Leisure battery cable question, 1st time install.

[rosebubble]

Hi all, have installed a leisure battery at the back corner of my iveco.

used this relay

GRANVIA SELF SWITCHING, VOLTAGE SENSING SPLIT CHARGE RELAY - 12V, 30 AMP | eBay

and about 6 meters of this cable.

RED 2.5mm Tri Rated 30A 50/0.25

10m RED 2.5mm Tri Rated 30A 50/0.25 Cable Hook Up Equipment Hookup Wire | eBay

the battery we used was in the van car battery 75Ah and didn't last long using laptop/cig 12v adapter before reading 11.7.empty.

I think the battery is probably shot so have a 110Ah numax coming.

My worry is though is 6m of the 2.5mm cable i used the right size, or maybe thats why it wasn't charging properly,voltage drop?

Is this cable size SAFE????? :rolleyes2: or should I have went 10mm?

Last time i got this job done at a auto electricians and Im sure he only used 2.5?

Although I was getting 14v coming though the relay while engine was running and checking with the multimeter.

Any advice welcome

Cheers.

 

[st3v3]

2.5mm would work - as long as it's fused correctly next to both batteries it will be safe.

You might find if the LB is really flat it'll blow a fuse though. The only way around that is to increase the cable size and fuses, or not let it get proper flat. (Sensible for the life of the battery anyway.)

The relay you have used is good, but not capable of carrying 30A. It's something like 10A per output. I don't care what it says in the ad - I took mine apart and looked up the specs on the Omron relays inside. Use the relay you have to switch a bigger relay, and connect the batteries through that.

 

[rosebubble]

Cheers for the advice St3v3,

we are only running 12v water-pump, 2 or 3 leds strips and 12v laptop adapter.= in the van.

If i was doing this again would 10mm2 or 16mm2 be a better cable choice?

Rekon I could remove the old and run new through the conduit installed under the van if need be.

can you recommend a decent relay, that doesn't need the alternator connection ( as its installed back corner of van near leisure battery.?)

Should i be looking at 70amp? Lots of conflicting information out there on this subject?

Cheers RB

 

[st3v3]

I would keep your smartcom relay, but use the output that you currently have connected to the LB to turn on one of these:

ON/OFF Heavy Duty 4 Pin 70A 70 Amp 12V Relay 12 Volt Car Bike Automotive | eBay

Then wire the heavy duty contact in this to do all the work joining your batteries together.

As for cable, you probably need to fuse the 2.5mm2 at 15A. So, you can leave as is safely and see how you go. If you are changing the cable, the bigger the better. 10mm2 would be loads though, let alone 16mm2. I think 6mm2 fused at 40A is a good compromise as it's easy to work with and terminate.

This is good for wire size etc.

http://www.rbeelectronics.com/wtable.htm

 

[rosebubble]

I would keep your smartcom relay, but use the output that you currently have connected to the LB to turn on one of these:

ON/OFF Heavy Duty 4 Pin 70A 70 Amp 12V Relay 12 Volt Car Bike Automotive | eBay

Then wire the heavy duty contact in this to do all the work joining your batteries together.

As for cable, you probably need to fuse the 2.5mm2 at 15A. So, you can leave as is safely and see how you go. If you are changing the cable, the bigger the better. 10mm2 would be loads though, let alone 16mm2. I think 6mm2 fused at 40A is a good compromise as it's easy to work with and terminate.

This is good for wire size etc.

Wire Gauge Tables

Hi Steve, thanks for the info and link, i've ordered one of those straight away

I have two 20amp inline fuses a few inches away from each batteryI forgot to mention.

So im looking at;

crank battery>>>>>>>>20amp fuse>>>>>>>>2.5mm cable under van to input of smartcom relay>>>>>>>out smartcom relay>>>into new 70amp relay>>>>out 70amp relay

>>>>>>>>20AMP inline fuse>>>>>>>>>leisure battery.

Sound about right?

Does that mean the 70amp relay is doing all the work? or im adding that to protect the leisure battery.

Sorry am slowly getting there.

 

[st3v3]

Here's a diagram:

Cheers.

 

[rosebubble]

spot on, thanks for taking the time for that St3v3

 

[rosebubble]

got the new relay St3v3, looks nice and solid compared to the smartcom "heavy duty" one. Have switched the wire under the van to 6mm and will fuse @ 40a once i order some.

I'm think now just to scrap off the smartcom relay, (mainly because i don't trust the connections with vibrations in the van)of and install the 70amp one under the bonnet with the 12v coming from the alternator. (Will have to get a mate to do that for me, too scared fiddling behind there and finding right wire

If i go the smartcom route have i got the pins mapped out right to your diagram?

Cheers again

RB