blue dog

Im upgrading my battery and was going to upgrade my alenator but i found on another forum that they are just high priced junk and wont last and can NEVER put out as much charge as they claim. Anybody on here running a MEAN GREEN or POWER MASTER have any input? other people are saying to just add dual batteries, but i was going to do both - dual batteries and HO alt.

88_cherokee

i put in a grand cherokee alternator and works fine

cruiser54

Upgrade your cables first:

http://www.kelleyswip.com/electric.html

macgyver35

The first question to ask is, do you really need higher amperage than what you have. Unless you regularly plan on running 400+ watts of additional lighting, or you have a winch, or a 600+ watt high-powered stereo that plays at full-tilt all the time, I don't know that you'll even benefit from the additional juice.
It would be like buying an extended range fuel tank and then only ever making short trips around town.

The previous advice about upgrading cables still reaps long-term benefits in any case, and is as good an excuse as any to clean and tighten all your main power connections.

blue dog

back in the day i would have a large stereo and lots -o- lights but not anymore - really just thought about upgrading since it was broke, and since i will be adding a couple LED offroad lights, a winch, and onboard air. - also really wanted to add dual batteries and possibly an onboard welder. im not building my jeep to be the ultimate party rig or ultimate rock crawler but more of an expiditon vehicle and wanted to make sure it would be able to sustain itself when way out in the backwoods. i look at upgrading my alternator and adding dual batteries kind of like adding a winch or roll cage, sure you might hardly or never use it, but when you do need it, its good that it was there. - but that being said, i read on another forum how they really dont put out the claimed charging power.
this from another forum -
"
I don't know how to tell you this, but the 'Super Duper' alternators and starters are just factory units that some guy has played with the numbers...

See,
Your factory alternator will probably will put out 250 amps at about the same 250 volts...
It just won't do it for more than a few seconds...

What I've tried to teach here before is...
There simply isn't room in the case for a bigger heat sink (Cooling fin surface area) for the rectifier...

SO!
No matter which alternator you get, if it's a Delco SI series alternator,
The absloute limit of SUSTAINED output is going to be around 70 or 80 Amps depending on what fan the alternator has, what the outside temprature is, and now much cool air flow is going through the engine bay.

Any more than that for more than just a few minutes, and you will cook the diodes in the rectifier, and the alternator will fail to function.

What you need to know is,
YOUR ALTERNATOR is RARELY TAXED BEYOND 35 OR 40 AMPS...

Since your fusible link from alternator to battery can't take much more than 40 Amps before cooking,
And most of you are still running the factory fusible link,
It stands to reason your battery has NEVER demanded more than 40 or so Amps MAXIMUM from the alternator at any time in the past 23+ years...

The SECOND thing you might want to know is,
There are TWO "CORRECT" ways to rate an alternator...

One is for 'Consumer' grade alternators, like the ones in your vehicles.
The rating of the 'Consumer' grade alternators is the MAXIMUM SHORT PERIOD CHARGE...
When a 'Car' alternator says 65 Amps, that means 65 amps for sustained periods, but not full time output.

Then there are 'INDUSTRIAL' rated alternators.
These are rated at their 'Nominal' output.
When a big truck alternator says it's '105 Amps'...
That means it has enough cooling heat sinks in the rectifier to put out 105 amps ALL DAY LONG, EVERY DAY,
Not just for short periods of time like 'Consumer' alternators are rated for...

Since the 'Aftermarket' doesn't have to adhere to any KNOWN or ACCEPTED industrial or remanufactured unit standards,
They often rate theirs at the MAXIMUM they will put out... Just before cooking it's self!

If it says '240 Amps', that is the rating average of the parts they use.
The altenator will 'Flash' to 240 Amps before it burns out the regulator or the rectifier, but the heat sinks in the alternator will still only handle about 60 or 70 or 80 amps for any period of time before it cooks it's self...

They are just playing with the numbers boys!
You are MUCH BETTER OFF to get a 10 SI or 12 SI alternator replacment from the local 'Discount' place with lifetime warranty (for about $40!), so when you fill it with mud/sand/water or whatever, you can just go get another one!

If you want slightly better low RPM charging, try using a Delco CS-130 alternator with $25 wiring adapter from NAPA.
IT will bolt right in, the adapter makes it a direct plug in, and you are off to the races for under $60 usually!
__________________

wrapstar

Everything you said is false my dads been rebuilding alternators and starters for the past 40 years I have a 180 in my jeep the amps output is all in the stator. For the old 10 si i can buy 150 amps units straight from the mfg. And a cs130 won't work in a jeep as jeeps are externally regulated and the alternator is internally regulated it'll kill the ecm .

If you want more amps cheap for a newer xj go get 99 durango alt. From a junk yard average amps are 160 just have to swap the pulley and shave the bracket

blue dog

that quote was NOT from me - i pulled it off another forum and just wanted to see some reactions and/ or responses that there is no such thing as a high output alt. sorry if yall took it as me saying all that junk - im just curious if it is a good idea to upgrade the alternator or stick with stock for eas of ralacement and low cost.

kjc

Hi blue dog.. I have nothing to contribute, but reading what you posted from another user, I just wanted to say.. sometimes the less someone knows about a subject, the more they seem to go on and on with misinformation. Saying an amp will 'put out' 250 amps is like saying the fuses in your box will put out 15 amps before they blow.. thanks for the chuckle

5-90

Not so - 1987-1990 XJ/MJ w/AMC engine got the CS-130 (except some four-cylinders that got the CS-121, but they're uncommon enough to call truly rare. And the 1987 Diesel got a Paris-Rhone.)

The Nippondenso wasn't used until 1991. And, 1984-1986 XJ/MJ got a Delco SI series (12SI, I think,) and this persisted in the YJ until the 6-258 was replaced with the 6-242 for 1991, as I recall.

(I usually have to counter information going the other way - people trying to throw 136A NDs into RENIX rigs. Don't work - not directly, anyhow. But, if you do it and throw in the voltage regulator, you don't have to deal with a persistent CEL/MIL...)

There are CS130 applications out there out to 140A, and it's just a matter of swapping internals. I really need to work up that donor list, one of these days...

As far as output, alternators are typically only "a little oversized" for the anticipated draw (I think there's something like 25-30% "overhead" there, to allow for topping up the battery after starting,) so you can rapidly run into trouble if you add accessories and have them on frequently. (If you don't turn them on for the first ten minutes or so you're driving, it's not a big problem - because you'll have the "overhead" to top up the battery.)

Of course, OEM wiring is usually selected with full output in mind - at a relatively low duty cycle (60%dc would be considered "excessive," from conversations I've had.) That's why upgrading wiring for an upgraded alternator is a good idea - we have to assume that you usually want the extra capacity so you can USE it (and that's why I use pessimistic assumptions when selecting wiring, except in certain cases where I know I don't need to.)

I have an upwound alternator because I was able to get it for a good price, and it was offered to me. It's come in handy - mainly, when offering jump starts (I can fully charge a flat battery in about three minutes, at a high idle. It's a surface charge, but it's usually enough to kick the vehicle on and let it take over.)

Another advantage to an upwound alternator is that, while you would still use the same current normally (an alternator will only put out what the regulator tells it to,) it's going to be a lower percentage of the total output, therefore a lower taxing of the electronics in the rear case. This usually means diodes and rectifiers last longer (with solid-state electronics, heat is the enemy. Now, which is going to generate less heat - 80A running rectifiers at 80%, or 80A running rectifiers at 55%? Which do you expect to last longer?) About the only component that can expect extra service life is the brushes - wear on them is due to friction - which means spring tension (pushing them into the sliprings,) slipring surface (although it gets gradually smoother with age - but if you have the back half off, a quick hit with 180-grit emery is indicated. Flush with contact cleaner) and spindle speed.

Also, an alternator cannot generate its full output at idle speeds, without changing pully ratios around. Figure that you're only going to get, say, 60% at idle speed. Sixty percent of 136A is going to be more than 60% of 90A, no? This can be at issue if you expect to idle for long periods of time with high electrical loading (that's why police cars have an "extended idle" switch - if they've got someone pulled over with the lights on, they hit that switch to bring up the engine idle speed, and supply more from the alternator. Later systems will automatically kick on the extended idle if it sees the lightbar is on, I've wired a few up.) You don't get to see full output from an alternator until about 3300-3400rpm at the spindle, or ~1100rpm at the crankshaft (it's usually about a 3:1 advantage.)

If you're going to do an upgrade using OEM/COTS parts, it's not a big problem - and usually relatively cheap.

If you're thinking about doing an alternator with something like Powerman, Mean Green, or Rush Power Systems - plan on doing a cost/benefit analysis to make sure it's worth dropping all that coin... For most people, it is not. (I'm not running down their work - just saying that most people really don't need to spend that sort of money. Save it, and spend it on your next set of tyres, or take your S/O somewhere nice so she doesn't kick up a fuss about that 6" lift you just got...)

wrapstar

Sorry I get mad when people feed other people a ton of garbage about charging systems. Custom charging systems is how I fund my jeep build. I can say powermaster is junk iv repaired a ton of them and toured there plant in tn. When I lived there.don't know anything about meangreen but there sales pitch is b.s. if you want good reliable power find a local rebuild and don't go over 180. I can winch with my 130watt lights, heat on, system cranked and it doesn't phase the alt. but I also have dual batteries

DNNDRTY

I am interested in what you decide on. I am thinking of upgrading my 90 amp alternator to a mean green, but have read a lot of mixed reviews and things about upgrading the wiring also. I can tell you that my 90 amp alternator is no longer strong enough to support my cherokee. drained a few months old battery. I have 6 aux lights, 2 of which stay on whenever headlights are on. a high powered sound system that i blast 24-7, and a lot of other high watt items.

what I may do is invest in a compacitor for the sound system and find a junkyard grand cherokee alternator like people talk about.

ZINGGG

If you upgrade the alternator, you are going to need to upgrade your cables as well. So make sure to factor that in. 5-90 (posted above), makes great wires that you should look into

blue dog

I of course would upgrade my cables if i upgrade the alternator -
correct me if im wrong but it seems like most of yall are saying that it is better to just replace it with a stock alternator and to upgrade the cables at the same time and to add a secondary battery, that way if i did mess up another alternator it is easy to find a replacement, and i wont be out as much $. So - i would get more benifit from replacing cables and adding secondary battery (id be running dual DIE HARD MARINE PLATINUM batteries / same as an ODYSSEY battery) and running a stock alternator - correct?

wrapstar

It depends on what one you have 90 or112 amp. A 90 will have a hard time keeping 2 batteries fully charged.

blue dog

ok - i will check -
like iv said - i dont need it for a large stereo - just trying to make it more reliable in the back country for when lights may be runnin, or winching, or onboard air, or if i get an onboard welder, but i seriously doubt ill be using any of them at the same time, so i guess it would stand to reason that as long as i have a decent alternator and a good reserve (aka: 2 depcycle batteries) i should be fine.