How many amps (alternator)?

[Ed]

Hello,

I'm curious as to how to determine the amp requirement of an alternator to use?

the car  will have EFI, 2 fuel pumps, and usual stuff (wipers, headlights H4, heater, no air con or big stereo).

will a 60A alternator be OK?

or would driving on a cold, windy night with all accessories on overload the 60A alt?

Reason i ask is I have found a small 60A alternator which will fit the engine bay superbly.

The auto elec reckons 85A min.  I just need some more opnions.

Cheers

Ed

[Jonno]

Hi Ed,

try here:

http://www.oldholden.com/possible/index.php/Maths#Amps_and_Volts

jonno

[Sarge]

Ed
   For what it's worth I have a 85A in my car and its only a six cylinder with heater sterio amp wipers H4 headlight and spottys, an all that standard stuff. On a cold windy rain night it strugle's to keep up. I am lucky we dont get too many nights like that up here on the coast. Hope this helps.

Cheers
Sarge

[Ed]

Thanks guys,

i also did some research into std commodore alternators and they appear to be 85A.  although the heater blower sucks a massive 40A going by the size of the fusible link... lucky i dont have one fo these.

The main fusible link is 60A and the engine (EFI) link is 30A, so I will persist in trying to use the alternator I have.  

I will modify a manually adjustable power steering pump idler pulley to tension the belt and solid mount the alternator itself.

Jus to share some of my alternator frustrations and research..

On early Holden V8s, an HK alt mount can be used with the alt placed over the top, standard low covers are probably better for clearance too.

On EFI Holden V8 the cover has a PCV outlet on the front side restricting alternator mount positions, plus the tall rocker covers.

A VS commodore alt bracket was obtained and this allows a standard size 85A alternator to be solid mounted above the oil pump, or a 60A Daihatsu Charade alternator (EFI model only) to be mounted conventionally, and adjusting it's position to tension the  drive belt. Although I doubt 60A is enough for an EFI V8 now.

I also have in my shed a 120A monster alternator which is much bigger than the 85A unit.  This has troubles fitting anywhere!  although with use of a double row (or even triple) V belt pulley on the crank I may be able to space it forward enough to custom make a mount for it... or hang it out high and wide enough (UGLY) to be used.

This is of course at the expense of using a normal engine fan, and having to use thermos mounted on the radiator.  Do thermos pull or push better???

Anyway.. hope somebody has got something out of this.

Aren't conversions fun?

Cheers

Ed

[smithy]

hi ed, from what ive seen with thermos most have been mounted at the front, but i guess it depends on which way the fan blades are set ( rotation) , one way the fan sucks the air through the other it would blow....

[smithy]

doh!!
sorry ed just re-read your post....
if the fan is a suck through type then it would benefit greatly with a shroud of some sort  to limit the amout of air being sucked in from around the radiator instead of sucked through.
dean

[Ed]

Thanks Dean,

Cheers

Ed

[GM]

HI ed, I have the old red 308 from an H.X. and it used to run a 55 amp. alternator, without the injection, but twin thermos. I ended up changing it for a 120 amp. Thermos are better sucking if you can sqeeze them in. [I didn't want to mount them on the radiator] Good luck in Jindabyne. Viva la Bali, leaving tomorrow.

                  Cheers Glenn

[Ed]

Hey Glenn,

Finally got the 120A alternator fitted.  Was an easy job in the end.
Im quite sure it's from a VS commdore, the wiring has me a bit miffed tho.

there is the alternator to battery lead.
also another couple of plugs I cant decipher.
Does this alternator require an exciter power source?

Any clues on wiring up the late model alternator would be appreciated.

Cheers

Ed

[GM]

Hi Ed, yes you need the power source to excite the alternator. I ran an ignition light (idiot light same thing) to put a small drain on it. Without this drain, you need to rev the engine much higher to excite the alternator.
          Hope this helps.
                             
                                  Cheers, Glenn

[Ed]

Thanks Glenn,

Also got a copy of a wiring diagram as well. Thanks Andrew.

Cheers

Ed