12 volt battery/charger help needed

[richy_374224279]

I am new to this caravanning business - but having had 12 holidays since January - am enjoying it immensly as are the 2 kids and she who must be obeyed.

We have a 1996 Lunar Premiere -which someone must have mothballed as it was immaculate and unused when purchased.

My question is can someone point me in the right direction as to how to progress a problem with the battery and 12 volt system.

On the last but 2 holiday in July - we awoke to a strong smell of bad eggs inside and outside the caravan - I blamed it on 6 month old Emma but eventually found it was the battery gassing what I assumed was hydrogen sulphide - the battery was also hot to the touch. I turned everything off as I gather it can be an explosive gas.

Someone suggested that the charger rocker switch should not have been left on 24/7 and the battery could supply power to the 12volt system with an occasional charge which made sense - so on subsequent days and holidays I only used it a bit - all the time the battery guage needle was showing full. Water pump - 12 v lights all ok.

However at the weekend just past - when holidaying again - the battery was dead and didnt recover when the charge rocker switch was on. The cells seems to have lost water also I assume related to the boiling.

Would I expect the 12 volt pump etc to be run from the battery -through the charger (if on) - and does the system work with a dead battery - I would not really mind as we always use a hookup.

Also is my diagnosis that

1) The charge over charged the battery killing itself and

2) The battery survived a couple of holidays - during the summer so not much power draw other than water pump. When run down that was it

3) The new battery which I got from halfords and put in is now supplying the power but not being recharged other than when being towed. The 12 volt charger system is no longer playing a part in the operation.

Any advice is welcomed from you experts - given that I couldn't find anything that resembled a 12 volt charger when I unscrewed the electric panel are they inbuilt into that ? - in which case we could be talking big money.

Would taking a stand alone charger and using that from the mains be a better cost option.

I am not planning on doing any electric work as unqualified but just trying not to fall into the gullible customer waiting to be fleeced trap.

Best Regards Richy

 

[JeremyClarksson]

I have no experience of a van with a charge switch fitted but if you can get access to a voltmeter (there might be one fitted as a charge indicater) and attach it to the battery the voltage will rise as the battery charges.

A normal permanently on on board charger will not charge above 13.85V as a safety feature to prevent gassing, if it goes higher than this than it is operating like a normal stand alone charger and will need to be switched off at or before 14.8V on a normal leisure battery (Elecsol 14.4V).

It sounds like this is what is required on your van and that is probably why you have a charge switch.

 

[gary]

The battery 'boiling' does not necessarily mean the charger is overcharging, it is just as likely an internal battery fault is responsible. Your voltage gauge should give a good indication if the charger is at fault, the green is from 12 to 15 volts and it should be reading 13.8 or 3/4 along. 13.8 volts can be left connected permanently as this is incapable of bring the battery to full charge, however if the gauge is fully over to the right then overcharging at 15v is the reason for the batteries demise.

The charger itself is a component within your overall power distribution box and is easily replaced by a competent person.

 

[richy_374224279]

Thanks for that. I have a multimeter - would a reading taken

at the charger terminal with it on but no battery attached be expected to be 13.8 or so volts then - showing that the charger is functioning and not dead ?

What I am having difficulty in working out is whether the charger is charging or not given that I have one dud (at 9Volts) and one new at 12.6 Volts.

Thanks for all your help. I looked at the rear of the distribution board but there was nothing larger than a match box really and I had expected something of a more substancial size.

I think I will take it to a competent person rather than risk a trip away - with winter coming on the lights are pretty esential.

Thanks again

 

[Damian]

Richy, to test your van charger, set your multimeter to 20v DC and measure the voltage acoss the battery terminals BEFORE connecting any power source.

Then connect the 240 v to the van in the normal way, and measure the voltage across the batery terminals with the charger switch OFF, then in the ON position.

You should get two readings the same, and one higher, when the charger is switched on.

Now you have the basic answer to work from,and can establish whether or not the on board charger is working or not, and at what level of charge.

Most vans are made to need a battery in the circuit to provide a smooth 12v supply, as a charger will put out more as demands are made on it, and could damage some electronic equipment.

If your van charger is not working, you can get by with a multi stage automatic stand alone charger, which wil take the battery to its full charge, then maintain it at that level.

 

[JeremyClarksson]

Richy

It is best to attach a battery to test the charger, I should start with the new one which at 12.6V is not fully charged.

Leave the charge switch in the off position take a reading and then take a reading in the on position.

In the charging position you should see the voltage rise immediately and then it will rise slowly over a few hours, if it holds at 13.8V it is an onboard charger and can be left on, if it goes above 14V appx only use the charger to top up.

Reading your original post again it sounds like your 12V system always runs from your battery even when charging (which is the case on the caravans I have owned), if the battery has had it I would not expect the 12V system to run from the charger as the voltage would be too low (because of the battery across it) and the charger would probably not supply enough current.

I would never try to run a van of the charger alone.

I have read of the multistage and pulsing chargers mentioned by Damian rescuscitating a dead battery, but I believe you should not connect it across the battery with the 12V caravan system connected as the pulsing and high voltages could cause problems with electronic equipment, although I would not swear on this.

As an aside I run on 12V only quite a lot and always take the batteries off the van to charge with a conventional charger, we seem to get almost twice as much out of a battery charged this way over one charged by the onboard charger.