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discharging battery


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I have a 2006 Rapido 986F. The engine battery goes flat after 4/5 days I have taken it into a garage & they said the battery wasn't great & changed it. It is still going flat I have double checked nothing is left on & the control panel is turned off. I have turned the alarm off but it makes no difference. I have disconnected the leisure battery & diito. The guy at the garage suggested taking the fuses out in batches to try & isolate the problem but to no avail. The control panel is showing +1.5 A with engine off. The panel shows appx 14v in both batteries with the engine running & as soon as I turn it off the leisure drops to 13v and main battery to 12.4. After 3 days the main goes down to 11.6 & leisure about 11.8. Any ideas anyone. HELP
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Hi and welcome to the wonderful world of the forum!!


I would expect the engine battery to also show around 13 volts when the engine is first switched off, but I would hesitate to use an on board voltmeter as my only proof and would much prefer to take readings from each battery with a digital voltmeter.


Does the engine start OK from cold having been left overnight?


A fully charged battery at rest should be showing something like 12.8 volts as 12.4v is well down.


First thing to suspect are the battery terminals and the earth connections from battery to chassis and from chassis to gearbox for cleanliness and security.


There are known issues with the breakdown of the braided earth strap from gearbox to chassis so changing that or adding a second one might help and even if it doesn't is well worth doing anyway as has been often discussed in previous threads, which of course being new you would be unaware of!


I would expect the engine battery to show rather more than 14 volts when charging from the alternator and possibly initially over 15 volts when very low.


The leisure battery charge voltage is often limited for alleged safety reasons and around 14 volts seems OK for that.


I'm not an expert - just a guy who has had more than his share of battery issues over the years and has learnt the hard way!!


The next stage is to disconnect the batteries when fully charged and see if they self discharge to the same degree over 3 days and if so they are probably both duff.


The next stage is to get a digital ammeter and place it in series with the battery terminal to measure the actual discharge and then by elimination remove fuses and disconnect various items to find out where the problems are.


HOWEVER unless you are very familiar with how to do this with an ammeter I recommend you DO NOT try it as serious damage or even a fire can occur if you get the connections wrong.


Does this help or just confuse it more?



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Hi and welcome

With the control panel showing +1.5A with engine off I would say there is something wrong there. There is no input so where does the shown +1.5A come from?

I think you should be looking for a m/home dealer or an auto electrician who has a great deal of experience of motorhomes.

One regular forum member Dave Newell, Dave Newell Leisure Vehicle Services

Tel: 01952 587702, springs to mind.

As tracker says there are a good few possibilities and it looks as though your current garage is not completely at home with m/homes.


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How are the batteries charged? You haven't mentioned a mains charger, only charging from the alternator.

If the only means you have of charging the batteries is the alternator, how often, and for how long are you driving the van?

The battery readings you are getting from the control panel (not aways reliably accurate) are far too low. Batteries with such low voltages will very quickly be irreparably damaged, if they are not already. You really need to get these batteries fully re-charged immediately, or they will both be destroyed. This will probably take 24 hours or so to complete. Then, disconnect them and leave them to stand for another 24 hours, and then take their voltages. If both then read around 12.7V, they are probably OK.

The reading you are getting from the control panel with the engine running is not the battery voltage, it is the alternator output. You need to leave the batteries for about one hour after running the engine before measuring their voltages, to allow them to "settle".

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It is possibly an alternator diode problem but as the discharge is being seen at both batteries it may be something quite different. When the ignition is off the leisure battery should disconnect from the starter battery as a relay drops out - so you may have a duff relay which is allowing both batteries to remain in circuit. It may be that a fridge relay is duff again allowing that to remain in circuit.


As Brian says the current voltages are far too low and I would suggest taking both batteries off and recharging them with a smart charger like this one - http://www.rallydesign.co.uk/product_info.php?products_id=13797 - There are others.


If the reconditioning cycle is used (recommended) it can take up to 48 hrs to bring them back up to full charge. Once that is achieved 1st put back the starter battery. Measure the voltage after about an hour and then again after 24 hrs. If there is a significant drop you can start by checking the base vehicle side of the motorhome. If it is ok then add the leisure battery and see what happens.


There are many components on a vehicle which can cause a drain. e.g Have you recently had a new radio fitted - modern car radios can cause quite a bit of drain even when switched off - It is not just the tiny amount used to maintain the preset station memory but modern radios with bluetooth and all the bells and whistles are like mini computers and can eat batteries for lunch. Has the cab radio been rewired so that it works permanently off the leisure battery - If so the radio may be acting as a bridge between the starter and leisure batteries as there are normally 2 live wires feeding a radio - 1 (normally) live when the ignition is on and the other permanently live to maintain the stations. Often a third which will be attached to the lighting circuit so that the display is illuminated when the side / head lights come on.


Good luck with it.

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Lots of good tips but it is best to check and test one stage at a time and then if it works you will know what it was and if it does not work you will know what it was not and if the system totally fails you will know what you did to bu@@er it up and thus how to rectify any carnage!


I would start by checking the things that are easiest to check without need for expensive expert involvement and if you don't have a decent digital multimeter now may as good a time as any to consider getting one?


Any of these will do but I find one that will measure up to 20 amps DC the most useful - as long as you fully understand how to use it!


Otherwise a cheapie just to measure dc volts and under 1 amp will suffice to check battery drain.



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