why gel??

[KeithR]

as batteries now have to be accurate as to the real ah rate, and my 75ah battery is in its dotage, i decided to get a new one, possibly in the 100-110ah range. having read much on this forum (always my first port of call), i chose lead/acid as agm confused me and gel appeared over expensive. however, when checking the housing for the battery size, i noticed that there was a label saying 'gel only'.

would this be purely because there is no obvious outlet for gassing, or something more technical tht has gone over my head??

i am aware that maintainance free lead acid gas (much?), do gel not gas at all ?(agm?). the battery goes under a lounge seat.

remembering my army days in radio apc's and lorries, we had lots of batteries but dont remember ever worrying about gassing, or having vents???.a bit long, but i dont want to spend £250 on gel if i can get away with £70 on lead/acid. tight yorkie you see.

[Clive]

There are two possible reasons for requiring GEL batteries.

1 As you suggested. A sealed GEL battery is unlikely under normal operational circumstances to gas.

2 The charger may be set to suit GEL batteries. If a wet electrolyte battery were fitted it could overcharge and gas excessively.

 

Options

1 AGM batteries are frequently treated like and perform similarly to GEL batteries so consider them an option - and expensive option though.

 

2 If the charger can be set to suit WET electrolyte batteries then you will get more effective ampere hours in your limited space for less cash. But you must either use batteries that have a gas collecting manifold and a connection for a venting pipe (that you could pass through a hole in the floor) or have a battery with special reformation cell caps that convert the gasses back into water and drop it back into the cell.

 

John Wickersham did a very good article in the July MMM on batteries and its worth a read.

 

Take care

 

Clive

 

[Klyne]

I don't know if this is of any use http://www.sterling-power.com/support-faq-2.htm Its mainly to do with a marine environment but I suppose there are similarities.

 

David

[Brambles]

Gel has a lot of advantages, one is it can withstand much deeper discharges than a wet flooded or AGM.

Bit like a lot of things, battery types are not all born the same, there are good gel battreries and bad gel batteries not really suitable for Leisure use.

 

Clive has discussed the reasons for gel re venting and charge voltage although there are some leisure batteries which will cope with the same charging regime, but just take longer to charge as current is limited when charging a gel to a lower level.

 

Initially calcium technology was used on gel and AGM batteries but now flooded use the technology increasing the charge voltage required. A gel is normally charged at 14.4 volts max, and 1st thing to do is check the specifications and parameters of your charger.

 

(Tell us what you have and I am sure someone will find the specs for you.)

 

Something not always apparent to battery users is capacity is not always what it first seems and people often are fixated on getting maximum quoted Ahours for their money. There is supposed to be a level playing field for quoting battery capacity but don't believe it. The large manufacurers pushed for standard methods for specifying to level the playing fields as so many smaller manufacturers, suppliers and importers where basically just quoting what they liked ...and some still do.

 

When comparing Gel with flooded you can get a reasonable 90 Ah flooded battery which can cope with discharges to 60% and still give a good cycle life....thats 54Ah available power.

Then there is a 110 Ah which can cope with a good cycle life ( similar to the 90 Ah) with a depth of discharge of 50%. I make that 55 Ah usuable power.

Now take a 80 Ah gel I looked at recently for someone on these forums, it can cope with 80% discharge and exceed both the 90Ah and 110 Ah for battery cycle life by far. It actually not really 80 Ah, its 75Ah in teh same language which is another story, but 75% of 75Ah is 56Ah and will way outperform the cycle life of the 1st two.

 

So they are really 54, 55, and 56 Ah available capacity and if you look at the fall off in capacity over their life the gel is twice as good and so twice the price.

 

So take a look at the Varta 90AH leisure full calcium technology, the varta 110 Ah Hybrid flooded and the Exide Gel G80. Which is also a Sonnenschein SL75 or better known as a GF 12065 Y.

I have picked these three batteries bacause they all give similar performance under normal heavy use per £ and have good protection against deep discharge should they be abused occassionally.

The Exide ( sonnenschein) gel can actaully be completely flattened and as long as it is recharged after a few weeks will recover although there will be some capacity loss...the others will not cope with this abuse Although the Varta 90Ah (and the 80 Ah in the series) will cope with 80% dod occsaaionally.

 

So there is a lot going for gel if it is a quality gel battery with a high spec. You pay twice as much, but it shoud last twice as long if looked after, but I think my money if you have been happy with the 75Ah you have is to go for a full calcium flooded and fit a vent pipe to it to the outside world, if your charger is suitable.

 

If you are wanting a total fit and forget and do not want to check fluid levels periodically , then the gel is the way to go.

 

The above is all a bit of a generalisation though and every Motorhomer uses the batteries in different ways and conditions and this can make a massive difference to choice of batteries and every choice has its own set of compromises. Some have solar panels, others need very low self discharge which the gel has, or maybe a full calcium flooded which is also excellant and has extremely low water consumtion is good enough ( you can get two flooded for the cost of a gel and hence get twice the life, or indeed fit both in parallel and have oodles more power and 3 or 4 times the life if never using the exta power and never topping up, and for others the Hybrid Calcium is fine with a slightly higher self discharge and water consumption....all swings and roundabouts and very confusing, not to mention physical size is usually the dictating factor and what will fit in the box.

 

So after all the tome above, KISS, keep in simple, will a G80 gel meet your requirements and are you happy to pay what it costs - its a darn good battery. Or, is more budget conscious go for a quality flooded and fit a vent but check your charging regime.

 

Another alternative if you are very light user of power is a cheap and cheerful 85Ah such as Numax, but do not expect the same cycle life, but if you are a very light user of power then natural aging for a battery even when not being used means it the best value option as cycle life is over taken by aging from just sitting there.

 

AGM is very similar to gel, they are also sealed and operate under slight pressure to reduce water consumption. They do not cope with as deep a disharge as gel, and have many disadvantages, one being they can not dissipate as much heat when charging or being disharged fast so in High ambient temperatiues care is needed. The reason is they are what are known as electrolyte starved. The glass mat is saturated with acid and there is no spare acid as a reserve and voids can exist between the mat and the case so heat transfer is not so great and plates get warmer.

If over charged and gassing does occur in a AGM it wil heal, in a gel a void is created and will not heal so is bad news but should not happen but can if being charged from an alternator from a deep discharge, so no revving of the engine when charging from a deep discharge overnight and moving away in morning - keep engine speed low for the 1st 30 mins or so.

but AGM tend to be cheaper than gel with somewhat very similar charateristics.

 

 

edit - just spelling mistakes.

 

[Brambles]

Klyne - 2010-06-21 10:19 PM

 

I don't know if this is of any use http://www.sterling-power.com/support-faq-2.htm Its mainly to do with a marine environment but I suppose there are similarities.

 

David

 

I used to quote this link quite lot but unfortuately it is out of date now and not entirely true, although a lot of truth in it. It is more true if talking about fairly run of the mill consumer quality budget type batteries.

Some good information in the link, but would like to see some parts rewritten.

 

[KeithR]

thanks guys, a lot to digest there!

i looked at the stirling-power link, and what i saw there was that gel does gas, so that would bring me back to what seems to be the consensus here, lead acid is still king. i thought these were now totally maintainance free and in truth i havent touched my car battery, ever (it has just died after 7 years). of course, common sense tells me that if a battery gasses, it does need a refill?? is the gassing of one battery enough of a problem to require outside venting? perhaps i need to look more at the gas recycle lead acid cos when im away for 2-3 months, i really dont want to have to check and top up my batteries *-) *-)

[colin]

KeithR - 2010-06-22 6:01 AM

is the gassing of one battery enough of a problem to require outside venting?

 

As other members on this forum have found out, if you get a problem with the battery (and the leisure batteries often get problems) then definately.

[Brambles]

I did say the link was not entirely true and was out of date.

You have just highlighted one such inaccuracy in saying gel does Gas.

 

When gel was 1st developed they were basically a lead antimony battery and to stop them gasing you used a lower charge voltage and much slower charge. The Gel moved on and used Calcium technology which raised the charge voltage and reduced the gassing by being valve regulated which bascally is they are sealed with a safety valve and operate under slight pressure. so now gel used a higher voltage. Using the correct charging regime (gel setting on you charger (unless it is an ancient one) the gel will not gas. (Then flooded caught up and also used calcium and the charge voltage for them overtook the gel. Now you get silver added to batteries which can make the charge voltage even higher.

Gel batteries are designed for many different applications, standby, emergency power, cyclic applications and so on. They all have different characteristics and different charging conditions. You need to pick the right gel battery and that is one which will cope with alternator charging and the G80 is one such beast amongst many others.

 

The sterling write up badly needs updating.

 

 

[Brian Kirby]

One thing to consider, is how much you really use your battery.  If, as you say, the present one is in its dotage - which I assume means showing signs of failure, you are probably getting a lot less capacity from it than it's nominal capacity, even allowing for Jon's (Brambles) revelations about what Ah you can extract for a given nominal capacity when new. 

I assume the existing battery is a gel, in view of that notice, so you may only have been getting about 60Ah when it was new - if you pushed it.  However, heavily discharging batteries shortens their lives so if yours has lasted, say five years or so, you won't have stressed it that much.  If this is roughly true, there seems to me little to be gained from increasing capacity, unless you propose changing your pattern of use to one that will make higher demands on the battery.

If the charger is switchable for gel and flooded types, and if you can arrange safe venting, you could increase capacity with the cheaper flooded battery/batteries, providing you don't discharge them much beyond 50%.  For that, with your (apparent) present pattern of use, about 120Ah should be OK - but may not be that much cheaper than just replacing the one 75Ah gel type you already have like for like.

Do remember to check the physical size of the battery as well, as they are not standard sizes even within the same type.

As a rough guide to the suitability/quality of what you may get, look at the weight.  For the same capacity (but check how that is expressed, it should be at the 20 hour rate, or C20, for a leisure battery), the heavier battery is likely to be the better one.

[KeithR]

brian, the battery is 6 years old, and hasnt failed but it does appear to take longer to charge, and appears to lose power quicker (although its not been tested recently in the field). although i use aires and free camping wherever i can, i havent been a heavy power user, so perhaps a greater capacity is a wasteage, especially as a modern 85ah battery should give 85ah, whilst my old 85ah would have given a good deal less. so venting is my problem, as i have a horror of drilling holes in my pride and joy! (i use a lot of velcro!!!!). my van is an 04 adria coral, so i imagine the ecb will be changeable to lead acid, so perhaps an 85/100ah lead acid with return channeling for the gas is my answer??? of course, there is limited space in the battery chamber so size is important ( no matter what any one tells you!!!). would anyone disagree (within your knowledge of my needs and your knowledge of reality!). any recommended brands?? thanks to all

[Brambles]

Can you give details of your existing battery please, make/model. Also your charger details, make and model, and the max size battery you can fit . length, width and height. I am guessing width will be 175 (or 171ish).

Is there a restriction on polarity, in other words which battery terminal is positive. Some batteries have the poles reversed and can be a pain if leads to not reach and need extending.

[Brian Kirby]

KeithR - 2010-06-22 10:15 PM brian, the battery is 6 years old, and hasnt failed but it does appear to take longer to charge, and appears to lose power quicker (although its not been tested recently in the field). although i use aires and free camping wherever i can, i havent been a heavy power user, so perhaps a greater capacity is a wasteage, especially as a modern 85ah battery should give 85ah, whilst my old 85ah would have given a good deal less. so venting is my problem, as i have a horror of drilling holes in my pride and joy! (i use a lot of velcro!!!!). my van is an 04 adria coral, so i imagine the ecb will be changeable to lead acid, so perhaps an 85/100ah lead acid with return channeling for the gas is my answer??? of course, there is limited space in the battery chamber so size is important ( no matter what any one tells you!!!). would anyone disagree (within your knowledge of my needs and your knowledge of reality!). any recommended brands?? thanks to all

I think there is perhaps a little confusion, which is far from surprising, as this is one of the most confusing subjects I've tried to get my head around for years!  First, they are all lead acid.  Gel batteries merely have a gelling agent added to the electrolyte - which brings various advantages and disadvantages.  Flooded batteries use the traditional liquid electrolyte, which has to be topped up from time to time, and gases when being charged.

I think I'm being fair if I say no 85Ah battery will give you 85 Ah.  If it is rated at 85Ah, at 20hour, or C20, rate, all that means is that if fully charged and then discharged at a constant 4.25A, it will take 20 hours to run the battery completely flat.  You do not want to do this, as it drastically reduces the life of the battery!

Some batteries are designed for relatively deep discharging, hence Jon's comment above about the Exide gel that can be discharged to 80% without damage.  That gives you 68Ah of useful capacity without too much loss of life.  However, that too is relative, so that if that battery were never discharged below 60% (only 51Ah used) it would last far longer that if regularly discharged to 80%.

Flooded leisure batteries generally are less tolerant of such deep discharging, so it is better not to discharge them so heavily, hence Jon's comment above regarding limiting these to about 50% discharge.  An 85Ah flooded battery would thus only give you a usable 42.5Ah.  They are also generally less tolerant of being left discharged, so need to be re-charged soon after use, but they are cheaper to buy Ah for Ah, though not so much cheaper when their reduced effective capacity, or potentially shorter life, is taken into account.  So, to get 51Ah out, you would need, say 110Ah flooded, to get the same useful capacity as the 85Ah gel above.

The flooded battery must be vented to air to prevent the hydrogen released by charging from accumulating.  I'm not sure what you mean by return channelling, but if you are thinking of a venting arrangement, the vent required is a quite small diameter plastic pipe direct to air.  It should be kept as short as possible, and it must not discharge into the van.

[KeithR]

brambles, i will get the info you asked for. i did have it written somewhere but god knows where!

brian, yes, i guess the more info i get the more confused i get (very worrying for my future education!). i think perhaps im confusing a system whereby the evaporated liquid is returned, so the battery doesnt need topping up. but still gasses. am i getting there? (^)

its beginning to look like i need to spend a lot, or drill a hole :-S

[KeithR]

the control is a schaudt electroblock ebl 208s, this does have the option of gel or lead.

the battery is Length 33cm (can go up to 37) x width 172mm x height 21cm (up to 23cm). all the cabling disappears underneath, but i dont know if there is an outlet which will allow venting.

sorry brian, i had taken the info on board, when i say lead acid and gel l mean wet cel or gel. im renown for using terminology that confuses people. i have my own planet (lol)

[Brian Kirby]

KeithR - 2010-06-23 6:49 AM ...........brian, yes, i guess the more info i get the more confused i get (very worrying for my future education!). i think perhaps im confusing a system whereby the evaporated liquid is returned, so the battery doesnt need topping up. but still gasses. am i getting there? (^) its beginning to look like i need to spend a lot, or drill a hole :-S

That's fine.  I think they are just called sealed lead acid batteries (which is also what the gel ones are) or, if I've understood properly, more correctly "valve regulated lead acid", or VRLA, batteries.  Their drawback is that although they don't need venting, they do benefit from occasional topping up, which then breaks the seals.

Again, if I've understood properly, the seal is imperfect so in hot conditions, or if charged at a high rate, electrolyte is lost.  To compensate they have a deeper fill initially, anticipating the working losses, but will eventually fail due to low electrolyte unless the caps are prized off and the level reinstated.  Honestly, this whole business is an endless merry-go-round: as soon as one problem is averted, another pops into its place!

The simple, cheap, solution is greater capacity, so that you don't discharge it too deeply, vented, flooded, lead acid.  My own conclusion, for what it is worth, was that there was little real advantage in the intermediate stages between this and the most expensive version, the sealed gel lead acid battery.

The former, due to larger capacity and hence size, will take more space and weigh more, which might be significant for your van, and will need periodic - though not continual - topping up, but should be cheaper even if you double the capacity which, if I were going that route, I think I would - by installing two batteries at about 85-100Ah each.  That way you get a genuine benefit in usable capacity and consequently don't work the batteries too hard - so they last better.  You should get quite a bit of change from £200 even buying the highest quality batteries.

Or simply replace what you have like for like, it has served you well for 6 years, so you must be kind to it :-) and there is no reason to think a straight replacement would do any worse - unless you intend changing your pattern of use.  It will cost you a bit over £200, but will not involve any loss in space or weight gain, and will not need venting or topping up.  Simplest overall, but not cheapest.

However, if you answer Jon's questions, he or Clive will give excellent advice on what to go for, probably right down to make and model!

[KeithR]

thanks brian, you are pointing me steadily towards spending my money! :'( but perhaps you are right, my useage will not change so i can get another 6 years without effort. however, i will wait and see what jon and clive come up with.

strangely, my battery has no markings on it at all? brand x?

8-)

[Brambles]

Hi Keith,

Have no forgotten about you - just very busy just now.

I will come back with a post shortly...just checking some battery numbers.

Jon.

[Brambles]

Take a look at the Tayna website - www.tayna.co.uk who are battrery suppliers ....

For flooded look at Varta

Varta numbers 956002 (type Din 95602) 80 Ah

and 957052 90Ah.

 

For budget Numax cvx range. they are sealed flooded but should still be vented. Theyare made by AtlasBX who are Korean and a repyable OEn vehicle manufacter supplier of car batteries. Also branded Lucas and Exrider although that name may have ben dropped now. They are budget batteries but should serve you well if a light user or are looked after and kept charged up. Numax also do a range of VRLA batteries AGM and gel, again budget brands imported by Manbat, and again cannot cope with being abused.

 

For Gel I suggest Exide or Sonnenshein. The G80 is identical to the Sonnenshein GF 12065 Y. I am looking for a larger one which will fit in which is just as good quality... also thinking Haze many have a suitabe battery like the HZY12-110. Its also got 500 cycles or there abouts at 100% discharge. There are not many gels whch can cope with 100% discharge which are a suitable size. Plenty about £20 cheaper but I feel if paying £200 odds for a battery what is 10% cost to get an extremely higher cycle life.

 

I am not convinced your gel is only 75Ah, are you sure about this as the size indicates it might be larger closer to 100 Ah, or is there any possibility it is an AGM not a gel?

There are a few other batteries I would like to recommend but they are all too tall for you.

 

 

 

 

[KeithR]

jon, all i know about my battery is that it is ( i assume) the standard fitted battery by adria ( in an 04 coral 650).

the literature i have states that the vehicle comes with an 85ah battery (no mention of type), and the sticker in the battery compartment saying use gel. i will go and check it out again though. i may also check the adria website and see if it mentions supplied batteries. after this i should be very knowlegeable, but i bet im not !!! :-(

[Brambles]

OK, getting somewhere, I belive it is a TAB 75Ah gel. I am checking out.

 

Any way TAB batteries are Tovarna Akumulatorskih Baterij d.d. in Slovenia.

I am now trying to find more information. My cross reference for the TAB 75Ah is the Exide G80 but may not be physically the same.

 

I am not sure TAB still exist, they had a big fire in 2005 I think. I also have abelgium address for TAB but cannot find any website. EDIT.

Scrub this, they still do seem to exist.

http://www.tab.si/