Upgrading alternator
 

What amp alternator should I upgrade to in my 1975 TA?
How should I wire it up and what size wires?
I am installing electric fans and maybe LED headlights and tail lights. It has halogen now.

I don’t want to rewire the entire car but I would love some help on some improvements I could make to the starting and charging wiring.

I’m darn sure not using the side post battery.

I know I’m going to fab up a a panel for the electric fans and thermostat that goes with it.

Pics of some of your set up’s would be great

Thanks!

What do you have now? LED's use less electricity. What is the requirement of the fans? It was recommended to me to use an alternator from a 1985 Buick Riviera with a 307 V8. It bolts right on and puts out 94 amps. Bought 2 from Rock Auto for my cars and they have been great. Last time I looked one was less than $80 with a $12 core charge. You of course will have to eat the core charge.

Thanks for the help Goatracer1 !

I recommend you spend some time reading these tech articles. Lots of good information on how GM designed the system and how to upgrade things.
It helped me convert from an externally regulated 37 amp system to an internally regulated 94 amp system. Without rewiring the whole engine compartment.

http://www.madelectrical.com/electrical-tech.shtml

GM moved away from externally regulated alts and was completely switched over in '72. No need to 'convert'.

The issue with the CS-130 alts is the bearings are small and susceptible to overheating, then failing. With a V belt, it's a effort to 'balance' between being too tight and slipping. Slipping belts overheat the shaft and cook the internal regulator, and too tight wipes out the bearings. Overtightened belts also wipe out water pump bearings.

Stick with a 12si, and I suggest the 100a Powermaster #7294. They are about $125 these days, and work both as OE or 1-wire. (I recommend OE hookup).

https://www.summitracing.com/parts/p...iABEgKmCfD_BwE

They are direct replacement, and can be clocked to face the charge post and connector to suit your app. Follow the included instructions for selecting the gauge charge wire (if it needs to be replaced/upgraded) and use only quality wire. For a 100a alt, the existing OE wiring should be fine. Powermaster takes into account for the quality variances of battery cables, and always recommends on the high side.

ALWAYS charge the (known-good) battery fully and use a new belt. Properly tighten belt, and check after about 25-50 miles.

I'm a big fan of the info provided by MAD Elec, good no-nonsense info. Some of the info there is meant to be used in pre-70 cars, but the info/principals are good to know in general.

If you are going to LED headlights, you don't need to do the 'Brighter Headlights' mod adding a relay, the OE wires are fine. As mentioned, LED draw a much lower amp load than legacy bulbs.

If you don't have a specific reason that you NEED to switch to electric fans, don't. The OE systems work great, just make sure your pulleys & fan clutch (correct application) are in good shape.

If you're having a 'running hot' issue, search here for possible causes and fixes. Look at the stickies in the Heating and Cooling section of these forums. And if you still have an issue or questions, post your running hot issue in that section in a new thread.


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Thanks for posting this information. I've heard folks rantng about the CS-130 alternator being "JUNK" but no one ever spoke to the actual reason. Of course I hadn't heard any this "bad mouthing" before I installed one in my Burban. Such is my life. 🙂

Thanks for the info! That gives me an idea of how to proceed.

The CS-130 was mainly used by OEs with serpentine belt setups, so slip isn't as big an issue due to great contact area of the belt. After a short while, they were offered with baffles, but they still suffered shorter life spans due to underhood heat.

OEs did for a while go to the CS-130D which had larger bearings and an open case to cool 'better', which was a knock-off of Denso alts (basically). They were a 'little' better, but are larger in size, and makes them a challenge mounting in non-OE cars.

Once you go over @ 130-150a alts, V belts struggle to not slip, so whatever alt you choose, try to stay around 120a max. With modern electronics and e-fans sometimes it's not enough amps, which can shorten life (duty-cycle) and kill regulators and batteries from the 'rollercoaster' effect.

If you are on the wall of that 130-150a load, you can manage/reduce the load by using more efficient accessories. But even then, you may still be on the ragged edge.


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Up to make this easier for me to find

I've had good luck with the Powermaster 12si on a few vehicles. On an older car where originality isn't a concern, I prefer to use relays for high current loads, and use the factory wiring to activate the relays. Good grounds and adequate current, things last a long time.

I'm running what I believe is a near 100A alt from a late 80's application, but it doesn't have the standard bolt spacing like the 10si. But I can get away with it on a 1st gen bracket setup. It has a 4 plug connector like a CS series.

I am thinking about getting an upgraded 10si. I run EFI and electric fan. My efan alone pulls about 20A. It seems like there are now a lot of high output 10si options out there.

On these upgraded 10si's, how is the idle charging output?

In alternator design, there is always a trade off between cut-in speed (shaft speed where the alt starts to provide output) and max output current.
The larger diameter of a 12SI helps improve the cut-in speed (all else being equal), advantage to the 12SI. The larger fan helps cooling, also. Alternator losses due to internal heat, friction, and windage can amount to about 50%.

George

Thank you. Will likely stick with my CS130 for a while for the idle charging. Was checking in because I see a lot of high output alts out there in the 10si packaging, wondered if there was benefit.

Another thing to consider is a PWM controller for the fans. Main reason being is the initial voltage 'shock' when the fans kick on are generally much higher than the rated amp draw.

If you have a fan that cycles full on/off/on/off, it will shorten the life of the ALT regulator. Drastically.

There may be 'soft-start' options that would be less than a controller, that may be an option.

Depending on your EFi, it may have I/O with +-PWM signal. You can use an OE type controller if so, which makes availability better, especially in a pinch.

As a note, I use marine batteries in my cars. They handle deep cycles and will charge at very low voltage levels. A bonus is some have threaded posts for battery cables, which makes it easy/nice to be able to make your' own cables.

I can't stress enough on the fact that you should use quality cables and ends, and when doing so, you usually can drop back a size or so. Battery cable should be clearly marked as SGT or SGX. SGX cable has a higher resistance to heat, and great for starter runs.

I get zero benefit for suggesting, but I use WireBarn.com, they are very affordable and ship fast:

https://www.wirebarn.com/Battery-Cable_c_1447.html

I usually go to Waytek for terminals, just to say.

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10si & 12si are nearly identical in case design, 12si are more heavy duty.

12si alts usually come in higher amp ratings than 10si units.

PowerMaster provides 'dyno' results which show amp output by shaft speed. Nice thing about that is you can see which have more amps at slower speeds.

When shopping the catalog, it has a general rating included for Idle/Cruise/Top End.


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