Disconnecting a leisure battery

[bootbags]

Handbook states, leisure battery can be discoonected at the cut off switch if the motor home is not used for a longer period of time ie temporary lay-up. No indication given of what constitutes longer period of time. When is it wise to disconnect and what is the likely discharge if NOT disconnected.

[colin]

I don't know what equipment your hymer has that might use power when laid up so can't comment on that, but if you leave battery without charging for long periods, say over winter, then it will lose charge even if disconnected, this is why I think solar panels MAY be good idea for those not using van regulary, with a decent panel and right connections both leisure and vehicle battery should remain fully charged

[howie]

Hi Boots. Apart from shorter periods, say a week or two, isn't it possible to give your van regular run outs during the winter or other times its not in use?. A hour once a week would not only keep your battery charged but would also make sure the brakes, running gear etc. are kept in good working order as well as airing the interior.

We don't use our van much for camping during the winter, but I do the weekly shopping run, hospital or family visits, or just the odd day out to make sure everything is as it should be.

Don't know your circumstances or if this is feasable, but having your van standing for long periods seems such a shame, especially when you think of all that capital you have invested in it.

[ROON]

Hi Bootsy, Hope you don't think I am stealing your thread, but you probably will also want to know the answer to my follow on question.

 

When the van is not used for say one week, what can you expect the reading on the leisure battery to drop down to from the fully charged 13 amp? My drops to 10.6 despite only the car alarm being on .... is this acceptable and where is it going to..

 

In winter, Boots, I used to just drive for an hour twice a week and had no problems. Hope this info of help to you too if someone can answer. Joy x

[bootbags]

ROON - 2008-08-07 11:17 AM

 

Hi Bootsy, Hope you don't think I am stealing your thread, but you probably will also want to know the answer to my follow on question.

 

When the van is not used for say one week, what can you expect the reading on the leisure battery to drop down to from the fully charged 13 amp? My drops to 10.6 despite only the car alarm being on .... is this acceptable and where is it going to..

 

In winter, Boots, I used to just drive for an hour twice a week and had no problems. Hope this info of help to you too if someone can answer. Joy x

Hi Joy,

We are all in this together so no, you're not stealing any thred, the more the merrier. Thanks too to Howie. the reason I asked the question is that we have not long had our vehicle - 2 weeks to be exact and as yet we haven't attended any events. It was only driven back from Southdowns who supplied it, (and very good service we had too). I haven't driven it yet, recent hip. op. But yesterday my other half had to go to where it is stored to take a picture of a part needed and when he came back he announced that as we hadn't used it, he had disconnected the leisure battery. I thought this totally unnecessary and told him so (i won't tell you how) The panel above the entrance with the digital read out of the current state of battery, water etc showed the leisure battery as minus 0.4 amp. Of course disconnecting it removes the power to the electric step. It is only a simple switch to re-connect. Also taking Howie's point, yes it is a big investment to have standing around, just so many things have cropped up that have prevented us starting to enjoy some events. I am determined that we should do Malvern, come hell or high water so hope to meet up with some people who to date have only been in my virtual sights. Other significant has just come in and I write thus as he reads from manual:

A completely charged 80Ah living area battery will be totally discharged via a closed circuit current: after approximately 9 months with the safety/drainage valve switched off (to the boiler) and after approx. 1.5 months with the safety/drainage valve switched on. Not sure if any of this is relevant to your vehicle. The self discharge rate of the battery is dependant on temperature. At 20-25 deg c the self discharge rate is approx. 3% of the capacity per month. The self discharge rate will increase with rising temperatures and that at 35 deg c the self discharge rate is approx. 20% of the capacity per month. If the battery is older it will no longer have the complete capacity available. Small things like some radio/cd etc. switched off but still with a display could also cause a drain and of course if the alarm is linked to the leisure battery that too would drain, but we thought that the alarm system was on the vehicle battery. Phew, a lot to learn - yiu should see the size of the manual. Good bedtime reading. This is all too technical for me, but given that info, I am still surprised that the leisure battery has been switched off *-)

[ROON]

8-) 8-) 8-) 8-) 8-) 8-) :-| :-(

 

On a good note, look forward to meeting you at Malvern all being well. Joy x

[bootbags]

That would be interesting.

[Derek Uzzell]

Bootbags:

 

I'm pretty sure that Hymer (like many German motorhome manufacturers nowadays) fits a 'gel' leisure battery. This type of battery has cons and pros for motorhome use - its cons include the high cost compared to a 'wet' battery, while its pros include that it has no free acid inside it, requires absolutely no maintenance and can retain its charge for an extended period.

 

Your Hymer has a master-switch that allows the leisure battery to be isolated, but this arrangement is not standardised for all motorhomes (my Hobby hasn't got it) and I'd guess that a lot more vehicles don't have such a switch than do.

 

Logically, if a motorhome is not being used and there's no pressing reason to keep the leisure battery connected, then it's good sense to isolate it, particularly if this can be done easily by a remote cut-off switch. That way one can be confident of the battery retaining its existing charge as long as possible and (especially important if a vehicle is in storage and visited infrequently by its owners) the chances are minimised of damage being caused while the vehicle remains unattended in the (admittedly unlikely) event that an electrical fault occurs in the circuitry connected to the leisure-battery. Also, when the battery has been isolated via its cut-off switch, anything leisure-battery-related still running when your stored motorhome was exited (eg. a light, or an electronically-controlled fridge, accidentally left on), will simultaneously get switched off.

 

If a motorhome has equipment powered by the leisure battery that it may be advantageous to keep operational while the vehicle is out of action, then one might choose not to disconnect the battery. But, generally speaking, I think your husband is a Wise Virgin and, whenever your motorhome is stored, it would be best practice to isolate the battery via the cut-off switch. OK, if he does this then he'll have to pole-vault out of and into the Hymer afterwards as the electric entrance-step will be 'dead' (or leave/enter via a cab door), but that's an unavoidable consequence of the battery disconnection.

 

 

Joy:

 

Vehicle alarms (and cab radios) don't normally involve the leisure battery. John Wickersham's "The Motorcaravan Manual" quotes the following voltmeter readings and the 12V battery approximate charge-states they indicate:

 

12.7v or over - charge state = 100%

12.5v - charge state = 75%

12.4v - charge state = 50%

12.2v - charge state = 25%

12.0v or under - charge state = Discharged

 

If your motorhome's leisure battery is genuinely dropping from 13v to 10.6v (that's flat as a pancake) within a week, and there's no equipment connected to the battery that one might reasonably expect to be imposing a current-drain on it, then you've got a problem.

 

If you can't find anything obvious causing a drain (eg. the light in my Hobby's wardrobe originally didn't switch off when the door was closed) then it's tempting to suspect that it's the battery that's duff (and, even if it isn't now, if it keeps getting discharged so heavily it soon will be), but there may be a system fault somewhere.

 

Assuming that your readings are correct (Sorry - it has to be said!) and (if your battery is of the 'wet' variety) that the battery's electrolyte level is correct, then probably your first step should be to get the battery checked out by a specialist. In theory, it should be relatively straightforward to confirm whether or not there's a continuous drain on the battery when the motorhome is not being used, but I don't know if you'd want to attempt this yourself.

[ROON]

Thanks Derek, I didn't do the test myself cos, as you seem to be aware :-D , I'm a bit dense on these things... I asked a neighbour to check with his equipment and they were the readings he got.

 

I will go and phone Discovery now and see where I stand with a replacement.

 

Thank you for those figures on percentages ... they are very useful to keep to hand.

 

Joy

[bootbags]

Derek Uzzell - 2008-08-08 8:47 AM

 

Bootbags:

 

I'm pretty sure that Hymer (like many German motorhome manufacturers nowadays) fits a 'gel' leisure battery. This type of battery has cons and pros for motorhome use - its cons include the high cost compared to a 'wet' battery, while its pros include that it has no free acid inside it, requires absolutely no maintenance and can retain its charge for an extended period.

 

Your Hymer has a master-switch that allows the leisure battery to be isolated, but this arrangement is not standardised for all motorhomes (my Hobby hasn't got it) and I'd guess that a lot more vehicles don't have such a switch than do.

 

Logically, if a motorhome is not being used and there's no pressing reason to keep the leisure battery connected, then it's good sense to isolate it, particularly if this can be done easily by a remote cut-off switch. That way one can be confident of the battery retaining its existing charge as long as possible and (especially important if a vehicle is in storage and visited infrequently by its owners) the chances are minimised of damage being caused while the vehicle remains unattended in the (admittedly unlikely) event that an electrical fault occurs in the circuitry connected to the leisure-battery. Also, when the battery has been isolated via its cut-off switch, anything leisure-battery-related still running when your stored motorhome was exited (eg. a light, or an electronically-controlled fridge, accidentally left on), will simultaneously get switched off.

 

If a motorhome has equipment powered by the leisure battery that it may be advantageous to keep operational while the vehicle is out of action, then one might choose not to disconnect the battery. But, generally speaking, I think your husband is a Wise Virgin and, whenever your motorhome is stored, it would be best practice to isolate the battery via the cut-off switch. OK, if he does this then he'll have to pole-vault out of and into the Hymer afterwards as the electric entrance-step will be 'dead' (or leave/enter via a cab door), but that's an unavoidable consequence of the battery disconnection.

 

 

Joy:

 

Vehicle alarms (and cab radios) don't normally involve the leisure battery. John Wickersham's "The Motorcaravan Manual" quotes the following voltmeter readings and the 12V battery approximate charge-states they indicate:

 

12.7v or over - charge state = 100%

12.5v - charge state = 75%

12.4v - charge state = 50%

12.2v - charge state = 25%

12.0v or under - charge state = Discharged

 

If your motorhome's leisure battery is genuinely dropping from 13v to 10.6v (that's flat as a pancake) within a week, and there's no equipment connected to the battery that one might reasonably expect to be imposing a current-drain on it, then you've got a problem.

 

If you can't find anything obvious causing a drain (eg. the light in my Hobby's wardrobe originally didn't switch off when the door was closed) then it's tempting to suspect that it's the battery that's duff (and, even if it isn't now, if it keeps getting discharged so heavily it soon will be), but there may be a system fault somewhere.

 

Assuming that your readings are correct (Sorry - it has to be said!) and (if your battery is of the 'wet' variety) that the battery's electrolyte level is correct, then probably your first step should be to get the battery checked out by a specialist. In theory, it should be relatively straightforward to confirm whether or not there's a continuous drain on the battery when the motorhome is not being used, but I don't know if you'd want to attempt this yourself.

 

thank you Derek, Book says 'dry fill battery' (not sure if this same as gel) yes there is a master switch for batt discon. under the dash. My husband is Wise if not a 'virgin', in fact he is actuall quite switch oon as he used to be an engineer in his quite long ago former life. My concern was that at 81 we were taking on too much by getting an A-class with all the mdern technology that goes with them. We would like to actually go somewhere in it rather than sit and read manuals and learn as we go. Not sure about the 'pole vaulting' I think a slower more considered entrance through the passenger door might be more fitting.

I really must add that your response to my query is very much appreciated. I am glad I joined the forum - I have contributed to and enjoyed too the lighter side as well. Now I am waiting for our first trip out!

Again, many thanks and hope too that our 'joint' post has given us both answers we sought.