Nigelord Posted October 20, 2016 Share Posted October 20, 2016 Sorry if this has already been covered... The leisure battery on my 2015 Ducato-based McLouis has started to discharge much more rapidly than it used to during the first year of running the MH from new. We could normally get three to four days out of the battery between charging, but that's suddenly dropped to around two. Obviously, I would expect some deterioration in battery performance in the time we've owned it, but it seems to have happened rather more quickly than I would have expected. The MH is fitted with a solar panel which normally keeps the battery topped up, but that doesn't seem to be overcoming the problem of it discharging more rapidly. Testing it yesterday - with everything switched off at the control panel - the battery level had dropped to around 72% in about a day. Today, I full charged the battery only to find it again fell to 85% in under an hour - the voltage reading (according to the control panel) having dropped from 12.8V to 12.5V - despite everything being switched off. Could anyone advise me on what to do - or how to test things more conclusively? I have a decent multi-meter - and some basic electrical knowledge. Thanks in advance... Link to comment Share on other sites More sharing options...
colin Posted October 20, 2016 Share Posted October 20, 2016 Is this without using anything in the van? What size solar do you have? Link to comment Share on other sites More sharing options...
Nigelord Posted October 20, 2016 Author Share Posted October 20, 2016 Hi, yes... everything that can be switched off in the van, has been switched off. About the only thing that's still on is the LCD display on the secondary control panel, where the heating/water heater is adjusted - and without disconnecting this, it can't be switched off. As regards the solar panel - unfortunately, this was fitted when I bought the van, so I'm not sure what type it is. However, it's about 75cm long by 30cm wide in size (if that helps). Thanks... Link to comment Share on other sites More sharing options...
colin Posted October 20, 2016 Share Posted October 20, 2016 That panel will be around 30w, at this time of year with a reasonable amount of direct sun, it should be able to keep the battery charged. So on top of dropping power at a greater rate than would be expected with no input, your battery is also using all the power input from the panel. Have you checked to see if there is power being used? It's either this or a very poorly battery. Link to comment Share on other sites More sharing options...
Nigelord Posted October 20, 2016 Author Share Posted October 20, 2016 Thanks for the reply... Yes, I would have thought the panel would have kept the battery fully charged if there was no other current draw - particularly as today has been pretty bright (if rather cold). Checking current draw was going to be tomorrow's job. What kind of draw would be necessary to explain the battery discharging, despite being trickle charged by the solar panel? Thanks... Link to comment Share on other sites More sharing options...
veletron Posted October 21, 2016 Share Posted October 21, 2016 My previous batteries did this, under a year of use, no issues, then as soon as the daylight hours got less, and the overnight temperatures got lower, they started to loose charge for no apparent reason. Over a couple of days with only 100mA being drawn they could drop from 12.8V to 12.2V. Suggest a full charge (24 hours+ on hookup), buy a specific gravity measuring tool, disconnect the charger and then test the specific gravity to see if they really ever did attain full charge. (only works on batteries with removable caps, eg Open Lead- Acid!) Leave for a couple of days and then re-measure. Note that accurate state of charge using just the battery voltage can only be read when the battery has had no load and no charge applied for about 4 hours. Also note that temperature effects the voltage based SOC reading. Taking a specific gravity measurement is always accurate - but alot more hassle! While taking the specific gravity, check the electrolyte levels in each cell, and make sure the specific gravity is about the same in each cell. Are you a 'heavy' user. Lead Acid is only good for 200-300 cycles, performance degrades over those cycles, and generally, at some stage it drops off a cliff. Also, how low do you take the voltage before driving/charging. 12.2-12.3V (no load) equates to about 50% state of charge for open lead acid - for long life, batteries should not be taken below this. NB: As measured at battery terminals with a voltmeter - the guages built into many motorhomes are extremely inaccurate. Best way to avoid damaging lead-acid batteries is to stick more of them in. 2 batteries in parallel less likely to end up below 50% SOC than a single battery. BTW: there is also '200W' of solar on the roof Nigel Link to comment Share on other sites More sharing options...
Nigelord Posted October 21, 2016 Author Share Posted October 21, 2016 Thanks so much for the detailed reply... Yes, it sounds like you experienced exactly the same problem. Will take your advice and do some proper measurements. I'm not sure if we qualify as 'heavy users'. Apart from the usual lights, we run a small TV from an inverter (the latter rated at 400W) - for probably a couple of hours a night. I also sometimes use it to charge a laptop - but that's about it. And I don't ever leave the inverter connected if it's not powering anything as it has a built-in fan. Thinking about it, the only thing that's different is that the MH has been used (without the leisure battery being re-charged) for more than two days in October in the UK. The last time we used it in Autumn was in Southern France, last year, when the battery was virtually new and, as memory serves, we didn't wild camp anywhere for more than a couple of days. So perhaps it's just that the 'honeymoon' period of having a new van with a brand new battery is now over and we have to start ensuring it's properly charged and that we don't overdo things in terms of leaving it too long between charges. Speaking of which, the battery had actually dropped to around 18% before I realised there was a problem and immediately charged it up. Is this likely to have caused any lasting damage? And would it be worthwhile installing a second battery irrespective of the results of the measurements? Thanks in advance... Link to comment Share on other sites More sharing options...
rolandrat Posted October 21, 2016 Share Posted October 21, 2016 How old exactly are your batteries? Have they ever been completely discharged? Have you removed them and charged them up individually? Have you then done a voltage check? These are questions you would normally be asked by someone in the know. It''s quite possible that your batteries are life expired. Link to comment Share on other sites More sharing options...
veletron Posted October 24, 2016 Share Posted October 24, 2016 Hi You are far better buying a 12V telle than using a mains telle via an inverter. I would guess that via the inverter, you are consuming at least 5A due to the various inefficiencies involved, while a 12V telle will use <2A Taking the batteries down to 20% may have caused damage already, depends how long they remained at that level before being charged up again. Adding a second battery is *always* worth it (assuming loss of payload is not a problem). They should be matched though and of the same age. If the existing battery is showing issues, I would personally replace with 2 brand new batteries, or wait until it is no longer able to sustain your usage pattern, and then replace with 2 batteries. Not tried them personally, but the Varta LFD90's get regularly recommended on here, don't be put off by the '90' vs the '110' or '115' you will see elsewhere, these are related to the time over which the battery is discharged, and in some cases are a work of fiction - aimed at fooling one into thinking one battery is better than another. Reality is that most batteries with a 350x180x220 (L*W*H) batteries are about 90AH at the 20Hr rate, its just that some are more accurately marked up than others! Personally, I have a pair of extra-tall '140AH' Exides - again they ain't 140AH - more like 110 @ 20Hr rate. Nigel Link to comment Share on other sites More sharing options...
EJB Posted October 24, 2016 Share Posted October 24, 2016 My cheap lead acid leisure battery is nearly 10 years old...110 amps. On the rare occasion that we don't use the MH for 5 or 6 weeks it falls from a reading of say 12.6v to 12.5 or 12.4 volts. Obviously it is switched off at the main panel and there is no load. If you can't find the source of any drain simply disconnect the battery and take a voltage reading each day for one week....if there is no change the battery is OK! Ensure the battery has rested for at least a couple of days before you do this! Conversely my vehicle battery has to be charged after 3 or 4 weeks standing due to the alarm and other drains. Link to comment Share on other sites More sharing options...
KeithM Posted October 24, 2016 Share Posted October 24, 2016 Battery capacity is also temperature related. ;-) If the specification of a battery is checked then almost always the stated capacity is for the 20 hr rate at 25° C That means if the battery is say at winter temperature then its capacity at that time is reduced. Not so important as most motor-homes have their batteries inside where the temperature is kept at 25° C. :-> :-> :-> When charging a battery it is always necessary to put back more than you take out, owing to losses in the charge procedure. That is why amp.hr (capacity) meters are inaccurate, over time, at telling when a battery is fully charged A guide when charging as to when a battery is at its full capacity (variable) is for the input (charging) amps to be about 1% of battery capacity or the reading has not reduced any further for about 30 minutes. Batteries like to be kept charged, leaving them in a discharged state damages them. As a guide batteries should not be allowed to discharge more than 50% of their capacity, generally about 12.2v with no load and rested for a minimum of one hour. Now as to size of battery bank this, as a guide, should be twice your usage, plus ten percent. So if you use 50 amp.hrs the bank needs to be (50*2)+ 5 equals 105 amp.hrs This is the minimum size required, in that particular situation and means the bank will always be taken down to 50% SOC (battreries working hard) Now personally I would double that available capacity to 210 amp.hrs, then using the same amount of energy the batteries would only be reduced to 75% SOC. ( batteries not working so hard, they like that) It would also give some leeway if not able to re-charge the batteries immediately The batteries should last longer (life) if they are re-charged correctly. I am not and do not pretend to be an expert on batteries, this is only what I have picked up over the years. Link to comment Share on other sites More sharing options...
Charles Posted October 24, 2016 Share Posted October 24, 2016 Our 400w inverter pulls 1.6 amps with the 18" LED TV on. They are not as terrible as people make out. Link to comment Share on other sites More sharing options...
veletron Posted October 25, 2016 Share Posted October 25, 2016 Charles - 2016-10-24 2:50 PM Our 400w inverter pulls 1.6 amps with the 18" LED TV on. They are not as terrible as people make out. That's very good. My 1KW inverter (admit-ably now almost 10 years old!) pulls 1.5A when its just turned on with no load connected!! Might be time for an upgrade! Nigel Link to comment Share on other sites More sharing options...
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