# Second Leisure Battery



## 98055 (Mar 9, 2006)

Hello Ladies and Gentlemen,

I would like to pick your brains.

If I were to connect a second leisure battery is it as simple as buying another battery and wiring it to the existing leisure battery and then making a cup of tea ....job done......or am I living in another world?

Also once fitted will the pair reduce in power simultaneously or will there be a slave and a master?

Will it effect my internal meter within the van on the control panel??

I have asked a lot of simple questions recently,just think when I get old and wise I will then be able to answer other peoples quires.

Many thanks in advance

DD


----------



## 88724 (May 9, 2005)

Hi 

just adding a second battery, they will be mismatched, same for discharge and recharge they will always be not quite working together. You can do it an it will work after a fashion, but they wont last as long as they could.

The meter will read the average of the 2 batteries.


----------



## 98055 (Mar 9, 2006)

George,

Is there a better way or is this the way it is period?


----------



## DABurleigh (May 9, 2005)

You can manually switch the active battery between the two mismatched ones, or you can buy two new identical batteries.

Dave


----------



## 88781 (May 9, 2005)

Ideally you need two batteries of the same Ah, mounted next to each other using 'proper' battery terminal connections and not those quick release jobbies that seem to plague the leisure industry!

regards M&D


----------



## 88724 (May 9, 2005)

Hi DDaddy

DAB Pretty much nailed the answer, my preference would be 2 new batteries

Just to add to what MaD said they do need to be same AH But also same Make, Type and age, even 2 new 110 Ah batteries would suffer the same problems if they were different makes and/or diffferent types ie AGM and lead acid.

The Bank of 10 I made up were all new and sequential serial numbers off the production line.


----------



## 98055 (Mar 9, 2006)

George,

Did I read that right.....bank of 10 batteries...am I seriously under powered with my 1 and considering a second or are you running a mobile power station?

DD


----------



## Malc (May 9, 2005)

No mobile welding business!!

:lol: :lol: :lol: :lol: Malc


----------



## chrisgog (May 17, 2005)

We will be going for two batteries soon but is there a *recommended* *make* by anyone. 
We will be ready to purchase at Newbury and one trader was selling Squadron marine and leisure batteries in Peterborough.

We have a new 95ah (3weeks) battery but were thinking of buying 2x110amp instead or 1 new 95amp to link to it?

In our last van we had an 85amp linked with a 110amp Elecsol battery and never had a problem with this.

We are aware that you really need two batteries the same but would like recommendations off others as to the *MAKE of battery *or are they all much the same as long as they are leisure/marine batteries.


----------



## 88724 (May 9, 2005)

Hi Chris

Quote _*In our last van we had an 85amp linked with a 110amp Elecsol battery and never had a problem with this. *_

Most people would never notice the problem's with this, but its bad practice and you are losing out on available power, the recharging is always going to be poor for both batteries and the life expectancy of both batteries is also lower.

Pick out pretty much any lead acid leisure being sold, buy a pair and they should last OK.


----------



## chrisgog (May 17, 2005)

thanks George


----------



## shortcircuit (Mar 19, 2006)

A lot of experience on this forum.

How are batteries matched as a pair?

How do consecutive manufacture numbers determine that batteries are matched?

What criteria are used to match batteries and how is it measured?

Hamish


----------



## 88724 (May 9, 2005)

Hi

How matched? buy 2 new together on same day

why go for consecutive? I thought that would be obvious if they follow each other down the production line they are going to be pretty similar I would think.

Most people aint gonna measure anything, buying new pair at same time is near enough.


----------



## shortcircuit (Mar 19, 2006)

Am I correct in understanding that there is no technical criteria as to how batteries are matched other than the assumption that as they were produced at the same time then they "should" be the same.

What are the consequencies if they are slightly different?


----------



## DABurleigh (May 9, 2005)

Yes, I'm not aware of any particular matching for lead acids.

It is a common practice where one needs the ultimate in performance from a battery - radio controlled racing cars springs to mind, where nicad and similar cells are regularly abused in terms of charge and discharge rates. They are grouped into matched sets from a common supply by charging and discharging each cell and recording capacity, terminal voltage, etc.

Dave


----------



## shortcircuit (Mar 19, 2006)

If I can rember correctly, NiCad developed a memory and are therefor not the same as a lead acid.

Still cant understand the logic of consecutive numbers


----------



## 88724 (May 9, 2005)

Hi

Consecutive numbers, would indicate that the batteries were made at same time and therefore the electrolyte mix would be from same batch also materials in plates etc etc, its no great fancy theory or anything


The consequences with unmatched batteries have been outlined above and are fairly obvious if you understand the physics involved, it matches all the info out there on matching battery banks.

There are plenty of technical criteria, but if you do not understand the basics of why its bad, it would be pointless explaining it in any great technical depth and in any case buying a matched pair is good enough, no-one really needs to go to any great lengths testing the individual batteries

Take matched to mean as same make and model puchased on same day (with consecutive numbers if possible)


----------



## DABurleigh (May 9, 2005)

shortcircuit,

Here is a readable link, but there are plenty more where that came from. Just google.

http://www.mpoweruk.com/balancing.htm

Dave


----------



## shortcircuit (Mar 19, 2006)

Dave 

Thank you for your positive input. I will look further at the link this evening.

George

Can you not put in a positive input without belittling all and sundry


----------



## 88724 (May 9, 2005)

Hi SC

Apologies if my post apears condescending, it seemed from your post that you do not understand any of the underlying reasons for matching batteries, that being the case getting technical would not really help. 

I will edit it to hopefully remove any condescention.

Regards

George


----------



## sallytrafic (Jan 17, 2006)

I am surprised that no one has mentioned another approach. That is to use two 6V batteries in series instead of two twelve volt ones in parallel (I know it has been covered in other threads.) Exact matching with age becomes less important, although you must stick to same Ah and type (but not necessarily manufacturer). In 12V, 24V, or higher, battery banks using 2V or 6V cells/batteries replacing a single unit that has become defective is quite common practice and has not lead to any problems as far as I know.

Perhaps 6V leisure batteries are not easy to get hold of in UK.


Regards Frank

Edit: Oops just read the link that DAB put in which is largely shows the series problems. In practice cell balancing is no problem for cells in a solar system or with a decent charger.


----------



## 88724 (May 9, 2005)

Hi Frank

Parrallel cells suffer more from lack of matching, side by side route of least resistance comes to the fore, in series the current as to pass through all cells. Again the expence of replacing all cells in a massive bank as to be mitigated by a small drop in performance, but
remembering here that there is an bigger average over a larger bank....


----------

