Adding a extra leisure battery

[Hockeyplayer]

Could anybody give a simple explanation of how to add another leisure battery to our 2008 fiat Ducato campervan. Simple terms please, nothing complicated. Many thanks. :$

[weldted]

Ideally batteries should be of the same type age and amp hour. Fuse the positive lead close to the battery, best if the

+ terminal to the van from one battery and the - from the other. You must have the positive terminals to each other and the negative to each other, otherwise you could end up with 24 volts. When working disconnect the negative first, reconnect last.

[Derek Uzzell]

Hockeyplayer - 2021-04-07 12:40 PM

 

...Simple terms please, nothing complicated. Many thanks. :$

Things are rarely simple with motorhomes ;-)

 

Regarding connecting the batteries together, the guidance on this (old) webpage is probably as simple as you’ll get

 

http://www.motts.org/second%20leisiure%20battery.htm

 

The batteries must be the same type (wet-acid, gel or AGM) and should be roughly the same age and capacity. Just adding a new 2nd battery to an existing old battery definitely should be avoided.

 

Then there’s the matter of where the motorhome builder has installed the original leisure-battery and where the 2nd battery is planned to go, as this can affect how the two batteries are best connected together (see attached diagrams below).

 

There’s a LOT of online discussion about this

 

https://tinyurl.com/4c9tt5tf

 

with some of the suggestions being well-informed and some not.

 

Excellent advice can be found here. -- but it is a bit in-depth.

 

http://www.aandncaravanservices.co.uk/add-a-second-battery.php

 

(I think your 2008 Ducato-based campervan is an Auto-Sleepers product. If that’s correct, could you please say exactly which model it is, as someone here may have hands-on experience of installing a 2nd leisure-battery in that particular model and be able to advise on whether there might be anything unusual to watch out for.)

[Keithl]

The late Allan Evans wrote a very good article on his website about adding a second leisure battery and the checks to make before attempting it...

 

http://www.aandncaravanservices.co.uk/add-a-second-battery.php

 

Keith.

[Hockeyplayer]

Many thanks for the help, we will have a busy weekend of reading up

[Derek Uzzell]

It would still be useful to know the make and exact model of motorhome you own. Details of the present leisure-battery might also be worth having (type, make, capacity and - if known - how old it is).

 

It is possible to purchase a 'kit' for connecting a 2nd leisure-battery for certain Auto-Trail motorhomes

 

https://sargentltd.co.uk/shop/product/auto_trail_additional_battery_harness_2003-2010/230

 

but I believe using this relies on the original single-battery installation having been factory-prepared for a 2nd battery to be retro-fitted. Generally that's not the case and a DIYer has to make up (or have made up) the necessary cables and connectors.

[John52]

weldted - 2021-04-07 3:13 PM

 

Ideally batteries should be of the same type age and amp hour..

Why would they need to be the same amp hour when connected in parallel?

[Derek Uzzell]

The important word is "ideally".

 

Within this 2009 forum thread

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Hints-and-Tips/Adding-a-second-battery/18114/

 

I said

 

"Exide advises that, when parallel-connecting 'new' and 'old' batteries, the oldest battery should be no more than 1 year older than the newest. Also that, when parallel-connecting 'small' and 'large' batteries, the ratio of their capacities should be no greater than 1:3. (eg. 60Ah + 110Ah should be OK, but not 60Ah + 200Ah.) Having said that, the usual (and safest advice) is to always match like with like - same types of battery having a similar age and capacity."

 

Clive Mott-Gotobed's first paragraph in the first link I provided in my initial posting above says much the same thing.

[Alanb]

I have not previously looked at the late Allan Evans article on this subject, as my PVC already has two habitation batteries. As I am currently modifying the installation, I decided to take advantage of the link provided by Derek and Keith, to browse the article.

 

Allan's collection of horror photos, drawn from his experience, are a stark warning. However when he ventured into downloading pictures of CBE equipment from the internet, he copied a mistake, and in another case, in ignorance of the facts, made an incorrect diagnosis.

 

I refer to the section headed CBE. In the first photo in that section shows a CBE DS300 without the B1 (Starter Battery) terminal, and the 70A rated split charge relay. The split charge relay would normally be soldered into the four slots near the lower LH corner of the picture, close to where the missing B1 stud would be.

 

The origninal French poster of the picture, mistakenly labelled a small 30A rated relay as the split charge relay. Allan copied this error.

 

The CBE DS300 illustrated, is clearly designed for use with an external split charge relay, such as the "Boite de Securite", hence the lack of a B1 connection.

 

If we move to the second picture in the CBE section, it shows the underside of a "Boite de Securite" which was being used as the split charge relay in a Chausson.

 

While the picture was probably downloaded via a Google search, it was originally posted by forum member, Mick Bajcar, to THIS forum on 21 August 2016.

 

Allan chose to use the photo as an example of overloading.

 

The background was that while driving, the fridge in the Mick's Chausson was discharging the habitation battery (B2). The fault was traced to what Mick descibed as poor quality soldering, internal to the split charge relay. Certainly a poor connection at this point would cause overheating, as both the fridge and B2 charging currents are routed via the split charge relay in the CBE system.

 

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On a different subject, can anyone explain why on Clive Mott-Gotobed's diagrams for two 12V batteries in parallel, the original battery fuse is retained? Unecessary fuses fractionally deplete the voltage available for charging the battery, and the voltage supplied to the load when running on the battery.

 

A simpler approach would be to remove or repurpose the original fuse as a battery fuse and downrate both battery fuses to 15A, provided that the original cable is suitably rated to match the combined fuse ratings.

 

In both methods some sort of insulated, and preferably shrouded, connection block, or binding post is required to connect the load side of the fuses.

 

 

Alan

[ageingandrew]

Excellent advice can be found here. -- but it is a bit in-depth.

 

http://www.aandncaravanservices.co.uk/add-a-second-battery.php

I read the ‘add-a-second-battery.php’ document and really wish I hadn’t.

Aside from Alanb’s statement that Alan Evans has used information that is plainly wrong, the document is typical of much of the content about electrics that is posted on the site. Instead of collecting a set of facts, performing proper objective analysis on the facts to reach a logical conclusion and provide a general set of recommendations he just waffles on and on, page after page in an attempt to scare.

 

Don’t waste your time reading documents like the one pointed to here, instead go read the ‘Wiring Unlimited' document at Victron or the plethora of well written documents elsewhere.

 

Could anybody give a simple explanation of how to add another leisure battery to our 2008 fiat Ducato campervan. Simple terms please, nothing complicated. Many thanks

It's not that simple. You will need to find out how your van charges the existing leisure battery, and understand the limitations of the current charging systems (mains charger, alternator, solar...). You'll consider where a second battery will fit, can it be used with the existing battery etc.

 

I guess the link to motts.org given in a post above shows how to wire the batteries but if they are in close proximity then I'd just use the one fuse on the common supply line instead of the 3 fuses shown.

[John52]

ageingandrew - 2021-04-09 11:02 AM

I'd just use the one fuse on the common supply line instead of the 3 fuses shown.

Yes I thought 3 fuses is over the top too. The unfused wire to the fuse is probably longer and more vulnerable than a wire direct to the adjoining battery. And every fuse creates a resistance that slows down charging.

[Derek Uzzell]

ageingandrew - 2021-04-09 11:02 AM

 

Excellent advice can be found here. -- but it is a bit in-depth.

 

http://www.aandncaravanservices.co.uk/add-a-second-battery.php

I read the ‘add-a-second-battery.php’ document and really wish I hadn’t.

Aside from Alanb’s statement that Alan Evans has used information that is plainly wrong, the document is typical of much of the content about electrics that is posted on the site. Instead of collecting a set of facts, performing proper objective analysis on the facts to reach a logical conclusion and provide a general set of recommendations he just waffles on and on, page after page in an attempt to scare.

 

Don’t waste your time reading documents like the one pointed to here, instead go read the ‘Wiring Unlimited' document at Victron or the plethora of well written documents elsewhere....

I well recall you going head-to-head with Allan Evans on this forum in the past (example here)

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Wonder-if-they-will-catch-on-here/51044/

 

and - if Allan were alive and still an O&AL participant today - I’m sure he would have been happy to reply to John52’s question and respond to Alanb’s and your comments.

 

As I said in my first posting above, there is plenty of online information about adding an extra leisure-battery and ‘connection’ enquiries have been made here over the years several times

 

https://tinyurl.com/6ajt6d4u

 

(and I’m certainly not going to retrospectively vet the content of those threads for accuracy and/or credibility).

 

This Caravan Chronicles’s article (in my view) adequately summerises the procedure for adding a 2nd leisure battery

 

https://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel-part-2/

 

but the task still demands a basic understanding of motorhome/battery technicalities and a degree of DIY skill.

 

For a comprehensive answer to the original enquiry I’d want Hockeyplayer to provide

 

1: The reason for doing this.

 

2: Details of the motorhome.

 

3:: Details of the existing leisure battery.

 

4: Where the 2nd leisure-battery would be installed relative to the existing battery.

 

5: Whether, realistically, he/she has the DIY experience to carry out the task safely.

 

I remember George Collings - editor of MMM Magazine’s “Interchange” section in the distant past - saying that the best (and safest) advice to a question asking how to do something, was often “Don’t".

[Tracker]

Going back to basics, why do you feel that you need a 2nd battery and would the problem be greatly reduced by fitting a new, if the battery is old or failing, identical or as large a capacity as will fit into the available space?

 

I get the impession that you do not have the knowledge to do alterations yourself and messing with high current and batteries can be very dangerous, or make the situation worse, if you get it wrong so please seek advice from an auto electrician, preferably one with motorhome or marine experience.