# Battery Life



## Philippft (Feb 16, 2008)

This is one for you battery experts out there.

My understanding is that leisure battery life is determined by the number of cycles it can perform?

If this is so, what actaualy constitues a cycle and is there a way of establishing how many cycles a battery is capable of undertaking.

If a battery is fully charged after loosing 20% of it's total charge does this count as one cycle?

Is it possible to establish how many cycles a fully charged batter has undertaken in the past!

Over to you!

Regards,
Philip.


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## pieterv (Feb 3, 2009)

The deeper the discharge the less cycles the battery will be capable of. A battery that can do 500 cycles with a discharge to 50%, will be able to do more if it is discharged less in each cycle.

So, number of cycles in itself doesn't mean much unless the depth of discharge is defined. And you can only compare different batteries if they specify the number of cycles to the same depth of discharge.

Pieter


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## Philippft (Feb 16, 2008)

Thanks Peterv. Do you know what percentage of discharge needs to take place to constitute a cycle ?


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## BillCreer (Jan 23, 2010)

Philippft said:


> Thanks Peterv. Do you know what percentage of discharge needs to take place to constitute a cycle ?


1%


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## Stanner (Aug 17, 2006)

BillCreer said:


> Philippft said:
> 
> 
> > Thanks Peterv. Do you know what percentage of discharge needs to take place to constitute a cycle ?
> ...


Or perhaps "more than" 1%.

Most batteries I've seen seem to quote ?? cycles at 50% - but 50% isn't 50% of the fully charged voltage, it's actually something like 10.5-11volts.

PS

"I think." :?


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## denisl (Mar 16, 2011)

It is difficult to find precise figures on this but I have always understood that a deep cycle is going to 50% discharge or greater, and a deep cycle battery should be able to go to 80% discharge.

I don't know if there are figures for a leisure battery (which as far as know is not deep cycle).

If a non-deep cycle battery is discharged too far, chemistry changes within the battery can stop any recharge.

As stated above, the deeper the discharge, the more that cycle will shorten the life of a battery, Also, the longer the battery stays at a low state of charge, the more the battery's life will be shortened.


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## denisl (Mar 16, 2011)

Stanner - I can't agree with your figures. I understand a voltage of 11.5 volts on a resting battery represents an approximate state discharge of 80%.

10.5 volts represents approx 100% discharge


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## Philippft (Feb 16, 2008)

I thought a leisure battery was a deep discharge battery! 


I have done some searching on various web sites since posting my enquiry and found a brilliant two page document from the camping and caravan club which I shall attempt to attach. 

It answers almost all of my questions; 

In short, never let your battery discharge below 20% 0f it's capacity 12.5 Volts. Fully charges battery =12.7 V. 50% charged battery 12.2 V. and 11.8 V. indicates a dead battery.


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## pieterv (Feb 3, 2009)

Philippft said:


> In short, never let your battery discharge below 20% 0f it's capacity 12.5 Volts. Fully charges battery =12.7 V. 50% charged battery 12.2 V. and 11.8 V. indicates a dead battery.


Exactely, the 50% or 80% is a percentage of the capacity in Ah, not of the voltage!

To use the voltage as an indication of state of charge bear in mind that the battery has to have been at rest for a good number of hours, i.e. no charge (so won't work in the daytime if you have a solar panel) or discharge. So, it is not very practical on a day to day basis, but will work if you check after a night (where you haven't flushed the toilet in the middle of the night, and there isn't a solar panel that will raise the voltage once day breaks).


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## Philippft (Feb 16, 2008)

pieterv said:


> Philippft said:
> 
> 
> > In short, never let your battery discharge below 20% 0f it's capacity 12.5 Volts. Fully charges battery =12.7 V. 50% charged battery 12.2 V. and 11.8 V. indicates a dead battery.
> ...


Thanks again Pete. Is there another method of determining battery condition other than the above or acid strenght ! Using a volt meter seems to be the most recommended method.

Philip.


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## Bill_H (Feb 18, 2011)

BillCreer said:


> Philippft said:
> 
> 
> > Thanks Peterv. Do you know what percentage of discharge needs to take place to constitute a cycle ?
> ...


 I thought a lead-acid battery would lose 1% of it's charge overnight (i.e. flat after 100 days of non-use), so if that represents 1 cycle, you would expect your '500 cycles' battery to last around 2 years before it needed replacing, even if the vehicle was run every day.
Most vehicle batteries are running clocks, alarms etc. and are slowly draining whenever the ignition is off, so even a 1000-cycle battery would last less than 4 years if a cycle is 1% discharge.
I've read some threads on here complaining that batteries are going flat after only 2-3 weeks in storage, which would seem to indicate a 5% a day discharge rate.
I've just had to replace the battery on my car, it lasted 9 years (3,285 cycles), including many week-long periods without use, and my connect van battery is still going strong after 7 years (2,500 cycles).
Just turning the ignition key and activating the starter motor is discharging the battery to some extent.


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## BillCreer (Jan 23, 2010)

Bill_H said:


> BillCreer said:
> 
> 
> > Philippft said:
> ...


I was just making the point, as someone had already stated, that as there were so many variables no meaningful number could be given that would apply to all batteries.


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## pieterv (Feb 3, 2009)

Bill_H said:


> BillCreer said:
> 
> 
> > Philippft said:
> ...


Yes, but a "cycle" that only discharges a small percentage of the total capacity does much lesss to reduce the life of a battery than a deeper discharge. As an example, a battery that is rated to 500 cycles at 50% DoD, might last many thousands of cycles at a 10% DoD.

Philip, battery voltage and density of acid are the two means of determining state of charge that I am aware of. Note that they don't tell you the overall condition of the battery. Both acid and voltage can tell you a battery is fully charged, but not if it has lost most of it's capacity over the years (so "fully charged" doesn't mean 100% of it's original capacity).

With starter batteries you can see how good they still are by a voltage drop test. They draw a large current and use the voltage drop as an indication of the state of the battery (big voltage drop = poor battery). This is not recommended for leisure batteries though, as they are not meant to give large currents. Instead you can drain the battery by putting a small load on (like a few Amps) and monitor the voltage. Stop when it has dropped below 12V (but don't go too far). Multiplying the number of hours you have drawn the current by that current (Ixt) gives you the capacity in Ah.

Don't do this too often as this is a very deep discharge cycle, and will make the battery deteriorate. Also make sure to fully charge the battery immediately afterwards, as leaving it deeply discharged would do further damage.

Pieter


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## BillCreer (Jan 23, 2010)

pieterv said:


> Bill_H said:
> 
> 
> > BillCreer said:
> ...


My brain hurts.


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## airstream (Jan 7, 2009)

*Information TV*

Hi,
Chrles Stirling has a few slots on UK Boating -- Information TV on Sky
He is showing the types,construction etc of lead acid batteries in use within the leisure industry
As owner of Stirling Power Products he has great knowledge and forthright views on the bul**hit resellers of "leisure" batteries and the unrealistic claims and guarantees
On for the next few weeks 
worth a watch
Regards Ray


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## mikkidee (Jun 19, 2009)

Well I think after reading this thread my question is probably answered, but I'll ask anyway.

I have had my leisure batteries on charge for 24hrs. Before I switched off the charger the display panel was reading 13.7, when switched off the reading went down to 12.5. So I geuss you are going to say they are knackered. They are 2 110 amp hour batteries.

Mike


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## mikkidee (Jun 19, 2009)

Well I think after reading this thread my question is probably answered, but I'll ask anyway.

I have had my leisure batteries on charge for 24hrs. Before I switched off the charger the display panel was reading 13.7, when switched off the reading went down to 12.5. So I geuss you are going to say they are knackered. They are 2 110 amp hour batteries.

Mike


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## Philippft (Feb 16, 2008)

Hi Peter, 
Do you remember this thread about battery life! 

I thought i would try an experiment and disconnect the external power to my motorhome and measure a load from the leisure batteries to see how well they perform and i am now somewhat confused. 

The motorhome is new this year and has two new leisure batteries 110 Ah which are maintained by an on board charging system. 

I disconnected the electrical supply and measured the batteries which initially gave a reading of 13.4 V and after rest for 30 minutes or so read 12.8 (fully charged) I have put a load of 6 amps onto the batteries and after 1 hour the reading is 12 volts with the 6 amps load still on. 

Does this make sense! My intention was to leave this load on for several hours and then remove the 6 amp load and see what voltage reading i have after the batter had several hours rest. 

Regards, 
Philip


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## spatz1 (May 19, 2011)

Philippft said:


> Hi Peter,
> Do you remember this thread about battery life!
> 
> I thought i would try an experiment and disconnect the external power to my motorhome and measure a load from the leisure batteries to see how well they perform and i am now somewhat confused.
> ...


my batteries are new, i charge them to 14.7v and they will do 5a for 12 hours before dropping below 12 v....(done test)

A heavy use overnight after a charge and they will give a healthy 12.78v in the morning....

i think the problem is you re not able to fully charge them with the van charger if only reaching 13.4v

( i bought a solar controler capable of sending a pulse to get rid of any sulphur build up and further protect the batteries)


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## Philippft (Feb 16, 2008)

Thanks for your comment. My charger is working fine it charges at 14.4V for both Leisure and Cab battery. this then drops down to 13.4 which i believe to be the float charge.

When i disconnect the power the batteries are showing 13.4V which then drops to 12.8V a fully charged battery.

This is the first time i have tried this test ! The batteries are i belive in a as new condition as they have always been maintained in a fully charged condition from new.

I'm not a battery expert but I have just looked at the battery readings again another hour and it has not dropped any further, still holding at 12V. When i switch of the load the voltage of the batteries increases immediatly ?

I will continue to run and monitor them with the 6 Amp load on, then rest them and see what happens.

I think that as soon as you put a load on the battery the voltage indication drops but this does not mean they have lost a significant part of their capacity, I Think you find this out after resting them and taking a further measurement which will show there true condition.

What i'm not sure of is how to ensure i do not discharge them too much as technically the voltage reading indicates they are almost fully discharged, when i am certain they are not.

According to my calculations, if the batteries are fully charged i should have 220 AH and if i run 6 Amp through them i should be able to run at this rate for 10 hours and only discharge the batteries by 20% (I read you should never discharge your batteries beyond 80% of their capacity). 

So, if this holds true and my calculations are correct, I should get a reading of 12.5V after using for 10 hours and resting for ? hours.

Does this make sense!


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## VenturerDave (Oct 2, 2009)

My understanding is that you will not get a true reading of the battery voltage while the load is still on.

You will need to disconnect it, allow the battery to 'rest' for a while then take the voltage. By doing this it will have recovered to its true level, or it should have done.


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## spatz1 (May 19, 2011)

not fully charged at 14.4v...

mine takes a further 3 hours and some 35 Ah before it trips to float...


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## Philippft (Feb 16, 2008)

spatz1 said:


> not fully charged at 14.4v...
> 
> mine takes a further 3 hours and some 35 Ah before it trips to float...


Fully charged at 12.8. see previous attchment for further information


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## Annsman (Nov 8, 2007)

Crikey, now I'm confused! I'm getting ready to change my leisure batteries, 2X110 Amp Elecsol, that are just over three & a half years old. They've had some heavy use over this time and don't seem to be holding their charge for very long. 

We have a couple of solar panels and these seem to have "hidden" the deteriating battery life during the Autumn in Spain, but now the Winter here is showing them to be failing, or so I thought from their readings.

Thing is, I've read on here that a reading of 11.8 means the batteries are dead, yet ours have shown a reading of 11.00 and still been powering the vans life support systems. Infact it got to 10.00 before the telly went off! So now I'm wondering whether they are failing afterall and we just had a heavy night!


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## pieterv (Feb 3, 2009)

VenturerDave said:


> My understanding is that you will not get a true reading of the battery voltage while the load is still on.
> 
> You will need to disconnect it, allow the battery to 'rest' for a while then take the voltage. By doing this it will have recovered to its true level, or it should have done.


Exactely.

For day to day monitoring of your usage you can get battery monitors, which will tell you how many Ah you have used. Some newer vans will have this as standard.


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## splitwagon (Oct 20, 2009)

Don't be confused!. The confusing factor is measuring the voltage only tells part of what you need to know...



Annsman said:


> I'm getting ready to change my leisure batteries, 2X110 Amp Elecsol, that are just over three & a half years old. They've had some heavy use over this time and don't seem to be holding their charge for very long.


Some people consider the life span of a standard leisure battery used in average conditions to be about 3-years. If you get more than this, you are doing well in my opinion.



Annsman said:


> We have a couple of solar panels and these seem to have "hidden" the deteriating battery life during the Autumn in Spain, but now the Winter here is showing them to be failing, or so I thought from their readings.


Your logic is correct, the solar panels would have put out a relatively high voltage, so reading voltage alone will give you a false picture of how the batteries are doing.



Annsman said:


> Thing is, I've read on here that a reading of 11.8 means the batteries are dead, yet ours have shown a reading of 11.00 and still been powering the vans life support systems. Infact it got to 10.00 before the telly went off! So now I'm wondering whether they are failing afterall and we just had a heavy night!


A battery will continue to give out some energy until only a few volts (say down to 8 or 9 volts or even lower), so if the telly is not too fussy, it would work down to 10V as you say.

What is happening though (and where values around 11.8V get bandied about) is the battery is being permanently damaged at these voltages levels - that is to say its ability to re-charge to its 'as new' capacity will be progressively reduced.

I can see two options -

a) Say your batteries have done a good job and send them for recycling

b) Do a load test (not just a voltage reading), prove they are expired, and send them for recycling!

Cheers

Split
~~~~~


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## Rosbotham (May 4, 2008)

Annsman said:


> Crikey, now I'm confused! I'm getting ready to change my leisure batteries, 2X110 Amp Elecsol, that are just over three & a half years old. They've had some heavy use over this time and don't seem to be holding their charge for very long.


Do you still have the receipt / warranty card? If they're failing, aren't they supposed to be on a 5 year warranty?


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## Annsman (Nov 8, 2007)

I'll get on to my dealer about the warranty bit, but I suspect that as good as they have been with me since we bought the van I don't think they'll swap the batteries now! But I can try I suppose.

Either way I'll check out some different makes and so on. Any recommendations?


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