# Lead Acid verses Gel Acid



## blackbirdbiker (Mar 12, 2007)

I am about to uprate the amount of power availability from my leisure batteries, at the moment I have 2 Gel batteries in parallel rated at 85 AH. 
Fine, all I need to do is add another 85AH in parallel with the other two to make it up to 255 AH brilliant just what I need. But the price of a Gell battery is approx £150 +?? where the normal battery is only £40!!!
I will fit the normal lead acid in parallel with the 2 gel batteries, and of corse I have checked my charging unit to be able to handel all three, and that I will also make sure that it will have a permanent vent to the outside of the van.
I have been an electronic engineer for the past 30 years and I cannot see any reason why doing this could cause a problem, but why have I read in another article that mixing the two types is a no no, our supplier of parts agrees with me, there isn't a reason for not mixing!!!! apart from venting.

Any thoughts please.

Keith.


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## sallytrafic (Jan 17, 2006)

If you are putting a gel in parallel with a normal wet cell and using the same charger you will have to set a lower highest stage voltage than is optimum for the wet battery otherwise you will gas the gel one.

Two problems 

If you set a lower voltage for the wet battery than optimum it will never charge fully leading to sulphation at the negative plate.. 

The internal resistance of the two types will be different hence charge and discharge currents will be different and the batteries will soon be at different charge states the only way to normalise the charge states will be either to charge the batteries separately to full charge, or discharge the batteries to a very low level periodically neither will be convenient and the latter will shorten its life. There also will be circulating currents.


Rgards frank


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## olley (May 1, 2005)

Hi Keith as I understand it they have different internal resistances and won't charge or discharge properly, shortening the lives of both types.

Olley


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## 88927 (May 10, 2005)

Hi Keith
Don't know if you are going to Newark show this coming weekend but there will be a chap there who supplied us with batteries at the Shire Horse show last weekend. Can't remember the name of his company but he had gel batteries for a lot less than the £150 you quoted, worth a visit?
I can get his info if you need it, he is based near Liecester......

Keith


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## blackbirdbiker (Mar 12, 2007)

Hi Frank and Olley,

Thanks for the quick reply, the reason I asked this question is because Smart Energy advised me that there is not any problems with what I intended to do. However my battery charger has a switch position for both types of battery, so I started to look for differences between the two types. As yet I have not measured the voltage on the two settings.

Will report later,

Keith.


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## sallytrafic (Jan 17, 2006)

blackbirdbiker said:


> Hi Frank and Olley,
> 
> Thanks for the quick reply, the reason I asked this question is because Smart Energy advised me that there is not any problems with what I intended to do. However my battery charger has a switch position for both types of battery, so I started to look for differences between the two types. As yet I have not measured the voltage on the two settings.
> 
> ...


Hi Keith the charging assuming a 3 or 4 stage charger may only show a difference on the relatively short highest stage which should be 14.4 for the wet and I can't remember the equiv figure for gel  but different manufacturer's will have their own advice on that.

Regards Frank


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## DABurleigh (May 9, 2005)

"I have been an electronic engineer for the past 30 years and I cannot see any reason why doing this could cause a problem,"

Okaaaayyyyyy. Um, the reason is Ohm's Law.

Dave


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## Scotjimland (May 23, 2005)

Mixing old and new, gel or otherwise, is not going to give satisfactory performance. 

My solution would 'ditch' the gels and buy 3 new 85ah 'bog standard' lead acid batteries, cost around a £100 and for a few extra pounds,(space permitting) upsize to 120ah ones. 

Gels have their uses, mobility chairs, golf carts etc but IMO a waste of money in a motorhome.


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## sallytrafic (Jan 17, 2006)

DABurleigh said:


> "I have been an electronic engineer for the past 30 years and I cannot see any reason why doing this could cause a problem,"
> 
> Okaaaayyyyyy. Um, the reason is Ohm's Law.
> 
> Dave


Well that and both of Kirchoff's really 

Regards Frank


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## mangothemadmonk (Aug 6, 2006)

Why do you need 255 AH? I know we all require more and more power for our "gadgets" but gadgets mean more power, power means more batteries, batteries means more weight, weight means more diesel........

Why not look at the ways you are using power and swap for low wattage/drain accessories.

Johnny F


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## spykal (May 9, 2005)

blackbirdbiker said:


> Thanks for the quick reply, the reason I asked this question is because Smart Energy advised me that there is not any problems with what I intended to do.


Hi Keith

I agree with the advice given already... Scotjimland summed it up nicely. What I would like to know is who is "Smart Energy" .... have they got a website I , because just out of curiosity I would like to see who or what they are. IMHO I would be wary of any advice from them if they have said there are "no problems" in your plan... unless they know something we have missed.. the advice is opposite to to all the other battery mixing advice I have ever come across.

Mike


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## blackbirdbiker (Mar 12, 2007)

Thanks for all the suggestions

I hope I haven't opened a can of worms here  I bought my van second hand when it was a year old. The extra internal wiring and the two Gel batteries was obviously added by the last owner!!! I have rewired to my satisfaction, ( as there was a 1.5 volt drop from fuse to sockets) and I have now decided to change the batteries to 2 x 110Ah as the price is only £47 each as compared to £150 + for one Gel priced by my supplier. Also I'm not sure of the state of the 2 Gels that I already have.

Why change.......well, we tend to not go on sites that have hook up, so we may be parked upto five days without mains charging, the LCD TV will start losing its' sound first, as this circuit takes more current than the two florescent tubes and their inverter/s in the LCD panel, this does happen.
Therefore this is the reason why I need to up the available power. After reading up a little on the battery make up I'm not at all surprised by the opinions from those who have answered, many thanks to you.

See below,
Keith. 

Lead acid batteries should never be run flat. The maximum recommended discharge is 75% of the total. This means that the battery should have a minimum of 25% of charge remaining when it is put on charge.

Lead acid batteries once filled with electrolyte, should always be regularly charged even if they are not in use. When left idle a filled battery will self discharge because of its own internal resistance. left long enough a battery can go completely flat without ever having been put into service. Storage also affects the rate of discharge. A battery should never be stored directly on the ground and especially not on concrete. The best storage method is wooden pallets which do not conduct or allow damp paths and do allow good air circulation. During storage, most manufacturers recommend a freshening charge once every two months or so.


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## spykal (May 9, 2005)

blackbirdbiker said:


> Snip:- Thanks for all the suggestions
> I hope I haven't opened a can of worms here


Hi Keith

No way... it is exactly this sort of thread that makes a forum like this work so well... so thanks for the thread.

and you new "plan" sounds spot on.

mike


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## blackbirdbiker (Mar 12, 2007)

Hi Mike,

Smart Energy was a link from one of the sites that I visited, and for the life of me??/ I can't find it now...I'll keep trying and let you know.

Cheers,

Keith.


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## mangothemadmonk (Aug 6, 2006)

Hi Keith was it this one on Smart Cells....

www.efoy.de/index.php?option=com_content&task=view&id=13&Itemid=56&lang=en

Or at

www.transleisure.co.uk/product_list.asp?cat1=21&cat2=19

Johnny F


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## Spacerunner (Mar 18, 2006)

. A battery should never be stored directly on the ground and especially not on concrete. 




Is this really true!! 8O


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## spykal (May 9, 2005)

Spacerunner said:


> . A battery should never be stored directly on the ground and especially not on concrete.
> Is this really true!! 8O


It was true once when battery cases were made out of pourous materials , tar lined wooden boxes for example :roll: ...... how do I know this little known fact? Well the truth is I read it at a website that lists some of the better info about batteries from a well respected expert on the subject, William Darden.... here is a link to his Battery Myths <<

Mike

P.S. if you want to see the rest of this well written site about batteries go HERE <<


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## DABurleigh (May 9, 2005)

"Well that and both of Kirchoff's really"

Frank,

Never having been one to forego winding up engineers such as yourself - please don't take this personally, only Guardian jibes should you do that for  - then even I presumed engineers appreciated energy and charge conservation, so didn't wish to point out the obvious 

Dave


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## mark_2cv (Sep 13, 2006)

>A battery should never be stored directly on the ground and especially not on concrete

Not sure that's still the case. I think that really only applied to cast rubber cased batteries of old.

How do others get on with gel batteries as a matter of interest? my employer the RNLI went through a phase of fitting them to lifeboats until they found they would die with no warning....

Mark.


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## DABurleigh (May 9, 2005)

Well at least lifeboats can invert and self-right ....


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## Borisd0 (Jan 3, 2006)

For what's worth.

I came across an a mini Gel Gel test in the Caravan Club Magazine(Feb 07)

Their Best Buy was a Elecsol 90/110. It seemed to a have a few things in its favour over other Gel Cells. RRP £93, 5yr Guarantee, Uses Carbon Fibre (light).

http://www.elecsol.com/html/products.html

Geoff.


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## mark_2cv (Sep 13, 2006)

Well at least lifeboats can invert and self-right ....

Well in theory Dave :lol:


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## sallytrafic (Jan 17, 2006)

DABurleigh said:


> "Well that and both of Kirchoff's really"
> 
> Frank,
> 
> ...


So you mentioned ohms law to the electronics engineer :lol:

FRank


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## DABurleigh (May 9, 2005)

Yes - the difference in battery internal resistance is the largest reason by far why batteries should come from the same batch when charged together. This is simply Ohm's Law, yet didn't seem to be appreciated.

Dave


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## 101368 (Oct 12, 2006)

DABurleigh said:


> Yes - the difference in battery internal resistance is the largest reason by far why batteries should come from the same batch when charged together. This is simply Ohm's Law, yet didn't seem to be appreciated.
> 
> Dave


I think you'll find very few batteries whose internal resistance obeys "Ohms Law". Though their internal resistance in any set of circumstances may be calculated using his definition of resistance


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## sallytrafic (Jan 17, 2006)

DABurleigh said:


> Yes - the difference in battery internal resistance is the largest reason by far why batteries should come from the same batch when charged together. This is simply Ohm's Law, yet didn't seem to be appreciated.
> 
> Dave


Yes my remark was as much tongue in cheek as I'm sure yours was 

As a major purchaser of batteries we used to insist on factory acceptance. This led to quite a few walk rounds of manufacturing facilities which also allowed us to talk to the guys making and testing rather than glib salesmen.

Most batteries bought by us for solar applications afloat were traction types which were mechanically stronger than the normal tubular plate solar ones. The chemistry is different and not altogether suitable for solar applications and so I was always seeking the perfect battery and trying to understand the subtleties.

I can't go into details but when I saw a small quantity of an unusual but inert material being added to the paste mixture I asked what does that do? and was told that it reduced self-discharge. How? I said **** knows he said but we've tried leaving it out. I was talking to their chief scientist at the time :roll:

Regards Frank


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## DABurleigh (May 9, 2005)

A man's gotta know his limitations 

I'm never tongue-in-cheek when winding up engineers or chemists.

Dave


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## VS_Admin (Nov 4, 2013)

*New Attendee Added*

vs_Admin has just added their name to attend this rally


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## philoaks (Sep 2, 2008)

VS_Admin said:


> vs_Admin has just added their name to attend this rally


?????????


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