[Healeys] Ignition Circuit

Bob Spidell bspidell at comcast.net
Sat May 25 11:05:13 MDT 2019

O/T (slightly).  I now understand how the 'ignition' light works; i.e. a 
balance between the battery output and the generator's. I've also read 
the using an LED is somewhere between ineffective and dangerous, but I 
used an LED for the ignition light and it functioned just like a bulb 
for years.  I did, however, heed the warnings and put a bulb back in 
that circuit.


On 5/25/2019 9:23 AM, Roger Grace wrote:
> Suggest that you consider powering the fan via a relay (reduces 
> current through ign switch) and also an in line fuse for good practice 
> when adding new circuits.
> Also as Perry says the ign warning light coming on is not a complete 
> disaster. It just tells you you are at full capcity and you could 
> probably drive for a few hours if your batt is OK. Sounds like you 
> have an ammeter - just keep an eye on it when using the fan and note 
> the discharge the current - probably less than 5A - and note too the 
> increased make up charging current after you switch off the fan.
> rg
> ----- Original Message -----
> From: Patrick & Caroline Quinn <p_cquinn at tpg.com.au>
> To: 'Michael Salter' <michaelsalter at gmail.com>
> Cc: healeys at autox.team.net
> Sent: Sat, 25 May 2019 05:24:07 -0600 (MDT)
> Subject: Re: [Healeys] Ignition Circuit
> Hello Michael
> And to obtain a wiring harness for a real Healey would mean that it 
> has to be specially made.
> Thanks
> Patrick Quinn
> *From:*Michael Salter [mailto:michaelsalter at gmail.com]
> *Sent:* Saturday, 25 May 2019 9:09 PM
> *To:* Patrick and Caroline Quinn
> *Cc:* healeys at autox.team.net
> *Subject:* Re: [Healeys] Ignition Circuit
> Hi Patrick,  I would agree that using the fused connection on the 
> "ignition switched" side of the fuse block as the source would be 
> a good idea. The ignition switch is not fuse protected so by using 
> that as a source you do run a risk of "letting the smoke out" should a 
> short to ground occur in your fan system.
> You may find that the electrical demands of your fan are more than the 
> fuses can handle as the system was not designed with heavy continuous 
> loads in mind.
> To circumvent that issue you could use the unfused side of the 
> "ignition switched" section of the fuse block as the source and 
> install an "in line" fuse to protect the fan circuit.
> I cannot overemphasize the importance of protecting the fan circuit 
> with a fuse, it very easy to damage a wiring harness and replacing one 
> is a major undertaking.
> M
> On Sat, May 25, 2019, 3:17 AM Patrick & Caroline Quinn, 
> <p_cquinn at tpg.com.au <mailto:p_cquinn at tpg.com.au>> wrote:
>     Hello
>     Seeking advice from those who understand automotive electrics.
>     My real Healey has an electric fan in front of the radiator that
>     was controlled by a thermo switch. Worked reasonably well, but
>     drew quite a bit of power but nothing concerning. When on, the amp
>     gauge needle would always hover in the negative.
>     Personally I don’t like thermo switches, so the fan has now been
>     wired direct and operated by a discreet switch under the dash.
>     Power is taken directly from the outgoing side of the ignition
>     switch so that the fan only comes on when the ignition is on along
>     with the specific switch.
>     Works well, but now when the fan goes on the ignition light is
>     illuminated and will not go out.
>     Does that mean that the ignition circuit doesn’t like what I have
>     done? I am thinking of taking the power direct from the incoming
>     side of the ignition switch so that the fan is powered direct from
>     the battery. Would that work?
>     Any electrical whizzes out there?
>     Thanks
>     Patrick Quinn
>     Blue Mountains, Australia
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