Even through Pam is more efficient, you still would need to switch the fan with a 16A midget which will get super hot and need very similar thermal protection to that causing the issues here.

Plus, the ignition would cause all sorts if hassle to digital electrics being so close without a lot of noise suppression

Edit: on phone... Pwm and mosfet

This sounds very interesting. You've been doing great work Mac. I have a couple of thoughts too. All the 'bench' testing was done with the motor inside the housing, but out in the open air. The inlet to the air box and the outlet were both unrestricted.

When they're installed in the car, you've got the bonnet scoop as the inlet, and the heater matrix and all the vents as the outlet. They must be offering at least some resistance to airflow and I would therefore suspect that the airflow is substantially reduced from your test rig under 'ideal conditions' so-to-speak. Would these restrictions cause the motor to 'freewheel' somewhat and therefore lower the current draw or would it cause a 'blockage' and stall the motor, raising the current draw?

The other thought, is the cutout switches and their cutout temperature. How is the spec formed? Is it an external spec or internal spec. Also, is there a maximum current spec and is the switching current momentarily going over spec whilst the motor speeds up?

Andy

pettaw wrote:and the heater matrix and all the vents as the outlet. They must be offering at least some resistance to airflow and I would therefore suspect that the airflow is substantially reduced from your test rig under 'ideal conditions' so-to-speak. Would these restrictions cause the motor to 'freewheel' somewhat and therefore lower the current draw or would it cause a 'blockage' and stall the motor, raising the current draw?

Good thought and I'm in agreeance, as I said when I fitted the Locost rad fan it's full voltage RPM dropped significantly between me having in in the lounge and bolted up to the heater matrix.

Afternoon girls,

Haven't forgotten the heater resistor project - attacking from a slightly different angle - decided to build a variable load device (Otter tell me they tend to specify the G6 as "operates after xx secs. @ yy amps) so I'm going to find out exactly how a new resistor pack performs.

I've acquired a rather Art Deco 0.3 variable resistor which should give me a good 20A at 13vdc. By the look of it I suspect it originally came out of a 1930s death ray but it should do what I need. I've built it into a test rig and we shall see!



Does it work? - dunno - only just finished it - will find out tomorrow.

Before anybody asks "why the bulb" - belt and braces - the device is unknown so I've built in a safety in case of a dead short.

Mac.

mac wrote:so I've built in a safety in case of a dead short.

Yer big blouse!

I wouldn't worry about damaging the VR... would make a fairly good 240W electric fire though I'd have thought

Personally I'd rebuild the '30's Death ray and forget about the resistors......

Just for you Roo - the death ray in action,



Mac

V3M's militant wing's research facility is coming along nicely. Those Saab infidels will soon regret messing with us!

Does it go up to 11...?

cheers

James

13 actually - using the revised warp scale!

Mac.

It still needs some knife switches and some large, round, bakelite gauges with needles with arrows on the end.

Give me a few days and we can sort knife switches... I'll have some nixie tubes somewhere for the upper class look?

(oooh, on that note, I was in a workshop not long ago and found a Bridgeport with a nixie tube DRO. You have no idea (well, you probably do) just how excited I may have become)

Your contraption reminds me of Regula 1:

Oh wow, a Bridgeport with nixie tube readouts -

Was it also steam powered, or perhaps by a small child from the village in a treadmill?

No... though was in a full sized steam train workshop...