Leisure batteries [voltage] dangerously low

Discussion in 'Auto-Trail' started by Dorset Diver, Dec 27, 2014.

  1. Dorset Diver

    Dorset Diver Funster

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    It has done it again.

    Autotrail 740SE with EC325 PSU, two 110 amp batteries and 100w SP. When not in use the vehicle sits on the drive with EHU connected but PSU charging switched off. Sargent control unit switched off also, i.e. in theory nothing using 12v. The batteries are normally easily kept up by the SP.

    Went to the van this a.m. to do a small job. Outside air temperature about 3 deg C. Activated the 12v with the intention of firing up the heating but was met with the unit flashing the message “leisure battery voltage dangerously low”. According to the Sargent book this message only appears if the leisure battery(s) gets to 6v or below. Vehicle battery okay and showing 12.4v. Fired up the PSU charger and the batteries seem to be taking a charge.

    This is the second time this has happened and I cannot find a reason; so over to the brains of the motorhoming world. Any suggestions?
     
  2. PhilandMena

    PhilandMena Funster

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    Hi, I too have an Autotrail with the Sargent intelligent system and hooked up on the driveway and like you 2 x 110 amp Bat. and a Solar Panel. I suggest you do as I do and switch your PSU on so the intelligent charger can do the job it's designed to do. It will monitor both your leisure and cab batteries and keep them topped up (Solar panel will function but charge will not reach batteries for obvious reasons). I suspect you battery has run low because there has been a steady drain on it from one of your appliances and the Solar Panel might have been switched to keep the Cab battery charged and as a result no charge going to Leisure batteries. (Not sure what regulator you have fitted ! On mine I have an intelligent regulator that will divert power to lowest batters set reading). Leaving your Motorhome on permanent hook up with the PSU switched on will not cause any harm to your appliances or batteries. Just make sure your appliances are switched off and the Sargent will do the rest. Pop in every few days and check your battery readouts for peace of mind if you need to.
     
  3. magicsurfbus

    magicsurfbus Funster

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    You're assuming everything 12v goes through the control panel. In my (CI) MH the blown air heater fan is completely independent of the control panel. I left it on once and it drained the leisure battery, which is why I fitted an isolator switch for the habitation area circuit when it's in storage.
     
  4. Dorset Diver

    Dorset Diver Funster

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    A lot of good points Phillippfit thank you, but a couple of things I do not understand.

    Both house batteries are a good quality pair and less than a year old.

    As far as I am aware when only the SP is being used to maintain the batteries the controller maintains both the house and vehicle batteries without human intervention. I also understand that when the EHU is connected and the charger is on, the default is to the house batteries; to charge the vehicle battery I have to manually switch it over. I also suspect that the battery has run low because there has been a steady drain on it but from where is a mystery. My heater fan will not run unless the 12v is switched on at the control panel and this has been switched off. I agree about keeping it on mains but it should also be okay without otherwise it will be useless when wild camping. I had a similar hiccup some months ago and it went away without me finding the problem. Any other thought will be much appreciated.
     
  5. Wickolad

    Wickolad Funster

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    I have experienced similar situations with my Autotrail and discovered that the cab radio which is linked into the media system of the motorhome appears to remain in a live state even when turned off. This is evident as the power light remains illuminated red. Apparently the cab radio is powered from the habitation batteries in some Autotrails but not all. I started removing the pop off front display panel off the radio/ CD /DVD player as a precaution. It may be worth you checking if there is current draw on your radio media system even when power is off. Its just a thought, i wouldn't want to be pointing you in the wrong direction but if it sorts things, it will be worth the 5 minutes it takes to remove the fuse and put your meter across. :)
     
  6. Wildman

    Wildman Read Only Funster

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    Dorset Diver you will now need to subscribe in order to post and let us help you further.
     
  7. peterc10

    peterc10 Funster

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    Are you sure it says that?????? Long before the battery gets to that voltage level it will be completely knackered and will never re-charge again.
     
  8. PhilandMena

    PhilandMena Funster

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    What year is your motorhome ?
     
  9. Dorset Diver

    Dorset Diver Funster

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    100% Peterc10. The EC325 book is on line on the Sargent website.

    2009 Philippft.

    I'm charging the batteries for about 24 hours then I will check each separately whilst on the van and see if I can find what is causing the drain.
     
  10. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    This is not strictly true, I have a van in at the moment being converted and when it was delivered the engine battery read 0.8 volts (zero point eight). I expected it to be knackered but recharged it on a recondition cycle with my CTEK 25 Amp charger and so far it has held charge since late August and only needed recharging once since. It has happily sat for up to two weeks without turning the engine over but will then start it when you need it to.

    D.
     
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  11. PhilandMena

    PhilandMena Funster

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    OK Thanks for that. Mine is the 2011 model and fitted with the EC500. The P.S.U. came with the Solar Panel regulator already fitted as standard, All I needed to do was buy the connecting cables from Sargent and drill one hole in the roof, make the connections and job done. With my set up both the S.P. regulator and Intelligent battery charger monitor battery condition and switch the charging supply to which ever battery needs it. When a 240 volt supply is hooked up the S.P. regulator still monitors battery condition but stops the charge going beyond this point. (You can see the Ampere reading from the S.P. regulator flickering on the display and this is a pulse signal send to the batteries from the regulator to check the charge state. (as confirmed to me in conversation with Sargent)). I suspect on your version you may have to manually select the set of batteries being charged and if this is the case it will go part way to explain why one set has been discharged. I do not think you have a significant problem here. I think it's a straight forward case of one or more appliances taking a small charge from the battery, It's just a case of establishing where this drain on the leisure batteries is when everything appears to be switched off. One way to establish if anything is taking power out of your leisure batteries is to start pulling fuses whilst measuring out put from your batteries. This should point you in the right direction. In the meantime keep your MH on hook up with the pSU switched on so your batteries are kept topped up, when on the drive way.
    I suggest you check your battery condition once there fully charged, just because they read full when on charge does not indicate they are OK. You need to discharge them a little and see how well they recover after the load is taken off (without hook up being connected).
    Please find attached a document on Leisure batteries you may find useful. At the bottom of the page there is a further link to another document which should be of value.
    http://www.campingandcaravanningclu...nicalhelp/power/a-guide-to-leisure-batteries/
     
  12. peterc10

    peterc10 Funster

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    Dave, I am not an expert but I have read regularly on this forum that I should not allow my batteries to drop below 50% capacity, which is well above 6V as I understand it. Is that information not correct or do you think you were lucky in managing to rescue that battery? I am surprised that the Sargeant unit regularly allows the batteries to drop as low as 6V before any warning comes up. My Schaudt unit for example switches everything except the frost protection valve off when the batteries drop to 10.5V, which, they say, shows that the batteries are "totally discharged"
     
  13. steevie

    steevie Funster

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    your leisure batteries are classed as discharged when they get below 12.4v. They will survive getting lower for a few occasions though. Many appliances will not work on less than 12v, especially some LED TVs. Your engine battery will also have its life shortened by keep getting low, but may still start your engine at just over 12v. All the batteries should be showing 12.8 to be healthy.
     
  14. PhilandMena

    PhilandMena Funster

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    You are correct ! (trust you are OK with me replying to a question directed at you Dave!). If you read the technical paper linked in my post your theory will be confirmed. (Actually, I've read don't let them go below 80%). I suspect any battery that is allowed to fully discharge and then be fully re charged will not have as much life left compared to a leisure battery that has never been allowed to discharge more than 80/50%. My reasoning is that Leisure battery life is determined by the number of Cycles they can perform. (the higher the number of cycles the better the battery) Whilst the above battery may appear to be fully recovered I suspect (though have no proof or knowledge otherwise) that the number of remaining cycles will be adversely affected.
     
  15. PhilandMena

    PhilandMena Funster

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    I thought I would quantify your quote. At 12.4 V a battery is 50% discharged.
    [​IMG]
     
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  16. peterc10

    peterc10 Funster

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    My Schaudt instructions for the display give slightly different figures. More than 12.8V = full, 12.5V = 75%, 12.3V = 50%, 12.2V = 25%, 12.0V = 0%, and less than 10.5V = totally discharged. Cleverer people than I can attempt to explain the difference between "0%" and "totally discharged". Mind you they say those figures apply to a lead gel battery.
     
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  17. Dorset Diver

    Dorset Diver Funster

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    Hello all,

    Thanks for all you suggestion and info. Here is an update so any further suggestions will be welcome.

    Charged overnight the batteries were back to full strength this morning (0830) and with the sun out, although not really up, the control panel was still showing around 13.5v about 30 minutes after the charger was switched off; some of which would have been due to the SP. Left them off charge for the day and have just checked again this p.m. Both batteries metered individually are still showing 13.4v to 13.6v with the assistance of the SP. I have also pulled every fuse and metered draw amperage on each circuit with all the switches off. Every circuit showed zero except the 5a permanent connection circuit which showed a 0.002 amp draw; hardly enough to drag down two 110amp batteries that are being topped off by the SP each day. I will keep looking but for the moment it is still a mystery.
     
  18. PhilandMena

    PhilandMena Funster

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    Just to make sure !!! You are aware of course if the batteries are still receiving a charge you will be reading the amount of voltage going in ! To measure the battery true state disconnect power and wait for battery to settle before measuring condition.
    I agree with you about the draw, I have this too on mine and it's the alarm system. The SP should compensate for this, so I too am at a bit of a loss as to why your Leisure batteries are flat.
     
  19. PhilandMena

    PhilandMena Funster

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    As an after thought ! I would be a little surprised if 2 flat 110 AH batteries were fully charged overnight. Do you know what the output is from your charger. ?
     
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  20. Dorset Diver

    Dorset Diver Funster

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    Hi Philippft,

    Up to 25 amp.
     

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