Starting engine with 230V still connected - problem?

[urs4_2008]

Hi

 

I have always started my motorhome's engine before disconnecting EHU, to avoid the fridge trying to switch to gas before 12V, as well as keeping the 230V heating running for as long as possible before takeoff. I've done this on all of my previous motorhomes.

 

According to Schaudt, this is not a problem for their EBLs. Is there anything else (chargers, fridge or any other units) that can be damaged if the engine is started while on EHU?

[StuartO]

Because most MHs have a separate leisure battery, I doubt that starting the engine while still attached to an EHU will have any adverse impact and I am sure I have done this myself occasionally and there has been no adverse effect. My fridge is an older type which relies on manual switching between energy sources but I doubt that is likely to make a difference in this context.

[Derek Uzzell]

Welcome to the Out&AboutLive forums.

 

This 2017 forum discussion may be of interest to you.

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Starting-the-Engine-While-On-mains-EHU-/46259/

 

I’ve ALWAYS disconnected my motorhomes from an EHU before starting the vehicle’s motor, and I NEVER have the motorhome connected to an EHU if I am planning to charge the motorhome’s starter or leisure battery using a separate battery-charger.

 

There is an obvious non-technical ‘forgetfulness’ risk in not disconnecting from an EHU before starting a motothome’s motor, and there are plenty of reports of people driving off having failed to disconnect the hook-up lead beforehand.

 

I can (sort of) appreciate the reasons you’ve given for choosing to start the motor while still EHU-connected, though the ‘benefits’ you’ve mentioned certainly don’t encourage me to do this.

 

This is one of those issues where if one does not do something there will be no repercussions, and if one does do it there might be. Personally, even if the Angel Gabriel assured me that what you’ve been accustomed to doing was 100% technically risk-free for motorhomes, it would make no difference - I still wouldn’t do it.

 

(It might be useful to know what motothome you currently own.)

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/IDENTIFYING-YOUR-MOTORHOME/54713/

 

 

[varonda]

What Derek says ---personally everything is fastened down, locked away and a final check walk round before I get in and fire it up , but each will have their own routine that works for them , mine works for me .

[Thai Bry]

urs4_2008 - 2020-12-21 8:08 AM

 

Hi

 

I have always started my motorhome's engine before disconnecting EHU, to avoid the fridge trying to switch to gas before 12V, as well as keeping the 230V heating running for as long as possible before takeoff. I've done this on all of my previous motorhomes.

 

According to Schaudt, this is not a problem for their EBLs. Is there anything else (chargers, fridge or any other units) that can be damaged if the engine is started while on EHU?

I do the opposite when starting up our van.

There is a time delay before the fridge will go on to gas operation.

If the heating has been on, then our Trauma blown air system, still puts the heat around the van before shutting down.

As soon as I start our van, the fridge will switch to 12v operation, the van is still warm as we set off.

This way I'm not - hopefully - affecting our twin solar panels - for charging up.

 

I suppose each to their own in how they start their vans, I have never started our van whilst on EHU.

If no issues, then carry on as you're doing.

[slowdriver]

Derek Uzzell - 2020-12-21 8:52 AM

..... and I NEVER have the motorhome connected to an EHU if I am planning to charge the motorhome’s starter or leisure battery using a separate battery-charger.

What are the risks of doing this?

 

In my case the EHU is permanently connected and on. (I used to leave my previous Bilbo Celex VW T5 hooked up permanently with no apparent damage in 10 years.)

 

The La Strada Manual advises "The charger may always be connected to the 230 V net as the system will automatically operate according to the power situation of the leisure battery."

 

Further "when the charger is turned on and depending on the level of the leisure battery, the engine battery gets charged with maximum 2A as well."

 

However the Bilbo did not have the separate alarm and tracker that the La Strada has, and probably fewer other potential drains on the vehicle (or leisure) battery than the La Strada. There is also dehumidifier (connected to a power bar connected to a 230v outlet in the van), that runs as and when the humidity reaches a preset level. It's not particularly dry where we are. Plus a small oil heater on a frost setting similarly connected.

 

So in addition I also have I have a Victron Energy Blue Smart IP65s Charger which I leave connected to the engine battery using the eyelet connections. The timer on is set to come on once a week for 12hrs just to ensure that vehicle battery is topped up and never seriously depleted.

The Victron charger has four charging stages: Bulk, Abs, Float, and Storage. When it comes on it usually settles immediately on Abs and fairly quickly moves up to Float in less than an hour, and eventually to Storage.

 

What's are the risks of this approach if any?

[EJB]

Example:- Solar panel is charging batteries......EHU is charging batteries.. vehicle starts and a large pulse of extra energy starts charging the batteries.

Virtually every time this happens the controllers will manage the assault........however if they don't it will be very expensive...just a thought! :-S

[Brian Kirby]

urs4_2008 - 2020-12-21 8:08 AM

Hi

I have always started my motorhome's engine before disconnecting EHU, to avoid the fridge trying to switch to gas before 12V, as well as keeping the 230V heating running for as long as possible before takeoff. I've done this on all of my previous motorhomes.

According to Schaudt, this is not a problem for their EBLs. Is there anything else (chargers, fridge or any other units) that can be damaged if the engine is started while on EHU?

When you do this you will be feeding 12V power into your system from two different sources. The on board charger, and the vehicle alternator. It is probable that both power sources will deliver differing voltages. I would imagine that, by means of (presumably) a relay or similar somewhere, there will be a separator that detects the alternator output (D+ signal?), to ensure separation of the two supplies.

 

The real question, it seems to me, is what might be the result of concurrently feeding in power from both sources were that (assumed) separation function to have failed? As I don't know the answer, and as I assume there is automated separation for those instances when one accidentally starts the engine with the EHU still live, I prefer not to place my faith in a system that might fail with unknown (to me) consequences, so I don't do it.

 

Nevertheless, it would be interesting to know if this separation is normal, and if so, how (at least in principle) it is achieved. Having said that, I do not think it should be assumed that all manufacturers of motorhome power systems will follow the same route. If one wishes to run the engine while on EHU, it seems to me it would be wise to find out how one's own van's system achieves the separation rather than relying on more general guidance.

 

A man fell from the roof of the Empire State Building. As he passed each floor he was heard muttering "So far so good, so far so good"! :-D

[Steve928]

On my Nordelletronica electrics the D+ signal and/or the 'charger on' signal from the EHU/230V charger both close a relay that connects B1 (cab) and B2 (hab) in parallel. B1 and B2 are only separated when neither the engine is running nor EHU is connected.

Then there is the 3rd. charging source, the solar regulator, which is permanently connected to and charging (when producing) both B1 and B2 (but preventing flow from one to the other at times they are not in parallel) so the system is already dealing with multiple charger outputs and algorithms.

 

All that happens if I start the engine whilst on EHU is that D+ switches the fridge to EHU. That there then may be 3 charging sources connected to the already paralleled batteries doesn't cause any problem. It's not something I tend to do but can't see any problem in so doing.

Other systems may be different of course.

 

[Derek Uzzell]

slowdriver - 2020-12-21 11:43 AM

 

Derek Uzzell - 2020-12-21 8:52 AM

..... and I NEVER have the motorhome connected to an EHU if I am planning to charge the motorhome’s starter or leisure battery using a separate battery-charger.

What are the risks of doing this?

I don’t have my motorhome permanently connected to an EHU when it’s parked at home.

 

When the Rapido is connected to an EHU (and its onboard battery-charger is charging the leisure-battery) the starter-battery wiill receive a low amperage/reduced voltage charge.

 

To provide a higher voltage/higher amperage charge to the starter-battery I occasionally connect my CTEK charger to that battery for a few hours. I could do this by connecting the Rapido to an EHU and powering the CTEK charger from one of the motorhome’s living-area 230V sockets (which would be convenient) but I don’t do that. And, if I connected to an EHU, remembered to switch off the onboard battety-charger and powered the CTEK charger from a living-area 230V socket, that should be perfectly risk free - but I don’t do that either.

 

It just offends my anti-risk gene to take a risk that I can’t accurately quantify when a) there’s no compulsion to take that risk or no obviously worthwhile benefit to me to do it, and b) by not taking the risk I know I can avoid any possibliity of potential problems occurring.

[Fred Duck]

With our Sargent system, if you start the engine with the EHU connected and the charger switched on, a loud, high pitched, buzzer sounds. Turning off the charger at the Sargent unit turns off the noise. Whether this buzzer is to tell me I'm doing something I shouldn't or simply to remind me that the EHU cable is still connected in case I'm intending to drive off I don't know but it does concentrate the mind!!

 

I did, once, attempt to drive our previous van away with the EHU cable still plugged into the side of the van (fortunately, turned off at the other end). Not the best thing I've ever done :-(

 

FD

[plwsm2000]

Steve928 - 2020-12-21 1:42 PM

 

On my Nordelletronica electrics the D+ signal and/or the 'charger on' signal from the EHU/230V charger both close a relay that connects B1 (cab) and B2 (hab) in parallel. B1 and B2 are only separated when neither the engine is running nor EHU is connected.

Steve, are you certain about that? If so, trying to start the engine with the EHU plugged in would mean the habitation battery would also try to supply some of the cranking current for the starter motor. This undoubtedly would blow the large battery fuse and possibly damage your split charge relay. It would also mean that your starter battery (normally wet lead acid) and your hab. battery will have to have the same charge profile so you could not use a Gel/AGM hab. battery. This doesn't seem right to me.

 

I don't know about the Nordelletronica, but EHU chargers generally have separate outputs for starter (trickle charge) and hab. (main charge) batteries. They are design so that they can be connected together without damage.

 

To answer Brian's point, I would say that all chargers designed for 12V batteries can have their outputs shorted to other 12V chargers. They are designed as a current source and they do not draw any significant current FROM the battery (i.e they do not "sink" current). The combined output voltage is defined by what ever charger tries to generate the highest voltage and the others just stop producing current.

It is quite common to have the EHU charger, solar charger and even a supplimentary charger on all at the same time. The alternator (or B2B) can be viewed just as another suplimentary charger. You don't need any relays to separate them.

 

[vindiboy]

I never start my vans engine with the hook up live, I read some time ago that if you do you can cause all sorts of electrical problems for your self, true ????? or false ????? I am not going to chance it ??

[Robinhood]

The last and only time I've ever been concerned about running the engine whilst on hook-up (so I didn't), was on a Swift Royale years ago, which had a specific warning:

 

WARNING: Do not start your motorhome engine if the mains supply is

connected. If the engine is started with

KT12SM/PMS4 switched on and the

KT9M5 switched to CAB then the output

fuse will blow on the KT12SM/PMS4.

 

The issue was specific to the particular equipment, and I've never had any qualms on any other 'van.

[spospe]

Not an electrical point, but assuming that you leave the engine running whilst disconnecting the electricity supply and some one jumps into the vehicle and drives it away; are you covered by your insurance?

 

Another point is, what do the clubs say about leaving a vehicle unattended with the engine running?

 

Not technical questions concerning reliability, but ones that I suspect have either not been thought about, or perhaps dismissed / ignored.

[Steve928]

plwsm2000 - 2020-12-21 3:02 PM

Steve, are you certain about that? If so, trying to start the engine with the EHU plugged in would mean the habitation battery would also try to supply some of the cranking current for the starter motor. This undoubtedly would blow the large battery fuse and possibly damage your split charge relay. It would also mean that your starter battery (normally wet lead acid) and your hab. battery will have to have the same charge profile so you could not use a Gel/AGM hab. battery. This doesn't seem right to me.

Yes that's definitely how it functions with the NE185 'fusebox' (see relay RE1 on the wiring diagram attached) and you raise a very good point - in fact I'm glad I've not started the engine with EHU attached now and hereby rescind my above post!

 

You're quite correct about the problem regarding mixing battery types too and that is far from ideal.

I don't need the cab battery charged by EHU as the solar does that job adequately and I have a B2B waiting to be fitted to handle alternator charging of the hab side, so RE1 will be disabled once I get around to doing the work.

[Derek Uzzell]

spospe - 2020-12-21 3:53 PM

 

Not an electrical point, but assuming that you leave the engine running whilst disconnecting the electricity supply and some one jumps into the vehicle and drives it away; are you covered by your insurance?

 

Another point is, what do the clubs say about leaving a vehicle unattended with the engine running?

 

Not technical questions concerning reliability, but ones that I suspect have either not been thought about, or perhaps dismissed / ignored.

LV’s advice here

 

https://www.lv.com/car-insurance/existing-customers/claim/claim-considerations

 

is

 

Question: My car got stolen when I was defrosting it. I left the key in the ignition to have the heaters on. Can I claim?”

 

Answer: It is very easy on a cold winter’s morning to leave our car unattended with the engine running , before we start our journey whilst we go back inside to finish our cup of coffee, or even if you leave the keys in the car while you nip inside to get something you’ve forgotten.

 

But did you know we will not cover you if;

 

- your car has been left unlocked;

- your car has been left with a window or roof open;

- the engine has been left running;

- the ignition key or other ignition devices like a keyfob or a smartphone is left in, on or attached to or left in -- the immediate proximity of your car.

- if your vehicle has keyless entry or a push button start remember if you’ve started your car and have the keyfob or phone in your pocket and leave the vehicle, it can still be driven away!

 

This Financial Ombudsman Service webpage may also be of interest

 

https://www.financial-ombudsman.org.uk/decisions-case-studies/case-studies/customer-leaves-car-running-unattended

 

Forum members may recall that earlier this year it was widely reported that Dame Joan Bakewell had accidentally left her car by the roadside with its engine running and went away for the weekend

 

https://www.standard.co.uk/news/crime/joan-bakerwell-fined-police-car-running-a4467116.html

 

but I doubt that sort of thing happens regularly...

 

I also doubt that motorhome/caravan clubs have any specific regulations regarding leaving an unattended vehicle with its enginge running on a campsite. It’s easy enougfh to envisage someone doing this in a parked vehicle - say to use the demister-blower to clear a fogged/iced up windscreen or run the air-con to cool the vehicle’s interior - but how often would that happen with nobody actually in the vehicle?

[Steve928]

Steve928 - 2020-12-21 4:43 PM

 

plwsm2000 - 2020-12-21 3:02 PM

Steve, are you certain about that? If so, trying to start the engine with the EHU plugged in would mean the habitation battery would also try to supply some of the cranking current for the starter motor. This undoubtedly would blow the large battery fuse and possibly damage your split charge relay.

Yes that's definitely how it functions with the NE185 'fusebox' (see relay RE1 on the wiring diagram attached) and you raise a very good point - in fact I'm glad I've not started the engine with EHU attached now and hereby rescind my above post!

It transpires that NE do have this situation covered - the diagram just shows what the inputs to RE1 are and not their effect.

What happens is:

- G (230v charger on in NE-speak) closes the relay that parallels B1 and B2

- G + Ignition ON opens the relay so starter current comes only from B1

- G + Ignition ON + D+ closes the relay again.