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Hi, I have two Exide dual purpose 115 amp batteries app 10 months old. Just recently they seem to be running down quicker than normal. I have 300 watts of solar panels and a 25 amp mttp controller which are five years old.

The maximum charge voltage is set at 14.4 volts as per the suppliers advice. I fully understand at this time of year the panels do not produce much. The batteries are never normally allowed to run below 12.1.

I had them on charge for ten hours yesterday final reading 14.4 volts before turning the mains charger off.

Using the Motorhomes onboard charger Elddis Aspire 255 2012.

Then ran the tv and Oyster dish for four hours, pump for the Aldie heating and one LED light the voltage this morning 12.4. About to go away for four or five months around Europe?? Should I be concerned

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Weldted, see this recent Post on Lithium batteries :



Can I say that two factors may have shortened the life of the Exides -

1. The Solar set-up, if it is on full time, rather than just when the batteries actually need charging, they may have been overcharged?


2. 12.1v is very low to drop a battery, most modern battery manufacturers, suggest no more than about 12.3v.

Because your Exides are Dual purpose batteries without any real advanced technology, even 50% DOD is a bit high for optimum life.


The Exides normally have a resting voltage of around 12.8v, higher than a conventional Antimony based battery which is usually around 12.6v. If you look at the chart below your batteries are more akin to the middle/first column, not the conventional column.


Different technology batteries have different resting voltages and therefore operating ranges, so you need to adjust your use to fit the battery you have.


The chart below is published by Yuasa, suggest you ignore most of the charts around which don't acknowledge different voltage ranges for different technologies?

Some of the charts around have such low 'acceptable' discharge voltages, we think they must have been published by Battery retailers to generate more business. Wherever they came from, they don't reflect modern batteries.


If you need to discharge your batteries to low volts, then the Exide Gel range will give you better life, but note that even a specialist Deep Discharge battery like the old G80 will have it's 1,300 (25% DOD) cycle life cut to 700 cycles at 50% DOD and 350 cycles at 80% DOD.


As it says in the Lithium thread Victron Energy manufacture a Long Life Gel with a 4,500 cycle life (25% DOD) that still returns 1,500 cycles (80% DOD) when very Deep Discharged. 2,500 cycles at 50% DOD.

The Life of a Lithium but without the hassle.


It costs, but far less than a Lithium, and works with most modern Motorhome chargers.


They allegedly tolerate a permanent Solar Float charge better than most batteries, but at that cost I wouldn't risk it if it was me.

I would turn off the Solar until the batteries actually need a charge.


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Many thanks for the info, have used this setup on the last set of batteries of the same make and model they lasted three years and still seemed ok in fact passed them on to a friend he is still using them. The van is used for around six months over the October / March period touring France/Spain. When not use stored at a compound with limited mains supply. Insurance require the immobiliser and tracker to be live so panels left on. Batteries are normally kept above 12.4 as panels keep the charge. The 12.1 is the result of turning the panels off. There is a battery mate fitted to trickle charge the engine battery when it is one volt lower than the leisure battery. During the summer storage the maximum charge rate is set at 13.8 only raising it to 14.4 when van is being used. Will get the batteries check or consider different ones. The onboard charger is not adjustable and will bring the voltage up to 14.4 volts so concerned this may not be suitable for some types. So what next?
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Are you sure the Solar regulator only charges at 14.4v when the van is being used? Most Solar regulators obviously shut down when the Sun sets and we have not seen one yet that 'restarts' the next morning where it 'left off' in a 'Trickle'/Float mode.

They all tend to start up at maximum charge rate for a set timer period, typically 1 - 4 hours, even if the battery was fully charged when they 'shutdown' the night before, only dropping to 13.8v after the 'timer' expires. Thereby 'overcharging' the battery.

It is not just the long term 13.8v Float charge that is the issue, but how the Solar charge behaves every day when it first starts up.


I would be surprised if your MPPT regulator behaves differently, unless it is one of the new Votronics? Run through a 'Start-up' test and see what happens?



If your Mains charger, Alternator and Solar regulator are not set up for the 14.7v the Exide AGM's need to perform fully, you might be disappointed with the end result, both real capacity and lifetime? Especially bearing in mind the £460 cost?


Have a read of our AGM battery page : http://www.aandncaravanservices.co.uk/agm-batteries.php


Gel batteries will work with the Alternators 14.4v and maybe give better results with the rest of the set-up, but obviously depends on what charge programs the Solar Regulator supports.? Downside with Gel is the slower 'charge-up' times, but they will most likely out live the AGM's 2 : 1.



The Exide AGM battery data sheet acknowledges that a Motorhome standard Alternator is not the ideal, needing assistance, "to keep the batteries at a full state of charge".


It states :

"The engine alternator usually recharges the battery during driving time. Nevertheless, to keep batteries at a full state of charge, you can undertake complementary recharges by using chargers plugged into the mains during parking time. By using batteries with our “faster recharge” feature (together with efficient chargers), you can reduce the time needed to complete a full recharge by up to 50%".


Never heard that from any other battery manufacturer that the Alternator 'needs help' for optimum AGM battery performance and the first hint ever that AGM are not the ideal 'standard fit'.

Cars have been running around for decades without EHU, Exide say we don't need to plug those in to mains.


If you fit a 14.7v AGM optimised Alternator, that might be different


You will also note that to achieve the stated performance, it makes the point that specialist charges are required - "(together with efficient chargers)" which another Datasheet specifies as being higher power, higher voltage versions than most Motorhomes have, even those motorhomes that have been rolled out with AGM chargers in the last year are not 'up to spec'.






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One other possibility :


The Varta LFD90's are a Silver based technology. Generally Silver batteries tolerate faster charging rates better than most.

In the mid 2000's Ford's car range (and Transit) adopted an intelligent Alternator system to 'save fuel' by faster charging a cold Silver Starter battery at up to 16volts.

They specified their own make Silver technology batteries which lasted well. After market non Silver batteries didn't last more than a couple of years.


You MIGHT find that Varta LFD 90 batteries, at £95 each, tolerate your environment better than almost anything else? Not only does the Silver technology tolerate higher change voltages better, but the Powerframe technology is far more resistant to the internal corrosion that occurs during 'overcharging'.


But that is not a recommendation, as we have never put it to a long term test.


However, at £95 a battery versus £230 each Exide AGM, if the LFD90's only give their best for 18 months it will still work out cheaper than the AGM option.

The LFD90's will work ok with the existing set-up so be at a higher state of charge, effectively more capacity, than the AGM option.


Would still recommend you think about 'managing' the Solar. Or even better ditching the inefficient battery maintainer and moving to a Votronic dual battery Solar Charger with a 13.4v 'trickle' charge.

If you opt for a new Votronic and two Varta LFD90's you would still be financially better off than fitting two short life AGM's?

You will probably see longer Starter Battery life as well.



We don't sell any type of battery, so if you want independent advice on what we have seen works well in a Motorhome, and why, see our Battery Technology page : http://www.aandncaravanservices.co.uk/battery-technology.php




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Many thanks for you in depth information, it is very much appreciated.

I have a Blue Sky 25amp Mppt controller

Solar Boost 2000E.

This was supplied by a German Firm based in Portugat. When fitting it the engineer showed me how to set the maximum charge voltage and how to adjust it. It has to be set when batteries are fully charged in clear sunlight. When the maximum is set at 14.4 even midsummer at midday bright and clear it has never gone above this. As I say this worked fine for three years on the last set. I have had the batteries on the mains for ten hours yesterday and since ten o'clock this morning but they have not gone above 13.7/13.8 normaly they would be at 14.4 by now and the Solar Controller light would be flashing to indicate fully charged.

Sorry about the AGM ones brain block!! Looking at Trojan 31-GEL same size as limited space for them £246.68 only 2kg's heavier than current ones.

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That isn't a bad 'dual battery' Solar regulator.

Out of the box it has a 14.2v main charge voltage with a Float voltage that is a perfect 13.2volts.


It also has a secondary output with a low power charge for the Starter battery that mirrors the main battery Float charge, giving a really healthy 13.2v Starter battery Float charge.

I wonder why they didn't wire that up, as it would be far more efficient and give longer Starter battery life than the 'Battery Master'?


The only downside is that the 'boost charge' timer is, as documented above, for 2 hours every day from when the Sun comes up, even if the battery is fully charged.


Charging any fully charged battery at 14.2v for 2 hours isn't going to be good when 13.8v is already documented as being 'too high'.


However, I am pretty sure that is adjustable down to zero minutes? Have a look in the instructions, assuming it isn't already configured?


If you could set the 'Boost'/Absorption timer to a few minutes, wire in the proper Starter battery charging output and ditch the battery Master, it would be a pretty perfect setup and be one of the few that looks after itself.



That the batteries are taking a long time to charge, yet give back very little, does suggest there might be an issue? The Elddis chargers from that era do tend to be quite weak units (10amp and fixed 13.8v) are you sure yours is :

a) Man enough for the job?.

b) working correctly?

c) allowing enough time, they can take 24hours to charge a big battery bank.



I don't have enough experience of cutting open Trojan's. Not dissected a Trojan Gel at all and only done a few Trojan wet batteries, so not able to give any useful feedback on them.



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Many thanks yet again your input is outstanding. My onboard charger starts off at 14.4 but drops down to around 13.8 not sure how long it takes to drop depends on the state of the batteries. When the regulator was fitted at the time with two 90 watt panels it was their last trading day before Christmas so a bit of a rush job. Possibly explains why the starter battery was not connected. I have since added 3, 40 watt panels to make the most of the roof space they are linked into a junction box on the roof with 4 mm solar cable supplied by them then from the junction box to regulator and then onto the batteries by 6 mm cable of the same spec all connections with h/d crisp terminals. Will look at connecting as you say and am taking the batteries into be checked in the morning, they have a programmable test set up and not just a drop test. I have used the same company for a number of years and found them honest and reliable.

I am very grateful for you time and help in this manner if only more companies would adopt the same level of customer service.

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Have just checked the controller there is no separate output for charging the engine battery, there is only plus and minus for one supply out and one plus and minus for the PV input. The system is not fitted with a battery temp sensor. All the panels vmp are within 0.5 v of each other. The charging set up on this Elddis allows current to be drawn from the engine battery to supplement the leisure battery above a certain voltage, and when the mains charger is on it charges both the engine and the leisure batteries the engine one to a lower voltage. As I said earlier the system has worked fine for the five years I have had the van, bought new it only came with one leisure battery so I stopped that with the two 110 amp one's from my previous van which were two years old and changed them a year later for new ones as we tour for long periods of time over the winter so change batteries at three years old regardless. (Wintertime short days long nights (tv) so don't want to be caught out. But these batteries were bought new December 2016.
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I think I have found your Solar Regulator.

If it is the right one, for a MPPT regulator it is quite crude as it is just a single stage, single battery charger.

It only has a single voltage setting, although adjustable, not the multi voltage stages we have come to expect, but then I note you did say it was five years old and the later versions of it are very different, as we described to you.



That means you can choose a voltage which better maintains the battery long term, like 13.4v, but not charge so quickly OR have a fast charge 14.4v which will degrade the battery over months. But not both.


It seems you have selected 14.4v to fast charge on these batteries?


What I don't understand is how the previous set of batteries lasted 3 years? I also don't understand how the Starter Battery has lasted.

I assume when you changed the batteries 10 months ago the Solar Regulator would have lost all it's settings so needed reprogramming? If so was the previous voltage really at 14.4v as you think or might it have been lower?



We would suggest you either need to put a lot of manual management into the existing regulator, by reprogramming it each day to suit the circumstances, or fit a modern dual battery regulator that has current day thinking on battery life time management? Something like the newer version of the Blue Sky 25a MPPT or a Votronic MPPT.


You might think we talk a load of rubbish, but ask yourself why the latest Motorhome specific Blue Sky 25a MPPT Solar regulator has a low 13.2v Float voltage?

Like this one : http://www.ebay.co.uk/itm/Blue-Sky-25-Amp-12-Volt-SB2512i-HV-MPPT-Solar-Panel-Charge-Controller-/112539315795?_trksid=p2141725.m3641.l6368



I have added the Instruction Manual for the Solar charger I suspect you have, so the basis for the above, to the bottom of this page : http://www.aandncaravanservices.co.uk/solar-panels.php


Let us know if it is not the right one and will look again.



Hopefully I am wrong and your batteries are undamaged.







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One thing I really like about this Forum, is the wealth of knowledge and the willingness to help others using that knowledge. We often get emails from a handful of people I value commenting on our posts, so while my posts and response might be 'from me' there is actually an additional knowledge base behind me. This can result in one of my Posts developing, or even changing, as ideas come in.

Not least our Senior Technician who is not only immensely qualified in electronic repair, but also Electronic design and real world experience on Boats to compliment my Motorhome skills.



We have just had an email from someone on the Forum whose 'Battery skills' are relevant and strong and they have pointed out that the Trojan Gels you are considering, which they have owned in the past and rate, specify a 13.5v Float charge.

They also point out they are not the best for charging/using in warmer climes and a comment in the documentation reinforces this stating :

"(Trojan Gel) Batteries may be utilized at higher temperatures with the understanding that battery life will be reduced by 50% for every 10° C (18° F) increase in operating temperatures over 68° F (20° C)".


I guess your 'Winter 6 month Tour' is more likely to be in Spain than Norway, so maybe another factor to consider?.



Therefore maybe not the best battery you could choose for your set-up, in their opinion. But then this probably applies to many Gel and AGM batteries.




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Hi, far from talking rubbbish I find you knowledge and willingness to help outstanding.

The starter battery is five years old all I did was upgrade it from the standard 2.200 cc to the 3000 cc one.

I religiously turn the charger down to 13.8 when the van is not in use and the Van Bitz battery master has followed my vans since 2003. I note on the Mppt controller you suggested has an automatic equaliser program built in. If this is the case I I do replace the batteries with gel ones will this be ok. As I am now 68 it is unlikely I will change the van again I might as well get it right first time.

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We are no longer Motorhomers but I find Alan's, and others, contributions about batteries and charging regimes interesting, not least because (as soon as SWMBO lets me) I hope to get a boat to help satisfy my craving for aggravation!!


It would take a lot to persuade me to buy anything other than a Varta or Bosch lead acid battery where the battery technology and charging needs are better known and better established.


So well done and many thanks, in particular to Alan who, despite some pretty heavy personal circumstances, continues to pass on his practical and timely experiences to us who struggle to get our heads around all this technogabble so beloved of manufacturers.


It seems to me that so often the theoretical battery capacity and life quoted by makers is very different to the realistic actual usable battery capacity and durability.


Thanks Alan.

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I have looked at the Varta but I could only fit 2 X 90 amp as the 120 is too big, the ones I have at the moment are 110 so would lose quite a bit of capacity. One has to go in the original battery compartment (Elddis) so max is 355 L 178 W 240 H
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Tracker, Thank you, it is because I don't feel so good that I have the excuse to let the Senior Technician and Natalie run everything and I can just play on the Computer!!



Weldted, thank you. Yes if you are replacing the Solar regulator with a late model Motorhome specific regulator (like the new Blue Sky or Votronic) it will work really with any battery as they have charging programs specifically for getting the best from a battery.



If you have already been managing the Solar regulator manually and setting it to 13.8v, then maybe your batteries are not Goosed? have them tested before you go for the very, very good Bosch L series.






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I've got a pair of Exide Dual '142AH' batteries. Same footprint as a 115AH, but much taller.

A year into use, I began to think these were dying, as they used to stay at 12.7V+ for eons without even showing any drop. These days they do drop off, but seem to sit at 12.5/12.4V for ages and ages. They still provide for all my needs close to 2-years down the road. My van is full of gadgets and I run appliances up to 800W off an inverter. I have 200W of solar and a 50A B2B. I never use hookups.


So - I suspect your Exides have quite a bit of life left in them yet.


Remember also not to rely on control panel as a measure of voltage (some are incredibly inaccurate). The meter on the solar controller (an hour after dark) gives a better indication of current SOC. Also note that any SOC vs Voltage figure quoted by a battery manufacturer is after a settling period of an hour or so, and OFF LOAD. Even a modest 1A load can give a distorted figure re the state of charge of the battery. I endeavour not to drop mine below about 12.2V OFF LOAD.



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Perhaps some clarification of what exactly represents a 'cycle' as far as battery use is concerned might help us all, well me anyway, understand it better please?


I used to believe, based on what I was told by an 'expert' many years ago that a cycle was the major discharge and recharge of a battery but that minor use and self discharge did not count as a cycle.


I now think I understand that a 'cycle' is any use of a battery no matter how small and it's subsequent recharge no matter how little, and as such any battery on permanent solar or mains ehu charge will get many such cycles every day which may go some way to explaining why batteries fail so regularly and 12v power is the bane of so many motorhome non ehu users lives?


But, I still don't understand why a car battery can last often 5 years or more given that it often has many start and recharge cyles every day and a motorhome battery often tends not to last anywhere near that long?


Maybe I am wrong but I have always had a mistrust of so called 'leisure' batteries and over the years some of the best and most durale leisure batteries I have had have been secondhand heavy truck starter batteries costing but a fraction of alleged specialist 'leisure' batteries.



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I think the battery manufacturers would do their utmost to avoid defining a cycle! They will also never tell you what a 'cycle' means to them - that way then can claim any old bollox and get away with it!


My take is that a full cycle is a major drain - eg 30% of the batteries capacity used overnight. Putting back that charge moving to a new location and then doing the same again = another cycle.


A cycle is not a brief stop to take in the view while listening to the radio or running a laptop/telle for half an hour - that's a part cycle! - now bigger part is not definable!



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veletron - 2017-10-13 2:07 PM


I think the battery manufacturers would do their utmost to avoid defining a cycle! They will also never tell you what a 'cycle' means to them - that way then can claim any old bollox and get away with it!




Ah - I sense that one of the forum's favourite words - obfuscation - the action of making something obscure, unclear, or unintelligible - is about to rear it's ugly head again!!

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