petrol -1y diesel, can battery stay under drivers seat?

[campercrazy1]

I have been told that i can leave the battery under the drivers seat, when going from petrol to diesel as it is a late (1988) van does anyone dispute this? or know why it is ok in late vans and not earlier t25s?

[Titus A Duxass]

As long as the wiring is up to the job you should have no problems.

[campercrazy1]

if it isnt I take it the wire will healt up and melt the plastic sleve, so i will 'smell' any problems?!

[colinthefox]

The problem with a long wire from the battery to the starter is "Voltage Drop". The very high current taken by the diesel starter means that the voltage at the end of the wire gets very low when operating the starter, and if the battery isn't perfect there won't be enough voltage to run all the other stuff like relays and electronics. Ask any Vol-vo V70 diesel owner with the battery in the back. Even my tractor battery won't start one of those.

You'll probably have to upgrade the big thick wire to an even thicker one, or an alternative and probably better solution is to take a separate additional wire to the back of the van to run all the other stuff, and leave the original thick wire for just the starter.

[campercrazy1]

cool, ill try it first and see how it goes, then adapt as necessary!

thanks

[campercrazy1]

You'll probably have to upgrade the big thick wire to an even thicker one, or an alternative and probably better solution is to take a separate additional wire to the back of the van to run all the other stuff, and leave the original thick wire for just the starter.

hey I KNow you suggested this along long time ago, but I recently tried to run it and it didnt work! When you said run a seperste wire to the back of the van, did you mean straight from the battery to the to the little black box in the engine bay? If i did this though, wouldnt the wire be live all the time?

thanks in advance

[colinthefox]

I've looked at various T3 wiring diagrams, and in typical T3 fashion there's no simple answer because it seems there are several different wiring schemes. Actually, on all of them, most of the other electrics seem to come off separately at the front, direct off the battery, so there is probably limited benefit to be had from the "separate wire trick" which works very effectively on other vehicles with the battery at the "wrong end". In that case you would need to upgrade the thick wire, and the copper cores will need to total about half inch diameter (70mm or preferably 90mm squared, in electrical terms).

In the end, it's poor engineering to have the battery more than a couple of feet from a diesel engine. It's asking for trouble really. Added to this is the fact that you can only get so big a battery under the front seat, and you'll need a big 'un to do the job.

[campercrazy1]

hey thanks for having a look for me and dont understand em at all! Right, sounds like i need to face facts and move the battery into the engine bay. Apart from fitting a battery tray, what else would i need to buy and how exactly would i go about doing it?
I'm pooh at electrics, but i supose the earth battery strap can just be earthed anywhere in the bay?
What about the positive lead how do i extend this or is that completely the wrong idea?

[colinthefox]

Take a look at this photo..........
http://www.windsorchair.co.uk/vwpicture ... nebayA.JPG

You can see the battery top left.
A is the earth wire from the battery -ve to the water pump bolt B on the engine Scrape B clean to get good contact.
C is the wire from battery +ve to the starter hidden away at D.
E connects to the original fat wire to the old battery position, to connect to all the other wires that might come from the old battery +ve. (you'll need a big fat insulated connector block under the drivers seat!)
F connects the alternator to the new battery +ve position. This may already run to the starter position, in which case it can stay there, cos that connects to battery +ve anyway.

Earth strap from gearbox to chassis must be good too.

Be careful. Serious damage is possible from short circuits of these fat wires. Especially with a big fat battery like this.

[campercrazy1]

hey colinthefox, thanks for the picture of the engine bay and notes, a real big help.I feel I can have a go myself!- dont worry I wil be careful not to short anythin out! One more thing. there are 2 wires that curently connect to the positive end of the battery, one smaller red one and one really thick black one. Is it the red one which goes to the starter?if so what is the really think one for? and do i need to extend the thick wire all the way to the back of the van with a wire of the equivalent thickness?

thanks craig

[colinthefox]

The existing big fat black wire goes to the starter, and the red one goes to all the other stuff. You'll need a big connector block to connect these together under the seat. Electrical wholesalers sell suitable ones in a plastic enclosure for joining domestic electric meter tails together. As that black wire goes to the starter already, you could just add another fat wire from the starter to the new battery +ve, then you won't need E on my notes (although E would be an improvement). That wire would then be a standard issue starter lead from a T3 diesel.

Note that you must strap all the wires to the starter tight to the starter solenoid with a cable tie or two, or the vibration will be sure to break the starter stud connection in a short time.

[campercrazy1]

Ok, its beginning to make some sense Final question before I go and have a go in the latter half of next week (probably xmas eve!).

When you say connector block, what amps does it need to be able to take?

is this:

http://cgi.ebay.co.uk/100-amp-Lucy-isco ... 35a230c0e0" onclick="window.open(this.href);return false;

ok?

[colinthefox]

Yes, that's the one, sort of. The Amp rating can be a bit misleading, but 100Amps is good (approx the output of your alternator, or more). That connector is for 25mm cable, but I believe the black wire is either 35mm or 70mm, so it might be a bit small to get the whole cable in. Now the black cable isn't doing the job it used to, (ie running the starter) so it would be permissible to either lose a few strands, or split the strands into two groups and use two of the holes in the block. If you split the strands, don't leave them exposed, wrap them well with tape. Last thing you need is a short circuit under your drivers seat........ouch

Happy rewiring. Let us know how you get on.

[campercrazy1]

hey , I hiked to the van today! I couldnt really do much as the chap hadnt got to work because of the snow. However, i did notice that the positve battery terminal was quite loose onthe wire- I actually pulled it off relatively easily. should this be possible? or is likely at his could have contirbuted to the van not turning over fast enough? Either way, there is no justment on the terminal to make it a tighter fit,but I have got a 'quick release'one from an old leisure battery box, would it be worth giving this a go?

[colinthefox]

All connections have to be really spot on to start a cold diesel. The slightest loosness will let you down. Try checking them all.