split charge relay with back emf protection

[wackos00]

Well as the title says realy, I am looking for a split charge relay with back emf protection, already messed one alternator don't want to do another! Went to a auto electircal place and they wanted over £60 which seems alot, does anyone know of a cheeper one or another solution.
Cheers,
Jack

[AngeloEvs]

Why Back Emf protection, what do you think is creating it and screwing your alternator?

[Titus A Duxass]

^^^WHS^^^
The relay fitted by VW does not have any back EMF protection nor does it need any.

You must have another problem.

[wackos00]

I don't have a VW/factory fitted relay all home made, my van has a Subaru engine in it and it is my understanding that when the contacts open you can get a back emf (electro motive force (Voltage)) down the wire to the alt light wire. This emf can and I belive has damaged my alternator.

[AngeloEvs]

true and VW pl;ace a diode on the dashboard membrane to prevent back emf damaging the DOPS and temperature gauge internal circuit. You can do the mod to prevent the back emf from the charge relay for about 10p if its worrying you. Just purchase an IN4007 diode (in fact any IN 4000 series will do) for about 10p and wire the cathode to the positive feed of the relay coil and the anode to the coil connection that goes to earth - job done and no back emf (never heard of this damaging or saving an alternator tho!). If you do buy one, they are ltlle black cylindrical devices with a wire sticking out each end, usually black or silver. The cathode end is denoted by having a black or silver ring around the body.

[bigherb]

Must admit I've never heard of back emf damaging a regulator but it is feasible, but as angelo says you can wire a diode across the 85 and 86 of the relay or buy a relay with one already fitted.
http://www.vehicle-wiring-products.eu/V ... relays.php" onclick="window.open(this.href);return false;

[Red Westie]

The solution is simplezzzz! fit one of the new type of voltage sensing relays..that way it doesn't even connect to the alternator, just fits between the leisure and starter batteries.
This ones heavy duty 100Amp but one over 50amps would be fine.

http://cgi.ebay.co.uk/100A-SELF-SWITCHI ... 1001r12927" onclick="window.open(this.href);return false;

Martin

[AngeloEvs]

Best mod you can make to a charging circuit and very simple to do, ditch the conventional relay.......