MORE Vehicle Battery woes

[crob]

I'm starting a new thread so as not to clutter up the previous one with my situation.

 

I have a Hymer with a 2 year old Varta 88A engine battery, still under the 3 year warranty. My normal MO in the winter season is to run the van "round the block", about 12 miles, every 3 or at most 4 weeks. I don't usually have a starting problem.

 

This year, I ran it early Jan, and tried again early Feb, but it had a flat battery. I jump-started and ran it round the block. I know that this short journey will not fully charge a flat battery, and as we were away on hols for 6 weeks shortly after, I disconnected the live battery lead.

 

Upon our return 2 weeks ago, the engine started OK and I ran it round the block again. Last Wed I tried to start it but I had a flat battery again, so another jump start. I took the van in for its pre-arranged service, and they spent quite some time trying to resolve this apparent battery problem. They fully charged it and cleaned the earth cable (which wasn't that dirty anyway). I drove the 30 miles back home and checked the reading from the van's control panel, and it read 13V.

 

Fri morning, another flat battery, with a reading of 11.2V. So I put it on hook-up overnight, when it read 12V yesterday morning. I then borrowed a battery charger, which is known to be working, and have had it on charge now for about 27 hours. This morning, the reading WHEN ON CHARGE was 13.5V, but when not on charge, having left it for about 30 mins "to settle", the reading was only 11.4V i.e. lower than before I put it on charge! It is now reading 11.75V when not on charge. Does this point to a feed problem? I have disconnected the radio, as I am suspicious that this may have been drawing current, even when switched off.

 

My objective has been to fully charge the battery, then disconnect a terminal to see if it holds its charge with nothing feeding off it. If it does, then it points to a feed problem; if not, it points to a battery problem. I am trying to eliminate possibilities before the garage come to take the battery away for testing. They are not too keen to do this, not too sure why.

 

I have read all the posts in the previous thread, but couldn't find one that matched my problem. Expert views would obviously be welcome.

 

 

[mandale]

I think you are correct to disconnect the battery, charge it over night and test it again after removing the charger and allowing it to settle. I would maybe test the battery when it is not connected again in a day or so to see if the voltage is still dropping.

 

I am not familiar with the managment system on your motorhome, however most systems have a voltage sensitive relay that prevents the habitation electrics from draining your vehicle battery. It is more likely that something on the base vehicle is causing this. I have heard of some TV/DVD systems being powered from the base vehicle battery, maybe this is on and draining the battery?

[crob]

Thanks for your reply. I forgot to say that the 12V habitation system has been off during the whole of this process.

[mandale]

Are you sure that nothing in the habitation electrics other than the charge system is connected to the main vehicle battery, ie tv/dvd, a lamp in a cupboard etc. If nothing is on it must be the base vehicle systems drawing power or a failing battery.

[crob]

I MAY have found the problem, but if I have, I've no idea what the solution is!

 

After 48 hrs on charge, the battery is still only registering 11.75V (when the charger is turned off). At this stage, I had left the battery connections on the terminals. So I decided to disconnect one of the battery terminals to see if this resulted in a faster charge rate. If so, that may indicate a battery drain.

 

BUT, as soon as I took the positive terminal off the battery (the negative terminal is very difficult to get to), the van alarm started up. It only stopped when I touched the wiring loom back onto the battery terminal again. I have left it with the wires touching the battery terminal. On previous occasions when I disconnected the positive wiring, when we went away for 6 weeks, there was no problem.

 

Does this indicate some sort of short-circuit in the alarm system? If it does, is that an auto-electrician I need to fix it?

[Derek Uzzell]

I believe you own a Mercedes-based 6-tonne-chassis Hymer S-Class motorhome that's about 10 years old.

 

Despite your Varta battery being only 2 years old, the symptoms point to it having developed a fault.

 

Voltage-testing when a battery is being charged (via the vehicle's alternator or by a separate battery-charger) will just reveal the voltage being provided by the alternator/charger.

 

If you want to establish the 'health' of your battery I suggest you:

 

A - Disconnect the battery completely from your motorhome's electrical system and check the voltage across the battery's terminals.

 

B - Charge the battery for at least 24 hours using your borrowed battery-charger.

 

C - Disconnect the battery-charger from the battery and (as mandale advises) leave the battery to "settle" for at least 6 hours.

 

D - Check the charge at the battery terminals.

 

The approximate across-terminals voltmeter readings for a 12V battery in good condition are

 

12.7V or over - 100% charge

12.5V - 75% charge

12.4V - 50% charge

12.2V - 25% charge

12V or under - Discharged

 

Obviously, how much your borrowed battery-charger will have been able to have raised your battery's charge-state over the 24 hour period will depend on the charger's performance and the battery's charge-state when charging commenced. However, if your battery is now showing a voltage reading of below 12V (as your original posting suggests it may well do), then your battery has probably had it. (A technical term!!!)

 

There is a need for care at this point, as my recent (bitter and expensive) experience showed that a battery that provides a reasonable-looking charge-state reading may be unable to maintain the charge when a significant load is applied to it. My Hobby's habitation battery (admittedly 7 years old) was showing 3 tell-tale lights (in theory fully charged) on my motorhome's control-panel and was able to run the vehicle's interior lights and water pump. But, when the heater's blown-air fan was switched on, the battery 'died' completely and a subsequent voltage test showed just 12.0V So, if your battery does shows a reasonably good charge-state, I suggest you apply a load to it (say by jury-rigging a headlamp bulb between the battey terminals) to check whether that charge-state is maintained. (The situation regarding load will be far worse for a starter battery that needs to cope with a huge sudden drain being placed on it.)

 

A battery specialist should have the equipment and know-how to confirm the condition of your battery if your garage is unable to do this.

[crob]

Thanks for your very detailed reply. I am intrigued as to how you know my vehicle - you are spot on!

 

At present, I daren't disconnect the positive battery wiring because the alarm goes off and I don't know how to stop it.

[Keithl]

crob - 2012-04-09 12:13 PM

At present, I daren't disconnect the positive battery wiring because the alarm goes off and I don't know how to stop it.

 

Colin, correct me if I'm wrong but is there not a 'procedure' for disconnecting the vehicle battery to prevent the alarm sounding?

Something like arm the alarm, disarm the alarm and then disconnect within a certain time? This would be to prevent a thief from simply disconnecting the battery and breaking in.

 

Keith.

[crob]

Keith.

 

There is an alarm sensor in the bonnet arrangement, so if you open the bonnet with the alarm set, it goes off.

 

When I've disconnected the battery before, there has been no problem with the alarm. I haven't had to go through any process. I've looked in the alarm instruction book and it says nothing about this situation.

 

Also, today is Easter Monday, so there's nowhere open to talk to about it, but tomorrow is another day!

 

Colin.

[alf]

crob - 2012-04-09 1:20 PM

 

Keith.

 

There is an alarm sensor in the bonnet arrangement, so if you open the bonnet with the alarm set, it goes off.

 

When I've disconnected the battery before, there has been no problem with the alarm. I haven't had to go through any process. I've looked in the alarm instruction book and it says nothing about this situation.

 

Also, today is Easter Monday, so there's nowhere open to talk to about it, but tomorrow is another day!

 

Colin.

 

Colin I suppose you have tried to turn the alarm off with your remote whilst its sounding.

It would help if we knew the make and type of your alarm system.

 

Alf

[Brambles]

When you disconnect the batt +ve. what is the voltage you read on the disconnected terminal of the lead. I am wondering if you have a problem with your Leisure batteries feeding the vehicle cab side of affairs. This would explain why your alarm still sounds, or does the alarm have its own internal back up battery. If it does then this may have failed and is constantly drawing a high curremt to charge it but as faulty just acts like an additional small load on the engne battery. Unusual for a vehicle alarm to have its own back up battery but not unknown.

 

Just a pennies worth as not analysed previous posts in detail.

 

However, whatever fault you find, I also believe your engine battery has ( now also) failed.

[alf]

Jon most top quality alarms particularly the ones to the Thatcham Cat 1 and 2 standard that insurance company’s require are self contained with NiCad batteries the idea being when set they will sound when the supply from the main battery is disconnected, ... but using the remote should silence it

 

Alf

[crob]

The alarm is a Sigma M34. When it sounded when I disconnected the battery, the remote wouldn't turn it off. I had to reconnect the battery to shut it down.

 

The alarm works fine on its own with the remote. I can turn it off and on, and if I open a door when it is set, the alarm goes off as usual. (That was about 2 hours ago.)

 

I've just gone out to the van - the alarm now doesn't work at all with the remote. I've taken it off the electric hook-up from the house; the battery reads 12V - not too good. I've also disconnected the positive from the battery, and the alarm didn't sound this time.

 

So, I've absolutely no idea what's going on!

[Brambles]

Your Battery is shot if you are charging it and is gettng a shorter and shorter time it is holding charge along with dropping voltage. Trust me, a new battery will resolve all the little annoying issues you are having. Next task when gettng new battery is to check you do not have a high current drain. I expect your alarm is draining more than desirable and a drive every few weeks is helping but not quite enough. You do not say what model Varta battery you have but mention 3 year warranty so suspect ot is a basic starter battery. If you have high drain from Alarms and other items then you woudl be better going for a Silver Calcium Battery which will cope better with the drain while parked up for weeks on end. If you keep at home on the drive, consider a trickle charger left on most of the time or a time switch and charger to recharge once a week.

 

My view is, get new battery then start testing current drain when parked up.

 

 

[Derek Uzzell]

crob - 2012-04-09 12:13 PM

 

Thanks for your very detailed reply. I am intrigued as to how you know my vehicle - you are spot on!

 

At present, I daren't disconnect the positive battery wiring because the alarm goes off and I don't know how to stop it.

 

No mystery - I just waded through your earlier postings.

 

It may well be that there's something in your motorhome's electrical system that's capable of dragging down your starter-battery from (apparently) fully charged to fully discharged within 24 hours, but I'm going to suggest that's academic at this point.

 

The Varta battery has been OK for 2 years but now won't start the motor reliably. Even if there is now something peculiar that's draining the battery (and you may be able to establish this fairly easily if you take an ammeter reading between the battery's + terminal and the connector that normally attaches to that terminal) if the Varta battery is now duff, you'll still have to replace it. The most important thing at the moment is to be 100% certain that the battery itself is not the root cause of the problem.