Goneoff Posted August 26 Share Posted August 26 Hymer MLT 580 2016 on Merc base: Currently traveling in Europe. I have a parasitic drain on my engine battery (like most people) and if I park up for two days without hook up my battery from fully charged drops to 11.5v and only just manages to start the engine. We need to stay over the next few days at a couple of spots for three nights without hook up so I rang our local auto electrician who advised just disconnect the battery. I’m at our first park up and have just disconnected the engine battery, well disconnected the neutral cable from the battery. Wasn’t an issue but the voltage monitor I use for both engine battery and alternator charging whilst driving dropped right down but is still showing 6.4v. Why would this be? Is the engine battery still draining? Do I need to disconnect the positive? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Labby Posted August 26 Share Posted August 26 Your leisure battery should be the source of power when parked up and your starter battery should not go flat in 2 x days (unless you are running your fridge from it on 12v) , I would expect it to take 3 weeks or more for parasitic drain to effect the starter battery power if the battery is ok. Have you had the starter battery tested ? Quote Link to comment Share on other sites More sharing options...
colin Posted August 26 Share Posted August 26 I wonder if the voltage monitor is the source of the drain. That aside, if the -ve terminal has been disconnected the voltage meter should read zero, so something doesn't add up, removing the +ve should make no differance as with -ve removed there can be no circuit. Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 26 Author Share Posted August 26 59 minutes ago, Labby said: Your leisure battery should be the source of power when parked up and your starter battery should not go flat in 2 x days (unless you are running your fridge from it on 12v) , I would expect it to take 3 weeks or more for parasitic drain to effect the starter battery power if the battery is ok. Have you had the starter battery tested ? Yes had the battery tested before I came out here, the garage said there was nothing wrong with it otherwise I would’ve put a new one in. Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 26 Author Share Posted August 26 54 minutes ago, colin said: I wonder if the voltage monitor is the source of the drain. That aside, if the -ve terminal has been disconnected the voltage meter should read zero, so something doesn't add up, removing the +ve should make no differance as with -ve removed there can be no circuit. I’ve obviously been giving it a lot of thought and the only thing I think the 6.4v reading could be coming from is the battery in the tracker feeding back into the system in fact the voltage monitor has just gone blank after several hours which in many ways confirms my theory. What are your thoughts? Thanks for your input. Quote Link to comment Share on other sites More sharing options...
colin Posted August 26 Share Posted August 26 Maybe disconnect the tracker (assuming you can still meet any insurance requirements), to see if that's the problem. If you have a multi meter you can check this quite quickly, same with any alarm. Quote Link to comment Share on other sites More sharing options...
onecal Posted August 26 Share Posted August 26 (edited) Hi Check for any in line fuses from your battery may have melted in their holder and may be shorting out . You also need to check your alternator and connections Disconnect your battery monitor also and see how you get on As in Colin previous post use a multimeter instead (cheap as chips one will suffice) Make sure you remove your vehicle key fob from the ignition switch when parked up Have you an aftermarket radio fitted ? Regards Edited August 26 by onecal Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 26 Author Share Posted August 26 27 minutes ago, onecal said: Hi Check for any in line fuses from your battery may have melted in their holder and may be shorting out . You also need to check your alternator and connections Disconnect your battery monitor also and see how you get on As in Colin previous post use a multimeter instead (cheap as chips one will suffice) Make sure you remove your vehicle key fob from the ignition switch when parked up Have you an aftermarket radio fitted ? Regards Thank you, will do and thanks for your input Quote Link to comment Share on other sites More sharing options...
onecal Posted August 26 Share Posted August 26 Hi , Hopefully it may help you, I have come across many a Merc Motorhome with also issues of the doors not closing fully Some have had accident damage, doors and switches not properly repaired and sold on This can keep some of the modules from going to sleep Again have you an aftermarket radio fitted ? Regards Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 27 Author Share Posted August 27 6 hours ago, onecal said: Hi , Hopefully it may help you, I have come across many a Merc Motorhome with also issues of the doors not closing fully Some have had accident damage, doors and switches not properly repaired and sold on This can keep some of the modules from going to sleep Again have you an aftermarket radio fitted ? Regards Sorry yes I do have an aftermarket Alpine head unit fitted. Quote Link to comment Share on other sites More sharing options...
onecal Posted August 27 Share Posted August 27 Hi I think to give any chance of a true diagnosis and not just guessing as it could be many faults (I have just mentioned some of the common ones that may occur on your particular vehicle , they may not actually be yours) you would need to confirm some of the following How long have you the motorhome? .When did this start? Have you added on any electrical equipment since purchase. Did your issue become apparent after the add on? Was this problem from when you purchased the motorhome? etc' Without actually being able to test the vehicle and have some history of the vehicle it's not so easy to diagnose So take it one step at a time until you find your fault Let us know how you are getting on and hopefully you will find your electrical issue and solve it and enjoy your holiday in Europe If I can be of further assistance you can PM me Regards Quote Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 27 Share Posted August 27 The photo in the original posting looks like a 'dual' usb charger with an voltmeter display (example here) https://www.diy.com/departments/hardys-dual-usb-charger-car-van-vehicle-lighter-socket-adapter-with-digital-voltmeter/5055521168413_BQ.prd many of which plug into a dashboard cigar-lighter socket. I don't know if that's significant or not, but - if the charger/voltmeter were receiving power SOLELY from a vehicle's starter-battery and cabling connected to that battery's earth-terminal were completely disconnected - no power should be reaching the charger and, logically, there should be no voltage readout. Quote Link to comment Share on other sites More sharing options...
onecal Posted August 27 Share Posted August 27 Hi Again ,this is why one would need to know what modifications electrically (add-on's) have been carried out on the motorhome Hopefully he will have disconnected same and checked the associate wiring Re trace his steps as to what was done and did the fault manifest it self after the modification or was it there from the time he purchaced the motorhome Regards Quote Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 27 Share Posted August 27 This long forum discussion shows that, in October 2023, Phil owned a 2020 Fiat Ducato-based motorhome https://forums.outandaboutlive.co.uk/topic/63138-engine-battery-draining-while-traveling-technical-help-please/ and later threads indicate that this had been replaced by a Mercedes Sprinter-based motorhome prior to July 2024. Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 27 Author Share Posted August 27 2 hours ago, Derek Uzzell said: This long forum discussion shows that, in October 2023, Phil owned a 2020 Fiat Ducato-based motorhome https://forums.outandaboutlive.co.uk/topic/63138-engine-battery-draining-while-traveling-technical-help-please/ and later threads indicate that this had been replaced by a Mercedes Sprinter-based motorhome prior to July 2024. You are bang on the money Derek you super sleuth :). We were helped out on this site by a couple of contributors along with “onecal”, however the sleeping arrangements of the Burstner proved not to our taste plus it was a heavy vehicle which could not be down plated if I lost my C1 licence next year. So sold it and bought an older 2016 Hymer on a Mercedes Sprinter base. We like it a lot probably the best MH we have owned simple and well built. We haven’t done anything to it or installed anything new. I’ve decided to change the engine battery whilst I’m out here even though my local garage tested it and gave it a clean bill of health. It’s the original one so I will start there and if the drain continues I have it booked in at our local auto sparks in the U.K. he was the guy who suggested I uncoupled the battery on my three day stopovers in Italy. I should also thank you personally for the help you gave me when our Truma boiler failed us in out then Rapido whilst we were in France several years ago. So thank you. Quote Link to comment Share on other sites More sharing options...
Goneoff Posted August 27 Author Share Posted August 27 3 hours ago, onecal said: Hi Again ,this is why one would need to know what modifications electrically (add-on's) have been carried out on the motorhome Hopefully he will have disconnected same and checked the associate wiring Re trace his steps as to what was done and did the fault manifest it self after the modification or was it there from the time he purchaced the motorhome Regards Thanks for your help “onecal”. No I have made no modifications as yet to the vehicle although I will be adding a Roamer lithium battery later this year with all the necessary changes this addition requires. See my reply to Derek Uzzell. Thanks for all your help and advice. Phil Quote Link to comment Share on other sites More sharing options...
onecal Posted August 27 Share Posted August 27 Hi Phil, Hope all goes OK Yes hopefully he may have got it wrong and your old battery was failing and may it be the cause of your starting woes Fingers crossed the new one works well Regards Brendan Quote Link to comment Share on other sites More sharing options...
Den Posted August 28 Share Posted August 28 I purchased a new Renault master in 2013 and the battery died 8 months later. On checking the build date it was already just over 2 years old and just been parked with the battery draining. after having a few minor repairs the lad in the workshop said they had to jump start it when unloading from the transporter and how they had worked hard to clean the Algie off. ( wasn’t a MH , but a 16 seater minibus) they wouldn’t replace the battery saying it wasn’t in the warranty. den Quote Link to comment Share on other sites More sharing options...
onecal Posted August 28 Share Posted August 28 (edited) Hi Den Batteries from new are usally covered for 2 years , You say you purchased your bus new so i would have expected a new battery to be fitted on purchase , or at least a new one to be replaced when your new bus was only 8 months old when the battery failed as your new bus would be under original factory warranty It was only subjected to "wear and tear" from the time you purchased the bus new and you say your new bus was only 8 months old at the time when the battery failed. Yes batteries do degrade and fail with time and this is a reason it's not usally covered under extended or used vehicle warranties Regards Edited August 28 by onecal Quote Link to comment Share on other sites More sharing options...
tonyishuk Posted August 29 Share Posted August 29 Most of my battery woes in cars and motor homes are with bulbs being left running. Ie cupboard / fridge / locker / awning or entry light lights. Even doors not closed completely , activating curtesy lights. Not so much of a problem now with leds but quite a burner if still on old halogen bulbs. rgds Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.