Using Movers When Connected To EHU
Comments
-
In my opinion, not a good idea, how long does it take to disconnect the caravan from the EHU? 30 seconds? Not to mention the fact that the MM could pop off the caravans' charger due to practically short-circuiting it by the excessive amperage taken by the MM, the very least it could do is pop off the chargers diodes or mosfets in the case of an inbuilt smart charger! but who am I to say what is right or wrong in this matter?
4 -
I agree with Paul, a battery in a good condition (charged) is the power source but in a bad condition the charger could well become the source of supply and the drain being pulled from that could pop its clogs. After all, in this scenario the battery is acting as the 'buffer'.
Disconnect from mains to be certain.
0 -
When moving the caravan in readiness to go away from home, it's kept on the driveway, always leave the orange cable connected as it helps extend the cable in a straight line as the caravan reaches the road and makes coiling up so much easier. Switched on at the socket in the garage, control panel above entrance door in caravan turned off.
When on site the orange cable is always unhooked from the bollard and coiled up as walking toward the caravan then unplugged before moving the caravan.
Not done any different, nor had any adverse effects thus far.
0 -
Various replies show some subscribers are still of mixed feelings...A friend recently tried moving his caravan from his driveway but because his leisure battery was not in its best state of charge he thought it would be a good idea to keep his 240 volt mains connected to his caravan whilst moving it out to the road. He regretted such a decision as the charger in the caravan burnt out. Result, his nearly new van had to have a trip to the dealers for a new charger to be fitted and the warranty didn't cover the repair. He learned a valuable lesson so I'd say don't use any source of power other than that from the leisure battery and make sure any mains cable is removed from the caravan.
2 -
In principle the caravans' charger will kick-out full whack the moment the MM is engaged (as the MM draws much more current than the charger can supply) no matter what the condition or charge state the caravans' leisure battery is at the time. This is due to the charger compensating instantly to the sudden high current demand which in turn, instantly lowers the leisure batteries terminal voltage.
This reacts in the same manner as your towcar does if you were to instantly switch on your headlights, heated rear windscreen and front & rear fog lights, in other words; the current required would not come directly from the tow-cars battery, it would be supplied directly from the towcars' alternator (in the caravans case, it's charger) as it would instantly self adjust it's output dependant upon required loadings. Should the towcars alternator (for whatever reason) not be able to keep up with demand, (in the caravans case, it's charger) any required surplus would then be supplied by the towcars battery.
So what I'm trying to say is; I agree with PaulRT's principles, that if the caravans' leisure battery is in good condition and charge state there should not be a problem as the charger will kick-out full whack with the remainder coming from the battery.
If however, the leisure battery is not in good condition and charge state the charger will try to kick-out full whack (thus on it's own being inadequate in any case) but will be prevented from doing so as the MM will have the effect of short-circuiting the caravans' charger, as mentioned within my previous post.
Is it at all worth the risk? I think not! Not even if your leisure battery is gold plated!
1 -
When our charger burned out, it was probably the third or fourth time I had used the mover with the caravan connected to the mains.
I guess that the previous times we were just lucky?
Certainly, I will never do it again.
Incidently, at the time of the burn out incident, the battery was fully charged
1 -
If you want a general answer it is - NO - it is not a good idea to run the mover when EHU is connected. The reason is that a standard charger runs at around13.7 volts and the battery has an internal voltage of 12.8 volts. As the charger is at higher voltage it will try to supply the 30 amps or so that is required by the mover and no charger fitted to a van can supply that much current. One result could be that the charger burns out, as reported in the thread above. That's why the isolator is often located so that to operate it you have to pull out the EHU connection.
Of course, things are never that simple and it depends how the mover is wired, the type of charger, state of the battery etc. Read the manual is always good advice.
1 -
Back to your old tricks of attacking the poster, Ian, without understanding what's been said?
3 -
I thought the same as tinwheeler myself.
I'm at a loss as why any charger should burnt out if its in parallel with a fully charged battery.
A decent charger has current limiting to protect it.
There is in most caravans a 20 amp fuse near the battery so not all the current would come from the charger anyway. It wouldn't take much over 20 amp for long with out rupturing the fuse.
My charger is rated to 20amp at 13.8 volts single stage. Next caravan kicks out 14.4 volts max and is multistage rated at 25amp. Both are switch mode types.
Different movers have varying starting currents, moving different loads.
So there is no definite answer to the op question.
1 -
I know this is a slight change of subject! The gentleman who runs the Caravan Chronicles Website, a few years ago undertook the testing of standard automotive type fuses to see how long with extra loadings it would on average take for each specified value of fuse ratting to blow. It was quite interesting to say the least how much extra and for how long these fuses would stand a higher current before blowing out. Obviously, a direct short will normally blow them out instantly!
1 -
The wiring diagram I have for a Powrtouch shows a 125 amp fuse. The caravan 20 amp fuse is between the battery and the dc distribution, not between the charger and the battery. The charger is designed to supply all dc loads but the battery charge feed is limited to about 5 amps.
So, the mover is capable of blowing up your charger many times over; in fact it would probably melt it completely. In theory the fuses or circuit breakers should protect the charger but why would you want to blow the fuses or trip the breakers?
Of course, it is fairly simple to put a relay in the circuit so that when the mover is switched on the charger feed is disconnected but that makes things more complicated and the simple solution adopted by Powrtouch and other mover suppliers is to prevent use by a mechanical system. Much better.
1 -
Not only is there a possibility of electrical damage, I managed to run over the EHU lead, the caravan was turning and in doing so stretched the hook up lead and pulled the wires out of the plug.
Tripped the house mains and the EHU lead needed to be rewired at the plug.
Other than that, no further misfortune occurred.
2 -
Hi S2SAP, are you any relation to ASAP? I haven’t heard from him since I retired! Seriously though, I understand your problem is that you can’t get at your EHU point when you’ve moved your caravan up against the wall? Would it be possible to fit a secondary hook up point on the other side of the caravan? Although I don’t think you should leave your mover control box connected up for too long. I think you’d still need to find a way of switching it off until you’re ready to go. Sometimes mine goes into a sulk and the only way to sort it out is to disconnect it for a few moments.
0 -
There has been many opinions on this subject i.e. Would it be OK to use the MM while connected to the EHU? In fairness, one could say that all the differing opinions could be correct under differing circumstances. Would it not be better not to use the MM under any circumstances while connected to the EHU, this way, you would never risk the possibility of expensive damage to your caravan.
0 -
The battery fuse on my caravan and others i have had is adjacent the battery and will isolate it from the charger.
The mover has a 125amp fuse because it can take that much at start up, no mover uses that for long otherwise the battery wouldn't last long before being discharged.
My mover and others don't have a fuse relying on the electronics to limit current.
I have never read about the charger only supplying 5 amp to the battery so can't comment, not until i get my new Swift with the swift commander, this shows the battery current.
Myself and others havent yet destroyed their movers, so i think its unwise to generalise.
I'll settle for best not to run the mover when on the mains. I have a spare PSU so not particularly bothered on the two occasions i ran the mover while on mains.
And the PSU is now 6 years old on a 2011 caravan.
1 -
I have on a couple of occasions moved the caravan on the mover while connected by EHU. This was while on my drive and luckily no damage was done.
Having said that my brother-in-law had booked a qualified home service engineer to service his caravan and was moving his van up the drive with the EHU connected when the engineer arrived.
The engineer was horrified and told my BIL never to move the van while charging. His explanation was that the motors on the mover operate on 12v and if you look at the voltmeter while on charge the output can be near 14v, this could burn out the motors on the mover. No mention of harming the charger but I have not moved mine while on EHU since then.
By the way my external power point has an isolation switch in the house so that I could leave the cable attached but with the power off. Could the op not do the same?
0 -
By the way my external power point has an isolation switch in the house so that I could leave the cable attached but with the power off. Could the op not do the same?
Not if he has opportunistically plugged it in to a socket in his neighbour's shed
When my son's 'van is in my drive and parked in its stored position against the fence (in front of my motorhome, his dinghy on its trailer and my motorcycle trailer) we cannot access the van's EHU socket so we leave the plug at the 'house' end disconnected until it's finally in the parked position and again before using the mover.
Of course I 'could' cut an access hole in my new fence and get to it from my neighbour's drive
0 -
Not if he has opportunistically plugged it in to a socket in his neighbour's shed wink
I didn't cover that option.
0
