[TransAMrit]

For my '70 Trans Am, I've been looking at the Powermaster 37806 alternator (200 amps), but it has the CS130 casing. I believe the stock casing type is 10si (this is what the Summit Tech Rep said as well).

Can anyone enlighten me as to how the sizes differ, whether anyone offers brackets, or just how easy it is to install a CS130 in a 10si car?

I've considered the simple drop-in units from HO Alternators, but if the Powermaster can be made to fit, it's much cheaper (and shinier).

Thanks

[ponjohn]

The cs 130 case uses a serpentine belt. This is an issue for on the road repairs. I chose the 12si.

The application is 84 z28 HO, 95 amp. I run msd, electric water pump, fan and fuel pump. No issues.

The alt. I use is also a 3 wire. It is believed the 3 wires sense the load better, I have no scientific data to confirm or denie this.

[george kujanski]

Mechanically, I haven't had any experience with the CS130 series, but as ponjohn says, the 12SI mentioned above is a drop in; you can get one at probably any auto supply. Wiring up the 12Si is easy with simple mods if you have the externally regulated original charging system.

George

[BILTIT]

Yup, i went 12si aswell, bolted/wired up like factory alt.

[TransAMrit]

Unfortunately the 12SI alternators I'm seeing all seem to max out at 140 amps. My other car has a ~130 amp that can't keep up, and this car will be drawing more power than that.

Guess I'll have to ask Powermaster whether they have any relevant info - if not, back to the 10SI from HO...

Thanks

[BILTIT]

What are you running that needs that much juice?

[Bill Hanlon]

Maybe it is an electric powered '70 TransAm and he needs the bigger alternator to make it run faster.

[TransAMrit]

Electric fans, big stereo, EFI, DIS, and after a while, a PC. The other car is a 2002 WS6, and the 'smaller" stereo in it (~1250W RMS) pulls the voltmeter down to 13 and below often. Prob a bad thing, I should upgrade that one as well....

[ponjohn]

Before I spend the money ona 200 amp alt, I would spend a day going over the integrity of the current system.

Make sure all the grounds are substantial. Be certain you have a 8 or 6g ground run from battery to terminal block. All high current devices should be tied to this block.

Make sure the alternator you are currently using is operating efficiently......Use a volt meter to measure voltage at output stud, then measure voltage at battery....any substantial voltage loss will need to be addressed.

any issues are going to be exploited with the more current needed.

[TransAMrit]

To follow up, I came across this resource earlier today - it appears that converting from an SI to CS alternator is pretty easy. While the page is talking about Novas, it seems that in general you just need to convert the connector type, possibly cut out part of your alternator bracket, and add some washers to space out the bracket.

[HWYSTR455]

I've run about every alt possible trying to find 'the' alt for my application(s), and will gladly share what I've learned:

First, the factory replacement 10si alts are mostly 42a units, and as you know, not enough when adding today's accessories. In my case, at peak load, I draw about 88a, and a good rule of thumb is to double that, so that you're not running at max most of the time. I could go into why I draw that much, but ANYONE who has taken the time to calculate what their' load is with added components KNOWS that a 42a these days just won't cut it on the street. My dual fans alone at kick-off draw 28-32a, just to give you an idea. You add high beams to that mix, brake lights, elec fuel pump, and a stereo, and you've exceeded the max 'capable' load of a factory alt.

Physical Case Sizes- The 10si is in the middle, slightly larger than the CS130. The 12si is larger than the 10si, and in most cases won't fit the brackets. The CS130 will directly replace and fit in 10si brackets, with the only two exceptions being that the clocking is usually not correct, and the belt will need to be about 1/2 -1 inch shorter. The pulley on CS130s, as noted, are usually serpentine, but it's cake to change them. Oh, and the strap bolt (as well as others) are metric on the CS, but no biggie. (See attached pic for a mounted CS130 on my daily driver).

AMP Ratings - Ok, here's the catch, with V-belts, once you go over say 100a, because of the drag the alt puts on the belt, it becomes a balance of belt tension and slip. If the belt slips, the belt is toast, and further slip will prevent the battery from staying charged. Too tight, and you start killing water pump & alt bearings, and in extreme cases, can wear main bearings. IT IS MY OPINION, from past experiences, that you can't SUCCESSFULLY run anything more than say a 140a with V belts. I'll argue this point with anyone, and can give first hand examples. To completely avoid the whole v-belt thing, you can upgrade to a serp setup, which is most likely what I'll be doing in the near future. (But an ex*****ive alternative). Then you can run a higher amp model and avoid the issues with running in high duty-cycle.

Load at RPM- One other thing to keep in mind is the output of an alt at a particular RPM. Just because an alt is rated at 140a, doesn't mean at idle it will put that out. Look for companies that list output at particular RPMs, since they usually pay attention to output ratings. Just to tick you off, I will say that some are not accurate at advertised ratings, just to add to the mess. A good application for an alt that has higher output at idle is like police and ambulances. for example. Watch your volt meter while driving, and usually anything below 13.2 for any extended period is a good indication you're not where you're supposed to be.


Harness Adapters- No problem, and not only do people like PowerMaster offer them (see attached pic), you can grab one from the Help! products section at local auto parts. I've heard there's a trick to making the idiot light work, but I've never had that issue. Will say though if the belt is slipping, the light won't light up, so best thing to do is have a volt meter!

Other Things to Know- Number cause of failure on CS130s is heat. There are some that come with fans that help cool better, but in the long run, life on these alts is limited. Best advice- always have a spare on hand! In the trunk if going on trips, as well as a spare belt or two. On average, I get about 1 year or 20k max miles out of a CS130, as an example. I just did 3 200+ mile round trips to Philly from DC, and cooked one in between. I dropped back to a 10si spare because my spare CS130 hasn't been repaired. You can do that, but over time, the battery will be discharged and will cook the 10si. NEVER use an alt to charge a battery, will argue that one too if any would disagree. After driving on a lower-than-required alt load rating, put the charger on the battery.

CS130 Sources- A couple auto parts now carry PowerMaster alts, which is nice. I've been having fairly good luck with East Coast, and there are others that are acceptable as well. You could buy a new one and change the pulley, but in x period of time, you'll be replacing it anyway, so why bother IMO.

I think that's all, but if something comes to mind I'll add. Anyway, hope that helps some!

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[george kujanski]

I say ALWAYS use an alternator to charge a battery, best charger you can use.

Let the argument begin.

George

[HWYSTR455]

I don't understand George, why would you say always? Scenerio: You buy a new battery off the shelf, toss it in your ride, you start the car and let it fast idle to charge it? For like hours? Or what if it doesn't even have enough of a charge to start the car? I know the documentation that came with all the Optimas and Odyssey batteries say to fully charge before use. What about a car that's sat all winter?

A battery that's below say 12v, will place the alt into a full duty-cycle state to charge, and wouldn't that put an undesireable load on the rec-bridge?

Another scenerio: Wet battery. Happens to be low on fluid, and the top of the plates become exposed. Or an internal short. Would you want to put a load on the alt, or would you rather find out using a charger?

George, you're just jerkin' my chain, aren't you!?!

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[jjscerbo]

Perhaps you are attacking this from the wrong front...If the Stereo system is that much of a draw, add a capacitor to handle the voltage flux..Also add a second battery.

I added another battery tray in my 65 GTO on the right side. My alternator only puts out 100 amps.. Uses Duel electic fans, HID headlamps and 1000 watt amp to power the subs. So far no problems..

[HWYSTR455]

I have been looking at caps, would prevent spikes, that's for sure, might make alts live longer. Was considering a cap for the fans as well (run 2 caps total). Second batt might be mute at that point.

[george kujanski]

HWY: Perhaps the previous was too strong a statement. However, assume you have a battery that's almost dead from say, leaving the interior lights on. Obviously you need to start the car first so either you charge the batt enuf from a charger or jump it long enuf to get a reasonable charge into it where it'll start.

At that point, once the engine starts, let the alternator do it's thing. It'll put out more current than a bench charger and get the battery up to snuff in less time than a bench charger. You don't need to run it a fast idle; simple driving around will do the job. Granted, why run the engine JUST to charge the battery...that's a waste of fuel, use a bench charger. But if you're going for a reasonable trip, go ahead.

A simple way to approximate how long you need to charge a batt....assume you have a 70 Amp-hour batt that has been drained overnite. You can use a 10A charger for 7 hours or a 30 amp charger for 2.5 hours. An alternator in a normal driving cycle should be able to charge the batt at 20 or 30 amps.

Having designed and tested alternators, I can tell you that OEM alts are designed to produce full output, all day long, at high underhood temperatures. We tested ours in a heat chamber at full output for hours on end with no failures, Failures would be cause for redesign. They are made to take situations such as mentioned above. I can't speak for units that are rewound by aftermarket companies that claim 140 amps, in a 10SI frame, for example.

George

[george kujanski]

Capacitors are used to store electrical energy and provide bursts of current for short times .
A capacitor connected directly to a stero amplifier, for example, will help since music has transients such as a bass drum that require short bursts of energy. For those bursts, the capacitor stabilizes the voltage at the amp and provides the needed energy. Once the transient has passed, the cap recharges from the battery feed, and the cycle repeats.

For electric fans that require high starting currents, the starting current transient may last a lot longer than the capacitor can support, even a large cap. In any case, the fan start current will be provided by the alternator, or if the alt can't provide it, the battery will. Once the fan starts up, the alt will recover and replenish the battery energy as long as the overall system load is below tha alt output capacity.

George

[HWYSTR455]

George, that makes sense, and I have to say, I am far from having the knowledge & experience you have, my knowledge comes from hard knocks!

Your comment about the 10si at 140 is well taken, and you warned me about the one I had, which to no surprise took a dump in short order! I'm still in the same boat, need an alt that will last, and am looking to a new OE replacement, with around a 100-140 rating. Suggestions?

A cap on the fan, actually had a conversation with someone regarding, and basically said the same thing. He also mentioned that if you depleat the cap, and the current is still high from load, that you can cook the cap pretty quick. So, the idea of a cap on the fans isn't a good one!

[Slick]

Originally Posted by george kujanski

Capacitors are used to store electrical energy and provide bursts of current for short times .
A capacitor connected directly to a stero amplifier, for example, will help since music has transients such as a bass drum that require short bursts of energy. For those bursts, the capacitor stabilizes the voltage at the amp and provides the needed energy. Once the transient has passed, the cap recharges from the battery feed, and the cycle repeats.

For electric fans that require high starting currents, the starting current transient may last a lot longer than the capacitor can support, even a large cap. In any case, the fan start current will be provided by the alternator, or if the alt can't provide it, the battery will. Once the fan starts up, the alt will recover and replenish the battery energy as long as the overall system load is below tha alt output capacity.

George

And, it's important to note that a discharged capacitor is effectively a short circuit to the voltage source. As it charges, the needed current will diminish. But a big cap will take awhile to charge, during which the alternator load is increased.

I've built many an amplifier/preamplifier, etc. Some diodes (like Schottky types) cannot take a joke. Exceed their maximum current rating and you'll let out the magic smoke. As long as the caps you are planning to use have a high enough ESR, you should be fine. But beware of adding lots of them, the current draw is not insignificant.

Stuart

[HWYSTR455]

I run a pair of 1.5F caps, and can attest, in my experience, prevented the constant alt destruction scenario. Search it here, I dealt with it for a pretty long time.

Someone from East Coast Elec (I think) suggested using a cap, and I said what the heck. It solved my problem in 2 cars.

I literally would keep spare alts in the trunk, and had a graveyard of burnt alts.


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