Battery charging
Our van is permantley stored on the drive way, & as it is “new to us” also being born again caravaners we need some advice please.
The leisure battery is a 110 ah unit with a solar (70w I think) panel connected also, we’ve just checked the voltage (with a multi meter) & its reading 8.5 v, this reading tallies with the volt meter on the van panel also, but upon connecting to the mains
it immediately shows 13v
Is it kaput?
Dumb questions below.
1/ Will the solar panel be enough to maintain the battery when not connected to the mains?
2/ We tend to caravan once a month for a long weekends at present, should the van be continuously connected to the mains when sat on the drive or just for short periods?
3/ Should the caravan master switch be on or off whilst plugged into the house mains?
4/ If plugged into the mains at home has the van got an on board charger to maintain the battery or will we need to purchase a battery maintenance type of charger?
Our van I a 2010 spec Bailey Monarch if that’s any help
Liz & Steve
Comments
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It looks like your battery is kaput, as you describe. The fact that it returns to 13V when on EHU is thanks to your charger.
1) The panel should look after your battery, so long as there’s nothing drawing more power out than the panel can put back in. An alarm system might draw significant power as would anything left on standby or unintentionally (like a light). Try to place
the panel so that it’s is not shaded by tress or buildings.2) It should not matter to leave your van connected if your charger is a ‘smart’ variety. ‘Dumb’ chargers will dry your battery out and cause premature failure. If you use the van monthly, that should keep the battery topped up nicely. Leave it on EHU for
a day after your return, if you have a motor mover or did not have EHU while away, to bring the battery back to full charge.3) If you turn the master switch off, you will get no benefit from EHU. It will need to be on.
4) I’d expect your van to have a charger on board. It ought to be good enough to do what you need.
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The battery at 8.5 volts is certainly "flat" by any standard though not necessarily "kaput", however being so low and if being there for long will kill it.
As said leave it on charge for 24 >48 hours and see after that how it holds up. Even if that seems okay the real test is putting it to "work" and seeing how long it can hold up for.
There is a high probability that the battery is no good as draining them too low and not promptly recharging is a typical abuse they get in caravans.
A 70 Watt panel if kept clean and "seeing" the sun without too frequent shadows should keep a battery healthy. Grime and shadows massively reduce solar panel performance.
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"...Try to place the panel so that it’s is not shaded by tress or buildings."
Always pays to keep your hair tidy.
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Good advice above. Some vans have dual chargers like the Sargent system which will boost charge a battery then bypass it once fully charged so that it doesn't continually have current forced into it, however, most vans have a conventional charger which will
give a regulated output but should not be permanently connected. Therefore, if you have been using the van off of EHU then as soon as you get home you should disconnect it and recharge with a conventional charger. The van charger will only supply about 13.8
volts approximately which is not enough to properly recharge the battery and you will get significantly reduced life.0 -
Battery chargers fitted in caravans are not powerful enough to charge a flat battery. If you have taken it out then hopefully you are using a more powerful charger. If you need the battery to get you up and off the drive then it sounds as if you are using a motor mover and you will be depleteing the battery even before you go away. At this time of year a solar panel will probably be limited in doing it's job. Ah, hitchglitch posted whilst I was writing
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Battery chargers fitted in caravans are not powerful enough to charge a flat battery. If you have taken it out then hopefully you are using a more powerful charger. If you need the battery to get you up and off the drive then it sounds as if you are using
a motor mover and you will be depleteing the battery even before you go away. At this time of year a solar panel will probably be limited in doing it's job. Ah, hitchglitch posted whilst I was writingIts not so much the lack of power, they produce enough current but a battery needs a 14.4 volt regulated charge whereas the van has to supply a steady load for the 12 volt system. Usually the compromise voltage is about 13.6 to 13.8 volts which is not enough
to properly recharge a discharged battery but enough to keep it topped up without blowing up anything in your 12 volt van system.0 -
Ok, thanks for all your help so far, much appreciated. What voltage should a fully charged battery read? We have had it on charge now for 24 hrs & it's reading 13.2v. We've borrowed for now a C tek charger (mxs 3600) & it's showing fully charged with this
unit, also checked it with a Ring multi stage auto charger & showing fully charged with this too. There is a battery condition window on top of the battery that should be Green if charged, this is Black which means it wants charging. Completley confused now......0 -
Those 'magic eye' things on batteries are a bit hit and miss IMHO. I'd sooner rely on some form of metering.
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Ok, thanks for all your help so far, much appreciated. What voltage should a fully charged battery read? We have had it on charge now for 24 hrs & it's reading 13.2v. Completley confused now......
Slightly difficult on two counts to be specific on this;
A battery just off charge holds what is called a "surface charge" making the voltage higher than the level it will settle to in time or if put on load. The 13.2 Volts is exhibiting a level of surface charge.
A full battery will settle in time, after the surface charge has dissipated to a value that reflects the trace alloying used within the lead the plates are made of. Typically this full charge will be between 12.7 and 12.9 volts, leaning in my experience more to the higher value with modern alloying.
See what yours settles to and use that as your datum; the CTEK will have fully charged it.
Without a load placed on the battery the surface charge can take quite a few hours to naturally decay.
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liz1955. When you have finished recharging the battery leave it for a few hours. Then if possible test it's condition using a multimeter. Turn the dial to 20 volts DC and a full battery should read about 12.7 volts, half full about 12.4 and 12.2 is about down to a quater. The battery should hold the charge and not drop quickly. Hope this helps.
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Flipping heck OCSID where as I appreciate your knowledge and obvious professionalism,you have just given me an headache and I am not much wiser now!.
Well, sorry about that but there is no unqualified answer to liz's question.
Put simply the battery's voltage when fully charged depends on its "brand" and you can't measure it for several hours after it comes off charge. For value see makers data sheets.
Hint; it will be between 12.7 and 12.9 volts.
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Ah well, battery performance is a complex subject but as ocsid says, you need to leave for a few hours after charging to get a true figure or you can apply a good load for a short period to clear the surface charge.
Our golf pro asked me if there was a device for measuring battery condition (for golf trolley batteries) and I did quite a bit of research. In practical terms the only way to measure the performance of a battery is to apply a steady load and measure the time it takes to go flat. Not very scientific but some golf clubs actually do this. Some garages will do a discharge test over a few seconds but I have never been convinced about the readings.
In terms of caravan or motorhome leisure batteries all you can do is check that after charging you get around 12.7/12.8 volts and that the battery will retain this voltage for a few weeks whilst standing idle. You then need to test it when using the van off of EHU and see what happens compared with what you might have experienced when the battery was new.
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Ok, thanks for all your help so far, much appreciated. What voltage should a fully charged battery read? We have had it on charge now for 24 hrs & it's reading 13.2v. We've borrowed for now a C tek charger (mxs 3600) & it's showing fully charged with this
unit, also checked it with a Ring multi stage auto charger & showing fully charged with this too. There is a battery condition window on top of the battery that should be Green if charged, this is Black which means it wants charging. Completley confused now......You seem to have done better than I had expected, Liz. The best way to see if you’ve got any charge into your battery is to use it and you’ll soon find out. Try a slow discharge (one light for a day or two) and then recharge when it has dropped to 12.2V
(no lower). The newer C-Tek chargers include a desulphation phase which may ‘clean’ the plates and improve the charge the battery will take. A few cycles, exercising it like that, may bring your battery back to life but I doubt you’ll get very far with it
if you use a motor mover (you’ll need a new one). If it’s a sealed battery, it may be no good because you may have lost electrolyte that you cannot replace.0 -
Ok, so after showing a full charge on 3 different battery chargers we left it to stand for 4 hrs. Result is 13.46v is this acceptable or not? We have planned to go away this weekend so if its not ok we'll need to get another battery ordered today for tomorrows
delivery. Your thoughts once more please.0 -
Ok, so after showing a full charge on 3 different battery chargers we left it to stand for 4 hrs. Result is 13.46v is this acceptable or not? We have planned to go away this weekend so if its not ok we'll need to get another battery ordered today for tomorrows
delivery. Your thoughts once more please.It is fully charged (expect the voltage to drop to 12.7 volts as soon as you apply load). Unfortunately you will not know if it s holding charge until you use it. If you are going to be on EHU then no problem, if stand-alone then you will discover fairly
quickly whether it will hold its charge.0
