Which fuse rating to between starter and leisure battery?

[ssdenis89]

What fuse rating do I need to put in between the starter and leisure battery? I have a 12V 75AH Starter battery and 110Ah leisure battery. Cable size 16mm or 8mm. (this is for my off the grid van )

 

[telectrix]

try 16mm cable with 80A fuse. are you fitting a split charge relay?

 

[PEG]

Hi,if your charge system,is primarily for the starter battery,you should not have a fuse there. It is a stone-age method of bypassing the correct way of setting up leisure battery use.

Nobody would give two people,the kiss-of-life,at the same time,by using a hose with a tee-piece at the end....

 

[ssdenis89]

yes I plan to add a split charger realay in between the starter battery and the leisure battery!
Yet I have 2 starter batteries and I want to connect one of them to my leisure batteries. Note that my 2 leisure batteries are connected to solar panels.
Is there a risk that I break the generator or harm voltage in one of the batteries?
PS : You can see how I connected the battery engine to the leisure battery in the bottom left corner of the diagram - see attached.

 

[DPG]

Remember standard car batteries are not designed to be fully discharged like leisure batteries are.

 

[ssdenis89]

Remember standard car batteries are not designed to be fully discharged like leisure batteries are.

===>If I put a split charger relay, that shouldn't harm the engine batteries in theory... ?

 

[DPG]

===>If I put a split charger relay, that shouldn't harm the engine batteries in theory... ?

Yep, sorry - forgot you were having a split charge kit.

 

[PEG]

Hi,with the outlay on all that equipment,i would seriously consider,investing in a charge control unit,current limited,instead of that 1950's relay.


Size it according to the leisure batteries,and,more importantly,the output of the alternator,taking in to account,the load which the vehicle may impose on it.

As is usually the case,you have several systems,all which can be adversely affected,by occurrences up or downstream. The system,as drawn,will have a mini-fit,the first time one of those four batteries,are flat.

 

[ssdenis89]

Hi,with the outlay on all that equipment,i would seriously consider,investing in a charge control unit,current limited,instead of that 1950's relay.


Size it according to the leisure batteries,and,more importantly,the output of the alternator,taking in to account,the load which the vehicle may impose on it.

As is usually the case,you have several systems,all which can be adversely affected,by occurrences up or downstream. The system,as drawn,will have a mini-fit,the first time one of those four batteries,are flat.

===> So I would need to get a charge control unit instead of a split charge kit.
1/ What output on the alternator should I look for in Volts or Amps? Once I have the information, how do I translate it to the charge control unit. Would love to have an example so that it speaks better to me. Kind of new all this for me! thanks so much.

2/ What do you mean by "mini-fit" and "the first time one of those four batteries, are flat"

 

[PEG]

Hi,you should be able to find the output of your alternator,in amps,from the vehicle specification,or from the alternator data plate.

The type of vehicle,and it's ancillary electrical equipment,would then give an indication of safely available output,for additional charging purposes.

This output,and the size of your leisure batteries,in A/h,would allow you to choose a current limiting DC/DC charge controller. This controls the charge output,to the leisure batteries,automatically,and limits the maximum draw from your alternator,protecting all components.

I am guessing you are conversing in varying languages,and i apologise,for my slang or flippancy.

A "mini-fit" was my description of when systems,such as you described,had a sudden overload,due to an expected flat battery,and blew any fusing or worse,started to heat things up.

A large set of leisure batteries,when fully depleted,require a charging current which can be far above what the alternator can manage,and then alternative sources will be sought,which can bring their own issues.

Seen this exact scenario,cause the demise of many a camper and horsebox,and a burnt out £100,000 equine coach,is a sad sight

 

[telectrix]

Seen this exact scenario,cause the demise of many a camper and horsebox,and a burnt out £100,000 equine coach,is a sad sight

if the horses were on it at the time, could have had a nice BBQ.

 

[PEG]

Seen this exact scenario,cause the demise of many a camper and horsebox,and a burnt out £100,000 equine coach,is a sad sight

if the horses were on it at the time, could have had a nice BBQ.

...Always with the free food...