Club 80-90 Forums

Red Westie, thats perfect cheers!

I have a 40A relay, so i think that sounds good considering its ample enough for westies, then sure it is for my van.

When you say switching wire you mean the alternator blue wire? Should this be fused aswell?

Cheers again!

Chris

Red Westie wrote: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.
and
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.
Martin

You obviously didn't read my post well:
"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."
When I draw 1400w using the invertor for the microwave I like to be able to be within sensible limits for the wiring.

The stupid little relay (a 30a one) in my caravelle blows fuses like there is no tomorrow, also the wiring is so puny it beggars belief. This is due to be relaced with a sensible setup as soon as possible - I will be looking at a minimum of 80A relay with 100 A cable. It cuts out voltage drops for the charging of your batteries for a start.I would suggest that you wire for maximum draw not minimum then you will have no problems.

Agreeing in theory to the above second quote should ultimately lead you to agreeing in fact! Check your voltage drop on your undersized cables - how are you going to get your maximum charge into the leisure battery? check your amps flowing to recharge your very low battery then say 30a cable is sufficient!
Yes, we are honestly saying that we need jumper lead sized cables!

Well I guess Westfalia backed by Volswagen got it wrong then and they should have come to you for advice.
Admittedly manufacturers do skrimp and save and maybe there wiring is lets say...only sufficient, BUT clearly, it has to pass construction and use regulations so cannot be dangerously under engineered as it may cause a fire etc
Point is: a little over spec is probably a good thing but the hardware you are suggesting is WAY OVER what is required....not dangerous in any way, just over the top.
I'll let the original poster make his mind up on which information he follows....both are correct.
Martin

Red Westie wrote:Well I guess Westfalia backed by Volswagen got it wrong then and they should have come to you for advice.
Martin

30 year old technology and thinking! Try getting a float charge when you have lost 1 volt due to puny wiring.
We don't know what the OP has for a leisure battery/ies, what his maximum draw could be, what alternator he has etc. so we are just kicking a ball around basically! That's why I said wire and relay for the maximum draw not the minimum (not what my 220 ah set up is wired with).

I'm even more confused now

Cheers for everyones input, i feel wiring for 100amps is over the top for what i have. I would guess that if it is good enough for a wessty then its good enough for me, i understand its an old van, but its fused so will not be unsafe?

So what everyone is saying is that i need to wire the circuit for the maximum amperage the alternator is likely to supply? As i'm 110% sure i will not exceed 20-30 amps draw with the items i plan to have.

The idea was just to have another battery to wire my propex into and 2 roof lights into, 2 amps for the propex max, and around 1 amp each for the lights.

Can anyone else let me know what they have in their vans? home install etc?

ChrissyT,
I have a similar power requirement as you have.
I run my propex, interior light (LED), Radio/CD Player and 2 Cig Ligther socket from the Leisure battery (63 amp/hour ).
This feed is via a 4mm square red wire which is fused (15amps) close to the Leisure battery.

I have another feed that provides power to the cool box when the engine is running, this is also via a 4mm square wire which is fused (15 amps).

The Leisure battery is charged via a split relay through a VW Loom which has a wire that is not bigger than 3mm Square and I get 13.5 volts at the Leisure battery from the alternator.

The feed to the cool box is switched via a split charge relay, this relay is a standard 12v 30amp automotive relay.

Thank Titus!

Do you have any problems with blowing fuses etc? Do you have a blade fuse box? Is the supply to this 4mm also?

Cheers

I have no blade fuse box.
Each wire has its own inline fuse holder which accepts standard blade fuses.

I have never blown a fuse or had any wiring melt.

I run the wires under the carpets, one goes forward from the left hand seat (drivers in my case) up to the fuse box.
I then removed fuse number 3 and connected the Leisure battery wire by sticking a spade terminal in the fuse holder instead of the fuse.

The cool box wire goes under the carpet between the seats to another connector for the cool box.

Chrissyt.....I think where you are getting confused is: there are three sides to the wiring.

1) The low amperage relay switching side from the alternator...this only needs to be 1.5mm as it takes very little power to actually switch the relay with a similarly rated looped earth wire with eyelet screwed to a clean earthing point.

2) The higher amperage circuit from the positive side of the starter battery that is switched by the relay to charge the auxillary battery when the engine is running and alternator charging (starter battery to relay, then relay to auxillary battery). This is the disputed thicker wire where to be safe, I would recommend using 4mm (needs to be fused close to the starter battery say 25amp inline fuse and holder)

3) Then finally the actual wiring from the leisure battery to your propex and lights: low amp demand so 1.5mm should be fine (again fuse close to the leisure battery 10amp inline fuse should do it) Use a seperate fuse for each supply circuit if you can (although not essential)

So you see it's the charge side between the starter and auxillary batteries that requires the heavier duty wiring and 40amp relay.

Personally I prefer soldered joints, I don't use Scotch Locs..use these at your own peril. Use proper eyelets, blade connections and inline fuses close to the feed source. As the vehicle itself acts as the missing wire in the circuit (negative earth system) always make sure your earthing connections are sound and screwed to bare cleaned metal.

Martin

Excellent cheers!

So based on what everyones saying and what i think i need my circuit will consist of:

40 amp relay
4mm wire for the charging circuit and inline fuses of 25 amps
1.5mm wire for the switching circuit (alternator blue wire and relay earth)
Then just need to rate my auxilary fuse box wiring in relation to what my items will be drawing? Propex, lights etc?

Cheers again!!!

Chris

Thats about the long and short of it....
If you have the choice you can buy a relay which has larger switched terminal posts (these are better for carrying the larger spade connectors and 4mm wiring) looks like a standard relay but the switched terminal posts are larger: like this one (also higher rated)
http://www.iem-services.co.uk/ShowDetails.asp?id=592" onclick="window.open(this.href);return false;
You can get away with the standard sized ones but these are designed for the slightly higher current and associated wiring (you will probably struggle connecting a standard spade connector to a 4mm cable)
Martin

Mikey9 kindly posted a link to an Auto electrical suppliers and purely by accident on the PVC wiring list is has a TYPICAL USE list and mentions standard and heavy duty charge circuits with recommended wire thickness ratings.
See:

http://www.autoelectricsupplies.co.uk/product/66" onclick="window.open(this.href);return false;

Martin

Also:

http://www.vehicle-wiring-products.eu/V ... mepage.php" onclick="window.open(this.href);return false;

Plenty of info in their pages, fast delivery and OK prices, good quality components.

Always aim for above spec, rather than right on the limit or below, over time your wiring will degrade/ oxidise/ whatever and you`ll get a voltage drop, `specially in a long cable run.

Thanks guys, if i cant get the cabe from my local place ll use these!

Very helpful as a size guide no less!

Chris