What wire/current draw for my splitcharging circuit?

[Chrissyt]

I'm wiring in my splitcharging circuit as on the Wiki, and have bought a blade type fuse box, is all being mounted under the pass seat.

I notice the wiki one has only 10 amp fuses, will this mean that the total current draw allowed on my leisure battery will be 10 amps? is this sufficient?

I aim to run my propex (2amps), lighting, the radio maybe, and a fridge eventually( not sure what these draw?) from the leisure battery.

I'm a novice at this so bear with me... do i need the fuses as close to the battery as possible? and how do I calculate the wire diameter for the length of wire, i.e. voltage drop??

Chris

[jamesc76]

fridge eventually( not sure what these draw?) from the leisure battery.
Chris

First thing first dont run your fridge from the les. battery, it will kill it you need to wire that through a relay from the main vehicle battery that only allows power to the fridge whist engine is running!

[Titus A Duxass]

15 amps is a better figure.
Your fridge will take about 9 - 10 amps and as James said it will empty your leisure battery quickly.

Fuses should be close to the battery to reduce cable fires if something shorts out.

I run my propex, my radio, internal light and three lighter sockets from the leisure battery.
My cool box is fed via an independant feed which is switched via a relay, this relay is energised by the same feed that energises the split charge relay. That means my cool box only gets power when the motor is running.

[Chrissyt]

ok thanks guys.

So 10amps should be ok, considering i wont run my fridge from the leisure battery?

Cheers again!

Chris

[jamesc76]

should be i have all my stuff wired through a blade fuse box so i can split it up so light, water pump for sink, heater, stereo, tv etc all all independantly fused so if one blows it dont take out another cicuit if that makes sense?

[Chrissyt]

ok yeah think so?

I have a blade type fuse box with 8 slots, i was just thinking 10 amps for the split cahrging circuit, and then wire each component independantly, i'e lights and heater etc?

Chris

[jamesc76]

You'll be supprised how little alot of the stuff uses, plus once the engine is off the feed from the main battery or alternator will be out the system ?

[Chrissyt]

Sweet, yeah very true! Just wondered because may have the heater on when i'm driving etc?

So 10 amp should be ok? ...

Chris

[Westy.Club.Joker]

If you are going to wire in the 8-way fuse-box, then I`d make sure that the feed to the fuse-box is heavy enough to cope with any eventuality, you may one day have lotsa things running from the various fuses. I`d factor in 10 amps per fuse, so you`ll have a potential current draw of 80 amps to the fuse-box. I wired in an auxiliary fuse-box same as you are doing, I used 100 amp cable to feed it, then each fuse was fed off this main cable coming in, making sure that there wasn`t any chance of any of the linking cables being overloaded by the next circuit, if that makes sense. Same with the earth wiring.

[Chrissyt]

ok, currently I dont think i need to as wont have the money for flash accessories that will draw that amount of current?

If i was to wire for a potential 80 amp draw, then i guess i would need a larger relay? the one i have bought is rated at 40amp.
Chris

[Oldiebut goodie]

If you are going to wire in the 8-way fuse-box, then I`d make sure that the feed to the fuse-box is heavy enough to cope with any eventuality, you may one day have lotsa things running from the various fuses. I`d factor in 10 amps per fuse, so you`ll have a potential current draw of 80 amps to the fuse-box. I wired in an auxiliary fuse-box same as you are doing, I used 100 amp cable to feed it, then each fuse was fed off this main cable coming in, making sure that there wasn`t any chance of any of the linking cables being overloaded by the next circuit, if that makes sense. Same with the earth wiring.

I agree - I have used 110 amp cable,a 15a voltage sensing relay and a 180 amp relay for my merc 508d with two 110 ah batteries.

You need to beef that idea up a lot , even if you are only running a 90ah leisure battery when it is discharged your alternator may be wanting to put 50 amps or so down your wiring and relay.You are better off using a small voltage sensing relay to switch a big relay to ensure that the vehicle battery is charged before the leisure one/s.The advantage of using the small voltage sensing relay is that you can use an output to power your fridge on the move but it only gives it power once the vehicle battery is recharged.

[Chrissyt]

Cheers! Thats what i was getting at really, no matter what current my items are drawing, will the fuses/wiring need to be greater than 10amps purely to charge the battery? If so why is the one in the wiki still up with 10 amp fuses?

roughly how thick is 80 amp wire? and surely if the fridge is going to drain the leisure battery it will drain the starter battery also?

Chris

[Oldiebut goodie]

Using the voltage sensing relay the fridge runs from your alternator not your battery, as the fridge only gets power once the vehicle battery has charged and the relays switch the power to the leisure side. The voltage sensing relay is available from towsure I think - it is a Smartcom relay. This has an output for a fridge and is also used to switch the main relay.Once the engine is stopped the voltage drops and the relay disconnects so the fridge is no longer connected to anything.
Look for starter cable or welding cable in the amp rating you want.You don't need to fuse it - think about, it you don't have fuses in your starting cable etc.! Just route it sensibly and safely. Fuses start at your distribution board, fusing your lower powered circuits. If you really want to put fuses in you will have to have them rated just below the cable rating. i.e. 100 amp for 110 amp cable etc. Good old bay of fleas is a rich source for what you need.

[Red Westie]

Reading this thread we have gone from one extreme to the other, 10amps is definately too low but Oldiebut goodie has taken it to the other extreme with 100amp cables etc.
Whilst I agree in theory a fully flat battery will draw a considerable amperage whilst charging, are we honestly saying here that this needs jumper lead thick cables to supply a split charge system? NO! of course not.
Look to Westfalia's original split charge relay and fuse for some clues. My California has a 90amp Alternater and is fitted with a 30/40amp 5 pin split charge relay and is fused with a 25amp ceramic bullit type.
The usual cable I've seen on light vehicle 12volt split charge systems has been 2.5mm which will handle 30amps, if you want to overate then 4mm will be more than enough (the switching side only needs 1/1.5mm)
Yes...I've seen lots of split charge relays rated much higher 80/100amps but these are usually for much higher capacity systems as seen on 24volt lorries and or multiple large 110amp/hr plus battery setups.
Martin

[dugcati]

15 amps is a better figure.
Your fridge will take about 9 - 10 amps and as James said it will empty your leisure battery quickly.

Fuses should be close to the battery to reduce cable fires if something shorts out.

Will you get the same kind of drain as a fridge from using a 12-240V inverter? I know a few people use them but don't know how much juice they pull - OK I know it depends on what you plug into the inverter but there is a maximum wattage to them?...