Upgrade original alternator? – maybe no need.

[Al Campbell]

I've already gone down the path of cleaning all the battery connectors (including earths) and terminals on the big power junction on the firewall and upgraded the output wire from  the original 65A alternator, so I am getting as much power to that terminal box on the firewall as I can. Then I measured the voltage drop from that terminal to the cigarette lighter socket. I was getting a drop of 2.85V under no load, which turned out to be all due to the ignition switch!

The wire that is the "run" output goes to fuses 6, 7 & 8 which feed windscreen wipers, window lifter, electronic injection, instruments etcetera. Rather than going to the hassle of replacing the ignition switch, I added a relay to by-pass it.

There was a spare relay socket on the fuse box, behind the windscreen washer timer/relay probably meant for the interior light timer. I ran  a big fat wire from the 12v terminal box on the firewall, to the relay and used the "run" wire from the ignition to control the relay.

I now get 13.8V at idle, no load. At idle with the rear demister on, aircon going full blast and with the wipers going, I get 12 volts at the lighter socket and the radio doesn't cut out!

In the past I had cleaned and regreased the wiper motor gearbox and being an engineer I timed 10 wiper oscillations on high (wipers lifted off the glass) at idle:

Original: 12.8 seconds
Regreased gears: 12.6 seconds

By-pass ignition switch: 10.0 seconds
With aircon, demister & fan on high:  11.6 seconds

I use rain-x in the windscreen washer as well and now the wipers work almost like a modern car, no shuddering.

I'd already added a relay for the starter solenoid, so the only remaining untreated output from the ignition switch is a 2nd "start" wire o the ballast resistor, I think.

Al Campbell

[MD]

Al,

Agree with all your hard work and point of view. My only comment regarding the topic question is this. More contemporary alternators usually provide at least an 85 amp charge capability which is not always a must but it can be a small asset as that they also provide a higher B+ voltage rail of around 14.2 volts. Given the age of these vehicles, not only do the ground connections develop resistance but the live connections do as well and they can be a difficult job to track them all down. If the resistance is minor, a small bump up in the voltage rail will often overcome these issues. This does not mean that one shouldn't take the trouble to sort through bad connections, it's more like a scatter gun approach for the remaining nuisances left. 

As an aside, a couple of years ago I did a current demand check on a GTV6 with all services running and they added up to 88amps. It would be a rare occasion indeed that this circumstance would arise so I wouldn't be too concerned about it. I just mentioned it if the information was of any use to readers for some reason.

[Al Campbell]

MD,

Yep good points. This is no substitute for cleaning up electrical connections. 14.2V now o.k. I didn't know that. Bit amused that I get 13.80V at idle. I did toy with the idea of squirting contact cleaner  in the key slot of the ignition switch.  I also balked at the idea of cleaning all the spade connectors on the back of the fuse block. I checked a few and the looked o.k. probably a friendly environment that the engine bay. The down side of what I've done is that I haven't repaired a faulty (and vital) part that may still fail.

The output of alternators is proportional to rpm and a 65A alternator won't put out anything near that at idle, but a 95A unit will put out more at the same revs, so an upgrade is still very worthwhile. It's still on my list, just been bumped down.

I can now sit at the traffic lights with demister & fan going and when the intermittent wipers come on, the radio won't drop out.

Your 88A, is that a calculation or measurement? Some time ago I turned on everything electrical I could and measured the current at 1500rpm using a DC clamp meter (professional one) and got nowhere near that. Sorry, I can't remember what the figure was, but  was surprised how low it was. I might check that again on the weekend.

AL.

[shane wescott]

All sounds like great ideas. It's on a list.

[MD]

AL,

When I say total current demand I mean everything on this list:-

Ignition load
Fuel pump load
Twin thermo fans running
Condensor fan running
Air conditioner operating with electric clutch engaged
All lights on high beam
Heater demister on
Hi Fi on
Cigarette lighter plugged in
Hazzard warning lights on
Wipers operating
Brake lights on

I probaly left some dribble off but you get the idea..

The figure was arrived by measuring the ignition base load and then adding various services as they showed up with whatever increase resulted when it was turned on. When finally added together, the sum was around 88amps.

Variables may arise from such things as headlight wattage differences, how loud the Hi-Fi is going ,what sort of thermo fans are being run etc.

Unless one is running some serious tar burner headlights, I am more than confident that an 85amp alternator will be up to the job in 90% of the cases for a GTV6. If we are talking about more recent cars that have electric windows, seat adjustment and bum warmers  , obviuosly this would need to be reassessed..

BTW Al, I take it you have seen my conversion article..?
http://www.alfaclubvic.org.au/forum/index.php?topic=3525.0

[Al Campbell]

MD,

On Saturday I warmed up the beast (too wet to garden):

Lights on high beam (50/60W low + 100W high x 2)
Demister
Rear fog light
Hazard lights
Air con (system is gassed and the clutch engages but doesn't cool much).
Interior fan on high
Wipers on high (blades off the glass)
Radio (for what it's worth)
Single radiator fan (I'm missing one and I waited until it came on)

I was using digital clamp meter and the reading fluctuated a lot, but at about 2000 rpm I measured  between 52 & 59A. That was the sum of the alternator output, current to the battery and the headlights (fed directly from the alternator). Thinking about it now, I didn't pay attention to the sign when measuring the current through the battery cable, i.e. was the 7A charging or discharging?

I was getting 11.7 V at the terminal block on the firewall.

I tried cycling the windows, but couldn't see the increase as I was trying to read the meter which was in the engine bay, while pushing the window switches in the cabin and trying to keep the revs up with my foot.

Looking at Bosch's curves for a 65A alternator, that's about all they put out between 2000 to 3000 rpm, so I think I was at the limit of the poor little thing. So an upgrade is definitely worth it.

As for conversions, yes I saw yours and a variety of others. For me, the cheapest option for my shot rings is a motor out of a 164 (according to the man at Monza),  which will presumably come with a later alternator (and a non-York a/c compressor). There was a conversation at home on the weekend about how much time & money is spent on that car.

Al "Smoky" Campbell