# Leisure batteries - gel or wet?



## jiwawa (Jun 22, 2007)

You may have noticed wink2 I'm getting a new van.

It's a while away yet but I have the option of:

1. having a 2nd gel battery to join the original 95Ah gel

2. having my own 2x125Ah sealed wet batteries, which are just a year old, transferred (I haven't measured them so let's just assume that they will fit).

I would have a 140W solar panel with a PPPT controller and a battery master in the mix.

I've been trying to find information and have come across the following:

A Gel battery of 110Ah can deliver 88Ah, so 80% efficient

A standard leisure battery of 110Ah can deliver 55Ah, so 50% efficient

Now, I don't know if this 80% and 50% works across the board but if it does then 2x95Ah gels would give 152Ah; and 2x125 wet would give only 125Ah. I presume you're not get anywhere near if you don't want your battery to die but still, there would seem to be more usable power from the gels.

I understand that gels don't last as long as wet batteries but given my existing ones are a year old, combined with the fact that the gels will deliver more, I'm inclined to go with the 2x95Ah gels.

But I would really appreciate your views.


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## listerdiesel (Aug 3, 2012)

Where did you get those battery figures from?

A battery is rated at the 20 hour discharge rate normally, so a 110AH battery will delivery 110AH over a 20 hour period.

"A Gel battery of 110Ah can deliver 88Ah, so 80% efficient
A standard leisure battery of 110Ah can deliver 55Ah, so 50% efficient"

Efficiency is the difference between what you put in and what you take out, you can't use those figures without relating to the delivered AH and how it was calculated.

GEL batteries are just as efficient as wet Lead-Acid batteries but are more sensitive to charge voltages and overdischarge.
Wet Lead-Acid batteries are more suited to situations where they may get over or undercharged, are cheaper and apart from the maintenance factor are a better deal, especially if you buy 'non-motorhome' or 'non-caravan' or 'non-leisure'.

Peter


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## Imbiber (May 11, 2007)

A couple of years ago I subscribed to the research and theories put out by Allan at A and N Caravans. As such I went down the Varta Silver Dynamic route.....and to be honest I have experienced no issues whatsoever and battery recharge time alongside efficiency does seem markedly improved.

It would seem that the industry has now moved on somewhat, however, the principles appear to remain. You can read all about it here: Battery Technology.

I certainly give over some time reading through the link if you haven't already. It may help you in your decision making.


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## Pudsey_Bear (Sep 25, 2008)

I've always gone for lead acid as they tend to be more available so more competition meaning good value and therefore cheap to swap once they do give up the ghost, never had any problems, I get 2 x 125 for around £150 delivered.


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## Mrplodd (Mar 4, 2008)

I'm with Kev, lead acid batteries every time.

Cheap and easily obtained.

Gel MIGHT give you a _little_ bit more BUT are you planning on pushing your leisure batteries that close to thei ultimate limit?? If so invest in another battery has got to be a more sensible option surely???

The link provided by Imbiber makes VERY interesting (and educational) reading !!!!

Andy

P.S. From experience DONT rely on your solar panels to do much more than maintain your LB's at this time of year.


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## WildThingsKev (Dec 29, 2009)

Gel for me but then we are heavy users during our 2 month skiing trips. Our original Banner flooded batteries lasted 3 years including 1 one month ski trip. Our current gels have completed 4 two month ski trips (using up to 40Ah per day) and 4 two month autumn trips without hookup.

Kev


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## listerdiesel (Aug 3, 2012)

The crucial thing with ALL lead-acid battery types is not to let them get overdischarged, and not to let them sit around in a discharged state.

That's where solar power is so useful.

I reckon 100W of panel for 100AH of battery as a minimum, more if you have the space.

Also, make sure that your on-board charging capacity is good enough to punch a decent charge into the batteries if you need to, but getting onto an EHU supply.

We have 26A X 2 in the trailer and 50A X 2 in the Mercedes.

Peter


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## Pudsey_Bear (Sep 25, 2008)

listerdiesel said:


> The crucial thing with ALL lead-acid battery types is not to let them get overdischarged, and not to let them sit around in a discharged state.
> 
> That's where solar power is so useful.
> 
> ...


You know far more than I on this Peter, but I've never had more than 100w of solar with MPPt or less than 375ah of LB, but I have never had a problem we sometimes use a 120w slow cooker, always something on charge as the hab 12v goes off when driving :roll: and we watch TV from around 7 til 10pm and a PVR both 230v via 600w inverted inverter, I've never had it dip below 12v even in winter, I've seen similar advice elsewhere, but I don't get why.


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## MyGalSal (Dec 8, 2008)

Our two 80amp gel batteries are five and a half years old and still going strong. As you know Jean, they get a lot of use! However, have never had lead acid so can't do a comparison.


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## listerdiesel (Aug 3, 2012)

MyGalSal said:


> Our two 80amp gel batteries are five and a half years old and still going strong. As you know Jean, they get a lot of use! However, have never had lead acid so can't do a comparison.


GEL are lead-acid batteries.....

Peter


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## MyGalSal (Dec 8, 2008)

listerdiesel said:


> GEL are lead-acid batteries.....
> 
> Peter


Say what????

Well OK Peter. Wet lead acid.


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## listerdiesel (Aug 3, 2012)

Generically, lead acid batteries are wet vented, wet sealed or 'dry' sealed or VRLA, which stands for Valve Regulated Lead Acid.

Wet batteries of any type are treated as the same, as they have a non-pressure vent system, this normally applies to ALL wet batteries where there is free liquid sloshing about in the battery. Break it open and you'll dump a gallon or so of very nasty sulphuric acid over your shoes.,

GEL batteries have an electrolyte that is 'gellified' and is not a liquid, flooded mat types have a plate separator that is also a fibrous mat that holds the electrolyte and does not allow any free liquid. All VRLA batteries have valves in the battery top that keeps any gases from escaping. 

When charging, all wet batteries will normally vent any gases produced into the atmosphere. Gases are generally produced when the battery approaches or passes the fully charged level, and are a by-product of the breaking down of water into Hydrogen and Oxygen. The gas mixture is explosive.

When charging sealed VRLA batteries, no gases are released and under pressure the gases will recombine into water inside the battery. Only under severe overcharge will the gas production exceed the recombination capacity of the cells/battery and as the pressure rises inside the battery, the vent valves will open and release the gas mixture

Losses in wet cells can be made up by topping the cells up, but sealed batteries cannot be topped up and the water loss will affect the battery's ability to store a charge if allowed to go on.

That is why charging settings are different for sealed batteries compared with wet batteries.

The other condition is thermal runaway, when a sealed battery is overcharged and the extra power going into the battery goes into heat which then melts the plastics of the case, sometimes with spectacular results.

Peter


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## jiwawa (Jun 22, 2007)

listerdiesel said:


> Where did you get those battery figures from?
> 
> Peter


Peter, I got the information when I was doing some investigation - it's from this post of WildThingsKev's from 2015 (post #3 ).

I don't pretend to understand the theory behind it, I just picked up the figures and was asking if they were realistic; if they were, then it was a no-brainer to go for the new gels.



Imbiber said:


> ...It would seem that the industry has now moved on somewhat, however, the principles appear to remain. You can read all about it here: Battery Technology.
> 
> I certainly give over some time reading through the link if you haven't already. It may help you in your decision making.


Thanks Imbiber, I did read the information and I will keep the info in mind for when I next need batteries!



listerdiesel said:


> ...Also, make sure that your on-board charging capacity is good enough to punch a decent charge into the batteries if you need to, but getting onto an EHU supply.
> 
> *We have 26A X 2 in the trailer and 50A X 2 in the Mercedes.*
> 
> Peter


Sorry Peter, I don't know what this means. I've only ever had the ordinary 16A plug for charging onsite - as I guess most people have.

So thank you for all your input.

Can I ask, if the choice was yours between 2 x 125Ah 18-month-old (at the time of changing) wet batteries or 2 x new 95Ah gel, no money involved, which would you choose?


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## Pudsey_Bear (Sep 25, 2008)

2x125ah every time for me even if paying.

As for Peters "26A X 2 in the trailer and 50A X 2 in the Mercedes." his is a 24v system, 26a & 50a are I believe the charging amps, as it would seem low for the capacity, but he'll correct me if that's wrong.


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## listerdiesel (Aug 3, 2012)

Both are for the 12V hab systems, the Mercedes has a 20A charger for the vehicle batteries.

Peter


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## jiwawa (Jun 22, 2007)

Thanks Kev. Are there any other views on: 

Can I ask, if the choice was yours between

2 x 125Ah 18-month-old (at the time of changing) wet batteries or
2 x new 95Ah gel, 

no money involved, which would you choose?


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## listerdiesel (Aug 3, 2012)

Personally I'd use the wet batteries, they would be fine, subject to having been looked after in their previous location.

Peter


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## TeamRienza (Sep 21, 2010)

What are the chances of transferring your wet 125ah batteries now and getting a credit for the 95ah gels to be fitted when the 125s die.

Davy


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## Imbiber (May 11, 2007)

Wet for me too.


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