On my 72 Cutlass convertible, I will be installing heated seats and HID headlights. Also power windows, A/C, and power outlets for electronics (phones, GPS, etc...) No plans for amplified sound system...
How big an alternator do I need to power all this stuff?


Dave

 

How much current will it draw?

How big is your present alternator?

- Eric

 

The heated seat pads draw 3-5 amps per seat,
I am trying to find out what the HID light kits draw from the manufacturers (binged and googled without much success...) the ones I did find are about 4 amps low beam and 4.5 amps high beam. (It looks like for high beams they use a relay harness to the battery)


Not sure what the power windows or a/c would draw. The GPS, phones, etc should be very low demand.


(And since we have bad tobacco allergies, the cigarette lighter will not be used!)


My current alternator is listed as 63 amps...


Thanks

 

If mounting isn't a problem I would suggest the CS144. If you need something to fit better the CD130 would do. Not only do you need suficient amps, but you also need the alt to be able to supply the power at low RPM. Both the above units have a good low speed output.

 

The HIDs draw 63W, not much more than your original bulbs, which I think were 55W.
The seats will draw about 140W max.

The 63A alternator will put out 63A, or almost 900W, which is probably enough, but you'll probably get slightly dim lights at idle when everything's switched on (which happens anyway).

I'd say, for the added draw of the seats, I'd get a 75A alternator and be done with it, but further upgrades, such as the above mentioned CS144 are never a bad idea either.

- Eric

 

thanks for the replies folks!

 

Dave,
My 72 has a 63 amp alt (DN) and will be getting the full load when done. If the stock alt can't handle what the factory would have installed in a highly optioned car, I'd be very surprised. I'd suggest you install your options and then do a load test to see if the alt can keep up. If it does you're ahead of the game. There are 2 rules to this:
1. Don't sweat the small stuff
2. It's all small stuff, ok?

 

The easiest upgrade is a 12SI internally regulated alternator. You can get a 94 amp version as used on the 1986 Caddy Fleetwood with the Olds 307. Since it's internally regulated, you'll need to do some minor rewiring, as described in many threads here and elsewhere on the web. RockAuto sells this alternator for under $100 for a Delco rebuilt, plus core. Be sure to upgrade your wiring to accommodate the higher current.

 

You cant install too much alternator, it will supply only the amount of current needed. If you install a 160 amp alternator and the charging system needs only 75 to power the accessories then the alt will put out 75 amps. The extra 85 amps will be there as a reserve.

 

you size an alternator so that it puts out no more than 1/2 of it's rated hot output consistently. as stellar mentioned, the CS130 is your best bet. easy install, about 45 amps available at idle speed, 105 amps rated output. you will have to upgrade your output terminal wiring. you will need to run additional feed circuits for the additional electronics-please wire and fuse accordingly.


bill

 

I got a 105 amp alternator from a 89 Pontiac Safari that bolted right up, including the V groove pulley. Had to rewire it for internal alternator.

 

That's a CS130, also used on the 1988-89 Custom Cruiser with Olds 307 motor. The CS130 is a nice unit, smaller and lighter than the 12SI family, but there's one thing you must be aware of if you use one. The voltage regulator in the CS130 is very sensitive to the ground path. If you bolt one into the stock alternator brackets, the ground path is from the aluminum rear housing, through the steel stator core, to the front housing, and into the bracket. Galvanic corrosion between the aluminum and steel causes resistance that puts the CS130 out of action. There's a TSB that calls for a ground strap from the rear housing to the block if there isn't a stock bracket that does this. I had this problem on the second wife's 1992 Regal GS, which went through one alternator a year until I found the TSB.

That fixed the problem - well, at least until that car went away in the second divorce...