130A alternator upgrade

[cactusman]

You could....only a 70 amp fuse will carry 130 amps for several minutes before failing.....quite long enough to allow the wiring to smoke...

[mtnjag]

What is a "safe" amp output alternator to run in a S1 wire loom. I'm about to convert to a GM 10si with either 65 or 85 amps with internal regulator.

[jagwit]

What is a "safe" amp output alternator to run in a S1 wire loom. I'm about to convert to a GM 10si with either 65 or 85 amps with internal regulator.

This is really a question for the Series 1 forum, but I installed a 55A alternator to a friend's 68 S1 and its working fine.

Again, that does not mean that the alternator is pushing 55A into the wires, it only means that it MIGHT if the car draws that much for some reason - which should never happen under normal circumstances.

[christopher storey]

They were designed for 30 amp setups. The wiring is of a cross section suitable for that . Any failure of regulation is a fire risk if you have an alternator of significantly higher capacity

[johnetype]

The sensible compromise for a Series 1 dynamo loom is to use a Lucas alternator from the 17ACR range. Readily available in 35 and 45 amp outputs which is more than enough for an E type. Looks period, internal regulator and around £50 new.

[Heuer]

What is a "safe" amp output alternator to run in a S1 wire loom. I'm about to convert to a GM 10si with either 65 or 85 amps with internal regulator.

Alternators are rated for their outputs as 'cold' and 'hot'. The two GM rated outputs (65/85 amp) refer to hot and cold measurements, The 'cold' 85 amp output is measured at 25°C ambient under the conditions you would normally see at startup and is about 10% - 15% higher than the 'hot' 65 amp output which is rated at 93°C ambient. These measurements are ISO or SAE standards and are done with an alternator running at 6,000rpm which is equivalent to about 2,200rpm engine speed after calculating the pulley ratio.

For an S1 a 60 amp 'hot' alternator would be the best choice - something like the Nippondenso described in detail here: http://forum.etypeuk.com/viewtopic.php?p=48278#p48278

[mtnjag]

Thanks everyone,

Picked up a 61amp GM Delco 10si. Period looking and a plentiful, dependable, easily available performer. Fits nice. Wiring it up today.

[mtnjag]

Wired up and operating nicely, except the charging rate is shown as 14.92 volts on my DVOM and right about that on my in car voltmeter.

Battery fully charged on charger, car warmed up and driven about 20 miles and it didn't drop until I turn on an accessory. Battery is cool to warm after drive.

Will be taking battery in to have it checked for weak cell but it's a recent Interstate and I don't have any other reason to suspect it.

Issue?

[jagwit]

14.9 is too high. Not good for battery.

Does your alternator have a sense input? If so, connect a wire from battery + to that terminal.

[mtnjag]

It has 3 wire input, Delco 10si, Main hot +, ignition hot, and an ignition light.

[jagwit]

Something is not right. At 14.9v battery won't last long.

In my book 14.2 is about as high as it should be.

[Heuer]

Charging voltage should be limited to 14.3 volts.

[cactusman]

The recommended max float voltage of a fully charged lead-acid cell depends on temperature, cell type (flooded, gell, agm etc) and manufacturers recommendations but a good guide is 2.27 to 2.3 volts max at 20 deg C which means a six cell car battery should be limited to 13.62 to 13.8 volts....I would say even 14.3 volts is a bit high...I would aim for between 13.8 and 14 volts....remember too that assuming car filament bulbs are actually designed for 12 volt operation, then running them at 14 volts Will significantly shorten their life. The same does not apply to LED bulbs though so long as they are well designed

[mtnjag]

Yeah, it's going back. Just put the battery back in after the store tested it good. Battery showed 12.46v before start up. Started car with the small power amp in car disconnected and I got 14.98 at the battery at about 1800rpm, disconnected battery lead to alternator and checked directly at alternator battery lead to ground and got 15.2v. Tested with DVOM.

Thanks, I'll be back.

[mtnjag]

The rebuilder said that was a high reading and they had a 14.8v regulator in the alternator which may be giving me a high reading, they switched it for a 13.8 regulator and based on my finding felt that would preform well for me.

Put it in this afternoon and now I think I'm too low!

With no accessories on I get 13.65 at the battery, so far so good, drops to 13.3 with hdlts/hrt fan/radio, add the radiator fan which is a big GM fan motor (custom install) which probably pulls 25 amps and I'm down to 12.6 at 1500rpm and 12.9 at the battery 2000rpm and up. Lower than I'd like. Same total load I get 13.4v at the alternator. There should be plenty of amps at the alternator to power these accessories.

Does indicate a voltage drop in the system by the time the charge gets back to the battery while the alternator regulator is doing it's job with the alternator output so despite the increased draw the alternator is still at 13.4v?

Thing is why does the voltage drop at the Volt gauge and battery terminal measurement and not recover with each accessory that is turned on? It just drops and stays there with each accessory that comes on.
Should voltage not drop and then recover if there is adequate amp output of the alternator to service the accessory turned on?
Isn't that the job of the regulator to keep the voltage up to spec or again is it a voltage loss in the system?

Think I may try a 6 or 8 gauge test wire direct from the alternator output lug to the battery terminal block to see it that brings up battery charge.

Is this additional direct cable acceptable?

Thanks for continued help here.

[jagwit]

With no accessories on I get 13.65 at the battery, ..., drops to 13.3 with hdlts/hrt fan/radio, add the radiator fan ... and I'm down to 12.6 at 1500rpm and 12.9 at the battery 2000rpm and up... Same total load I get 13.4v at the alternator.

13.65 with 0 load is now a bit too low again. Should be at least 13.8V.

13.3 at the alternator under full load is a bit low, but it won't leave you at the road side.

If I understand you correctly, you are losing 1.05V (13.65 - 12.6) between the alternator and the battery with all the loads on??

That is bad. It means all the connections, terminals and wires between the alternator and the battery is responsible for this voltage drop.

Think I may try a 6 or 8 gauge test wire direct from the alternator output lug to the battery terminal block to see it that brings up battery charge.

6 or 8 gauge is bit too thin!!!

Use at least 4 gauge (the closer to 00 gauge the better)!! There should be a minimal voltage drop (my gut feel says less that 0.2V) between alternator terminal and battery terminal.

[mtnjag]

The factory harness is only 8 or maybe even 10 gauge from alternator output through the dash and back down to the terminal lug that the battery positive lead comes off with a heavy gauge wire. Starter also connect here.

Perhaps we are talking about different legs of wire. I am talking about from the alternator to the terminal junction lug the battery positive connects to.

The battery positive terminal to that junction is a typical battery cable, maybe 0 gauge or so.

[jagwit]

The wiring on the early English cars were done before Ohms law was invented = prehistoric. Running an unfused wire from B+ on the alternator into the dash (as per factory) is downright recklessly dangerous!!

I recommend you run at least 4 gauge (Preferrably thicker) from the B+ output of the Alternator DIRECTLY to the battery + terminal (on the physical battery). This way you also eliminate poor connections on the terminal post!

Please do this and let us know what VOLTS you get then.

(The ammeter reading will then be rather meaningless.)

[mtnjag]

OK, will do.

I have installed a Volt meter in place of ammeter. Volt meter goes to a ignition hot terminal on fuse block in dash and grounds to a mounting lug of volt meter. Volt meter is metal. Joined wires going through the orig ammeter.

Thanks

[mtnjag]

0 gauge battery cable from alternator direct to battery + post.
Readings done at 1500rpm, similar at 2000.

No accessories on was 13.6x at battery is 13.7x with cable
Drops to 13.6x (was 13.3) with hdlts/hrt fan/radio, add the radiator fan which is a big GM fan motor drops to 13.5x after a drop to 12.6 and quick recovery to the 13.5 (was 12.6).
Reading at alternator with all on is 13.7 at 1500rpm.