Why shouldn't I be plugged into EHU all the time?

[StuartO]

I'm not living in the MH of course, so the batteries are not doing any work. So far the solar panels are certainly keeping them topped up in storage, despite being in UK. The MH is likely to be back at home on EHU before winter sets in properly but based on what I've seen so far I'm optimistic that the batteries would continue to be kept topped up by the solar panels throughout the winter, even without EHU.

[Rayjsj]

Had my reply from Sargent regarding leaving EHU and charger charging all the time. They say that their chargers are designed to be constantly connected to mains electricity, and will keep both vehicle and leisure batteries in a fully charged state, without overcharging or damaging them or the charger, also there are 'failsafe' systems to protect both batteries and charger should a fault occur.

Sounds good enough for me, so, I will carry on leaving the charger on all the time. Ray.

[aandncaravan]

The advice given is as a result of what we see inside the chargers when we repair them.

We are advising they are used less often which can only be good for any unit and prolong it's life.

 

We certainly have no issue with the units charging continuously, as if they do break we get more business. As, of course, do the manufacturers and Dealers that give out the advice to use them all the time.

 

We gave out the advice in good faith, we certainly have no issue (indeed very happy) with anyone ignoring it!!

 

 

[Charles]

they're probably not as unreliable as you think aandncaravan , it's just that every time you see one it's gone wrong, there are probably thousands out there on mains 24/7 with no problems.

I used to work on commercial refrigeration systems and I used to think they were useless, always icing up, motors, probes, compressors failing every verse end. They weren't unreliable really, just that I got called out to all the problems.

[747]

bimbo - 2015-10-14 7:59 AM

 

With all respect, but you live in the uk ? solar panels only charge when there is sun .

 

My 100 watt Panel keeps 2 x 110 Ah Leisure batteries and the engine battery topped up throughout the Winter on my driveway.

[laimeduck]

747 - 2015-10-14 4:11 PM

 

bimbo - 2015-10-14 7:59 AM

 

With all respect, but you live in the uk ? solar panels only charge when there is sun .

 

My 100 watt Panel keeps 2 x 110 Ah Leisure batteries and the engine battery topped up throughout the Winter on my driveway.

 

Ditto for me.

[Colin Leake]

We have ours turned on four hours a day from 11am to 3pm on a timer mainly because we have a dehumidifier pluged in inside. Sargent system in out AutoSleeper monitors both batteries to see which one needs charging. If both are OK it puts a maintenance charge into the leisure battery. Been doing this with all our motorhomes for years with no problems.

[Listerdiesel]

I am new to the forum, so hello to all.

 

Our company designs and manufactures battery chargers up to 100kW output, but most are in the 3kW to 12kW range, mainly for railway rolling stock/locomotives and for utitilty standby power and switch tripping purposes.

 

We do not make any consumer products, let's get that out of the way!

 

I have an interest in this thread as we have two vehicles, one is a 3500kg 6-wheel drawbar turntable trailer which we take our show engines to rallies in, plus we live in it while away, and the other is a Mercedes 614D minibus that we are converting to a motorhome.

 

Both have similar arrangements, four solar panels in 2 sets of 2 80W with dual MPPT controllers and sealed batteries. Dual mains chargers are also fitted to act as shore supplies when we have EHU.

 

We have run the trailer on mains while parked outside the house, and the solar was also working. By setting the chargers slightly above the solar threshold we managed to keep everything happy.

 

The Mercedes is similar but everything is bigger, the panels are 100W and the batteries are 225AH GEL types in two sets.

 

In both cases we have split the battery loads between the services on the vehicle. More details on our website if you fancy a read up.

 

Regarding the EHU use, it should not be a problem for any decent bit of electronics to last for 10 years or so, we have kit out in the real world that is getting on for 30 years of continuous operation in sub stations, but what you buy as a consumer and what we build for our customers is very much chalk and cheese.

 

We build for 20 year life in service, whether in continuous use or not. Most consumer equipment is not built for life but rather to sell at a price that makes a decent profit for the manufacturer. Most consumer kit is not rated for continuous use either, read the handbook!

 

Our batteries in the Mercedes have been running on the solar panels since April/May time with no ill effects, no overcharging, no forced gassing out of the pressure vents etc. I'd be more than happy to leave them on, indeed they are, so I haven't bothered with the twin mains chargers yet, they are bought but not installed.

 

We could make a 20-year life consumer charger, but nobody would want to pay for it.

 

Regards,

 

Peter

 

 

 

[Brian Kirby]

Back in the 16th century, a clever chap named Galileo Galilei reasoned that the earth went around the sun, and not, as was then widely believed, that the sun went round the earth. This put him in direct conflict with the Pope and the Jesuits, resulting in him being tried before the inquisition, forced to recant, and placed under house arrest.

 

Relevance? Well. Galileo based his conclusions on his own observations and reasoning, whereas his prosecutors based their case against him on received wisdom and their strongly held religious beliefs. Now, conclusions based upon personal observation have led to many outstanding scientific discoveries - but have also resulted in many false conclusions, sometimes because current knowledge was inadequate, and sometimes because the conclusion was based on false reasoning.

 

My point, with this string, is whether we are seeing the brilliance of a Galileo being rejected merely because, as with his conclusion, it runs counter to established wisdom, or whether we are seeing an example of accurate observations interpreted against inadequate scientific knowledge, or merely being misinterpreted through false reasoning.

 

I confess to having some qualms about some of the claims being made, not because I have any knowledge of electronics, or any knowledge of the underlying science of batteries, but because I seem to see examples of what look to me to be, if not actually false, then insecure, reasoning. For example, all the chargers that are repaired must, logically, first have failed. Reasons for these failures are then logically deduced, unavoidably based on what the owners of the equipment have to say about their use. I see two problems with some of this. First, that the descriptions of how the chargers have been used (abused?) may not be 100% reliable; second that there is no apparent way to determine how many other chargers, of the same type and make, may continue in fault-free service, even under the same regimes of use as those that failed. Or have I missed those bits?

 

So, to me, there is just the tiniest risk that an "all pillar boxes are red, so all red objects are pillar boxes" type of reasoning may have crept in. Not seeking to pick a quarrel with anyone, not to disparage anyone's conclusions, but just a humble seeker after truth in a confusing world. :-D

[747]

Very well explained Brian ........ although I had to read it several times. :D

 

I only have one fact I can contribute to this thread. While in a Motorhome/Caravan Service/Repair Company, I noticed that they had a huge cardboard box in the corner of the Office. An employee came in and removed a Caravan charging unit from the box and remarked "We are getting low again". When I enquired if they got through a lot of them, the answer was "Yes we do, so we buy in bulk". 8-)

 

I'm afraid that I forget which company made them but no doubt someone on here will know.

[aandncaravan]

Brian, I like what you have written. Luckily I have a thick skin and don't feel at all persecuted. I am certainly not in the same intelligence league.

 

Yes we are known for repairing 'Chargers'. But around 40% of our work is fixing units like the EBL 99 or the Reich e-box, Sargent EC500, etc that have fully functional chargers but power distribution issues. For example Mr Smith replaced his 10A fuse to the TV with a 30a one so it didn't blow when his wife unplugged the TV it to use the battery 'Hoover'. Guess what happened to the tracks supplying the power inside the EBL 99?

Or Mr Williams who reversed the battery leads? This blows up the Power Controller (just won't power on) but the Charger is unaffected.

So we do see a lot of chargers that do not need repair as the unit has come in because of another issue. Both good and bad.

 

 

We don't say that running a charger continuously causes it to fail, that is a conclusion others have jumped to. We say it has an impact on the chargers life time, which is very different.

A person who smokes may not die from directly inhaling smoke (i.e. suffocation), but it can make them more susceptible to a Heart Attack

 

There is one primary reason why most chargers that we have seen fail and that is a battery past it's best, exactly as we say on the website.

However, leaving any electronic device on all the time is going to have an impact on it's life.

We also suspect, absolutely no proof whatsoever, that running a charger continuously makes it more susceptible to battery degradation.

Running a charger continuously is not the primary cause of failure, even in the case of the Reich box.

Just to double clarify that : you could run a charger for 20 years non stop, but if you did not stress it with a poor battery it might never fail.

 

I would no more leave my low power LED Television on all the time, even though the handbook says I can, than I would anything else.

There is a lifetime issue with any electronic device, that is supported by the contributor above who manufactures these charger devices.

 

We note that in the above responses where users have sought manufacturer advice, only the CBE has contradicted our claim that the chargers do not switch off. Not one has said they stop using 240v mains power, when the battery is full.

Nor has anyone, really, contradicted our claim that leaving them on is environmentally unfriendly.

 

The manufacturers have allegedly responded to say that they can be left on continuously, even though there is now growing evidence to support that battery life may be shortened. As witnessed by the Victron document. The problem is that many who 'overcharge' their battery may never know they have. Any more than I can say they did.

 

Also consider that the responses have primarily been based on the assumption that the battery is perfect. Some people leave the charger on all the time, specifically because the batteries are getting a bit tired. In these instances the charger may never get to the point of slow charge, i.e. going into 'trickle' mode. The charger will clearly work harder in these instances and consume even more power.

It is fact that a battery starts to deteriorate from the moment it is made, so leaving a Motorhome charger continuously charging a 4 year old battery may generate a very different charger loading than a 2 month old battery.

 

When I posted the thread I expected the ingrained folklore of it being 'an acceptable practice' to dominate.

 

 

Maybe our view is totally wrong.

If so why are there specialist 'battery maintainers' (like the Optimate that do not run continuously often spending 50% of their time without any charge activity) if they are not a good idea?

 

Why do these specialist units have a lower charge voltage (in line with the Victron document) and current than almost all Motorhome battery chargers? The optimate has been around over 20 years and has a huge following amongst Classic Vehicle owners who generally only use the vehicle in the summer months and leave it on a specialist Optimate style battery maintainer through the Winter.

 

In their world the folklore is DON'T leave your battery on a charger, but only use a specilaist battery maintainer that has a lower charge voltage/current and spends some of it's time properly idle. Not continuously in low power 'force feed' mode.

 

 

 

 

[Listerdiesel]

aandncaravan - 2015-10-15 9:27 PM

In their world the folklore is DON'T leave your battery on a charger, but only use a specilaist battery maintainer that has a lower charge voltage/current and spends some of it's time properly idle. Not continuously in low power 'force feed' mode.

 

Not quite sure where this 'Force Feed' term you are using comes from.

 

A decent constant voltage charger will bring the battery voltage up to its set output voltage and hold it there, it doesn't 'force' anything, in most cases the actual current going into the battery is extremely low at this stage, probably below an amp, which is fine for a 110AH battery on a float charge.

 

Remember that a battery will not naturally sit at 13.80V or whatever, it would much prefer to be down near 12.60V or around that figure, so any charge is being used to artificially raise the voltage up and replace the self-discharge losses in the battery.

 

Our 225AH GEL batteries are on continuous charge from the solar panels, but the charge going in is so low that it doesn't register on the display.

 

Some of our substation battery/charger sets have a problem with new lead-acid batteries not taking any maintenance current at all, or less than our charge detection system will show, so we tell the customers to apply the test load for 10 seconds which then shows that the charger is alive and kicking.

 

Peter

 

[StuartO]

aandncaravan - 2015-10-15 9:27 PM

 

.....We note that in the above responses where users have sought manufacturer advice, only the CBE has contradicted our claim that the chargers do not switch off. Not one has said they stop using 240v mains power, when the battery is full.

Nor has anyone, really, contradicted our claim that leaving them on is environmentally unfriendly. ...

 

......Maybe our view is totally wrong. If so why are there specialist 'battery maintainers' (like the Optimate that do not run continuously often spending 50% of their time without any charge activity) if they are not a good idea? ...

 

 

With respect you are beginning to sound like a person who is getting a bit paranoid and determined to stick to his guns regardless - and some of what you are saying is starting to damage your credibility. All that's happening is that rational people are pursuing the discussion by putting questions and presenting alternative views. Don't take it personally.

 

The fact that no one has (so far) bothered to challenge a particular point of yours doesn't prove your point at all. Maybe people just think that point is not worth even responding to. For example leaving the MH plugged into the mains and the charger unit powered up doesn't necessarily mean that significant mains current is being drawn just because 240v is still applied. nor that the planet is being put at risk. I bought a meter device to monitor what my MH was using and it showed that in storage on EHU not much electricity was being used at all. It wasn't using enough electircity to be worth continuing to monitor. I think presenting arguments about saving the planet in this context does you no good at all.

 

A few years ago I kept two motorcycles in an outbuilding over a winter with a purpose-made motorcycle Optimate chargers attached to each, to maintain the batteries, as it said on the boxes I could do. The Optimates were supposed to fully charge and then back off to deliver only a float charge. The float harge state was indicated by a green light. Both batteries were good ones and relatively new but both batteries were ruined by Spring because the electrolyte levels had dropped markedly and exposed the plates. The Optimates must have over charged them. I binned the Optimates, bought new batteries and charged them once per month over winter with a CTEK charger instead, which worked well. I don't understand why these two Optimates failed but clearly they did, perhaps they were part of a bad batch. Even supposedly good stuff can fail sometimes but two at once?

 

On the other hand my Hymer/Schaudt/Exide kit in the MH has worked consistently well for ten years so far, despite being plugged in all the time while in storage. That is presumably part of what it was designed to cope with in service.

[aandncaravan]

About 12 - 15 years ago I bought an Oxford Oximiser, an Optimate copy, for my Motor Bikes and that overcharged my batteries. Several of my friends also had issues with their bike batteries on the Oximiser. There was a bit of bad press at the time.

We all then bought Optimates, I think version 2? No more issues for any of us.

 

I wonder if your 'Optimate' was actually an Oxford Oximiser that was billed at the time as better than the Optimate?

 

 

 

[colin]

Brian Kirby - 2015-10-14 10:49 PM

 

Back in the 16th century, a clever chap named Galileo Galilei reasoned that the earth went around the sun, and not, as was then widely believed, that the sun went round the earth. This put him in direct conflict with the Pope and the Jesuits, resulting in him being tried before the inquisition, forced to recant, and placed under house arrest.

 

 

 

Close but no bananas

;-)

[artheytrate]

I bought a new Harley Davidson Road King Classic in March 2000, which I used an optimate on, When I sold the bike in Oct 2010 it still had the original battery fitted.

 

John.

[kevina]

48 hours ago I switched on my CB516 to give my leisure batteries their monthly top up. The initial charge rate was about 6A into 2 110Ah gel batteries, the next morning the charger had switched off and the batteries had dropped to 13.2v as expected. Once the batteries drop below 13.0v this charger will start up again.

 

After 24 hours I noticed the charger was on again and the voltage was 14.27v, ok. I didn't check again until this evening and found it (still?) on with the batteries at 14.53v and current of less than 0.2A, voltage at charger output was 14.54v. I turned it off of course but wish I'd checked it earlier in the day and was tempted to let it continue and see what happened!

 

The temperature of the batteries is only about 10C so this voltage is just about ok , BUT. This charger is supposed to have a 14.3v output on the gel setting and I'm pretty sure it has no temperature compensation built-in, there is certainly no external temperature sensor let alone on the batteries.

 

So something is not right. I do randomly check it when charging and on the whole it is in the "correct zone", though I think I may have noticed a similar higher than expected reading once before. However, I will be sticking to my normal once a month overnight charge as I don't feel confident leaving it on long term.

 

Kev

[aandncaravan]

Kevina, 14.53v is not a bad charging voltage in normal use for cold, Gel batteries. But it is not the ideal for maintenance/trickle mode, which, as you have already witnessed, can be a near perfect 13.2v on your charger when it is working as it should.

 

As we have already stated above we don't do a lot with the CBE CB516 but from what you report it does match exactly what Robin Hood was saying about the sophistication of the CBE, so he should feel vindicated.

 

Not wanting to sound paranoid or anything, but couldn't a potential charger malfunction on any unit, change from just an inconvenience to quite messy/serious consequences if it did occur unnoticed on long term EHU?

[aandncaravan]

As the above thread suggests, we don't advise a battery is left on long term EHU. Aside from the damage to some charger units, some of the battery manufacturers are becoming aware of this user trend and starting to advise against it.

 

There is now new evidence that while a float charge of 13.8v given out by most chargers is ok for short term maintenance charging, there is growing data to suggest that it is higher than ideal for long term maintenance.

The new Schaudt LRM1218 AGM Solar Regulator has a Float Maintenance charge of just 13.4v, down from the previous modules charge rate of 13.8v, therefore, in our opinion, supporting this new thinking that 13.8v is higher than ideal. See the Schaudt charging voltage table in the document at the end of this page : http://www.aandncaravanservices.co.uk/solar-power.php

 

So to update this thread, if you have a charger that has a maintenance charge of 13.2v - 13.4v, like the CBE 516, it is probably safer to leave it on long term EHU, although we think it isn't ideal.

 

 

We suggest that this new data has implications for Solar charging, which is usually a long term maintenance charge for many, in the same way that long term EHU is?

Maybe any Solar Regulator you fit should also have a maintenance/Float/trickle charge of 13.2 - 13.4v in line with this lower emerging standard?

 

 

The usual 13.8v Solar charger maintenance/float/trickle charge may be the reason why some are reporting 'overcharged' batteries?

 

 

 

[Will H]

With sincere apologies to Brian,

 

Now perhaps you would most kindly explain to an elderly person whose educated years were employed sitting in air raid shelters.

 

What you are saying. ?

 

Will

[aandncaravan]

We have been sent a Technical document on batteries that is apparently a 20 year study, the Author describes it as his life time work.

 

The person who sent it works in the Battery Backup (UPS) industry and writes thus:

 

"Hi Alan, read some of your comments on the adverse effect of long term charging at 13.8v. Such batteries will have life shortened.

The norm for UPS is a float of 13.5v, 2.25v per cell, even at these low levels we suffer dried out and corroded batteries.

Newer systems are using 13.2v float

You will find the attached doc. interesting, especially as I know you are not an AGM man".

 

 

What I found interesting is that the document quotes Battery manufacturers max recommended float voltage is 13.5v, not the 13.8v of many modern Motorhome chargers or Solar Regulators. Plus a comment that new systems are using 13.2v float, such as the systems from Victron Energy as already noted above.

The new Schaudt Solar regulator and the latest version of the Votronic Solar regulator have a 13.4v, or less, Float voltage. Maybe suggesting that Solar chargers with 13.8v float on long term may also be less than ideal from the batteries point?.

 

 

The Technical document quotes surveys with samples of 35,000 cells and over 1,000 installations. It publishes a chart of the reasons batteries fail, which I found particularly interesting.

 

Especially the entry that, of AGM/Gel batteries that failed, 33% did so from 'Drying Out'.

 

When you consider that the AGM/Gel batteries used by these installations are very expensive 20 year life units, not 'High Street' 5 year versions (see the document where this is quoted) that seems to firmly 'kick into touch' another myth that AGM/Gel batteries don't gas off fluid.

 

The chart shows that Grid Corrosion accounts for 86% of Wet Acid failures and almost 60% of AGM/Gel failures.

 

 

I particularly loved the bit,

 

"....the industry is beginning to acknowledge that a 20 year VRLA (AGM and Gel) battery life is unlikely to (be) realized. Recent industry experience indicates that a 4 to 7 year VRLA battery life is more likely".

 

And :

 

"Absorbed Glass Matt-type cells demonstrated a higher failure rate than did gel-type cells.

Representatives of a major battery company recently provided an update regarding VRLA cells’ expected life. Four different VRLA cells were tested, including three different AGM types and one gel-type. It was concluded that 20-year class AGM cells (as quoted by the manufacturer) actually have an expected life of 5 years at 25°C (77°F), dropping to about 3 years at 32°C (90°F)".

 

But that is another discussion altogether.................

 

Full document and Failure chart here : http://www.aandncaravanservices.co.uk/how-does-a-battery-work.php

Tried attaching it but it is too big.

 

Regards from Galileo. *-)

 

 

[Guest pelmetman]

I have a query?.......I have never kept Horace plugged in full time when not in use......just plugging in occasionally when I felt the urge ;-) ........

 

It seems to have worked given that I've only just replaced my batteries for 4th time in 26 years :D .....

 

But.....now that we're full timing, should I leave Horace plugged in full time when onsite, or should I unplug occasionally to let the leisure battery do a bit of work? :-S .......

 

 

 

 

[Robinhood]

pelmetman - 2016-10-04 10:17 PM

 

But.....now that we're full timing, should I leave Horace plugged in full time when onsite, or should I unplug occasionally to let the leisure battery do a bit of work? :-S .......

 

 

....yes B-)

[aandncaravan]

pelmetman - 2016-10-04 10:17 PM

 

I have a query?.......I have never kept Horace plugged in full time when not in use......just plugging in occasionally when I felt the urge ;-) ........

 

It seems to have worked given that I've only just replaced my batteries for 4th time in 26 years :D .....

 

But.....now that we're full timing, should I leave Horace plugged in full time when onsite, or should I unplug occasionally to let the leisure battery do a bit of work? :-S .......

 

 

 

 

REPLY :

 

The less work your battery does the longer it will last.

The issue with Float charging at a higher than ideal voltage only applies if the charger power is getting to the batteries.

If the electrics are being used, in theory, the charger power should be 'siphoned off'.

This is only about the vehicle being long term idle, like when in storage.

 

 

But remember not all Motorhome chargers float at 13.8v, many of the pre 2007 British built Motorhomes (and many Caravans) have a fixed 13.5v 'power supply' rather than an efficient multi stage charger, which it is now shown may not create so much of an issue.

 

 

This page is more up to date than the thread above which has stayed pretty much static since written : http://www.aandncaravanservices.co.uk/ehu-full-time-yes-or-no.php

 

 

[StuartO]

Interesting to come back to this old thread, which I have read through again from the beginning.

 

The issue is whether it safe to leave a MH on an EHU continuously when being stored?

 

We have been given technical reasons why 13.5 volts might be better than 13.8 as a floating voltage and we have been told that different chargers behave differently, as do different batteries.  There have been stories of batteries being ruined when continuously charged and stories of batteries lasting ten years despite being continuously plugged in.

 

It doesn't strike me that there is a credible "right" answer for all MHs.  My Hymer (with a Schaud Electroblok) had no problems plugged in all the time during storage for over ten years and since moving house (where the MH now lives outside and so its solar panels are active) the leisure battery (a new one,purely on age) still seems to just stay fully charged without being plugged in during storage at all.

 

If your MH has a decent charger, leave it plugged in if you like and the floating voltage shouldn't do much harm, even if it is 13.8v.  You are extremely unlikely to use much electricity because of the battery charger.  If you have solar panels and your MH is stored outside, even if you are in UK, you will get something like 14.3 volts from them but only for part of the day so that shouldn't do much harm either.  There is therefore no need to stay plugged in if you have solar panels but you can do so without serious risk if you wish. 

 

If your MH has a poor quality electrical system and/or charger or has poor quality or knackered batteries, it might be a different story.