Starting the motorhome Engine while on hookup
Yesterday went to take the motorhome out, which hadn't moved before Christmas, it failed to start due to a flat Battery not sure of the reason it had been on hook up during this time, l had unplugged the hook up cable and went to start it, l noticed when l started it up the radio came on but wasn't sure this had caused the battery discharge. What l did was to reconnect the hook up and switched on the power l left it for 20 min and started the engine without disconnecting the power, the engine immediately started. l uncoupled the hookup and took it a run.l am unsure if l have done anything wrong in starting the engine this way, your advice would be greatly appreciated on this matter before l invest in a power pack or new battery
Comments
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I had always understood you shouldn't start the motorhome engine whilst connected to the mains. Not sure of the technical details as to why but I understand it can cause serious problems to the engine electrics?
One the other point about the battery being flat. Not all motorhomes have their cab batteries charged whilst on hook-up. One way round this is to have a device like a Battery Master fitted which basically takes any excess charge from the leisure battery (which is charged whilst on hook-up) and pushes it into the cab battery to keep it topped up. I have had them fitted to both my motorhomes and not had an issue starting the motor.
David
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I wired my solar setup to 90% habitation battery and 10% engine, so that keeps it topped up nicely, even with the alarm taking a small amount from the engine battery.
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Our solar panels also charge both (not sure of split) and keep them topped up even in this really dull weather we have been having. We have both an alarm and tracker drawing power and as the van is in storage didn’t want to take the risk of a flat battery.
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I have started my engine with the electric still connected and not noticed any ill effects! My thoughts are the regulator controlling output from the alternator will kick in and control the current to both leasiure and engine battery. If the electric is connected then the regulator will see the voltage from the on board battery charger and send zilch to the batteries. That is my thinking. If you have any other views I would be interested to read them.
peedee
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ideally, both leisure and vehicle batteries should be charged from all three sources....EHU, solar, alternator.
Heethers, What van do you have?
im with most others, you wont have done any damage but you can check the charging regime by hooking up and putting a volt meter across the cab battery.
of it isnt charging it, i would second others and get a Battery Master fitted.
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On Autosleepers motorhomes there is an interlock to prevent starting the engine if the EHU lead is plugged in so I assume that it would be detrimental. I can think of many reasons for not trying to start the engine whilst on hook-up but the fact that you have no interlock is perhaps a sign that this is allowed and all is well, however, I would suggest trying to avoid in future.
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the fact that you have no interlock is perhaps a sign that this is allowed and all is well, however, I would suggest trying to avoid in future.
Perhaps the lack of an interlock maybe so. Nevertheless I do agree with you HG, it is not something to continually do. I question if I have done it a handful of times over the years, it is not normally in my routines to do so.
peedee
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They reckon when staring a car the starter motor can draw up to 200 amps which would possible be no problem with fully charged vehicle battery when connected to the mains but when the battery is flat its a bit much for the poor the charger and of course the leisure battery is only designed to give out low current, in fact i've just replaced one of the rectifier bridge diodes on a small 230 volt AC/12 DC volt power supply we use in the caravan for awning lights and blowing up the tyres it had been burnt out due to being overloaded thus causing a power surge, so it won't be loaned out again
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Thanks for all your help, l have taken the motorhome out, doesn't seem to have caused any problems but will keep a close eye on it. My motorhome is Autotrail Tribute 625 2015, this Monday l am having a door fly screen fitted by my Autotrail dealership, l will ask them to do a drop test on the batteries, its five years old this September not sure how long motorhome batteries last, l had one thought it has a tracker fitted but didn't sign up to it has we keep the Motorhome at home, l have heard they can deplete the power in the battery, l had this issue on a caravan l had, they used to ring me up at all hours saying the caravan alarm had gone off due to battery discharge, not sure if this could be the problem. Was thinking of investing in a power pack but the ones l have seen are around £170, may be best go to go to the top level on green flag. Once again thank you for all your input.
Heethers
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My van is stored at a CAMC storage site and I regularly log onto the van via a Swift app on my phone to check that the solar panels are working and charging both batteries. During November I logged on and noticed my vehicle battery was not been charged but Habitation battery was. I then rang Sergeant Electrics who are contracted by Swift to install all of their electrical equipment and they logged onto my van and said I was right. They explained that there is a Smart Meter in the PSU and if switched on will charge each battery for 4 hours alternatively, however, this meter was switched off. He switched it back on and charging of both batteries resumed. I remembered that I blew a fuse during October and had my dealer check the electrics to see why the fuse blew. The dealer checked everything and couldn’t find anything wrong, but he did pull out the PSU to check behind and must have accidentally switched the meter off. I didn’t mind this experience because I learned a lot about how the PSU and battery charger work and charge my batteries.
BillC
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