Electrical Upgrades

[mylesw]

Hello

I am about to install the electrics in my 3.8 FHC as part of a restoration and was wondering what I should upgrade and what to leave stock.

I am thinking about an alternator (the one that looks like a dynamo), relays for the headlights, solid state control box (not sure I need this with the alternator?), modern starter motor and halogen headlights. Is there anything else I should consider?

Thanks

Myles

[Heuer]

The Nippondenso alternator can be found on eBay for about ?50 and has a built in regulator; a very good product if originality is not important to you. Other things to consider are the mechanical brake light switch (essential), relay for the brake lights (makes them much brighter), LED instrument lighting, voltmeter, USB sockets, intermittent wipers and hazard warning lights. Details of all these are in the Upgrade part of the Forum. You also may want to consider running a bundle of spare wires to the rear of the car so that if you, or future owner, want to install rear speakers or other electrical gear the tails will be there. A co-axial cable might also be worth running as an aerial at the back of the car is more immune to RF than one on the front scuttle.

[christopher storey]

If you decide to stay with the dynamo, have nothing to do with a solid state control box as a substitute for the RB340 ( or just possibly 310) that is there at present. The solid state ones, made Lord only knows where , are absolute rubbish

[64etype]

Hello

I am about to install the electrics in my 3.8 FHC as part of a restoration and was wondering what I should upgrade and what to leave stock.

I am thinking about an alternator (the one that looks like a dynamo), relays for the headlights, solid state control box (not sure I need this with the alternator?), modern starter motor and halogen headlights. Is there anything else I should consider?

Thanks

Myles

I followed the general architecture developed by Bob Skelly almost ten years ago (see link below). While it's a complete revamp of the S1 electrical system, he has some very good ideas that you might want to selectively incorporate. In my case, I have a seven relay and ten fuse panel at the location of the original voltage regulator, plus a six fuse and two relay panel behind the glove box (which has a false back panel). All of the relays that were originally scattered around the car are centralized on these panels. Relayed items include the headlights, parking/panel lights, heater fan, radiator fan, reduction gear starter, the RetroAir A/C, and the electronic ignition. Virtually everything in the car is now individually fused with particular emphasis on the white wires, which I believe have been responsible for most harness meltdowns. While the ammeter remains, it carries virtually no load. Harness/looms are all new/original with no modifications other than a few jumpers to the new relays and fuse panels. So the car can be returned to original if the next owner so chooses. Two 40 amp "main fuses" are used in lieu of the single 100 Amp main fuse in Bob's architecture. One of them powers the main fuse panel and one powers the "switched" items. An emergency override switch addresses the unlikely event of a failure of the main relay to the switched power panel (where the fuel pump resides). I'm using an internally regulated, one wire alternator from a Suzuki Tracker (U.S.). Bob Skelly's web site is worth a look...

http://bob_skelly.home.comcast.net/~bob_skelly/

[Dave K]

Hello

I am about to install the electrics in my 3.8 FHC as part of a restoration and was wondering what I should upgrade and what to leave stock.

I am thinking about an alternator (the one that looks like a dynamo), relays for the headlights, solid state control box (not sure I need this with the alternator?), modern starter motor and halogen headlights. Is there anything else I should consider?

Thanks

Myles

If you buy the alternator that looks like a dynamo (Dynalite) it comes with its own regulator and it works very well, also a relay for the ignition.

Dave

[abowie]

Hello

I am about to install the electrics in my 3.8 FHC

Myles

The only thing I changed on my 3.8 was to install a modern starter motor. I also converted it to negative earth which is trivially easy to do.

The dynamo seems to charge the battery fine and I don't drive at night so the headlights are a moot point. A friend with a 1930's MG has just installed LED headlights in his car which he is very happy with and gets around the low power output from the dynamo.

Installing a modern radio might require an alternator for extra power input. I don't have a radio in my car.

[cactusman]

A few observations. Agree with a relay activated by the hydraulic brake switch. Repro ones are not as good as the originals so it makes sense. However...it is well worth adding a diode inverse polarity across the relay coil terminals or the back emf when the relay switches off will cause arcs in the switch and negate most of the advantage of lower switching current. A 1N4007 is ideal. My 3.8 has a relay and LED brake/rear lights. More light and less amps. Just over an amp for both brake lights.
Fusing is vital.All the main circuits bar the feed to the starter should be fused appropriately. Remember though that a 20 amp fuse will carry 40 amps for up to a minute before it fails and will need 200 amps to fail in 20 milliseconds...and that is assuming it is a well made precision device and most car fuses are not! See the internet for lots more on fuse times.
A 100 amp fuse would fail within 0.3 seconds with a fault causing 400 amps to flow. Given a 12 volt supply and wire resistance such a current is highly unlikely to flow in most fault circumstances. Thus a 100 amp main fuse is, in my opinion, of questionable benefit as only the cable to the starter motor can carry anything approaching 100 amps. Wires will probably be smoking long before a 100 amp fuse fails. Better to protect all circuits with appropriately dimensioned low current fuses. Also well worth having a battery isolator bypassed with a five amp fuse or resettable 3 amp cut out so courtesy lights and radios work. That way when unattended the whole car is protected by a 5 amp fuse and cannot be started so a bit of security too. Happy wiring what ever you choose. Julian

[Heuer]

Using a relay operated by the hydraulic switch is a step in the right direction, eliminating the hydraulic one entirely is better. You get instant response from a light touch of the pedal. The relay should be deployed in the boot area with a dedicated feed for the brake lights which ensures maximum brightness.
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