printed list of 'things to check' before driving off. They keep this list stuck on the dashboard!

Hi All,
To see my own check list put lists into the search box, this covers everything I have found important and has not been altered for several years.
I use this way of doing things to encourage members to use the search box rather than start a new thread on subjects which have been disscussed sometimes many times before.


Brian2

Further to the fridge fuse melting.Thats happened to me BUT nothing to do with external power or starting with the power connected.
I suspect its to do with resistance of the fuse if corroded and or an excessive current to the fridge.
regards
Mike

Regarding driving off with the EHU connected.
This was one of the first things I saw as a potential problem and one I cannot believe has not been addressed by manufacturers.
Over the winter I'll be rigging a micro switch activated by the lid of the EHU door so that if the engine is started with the EHU connected, a buzzer will sound in the cab.

Hi All,
If convertors fitted the EHU socket without a catch on it on the rear of the van you could drive off without damage, though if you got to far away before realising it may not be practical to go back for the lead.

Brian2

Celticbiker wrote: I'll be rigging a micro switch activated by the lid of the EHU door so that if the engine is started with the EHU connected, a buzzer will sound in the cab.

The lid on my EHU has a tendency to pop open while we're travelling, I do not know whether this is due to flexing or what? I fitted a new one because the old one did it, but the new one does it too So now I just live with it. Don't think I could live with a buzzer sounding all the time though!

Frank

maybe my background in the RAF with aircraft but i checked things in a methodical way,some times twice.
I doubt if many members check tyres or rear lights very often. Its also very easy to be distracted.
Surely you check roof vents ,cupboard doors etc before driving off?
regards
Mike

boxerman wrote:The lid on my EHU has a tendency to pop open while we're travelling, I do not know whether this is due to flexing or what? I fitted a new one because the old one did it, but the new one does it too So now I just live with it. Don't think I could live with a buzzer sounding all the time though! Frank

Hi, Frank

If it's the hinged cover flap you mean, ours broke at the bottom where the clip-on piece was and so I could see it flapping about annoyingly in the mirror. As a temporary measure until I could get hold of a new one, I used some Velcro dots to keep it shut. That was several years ago and still works fine, I never bothered to get a new one.

[quote="rogerblack"]

boxerman wrote: As a temporary measure until I could get hold of a new one, I used some Velcro dots to keep it shut. That was several years ago and still works fine, I never bothered to get a new one.

Thanks! What a good idea I think I might make a similar temporary repair to mine

Frank

Yes thats a good idea. I think Doris will get the same velcro treatment
Brad