• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR4/4A Power (+) Sources

Share this page

OP
RJS

RJS

Jedi Warrior
Country flag
Offline
Hi All,

Not being an electrical expert, looking for some advice to connection spot for power (+).

First one is a connection for headlight power. I have recently installed relays and presently have the power (+) lead connected directly off the battery (+) terminal. Is this OK or is there a preferable spot off the fuse box? If so, which terminal? This connection does not need to be switched with ignition power.

Second, I have new headlights with a city light option. I am using the city light feature as a DRL for safety. This one needs to be switched with the ignition. Presently it is wired to the (+) terminal on my ignition coil. I suspect this is not ideal. Other ideas/suggestions?

Thanks

Bob
PS: later I am planning on installing a USB power supply descretely under the dash. Will likely want to power this same as my city lights
 
Sort by date Sort by votes
Hooking the lead to the (+) side of the battery will work, but it's not optimal, as the headlight current won't register on the ammeter. Better is any point after the regulator. The current form the battery goes from the battery through the ammeter into the regulator A terminal and out the A1 and out to the car. I suspect that the only really practical place along that circuit is the regulator's A1 terminal itself.

I don't know how much current the city lights will need, but if it's more than a few amps, I would use a relay. The relay coil goes to the ignition switch's terminal (the one that connects to the coil) and ground, and a wire goes from the regulator's A1 to the lights.

This is a lot of connections to the A1, so it might be a good idea to find some kind of terminal strip for the connections and run a single wire from it to the A1. Of course, put in-line fuses in the high-current leads to the lamps.

I hope this isn't confusing. I think you should be able to follow it if you have a copy of the wiring diagram.
 
Upvote 0 Downvote
Brilliant, thanks all.

The city lights and the headlights are warm white LEDs (3000K) both from ClassicCarLEDs in the UK. Pull 1/3 amps and 3.2amps per pair, respectively. But, still want to wire everything correctly. Appreciate the advice (Steve) and wire diagram (Tom).

Bristol401, battery line is fused feeding a relay (relay probably not needed with LED lights but, hey...)

Bob
PS: BTW, super pleased with these warm white LED bulbs, as posted here with photos: > General TR - Warm White H4 LED Headlight Bulbs <
 
Last edited:
Upvote 0 Downvote
For 1/3 amp you don't need a relay. I'd just wire it to any convenient point after the ignition switch.

For 3A it's probably OK not to use a relay, but I would use one anyway, as it will probably give more satisfactory results overall. You're less likely to have erratic behavior, as the switch starts to wear out. And new TR4A light switches ain't exactly cheap, available, and easy to replace.
 
Upvote 0 Downvote
Thanks Steve,
So, will look to connect the headlight lead to the A1 (vs battery) and will likely leave the DRL lead connected to (+) of ignition coil as it is only drawing 1/3 amp, and is a close easy source

Bob
 
Upvote 0 Downvote
Back
Top