How does a Leisure battery work - Not the way you probably think?

[aandncaravan]

I have had a lot of battery emails lately, many of which talk of elderly batteries. The symptoms of the issues they are describing clearly point to a battery past it's best.

 

When it comes to Motorhome Leisure batteries there is so much conflicting advice on how they work, much of it based on Starter batteries which are used completely differently, it is no surprise people don't appreciate the issues.

 

I have therefore updated the webpage to explain how a Leisure battery works. This is specific to Motorhome and Caravan usage, not Starter batteries. I think it presents a very different battery expiry scenario to that which most believe is the case.

 

Did you know batteries rarely ever 'Fail', they are murdered?

Actually, it is usually manslaughter because in most cases the owner doesn't realise what they are doing.

 

 

 

First of all a battery doesn't generally suddenly 'Fail', it deteriorates slowly over a period of time, gradually losing capacity until it's capacity falls below the industry definition for an acceptable battery.

 

 

Each time a battery is charged and discharged (a charge/discharge cycle) a little bit of the battery capacity is lost, this applies to all Lead Acid batteries : Wet, Gel and AGM.

So a battery eventually loses capacity until it becomes 'Exhausted', when only 80% capacity remains.

The industry regard a battery as having reached End Of Life(EOL) at this point.

Even though it may hold it's charge and perform normally in all other respects, it will have the capacity of a much smaller battery.

This gradual deterioration is typified when you hear someone say, "the batteries used to last 3 days off grid but now I only get two days".

 

 

A battery normally only 'fails' if used beyond this 'Exhausted' point.

For example, continued use of the battery until 'structural' failure occurs, like Paste shedding (causing shorting and faster self discharge), excess corrosion, Plate warping, Antimony poisoning etc.

 

Trying to keep it going beyond the industries definition of EOL, is when issues occur.

 

 

For example on each discharge, a typical 100Ah quality wet battery might lose 0.2Ah so drops to 99.8Ah capacity when discharged down to 50% DOD. So by the time 100 cycles have been used, the battery may be down to 80Ah capacity.

By 200 cycles, it may be the equivalent of a 60Ah battery, with just 10Ah available if it is discharged no more than the recommended maximum 50% DOD. I.e ensuring at least 50% of the batteries rated capacity remains, or 50AH remaining charge.

Clearly taking 40Ah out of a battery that is down to only 60Ah capacity (just 10Ah 'real' capacity remaining) is going to have significantly greater impact and more likely to create a catastrophic failure.

 

 

The above examples are not exact and scientificly accurate, as many factors affect how a battery performs, but it does provide a good guide.

This loss of capacity is impacted by several factors, Primarily : battery chemistry, quality, technology, temperature and usage

 

 

This next bit is our own theory where so many owners report the battery, "suddenly failing."

Once a battery gets below 80%, further degradation is accelerated, purely because the owner is used to drawing 50Ah from a 100Ah battery, except now they are drawing 50Ah from an '80Ah' battery which amounts to a much greater Depth Of Discharge.

In a very short space of time the battery is down to 65Ah 'real' capacity, so the drawing of the same 50Ah they are used to draw is more likely to cause accelerated damage.

 

However, regardless of 'our theory' a document that we publish later in the webpage, states, on page 3/13 :

"A reduction to 80% of the rated capacity is usually defined as the end of life for a lead-acid battery.

Below 80%, the rate of battery deterioration accelerates, and it is more prone to sudden failure resulting from a mechanical shock or a high discharge rate. Note that even under ideal conditions, a battery is expected to eventually wear out".

 

 

Different technology batteries lose capacity at different rates, but just as relevant, in our experience, is the quality of a battery.

From all the work we did in cutting open all types and makes of battery in 2012 and 2013 to see how they had fared in use, it was clear that budget batteries deteriorated much faster. They also had a greater tendancy to suffer early 'Failure'. For example, in the 'budgets', Corrosion of the Plates becomes a serious issue within a few months of heavy use.

 

The general trend is for many people to continue using batteries beyond EOL, until they show signs of failing. Any battery showing any signs of actual failure is almost always well beyond EOL.

 

 

Sorry to labour the point above on 'EOL' versus 'Failure', but the depths of destruction that the users of Leisure batteries sometimes take them to before they regard them as 'failed', is very different to the industry definition of EOL.

 

 

So why is this relevant to A and N Caravan Services?

 

Charging systems are designed to cope with batteries within the industry 'fit for purpose window', not a battery with disintegrating Plates that are taken beyond any limits the manufacturer ever imagined.

 

We are asked all the time why a Mains Charger/Alternator can't cope with a 'poor' battery, when in their mind 'poor' doesn't mean a 110Ah battery that still has 82Ah left, but one that has warped/shorted Plates, excessive Corrosion and less than 10Ah capacity remaining.

 

See the webpage for a lot more info and the documents that support what we say : http://www.aandncaravanservices.co.uk/how-does-a-battery-work.php

 

At the bottom of the webpage can be found a graph, from the battery manufacturer, that shows how the capacity drops off as it is used.

 

You can see that any battery that has been used to any extent, will be very difficult to describe as a 'good battery' if it is 5 years old.

If it older than the warranty, it is most likely past EOL so get it tested. Remember to fully charge it and leave it two weeks to settle before testing.

 

Some Gel batteries have a longer life, they cost double the best wet batteries so should do, therefore 5 - 6 years to EOL is typical. But they are never going to be of their best after that time if they have received typical use. If in doubt test them. See the bottom of the Battery technology page on ways to do this : http://www.aandncaravanservices.co.uk/battery-technology.php

 

The graph has also been added below, but is clearer on the webpage

 

 

Please don't ask

 

 

 

 

[vindiboy]

In other words, when it is dead it is dead Hee Hee.

[Brian Kirby]

One might almost say, use it, and lose it! :-)

[laimeduck]

Allan hi 

Hopefully not a silly question.

We spend all our time on sites on EHU so rarely use the 2 leisure batteries at all. The installed solar panel keeps the batteries topped up, or the built in EHU charger.

So the number of "cycles" is minimal. (or is that an incorrect assumption?)

How does that affect the life/longevity?

[aandncaravan]

laimeduck - 2018-04-08 7:32 PMAllan hi 

Hopefully not a silly question.

We spend all our time on sites on EHU so rarely use the 2 leisure batteries at all. The installed solar panel keeps the batteries topped up, or the built in EHU charger.

So the number of "cycles" is minimal. (or is that an incorrect assumption?)

How does that affect the life/longevity?

Yes the number of 'cycles' you use will be minimal and where you do use the batteries you probably only use a small amount of power before recharging the battery, effectively shallow cycles. Typically, a Wet acid battery will deliver over a thousand cycles when shallow discharged to 20% Depth Of Discharge (DOD). but little more than 100 cycles if you deep discharge them to, say, 50% Depth Of Discharge (DOD).So your battery use should deliver thousands of 'cycles'.However, a battery deteriorates from more than just cyclic use.I would guess that your greatest risk to long battery life is probably the Solar?

[Aethelric]

Excellent post. It ties in pretty well with what I have discovered by experience over the last four years. I bought a Banner leisure battery four years ago and have just replaced it. The capacity did seem to go down quite fast in the last six months or so.

It has never been discharged very far but it has been discharged a little lots of times. (the van gets used all year round).

I've wrote a little about our experiences with the van power system if anyone is interested.

 

http://photo-electric.com/motorhome_electric_1.shtml

[keninpalamos]

I will soon be back in the sunny UK & will need to reconnect the engine battery on my Mercedes Vito 1998 diesel campervan that has been stored inside for 4-5 months. I know the battery is past it’s best and will replace it with a Varta LFD 90 if I can fit it under the front passenger seat. The “leisure” battery will be replaced with the same which is under the drivers seat. Are the Varta LFD batteries suitable for both engine and leisure use?

[aandncaravan]

A wet acid Car Starter battery is generally designed to do very little work.

All it does is start the engine, these days that takes less than a second, and the Alternator takes over to charge it back up and supply all the power required by the lights, wipers, etc.

They are rarely idle for more than a few days before being 'topped up' with a charge, so they can last 10 years.

 

 

A Motorhome Starter battery is often used very differently, it can stand idle for weeks, being slowly drained down by the Alarm, immobiliser, Tracker, Stereo, etc.

By the time it gets it's 'top up' charge, the batteries can be as low as 50% discharged.

Therefore they are often used a bit more like a leisure battery than a typical Car wet Starter battery.

 

 

So a Starter battery that also 'Deep Cycles' should last a lot longer.

The Dual purpose Varta LFD90 has a CCA of 1,000 cranking amps, better than many dedicated Starter batteries, yet it also handles deeper discharges.

It also performs better than most other batteries when the temperatures drop to freezing or climb to those found in Morocco.

 

In freezing conditions, a 2 year old Varta LFD90 Powerframe battery will outperform any other Starter battery the same age, because it won't have suffered the corrosion found in almost all conventional batteries that robs so much power when the conditions become extreme.

 

Because the Starter LFD90 will do so little work, but the Leisure battery probably get a hard time, swapping the batteries around after 3 - 4 years will extend the usability of the Leisure battery significantly.

 

 

The above doesn't apply to all Leisure batteries being used as Starter batteries, only the Varta/Bosch Powerframe architecture which is unique.

For example an Exide G80/ES900 has less than half the Starting power, around 400 cranking amps, and will have a very short life as a Starter battery, despite it costing twice as much.

 

Keninpalamos, I know you are already aware of most of the above, but explaining it in greater detail for other readers.

 

[keninpalamos]

Not at all. I just had a vague recollection of someone posting the interchangeability of the LFD units. It was proberbly Allen. Knowing my luck the seat boxes will be to small :-D

[davidmac]

Hi a little off topic but, I have got 2 LFD90's being delivered today, 1 hab, 1 starter and will fit them over the weekend. When swoping the hab battery over is it best to cover over the solar panel to avoid any problems with live wires?

Regards David

[aandncaravan]

If you don't have a fuse you can remove between the Solar Panel and the regulator, then yes cover the Solar Panel to be safe

This applies not just to Habitation batteries but the Starter as well on a twin battery bank Solar Regulator.

 

 

 

[zeddykay]

The detail of this thread defeats my simple mind. However, I have a question. My leisure battery is the original supplied with my vehicle registered in 2006. Should I replace it now? I have never had a problem with it so far!

[PJay]

zeddykay - 2018-04-14 9:53 PM

 

The detail of this thread defeats my simple mind. However, I have a question. My leisure battery is the original supplied with my vehicle registered in 2006. Should I replace it now? I have never had a problem with it so far!

 

We have a 2006 van, and our original battery "exploded" in the compartment. a few years ago now, so I would definitely change it for peace of mind 12 years is a long time for a battery , and if it does give up, tt is bound to be at an "inconvenient " moment

PJay

 

PS just got back (not in van) from Yorkshire Dales, Had some good weather as well!

 

[zeddykay]

Thanks for that, what you say makes very good sense to me. Anybody recommend a particular battery?wehave a Devon conversion panel van.

PS We do occasionally get good weather up in Yorkshire, but don't tell everybody or it will get too crowded!

[aandncaravan]

zeddykay - 2018-04-14 9:53 PM

 

The detail of this thread defeats my simple mind. However, I have a question. My leisure battery is the original supplied with my vehicle registered in 2006. Should I replace it now? I have never had a problem with it so far!

 

How about this simpler version :

 

A battery loses a little bit of capacity each time it is discharged/charged, that applies to all Lead Acid battery types Wet, Gel or AGM.

So any battery that has had typical use and is more than 3 years old, might hold it's charge but won't be anywhere near decent capacity. A 110Ah budget battery is most likely to have no more than 65Ah left at 3 years.

So long as it has not suffered any serious physical issues, it might hold a charge and appear normal, just be equivalent to a small battery in terms of the power you can use. When the 50% DOD 'usable power' equivalent of a 110Ah battery is 55Ah, a depleted capacity of 60Ah means you don't have any real capacity left.

Unless of course you take it below 50% DOD, which is when the serious damage starts.

 

 

The best battery for the money, we think, is the Bosch L5 or Varta LFD90 Powerframe, the same battery from Johnson Controls, just different labels.

 

1. It doesn't self discharge. Left on the bench in the Garage for 6 months it won't drop a volt.

2. It doesn't lose any fluid so not just labelled 'maintenance free', but truly zero fluid loss.

3. It doesn't Gas.

4. It doesn't corrode internally so performs at it's best right to End Of Life.

5. It can have 70% better electrical flow than other Lead Acid batteries, including Gel and AGM.

6. It charges faster than any of it's peers, up to twice as fast as some Gel batteries.

7. It has higher efficiency, up to 30% greater than the worst performing, meaning that any Solar set-up can harvest 30% more usable power. For comparison, using a tired budget battery can be similar to driving around with a blanket over half the Solar panel versus using a new Varta LFD 90.

8. It costs just £95 from Tayna Batteries.

9. It has a higher initial capacity than most other batteries. many FULLY CHARGED batteries only have 85% capacity when new. This slowly increases to 100% as the battery is charged/discharged a few times. One battery we know of takes 50 cycles of use to reach it's 100Ah on the label. The Varta LFD90 we tested recently had 93% capacity from new so not only holds onto it's capacity better to EOL, but starts off with more real capacity than a budget.

10. It doesn't suffer from thermal runaway like Gel and, especially AGM, can. Therefore, battery explosion isn't likely. That, and it's zero gas architecture, makes it the safest battery for installation inside a Motorhome.

11. They work well with all existing Motorhome and Caravan charging systems. Unlike Gel and AGM which require specialist chargers.

12. They have better capacity/power delivery at low temperatures than most batteries and tolerate the temperatures of Spain in Summer without deteriorating like most other batteries. Especially better at this than Gel and AGM batteries. In extreme temperature conditions a Powerframe battery has been shown to last more than twice as long as a conventional battery. For a battery costing only £10 more than a 'budget' that is real value.

13. The Silver technology they use suggests they will tolerate overcharging better than any other battery in their class.

14. Obviously such an efficient battery is going to place a lighter load on your charging systems and the entire electrical architecture inside a Motorhome or Caravan.

15.It also makes the perfect Motorhome Starter battery.

16. Please don't torture one with a big Inverter. They are nice batteries, be kind to them and they will be nice to you.

 

For £95, a really cracking battery, thanks to the unique, patented technology inside.

Tayna or Battery Megastore are both good suppliers of freshly manufactured Vartas.

 

 

[Dickybeau]

I'm finding this discussion really helpful. I have a 3 year old 80AH leisure battery and want a bit more capacity to increase my chances of existing off grid for longer than a night or 2 since I will be using Aires and Stellplatz on my trip. I'm thinking about fitting 2 LFD 60 or 75 batteries largely because I also need to balance extra capacity with a need to manage my van weight. I read quite a lot on the aandncaravan website and your advice here. If I am correct, I need to balance everything including starter battery within a 200ah load? (EBL99 from 2015). Although I will be running 2 smaller batteries, the load on each cycle will be better for the batteries.

 

I was considering adding a solar panel but now I'm not so sure. From the advice here it looks like the extra cycling isn't great for battery life and EHU every few days will be sufficient to keep me topped up. Not every Aire has power and I want to revisit some places from previous trips that I couldn't stop on.

 

I'm not a big tv watcher but we run 2 iPads and a Mifi unit, put the fridge and hot water on gas occasionally watch DVD when the weather is and have a couple of li ion battery chargers that I recharge when driving to cover iPhones and readers. Showers and dish washing are our main electrical use beyond that. Wild camping in Scotland requires more heat, light and General power use.

[plwsm2000]

Dickybeau - 2018-04-19 9:08 AM

 

I was considering adding a solar panel but now I'm not so sure. From the advice here it looks like the extra cycling isn't great for battery life and EHU every few days will be sufficient to keep me topped up. Not every Aire has power and I want to revisit some places from previous trips that I couldn't stop on.

 

Although it may not be clear if solar vs. constant EHU is good/bad for your battery over the winter period (daily discharge /recharge cycles with solar vs. constant float charge on EHU), I don't think there is any doubt of the advantage in solar in typical usage.

In my case, we use about 4Ahr per night for some lights, pump, fridge etc. and with solar and a bit of sun, the battery is back to 100% by 11am. For the rest of the day, the pump, fridge, phone charging is "free" (no battery drain). If we didn't have solar, we would be using another 4-5Ahr from the battery during the day so over 3 days, about 24-30Ahr.

You will get better life out of the battery with these levels of %DOD even though the number of cycles will be greater with solar (3 cycles at 5% are a lot better for your battery than 1 cycle at 30%). Obviously the above only applies if you are stationary for a few days and there is even a small amount of sun.

[aandncaravan]

"If I am correct, I need to balance everything including starter battery within a 200ah load? (EBL99 from 2015). Although I will be running 2 smaller batteries, the load on each cycle will be better for the batteries".

 

 

Yes we would advise that you balance the load to all the charging systems of the vehicle, not just the EBL99 mains charger unit.

If you had an older vehicle with a low power Alternator, that needs to be considered as well. Clearly a 90Amp Alternator that is already coping with 70amps of 'Base' vehicle (ECU, Injectors, Lights, wipers, air con fans, etc.) is going to be working pretty hard supplying another 40 amps (max) charging for two 90Ah batteries, plus 17amps for a 12v Fridge.

 

In your case, your later vehicle will have a higher power Alternator so unlikely to be an issue, but should be considered.

 

As to the 18a mains charger, yes you do need to think about the load in terms of both the Habitation batteries and the Starter battery, but two LFD90's, or 75's, should be fine.

 

The usual rule is that a charger will support 10 times the current output converted to AH, so 18A x 10 = 180Ah max battery bank size.

However, this 'rule' is from the days when old fashioned conventional wet batteries dominated, newer technology batteries don't necessarily place the same load so, the 'rule' is a guide only.

 

For example one quality AGM battery manufacturer suggests anything less than double the usual current charge can shorten life of the batteries. Concorde suggest a 20amp charger per 100Ah battery, 40amps per 200Ah, etc. or battery lifetime will suffer.

 

The opposite applies to Bosch L5/Varta LFD Powerframe batteries as they place a much lighter load on the charger, so stretching the limits isn't an issue, so long as you understand you are stretching the limits and act accordingly.

For example be more careful about the depth to which you discharge the Powerframe's, we suggest no more than 50% Depth Of Discharge/12.3v.

See the attached chart and use the VRLA column for a guide to the discharge levels for Powerframe batteries.

 

 

I would guess that from your 'power usage' profile the DVD might be the biggest consumer of power so, maybe try and be frugal with it's use when not on EHU?

I would also suggest that "a couple of li ion battery chargers" plus iPads could also be significant power users, so maybe try not to connect them to 12v except when driving and the Alternator is supplying the charge?

 

 

I am not a big fan of Solar power so not the best person to advise. When you really want lots of Solar power is during the deep Winter, when it's value is severely limited (typically around 4Ah a day for a 100w panel), and when you don't need Solar Power for the lights and heating is when it's at the most abundant, up to 75Ah a day.

Solar works well for some, but as you surmise the cycling impact on the batteries can be significant, resulting in higher running costs than most expect.

 

And of course that doesn't take into account the impact of long term charging of a battery by Solar that is already fully charged?

If you look at this FAQ from Banner : https://www.bannerbatterien.com/en-gb/Support/FAQ

You will see it says you must remove the Banner Bull battery from the charger once fully charged -

 

"In order to obtain the maximum service life from your battery, please ensure complete separation from the on-board supply when the vehicle is not in use (>7 days)".

 

That was in a section on long term Float charging, yet it still said turn off the charger, quite a good indication that the impact will not be beneficial if you ignore it.

 

Most advocates of Solar tend to only quote the mid summer figures, when mid winter figures are very different.

For example, just moving the same Solar Panel from Spain to the North of Scotland can drop Solar power production by a 1/3rd.

See the chart on here that shows how Solar production varies by up to 30%, just within the UK : http://www.aandncaravanservices.co.uk/solar-panels.php

 

If you intend to holiday in Scotland, outside the optimum Solar months, you might find Solar isn't the best.

 

 

 

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[Matrix Meanderer]

Fully support Allan's analysis and excellent work to better inform the motorhome world about batteries.

 

Our last Lucas AGM habitation battery (installed by the dealer - don't ask!) lasted 32 months.

 

I've now got a Bosch L5013 90 Ah Powerframe battery sitting quietly in the habitation area. I expect it will last at least four years and hopefully five.

 

Thanks to Allan for his advice and to Tayna Batteries who sent the new battery to me in Benicassim, Spain for only £15 carriage. It arrived in perfect condition despite the long journey :-D

 

 

[Dickybeau]

Thanks for that input. Since I live in Scotland I'm not overly endowed with sunshine. My house came with solar for hot water and I still need gas or electric top up most of the year. While it is different from extracting electricity from panels it gives me a clue about whether investment is worth it for me. In summer I do t need it..

2x 75 batteries it is. What weight of cable? And does the cable to each pole need to be the same length? I saw something about cable spec in my journey through the topic but can't find it again when I need it.

[aandncaravan]

If you have an EBL 99, then Schaudt specify thicker, better quality cable than most so just stick with the same.

 

You are aiming for exactly the same resistance for both batteries so ideally the same thickness of cable and the same lengths.

 

By taking the Positive cable to one battery and the negative to the other battery, the lengths of cables between the two batteries, positive to positive and negative to negative, becomes less relevant.

 

Suggest you ensure the battery retailer knows you want a matched pair of batteries and they should supply you with batteries from the same batch.

 

One of the threads, I think on here, the OP reported that they didn't do this and the retailer supplied one battery almost a year older than the other.

I have tried a search but can't find it.

:$ *-) >:-) :D

 

Sorry about the Emoticons, but my 7 year old wanted them added.

 

B-)