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molemot

Uprated alternator

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Whilst the thing is in bits, I'm thinking of fitting an uprated alternator. The existing one, rebuilt by Sahib's Auto Electric, has been on the beast since 1989, iirc. There are 65 amp ones on offer on eBay for £58...new.... sounds inviting. The have Euro plugs...anyone know anything about Euro Plugs? My alternator has only two connections, the big one for output and one small one for sensing/warning light. Any info on fitting a higher output alternator would be welcome. 


Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Hi John, i've bought one these alternator. It's good and euro plug is the standard connector for the Lucas alternator. The USA cars were fitted with a Motorola and they have 2 wires connected directly to the alternator with stud and bolt. Seems strange that your car has a 2 wires terminal instead of euro plug.

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My original alternator blew up in the late 80s...the current one (no pun intended) came with stud connections...and my wiring loom only has two wires in it for the alternator...one big thick one that goes to battery +ve (the connexion to the starter motor) and the other a thin sense/warning lamp wire. No worries...I shall get one of the 65 amp beasts and sort the wiring to suit.

Cheers, Giorgio!!


Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Not really sure what advantage a higher rating would bring. It would charge up the battery a bit quicker after starting, but load the engine more while doing so.

With everything switched on the load would not be anything close to 65 amps unless you have a massive stereo or arc lights :)

Presumably the alternative Ebay ones are the type used on non-aircon cars, the version with aircon is different because it mounts differently and I could not find any alternative for this.

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I've found that, driving at night with the headlights doing their stuff, if one gets stuck in traffic and the fans run as well, then the volts go waaaaay down. 65 amps is an overkill, for sure, but it won't squirt 65 amps unless it's needed. Ought to keep the volts up to something sensible, though....never liked watching a system that can't cope. Did once run out of battery volts at night in the rain on the South Circular...not in the Lotus...turned out the dynamo had lunched itself and the warning light had blown. Trying to accelerate away from a roundabout it all just died. I was on my way back from France in 1980....had to take the battery out and fortunately found a filling station just down the road that had a charger and give it a couple of hours boost charge, which got me back. Took a lot of explaining as to why a jump start wouldn't help!!


Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Long time ago, I have investigated this problem and I found out that the stock 90A Valeo alternator does not meet our cars appetite for electricity.

Summing together just few bare minimums, like two pumps, ignition system, ECU (misnomer, it is just a Frequency Valve controller regulated by the Lambda signal from the O2 sensor) and air blower and stop lights, our cars require a minimum 50A at idle.

An antiquated OE Valeo can not deliver it at idle, (worth another "Emperor has no clothes" rant!).

Everything depends on the power curve shape.

Here is an example. I don't have the actual PC-s, but for the purpose of this discussion, let's say the red line is our Valeo alt and blue is a modern day machine.

Draw a vertical line at 2000 rpm and see where it crosses the blue and red lines. Some folks say: "Why do I need 200 or 250A alternator? I would never draw more than 120!"

The answer is simple: Steeper power curve provides higher output at the lower alternator rpm (think idle in the traffic in the storm). In addition, higher output alt will never reach the burning point (100% of the capacity), and runs much cooler. It does not allow the battery to drain deep and often. Batteries have a limited cycle life. Regular "start" batteries (not deep cycle ones) should not be discharged below 75% of the full charge. High alternator temperatures reduce the maximum output of a charging system, so cooling and sizing based on the continuous load matters. Heat kills alternators, so Bosch, for example, has water cooled models available.

Old OE Valeo (emphasis on "old", because Valeo makes some wonderful modern and very compact 145A machines), has a flat power curve and "kicks in" at the much higher rpm.

It has to work at the maximum (100%) output for a long periods of time, resultant in melting the regulator.

Electronic components should never be allowed to work at levels higher than 80% of their capacity, otherwise, they'll burn out.

Rebuilding the old OE machine = polishing the old turd. You'll spend the money and the result is guaranteed: 100% failure in the future.

The other victim of the underrated alternator is your battery. Some owners are spending themselves silly on some "exotic" (expensive!) batteries, like Optimas, and other.

Believe me, without replacing the alternator, they don't last any longer! I have a "regular" 850 CCA Duracell battery from Sam's Club for 95 dollars and it works perfectly well.

>> No matter how expensive is your battery, if consistently undercharged or overcharged, a lead-acid battery will lose capacity and performance and prematurely fail due to sulfation or loss of water.

For trouble free life,  one needs the largest battery and highest output alternator, limited only by weight, space available and cost.

 

                                     Lotus Battery                                                 86-88 tray dimensions 180mm f-Aft, w=7.08”

                               CA = 1000 (at 32°)                                                                                270mm side,  L= 10.6”

                               CCA = 850 (at 0°)                                                                                                         H=7.5+

                               L-10", W-7", H-7.5"

                               Group Size = 78DT

                               Type = 78DT-875  http://www.batterygiant.com/Product/78DT-875

Power Curves.JPG

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USA cars have a lot more gubbins on them, and the electrical system is completely different. It probably is worthwhile on these cars.

Standard cars have very basic wiring, only 8 fuses in total and only 4 relatively thin wires running from the battery to the whole car (excluding the starter). If the consumption on a standard car were 50 amps, the wiring would melt.

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Fantastic work John. I think the S3 fares a little better with less draw: that said after reading your post I will be upgrading my alternator soon.

cheers

Simon

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When driving my turbo in the dark with lights on I notice my battery light appears on sometimes but quite feint. 

I like the idea of fitting a more modern alternator but I think its the mounting thats thre problem. My turbo one is quite a special mount compared to most on the market.

 

Buddsy


 

"Belief is the enemy of knowing" - Crrow777

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The standard alternator on S3 and Turbo is 70 amps. Not sure about S1-S2.

The only time anything close to that would be drawn would be when recharging the battery after starting. On modern cars which have higher output units, they are driven by a poly-V belt. Loading a single V belt with a higher mechanical load of a higher output unit would mean either it would squeal after starting or would need to be really tight which would load the alternator bearing and the crank bearing more heavily.

if the light is coming on then there is something wrong with it, maybe one of the diodes is on the way out.

The alternator on air conditioned cars has special mountings. Non aircon are pretty standard I think.


 

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On 2/23/2016 at 05:33, Buddsy said:

When driving my turbo in the dark with lights on I notice my battery light appears on sometimes but quite feint. 

I like the idea of fitting a more modern alternator but I think its the mounting thats thre problem. My turbo one is quite a special mount compared to most on the market.

 

Buddsy

Here is a simple check procedure: http://www.allpar.com/fix/codes/sensors/charging.html

http://www.knowyourparts.com/technical-articles/alternator-and-starter-diagnosis/

 

 

Edited by MrDangerUS

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On 23/02/2016 at 10:33, Buddsy said:

My turbo one is quite a special mount compared to most on the market.

 

You can almost visualise the head-scratching which went on over this in the factory. On the dry sump cars the alternator is mounted where the A/C pump normally goes, and the A/C was on the other side. On the wet sump the sump is in the way so they had to move the A/C back to the right, and then there is no room between the A/C pump and the plenum to fit the alternator in.

So they had to move the alternator further forward so it clears the plenum and upwards so they fitted the tall mounting bracket onto the auxiliary housing and a long metal adjuster strap and the different mountings on the alternator.

According to Mike at Lotusbits they had some of the metal straps break, with disastrous results, so they changed to a nylon strap and added the triangular brace bracket which bolts to the alternator, tensioner and water pump. 

Thats the reason for the odd shaped alternator on the A/C turbos. This must be from another car but dont know what. The people who rebuilt mine didnt recognise it at all. It might be from an American car.

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2 minutes ago, andydclements said:

Or just drive at higher revs :devil:

Say the man who's Esprit Electrics work such that sometimes your headlights go a bit dim and the solution is putting them down and popping them back up while driving at 90mph in the dark..."Oh they dont always come back up...." :lol: Pants prepare to be soiled!

 

Buddsy :hrhr:


 

"Belief is the enemy of knowing" - Crrow777

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I have bought one of the 65 amp ones from eBay...when I get everythng back together, I shall report back on the results.

 

My boat is driven by a Ford 105e Anglia engine, marinised by Watermota. It had a dynamo for years and years..I replaced this with an alternator when I revised the electrics to have a seperate battery for the hotel load, as well as the normal starting battery...working through a diode splitter. Since the engine only ever runs at pretty low RPM (especially when stuck behind a péniche barge!) I fitted the alternator with the smallest diameter pulley I could find for it. This definitely helped the charging, by increasing the alternator RPM.

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Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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3 hours ago, molemot said:

I have bought one of the 65 amp ones from eBay...when I get everythng back together, I shall report back on the results.

 

My boat is driven by a Ford 105e Anglia engine, marinised by Watermota. It had a dynamo for years and years..I replaced this with an alternator when I revised the electrics to have a seperate battery for the hotel load, as well as the normal starting battery...working through a diode splitter. Since the engine only ever runs at pretty low RPM (especially when stuck behind a péniche barge!) I fitted the alternator with the smallest diameter pulley I could find for it. This definitely helped the charging, by increasing the alternator RPM.

The Ferrari 328 uses a custom small alternator pulley as well so you are in good company :)

But on the Esprit, a 65 amp one does not really tie up with the thread title since its a downrated alternator by 5 amps.

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Not on mine, it isn't!! Mine dates from 1988 when the original died and I fitted what is on there now. Whatever it is, it sure isn't anywhere near 65 amps....it won't even support the lighting and the fans at the same time!


Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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On 2/23/2016 at 05:33, Buddsy said:

When driving my turbo in the dark with lights on I notice my battery light appears on sometimes but quite feint. 

I like the idea of fitting a more modern alternator but I think its the mounting thats thre problem. My turbo one is quite a special mount compared to most on the market.

Buddsy

TIP: if we rev the engine, we increase alternator speed and output, and if as a result the light gets dimmer it means the alternator output was weak (it must be increased by revving the engine to try and equalize the voltage across the lamp).

If, however, the lamp gets brighter when we rev the engine, it means the battery voltage is low. This is because battery voltage does not vary with
RPM. Therefore, if an RPM increase causes an increase in lamp brightness, it can only be because the increasing alternator output is getting even higher than the battery voltage. With a healthy battery, this won't happen - battery voltage will match alternator output. But if the battery is unable to take or hold a full charge, the more we increase the alternator output the more it exceeds the weak battery voltage and the brighter the lamp will glow.

In summary, we can say that:
Any time the alternator warning lamp is on, there is a voltage difference between alternator output and battery voltage.
The light should come on bright when the ignition is on but the engine is not running [battery voltage ~ 12.6V / Alternator output 0V]. If it does not, or is only dim - suspect either:
Burned out lamp
A problem with the field current supply (low battery voltage or switch/wiring problem)
A problem with the alternator ground.

If the light comes on when the engine is running, either the alternator is failing/has failed or the battery voltage is dropping. Try revving the engine and observe the intensity of the tell-tale light:
If the lamp gets brighter, suspect a bad battery
If the lamp gets dimmer, suspect a bad alternator

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