Leisure battery not fully charging from altenator

[bolero boy]

Hi all, posting this on behalf of friends who are the 2nd week into a 3 month trip to france and Spain.

They have a new (to them) motorhome, a 2006 Adria Izola.

They are using a mix of aires and sites, often without EHU.

The issue is that after 4 hours of driving to a site without EHU, they noticed that the leisure battery (single 85AH unit) had only moved from a previous recording (on the internal control panel) of 25% when they left, to 60% on arrival.

When camped with EHU the battery rises to 100% (or whatever full is on their guague) within a couple of hours.

It seems the vehicle battery gets fully charged from either source.

Assuming they have, or can get, a multimeter what readings need to be taken (and in what conditions) to be able to provide some baseline info to aid diagnosis?

Alternatively, any inspirational thoughts related to these apparent symptoms?

Many thanks!

[sshortcircuit]

An expert will come on and give a more technical explanation, however as far as I understand it the output from the alternator is controller by the state of the vehicle battery. After you start the vehicle a high charge is provided to return the starter battery to its normal condition and once charged the alternator output is considerably reduced so providing not much of a charge to the leisure battery.

 

You can fit relay ? Units that will enable a higher/longer charge to the leisure battery, but watch this space for the expert.

 

[Derek Uzzell]

It may well be that, with a single 85Ah leisure-battery and discharging it down to an indicated 25% charge state, an increase to 60% after 4 hours driving is the best that can be expected. The rise from 25% to 60% does at least prove that the alternator is charging the leisure-battery and, consequently, I'm tempted to think that there's nothing actually wrong.

 

If a battery has been allowed to 'rest' for at least 4 hours with no charge applied to it during that period, and with no current-drain being placed on it, then voltmeter readings (taken at the battery's terminals) should represent:

 

12.7V or over - 100% charge

12.5V - 75%

12.4V - 50%

12.2V - 25%

12V or under - Discharged

 

Off EHU, it will be easy at this time of year to rapidly run a relatively small-capacity battery into the ground, as interior lighting, heating, TV (?) etc. are likely to be operating for extended periods. Perhaps your friends don't appreciate this and are squandering their small leisure-battery's charge without realising that there ain't a great deal of it. Waste not: want not and all that!

 

I think your friends will need to seriously economise with their leisure-battery's 12V power when off EHU, otherwise there's a fair chance they'll kill the battery.

[lennyhb]

I agree, to get back to 60% after only 4 hours driving they are doing well. After the first 10 - 15min after starting the engine where you will get a decent charge level the internal resistance of the battery will increase and the charge rate will drop to around 3 to 5 amps, to get back to a full charge you would need 12-15 hours driving.

 

They are also probably being fooled by the reading on their meter as the meter will be reading the potential across the battery which will be effectively the charger voltage.

As Derek says you need to measure the state of charge with the charger switched off and no load on the battery for a few hours.

[Brambles]

Agree, 4 hours driving is just not going to be enough to fully charge the battery after a lot if use the night before.

However I would have thought it should take it above 60%, but if the battery is aging this might be a tall order. The reason the EHU is showing 100 quickly is because the voltage is being raised by the charger so gives a false result.

One thing they can test is what is the level of charge meter showing when they have the engine running, it should be similarly a lot higher, and this will show the alternator is charging the battery.

 

There will be quite voltage drop in the charge circuit cables because of their length and replacing with heavier cables may help improve charge rate. Also if the battery is aging or depending on type may be slow to charge from an alternator anyway.

 

Might be prudent if it is fooded battrey that can be topped up, they check the acid levels and top up with de-ionised or distilled water if required. Top up to about half way between min and max or just cover the plates initially then after charging top up again if required. If it is low on electrolyte this will slow down the charge acceptance rate quite a lot.

[bolero boy]

Many thanks Derek, Lenny and Jon.

I have emailed the link to this thread so that they can read the responses.

I think Dave (my friend) may be a forum member so might respond with any extra input regarding battery quality (which I think was changed from the original one supplied) and any appropriated meter readings.

Thanks again, all.

[Brian Kirby]

To be honest, I'm also a bit suspicious that the charge actually reaches 100% after a "couple of hours" on EHU.

 

I wonder if they are using the indicator while still connected to mains, in which case they will be reading the charger output and not the battery state. As Derek says, they need to leave the battery disconnected from all charge sources, and devoid of any load, for about 4 hours, to allow it to "settle" (not easy at this time of year while the van is in use!) and then see what the readings are. Within the limits of the on-board meter, that will give the best indication, but otherwise a multi-meter, applied to the battery terminals, but only after the same 4 hour interval, will give the most accurate indication of its state of charge, but will say little of its actual health.

 

If it is the original, it is now 5 years old with no knowledge of how the previous owner treated it, so must be under suspicion.

 

If new, it is not guaranteed to be fault free, so could still be the problem.

 

If it is located some way back from the alternator it is possible, as Jon (Brambles) suggests, that the cable is of inadequate size to maximise the charge from the alternator.

 

Without (I hope) over-complicating things, I assume we do not know what level of actual charge equates to the on-board meter's readings of 25%, 60% or 100%. It is possible this is set to record somewhere around 10V as 0% charged - which is the point at which some systems are set to disconnect all consumers - rather that th 12V level Derek correctly quotes.

 

They really need to find this out as they are, as stated above, using a fairly small battery very intensively, and they just may be caning it too much.

 

As almost everyone else has commented, driving for a mere 4 hours is far too little to take a battery that is down to 25% charge, back up to 100% charge. For what they are doing they need to go to an aire, or a campsite, where they can use EHU overnight, at least every 2/3 days, and then leave the battery continually charging for the whole time. A couple of hours on a borne at an aire really won't do the trick, especially if they have lights, or other 12V consumers, going at the same time, because they would be simply draining it at one end while trying to fill it from the other. Bit like trying to fill the bath with the plug out!

[Guest Tracker]

It may well be as simple as dirty fuse contacts in the split charge relay just under the bonnet and in front of the battery - right where all the road dirt and crud can hit it!

 

Take out the fuses and clean or replace them and also clean the fuse contacts in the relay itself. A cut down thin emery board or nail file works well for this or a bit of folded wet and dry but be careful not to open up the contacts or the fuse will not connect properly.

 

This is a common problem with many vans. How do I know this - because almost every Sevel based van I have had has suffered from it at one time or another! But only once because I run some duct tape over the fuses to keep the water out having once cleaned 'em.

 

May not be your problem but worth checking anyway?!

[Brambles]

Please do not attack your lightly plated contacts with emery or a nail file. Far too abrasive and will remove protective plating and then you will start to get problems. Cotton bud with T cut or other light oil based solvent is all you need. Alternativly if they are tarnished, just use thick paper to clean.

[Dmeehan]

Hi all, Dave the hapless traveller friend of Chris here.

 

Thanks for all the very helpful advice. Rest assured that we are not numpties, just new to motorhoming. We are used to sailing and therefore have a good appreciation of living off a leisure battery!

 

We are living frugally off the battery when not on hookup, although the heater fan appears to be the biggest consumer overnight. We have moderated the heating levels already to help with this, will get out the long johns if necessary!

 

The 25% level was only after running of battery for two consequetive days with minimal driving time. 25% is what I would consider the safe low water mark so as to preserve long term battery life.

 

I agree that the maths is without dispute - 3-5 amps of charge off alternator (according to panel) is going to take 10+ hours of motoring to make up 50% charge.

 

Have taken on board all of the advice, and will take some readings over the next few days and report back.

 

Many thanks

Dave

[Guest Tracker]

Brambles - 2011-11-21 1:31 PM

Please do not attack your lightly plated contacts with emery or a nail file. Far too abrasive and will remove protective plating and then you will start to get problems. Cotton bud with T cut or other light oil based solvent is all you need. Alternativly if they are tarnished, just use thick paper to clean.

 

That's fine in theory.

 

I've been using my method for years and never had a repeat problem and there is no way you can get in to clean the fuse contacts with tcut or solvent especially if they are heavily soiled or corroded.

 

It may not be considered 'best practise' but it is practical but it is of course up to the user to do what they feel is needed to restore current flow - and at least they now have choices!

 

[JamesFrance]

Unless you have an advanced alternator controller, you will have trouble ever charging a leisure battery to maximum level by running the engine. 60% is about it.

 

When I lived on a narrowboat I could keep the batteries charged by running the engine for one hour per day. That kept a 240 volt fridge running together with TV, pumps and lights. You need to sense the state of the leisure battery so that you can tell the alternator to give maximum charging rate and high voltage.

 

I used an Adverc product which would be expensive for a motorhome, but Sterling make a range of cheaper solutions.

 

http://www.sterling-power.com/products-altbatt-benefits.htm

[Derek Uzzell]

Tracker - 2011-11-21 12:46 PM

 

It may well be as simple as dirty fuse contacts in the split charge relay just under the bonnet and in front of the battery - right where all the road dirt and crud can hit it!

 

Take out the fuses and clean or replace them and also clean the fuse contacts in the relay itself. A cut down thin emery board or nail file works well for this or a bit of folded wet and dry but be careful not to open up the contacts or the fuse will not connect properly.

 

This is a common problem with many vans. How do I know this - because almost every Sevel based van I have had has suffered from it at one time or another! But only once because I run some duct tape over the fuses to keep the water out having once cleaned 'em.

 

May not be your problem but worth checking anyway?!

 

Dave's motorhome is a 2006 Adria Izola.

 

I've browsed MMM's February 2007 test report of an Izola S687-SP (that confirms the 85Ah battery as standard) but, unsurprisingly, there's nothing much about the vehicle's electrical system. However, as the Adria is Continental-built, there's a strong likelihood that a 'coupler/separator' is employed rather than a split-charge relay and that this will be located within the motorhome's living-area not in the engine compartment.

 

Received wisdom seems to be that discharging a leisure-battery much below 50% charge state will harm its longevity, but keeping to that rule-of-thumb may be hard off-ECU in cold weather.

[Brian Kirby]

Tracker - 2011-11-21 2:19 PM

 

Brambles - 2011-11-21 1:31 PM

Please do not attack your lightly plated contacts with emery or a nail file. Far too abrasive and will remove protective plating and then you will start to get problems. Cotton bud with T cut or other light oil based solvent is all you need. Alternativly if they are tarnished, just use thick paper to clean.

 

That's fine in theory.

 

I've been using my method for years and never had a repeat problem and there is no way you can get in to clean the fuse contacts with tcut or solvent especially if they are heavily soiled or corroded.

 

It may not be considered 'best practise' but it is practical but it is of course up to the user to do what they feel is needed to restore current flow - and at least they now have choices!

 

The fact you've had few repeat instances, Rich, seems at least as likely to be due to the duct tape keeping the wet off, as to the method used to clean the terminals.

I'm with Jon on this. The zinc coatings are very thin, and the zinc itself is a sacrificial anode. It will gradually be lost through electrolysis in order to prevent the underlying steel from rusting. After time, all zinc coated, or galvanised, components will begin to rust because the zinc has been eroded away. You will then be using any zinc remaining on the blade fuse itself to prevent both components rusting, and after that has gone, the whole lot will fuse into a rusty mess.

Using something like WD40 to film the contacts, and then keeping the wet out, will probably work better and for longer than abrading the contacts.

[rolandrat]

Rich, you are probably right in what you say, usually the split charger fuses are located on the r/h side sat in the driving seat under the bonnet. They are definately an area that needs checking out. Once checked and cleaned of any oxidisation they need some white grease spraying on them. The leisure battery should then charge no problem at all. Failing that fit a new carrier.

[Clive]

The starter battery and the leisure battery when charged via a conventional split charge relay will never get to 100% charged. This is because the output voltage from the alternator is limited to 14 (or sometimes up to 14.4) volts so that the batteries seldom gas and therefor require minimal maintenance. If your motorhome has one of the later Sargent electrical systems fitted or perhaps you have a CTEK B2B charger fitted then you will achieve 100% charge eventually because the voltage is increased by the electronics, but not after just 4 hours driving. If you are doing lots of wild camping and not much travelling then you should look carefully at your consumption of 12 volt energy. Use all LED lighting for instance, Don,t have a diesel heater!! (sorry but its true!) Ration your use of TV and satellite. Have the biggest solar panel you can acomodate on the roof.

 

Otherwise you will be into noisy generators (fine if its only you) or an EFOY fuel cell.

 

Least expensive way is more batteries but these eventually will need charging and it will take proportionally longer.

 

C.

 

[Dmeehan]

Sorry for the delay in replying, but wanted to gather some stats. Unforetunately I managed to look the last few days worth, but you'll get the gist.

 

We are less worried than we were when we originally posted, we seem to be able to last 2-3 days off the leisure battery with a couple of hours driving each day. We intend to find some LED lights when we can track down a dealer/shop, as we think this represents a large chunk of the unavoidable drain.

 

Any further comments greatly appreciated.

 

Please see the attachment.

Battery Logbook.pdf

Battery Logbook.pdf

[Brambles]

Not entirely clear how many hours you are discharging batteries using your data. However deciphering what I think it should be it looks reasonable especially for a typical 85 Ah battery which is probably more like a 60 Ah and then aged as well reducing further. So I came to the conclusion I am not analysing the data correctly or just too much spread of unknowns and tolerances.

 

It does appear though your battery is generally charging at a reasonable rate but you do get down to the 50% level on occassions and this indicates you need slightly more capacity as you have none in reserve unless you had a battery capable of continuous 60% dod, and ocassional 80% without too much aging as a result.

I personally would rather up my battery capacity and forget LED lamps as I do not like the light temperature (colour) they produce, expensive and hit and miss as to reliability. Personal choice. I have a 80Ah battery, and using lights and heater fan, along with extractor when cooking manage three nights with ease without any driving to recharge. Oh yes, and a netbook in evenings to watch a movie for say an hour each night using an invertor.

What you may find helps with recharging is if you have fairly light cables in the split charge relay circuits then these may be dropping excessive volts and using heavier cables will boost the charge current from alternator albeit slighty but can make a big difference when the charge current is high because depth of discharge is large.

You seem to know what you are doing so shall leave you to it for the time being, but did find your statistics interesting once I worked out what was what.

Jon.

 

p.s. Do I really have to check the above for spelling and typos.

( No, thats OK Brambles, we will do it - Editor)

[Dmeehan]

Brambles

 

Thanks for the analysis - I know the stats were not exactly scientific.

 

You do seem to have a usage similar to ours and appear to be getting more out of your battery than we are. On nights when we are on hookup we've been relying on the laptop battery and not really using the inverter, so it would appear we get quite a bit less. Essentially we use about 25% of the reported capacity, which is more like 50% of the reasonable capacity i.e. treating 50% as the low water mark.

 

I tend to agree on the lamp issue, although we have many LED's at home and so are not unused to the light quality. We will probably investigate a replacement battery of higher capacity to see what difference that might make. Changing the spit relay cables at the moment is probably more effort than its worth, but maybe a job for when back home.

 

If anyone can quote what a reasonable split relay cable size should be that would be a help. I suspect 2-3 metres is needed to bridge the gap, but I've not looked in detail at the cable route. It might be a little longer.

 

Cheers

Dave

 

[Brambles]

Rather than type it all out its easier to post a link to a suppliers site which gives cable sizes and amps it is suitable for.

 

I have seen motorhomes using cable typically 4 to 6 mm square cross section. This is really a bit light because of volt drops better with 7 to 10mm sq cross section. The heavier the better. Never use a cable which can not carry the fuse blow current and 1.5 x fuse rating is a nice safety margin.

So for a 40 amp fused charging circuit then the cable size should be 7mm sq section minimum.

 

I have seen charge circuits using just a 20 amp fuse and cable to suit of just 2 or 2.5 mm sq section.

This is not heavy enough and is really just a case of making sure you are not as light as this because of teh volt drop over a long run.

 

It actually gets a bit more complicated because of the range of modern cables and with the use of silver plating and extremely low oxygen or alloyed copper along with high temperature hard thin walled insulation cables can look incredibly thin. Vehicle manufactures, although generally not Motorhome builders, have gone this route. Apart from the cable being lower resistance the insulation can withstand higher temperatures and in DC circuits typcally not all cables in a bundle.harness carry much current so actually act as a heat sink for the cables which generate heat. This means they can pass very high currents down thin cables such as have 20 Amps down a 1mm cable this making a harness a lot lighter, less bulky and much cheaper to produce. But I digress of the topic in hand. What size cable for charging and I should stick to what is normally used and what is available in the aftermarket easily such as the link I posted.

[Brambles]

" Essentially we use about 25% of the reported capacity, which is more like 50% of the reasonable capacity i.e. treating 50% as the low water mark. "

 

 

Stick to just using a %age of total capacity, it makes it less confusing as most data refers to %age of total.

If you can post what battrey you have I an look up te dta an see what you actual capacity is to begin with.

I see no reason to replace yoru battery just to make sure you operate with in best practiocve for max life. Just use what you need to and when it fails to meet requitements is teh tome to upgrade teh battrey. I so suspect though like I mentioned in my earlier post your battery is a lot less than 85Ah. However I said this to someone once and they popped back to comment it was a Exide G85 Gel which is an excellent battery and probably can not be beaten. So mud in my face for this one.

 

Depending on your results, either your battrey is a cheap 85 doing very well, or maybe an Exide or varta 85 gel doing very badly!!! Do post back with what your battery actually is because it actually also makes a big difference with analysing charge and discharge data.