Batteries, Alternators, and Winches (AGAIN!)

I've been told by guys in my local club, and have seen on here, that I need a high amperage alternator (160, or preferably 180 Amps) and an Optima yellow top gel-cell battery for my new 8000lb winch. But, a couple of things come to mind.

1. A 6000lb Ramsey winch was offered for the XJ from the factory, and an 8000lb winch was offered as a factory option for the TJ, yet these vehicles only came with a 90 AMp or 120 Amp alternator. Would the factroy risk cooking the alternator or the winch motor on a vehicle with factory warranty?

2. My service manager at the garage where I work is a long time, hard core off-roader. (1980 Chev stepside, on a military 5/4 ton frame, running 40"tires, D60 and 14 bolt, 500+HP big block, and a rock buggy on 2.5 ton rockwells, coilovers and running 53" military tires). He told me to pick up the highest amperage factory alternator I could find, and the highest CCA battery with the best warranty I could get. This, with good connections would adequately handle the winch. He said I didn't need a deep cycle battery as I am only an occasional off-roader, and won't be draining it again, and again, and again.

Shopping locally, I can get a 180 Amp alternator and Optima battery for $525 Canadian. They won't take my alternator as a core.

A rebuilt Grand Cherokee 136 Amp alternator (5 year warranty) and 800 CCA lead acid battery is $337, and they will take my alternator as a core, so about $310. The battery has a 5 year replacement warranty, and a 7 year pro-rated warranty. If I go the junkyard route for the alternator, I can be set up for about $200.

It's important to me to shop locally. I've comparison shopped over the net and once shipping and exchange rates are accounted for, the differences in price aren't enough to sway me. I like that if something breaks, I can walk back into the place where I bought it and get a replacement right away.

ideas, insights, opposite opinions?????????????

Thanks,
Geoff

just remember that the rating of an alternator is the MAX OUTPUT, you will not get this at idle. Okay you can get it at idle with some very expensive alternator ($500 and up) or with a very small pulley. and the larger the output the faster you have to turn the alternator. for example take a 55 amp and a 210 amp alt. at the engine idle speed the 55 amp will put out prolly between 40-50 amps just of idle it will put out all 55 amps, the 210 amp model on the other hand, well i have seen one on an ambulance that put out only 3 amps at idle, just of idle it was about 40, but it took almost full engine rpm (diesel) to get all 210 amps. this was a factory ford econoline setup with the ambulance prep package. needless to say the batteries went dead fairly quickly when sitting a scene running the lights at an accident.

I have a winch, a better stereo (not huge only 1 sub) a lot of lights and a lot of creature comforts (heated seats, heated mirrors, etc etc.) and my electric fans pull a continuous 40 amps, and i have been running a 140 amp alternator for over 5 years and never had a problem, wit the alternator. the battery on the other hand is a different story, i hate optimas. enough said.

anyway i would look into ordering a smaller alternator pulley from Brad at http://www.kilbyenterprises.com/. he can set you up with a smaller pulley to turn the alternator a little faster giving you more amps at idle.

for batteries i would look towards the Odyssey, i have never had a problem with it and currently i am only running one of their PC1700MJT model, although when i win the lottery i will add a second one. Very good batteries but a little expensive at around $180 each. but worth it ion my opinion. smaller than a optima (no wasted space due to round cell design) and has the a better starting output the reserve is not there, but as you've been told and i agree you don't need a deep cycle. although the odyssey will do both.

just my $.02 worth, take it for what's it worth

Dingo

Excellent point regarding alternator output at idle. i have been looking for a smaller pulley to boost alternator output at idle. alternatively, I was thinking of just slapping in a 120Amp alternator, and a throttle cable. A 120 amp alternator at high idle is worth more than a big buck alternator at low idle, I figure.

BTW, this guy told me his alternator put out 70-80 Amps at idle.

http://cgi.ebay.com/ebaymotors/Jeep...emQQcategoryZ33573QQihZ003QQitemZ130002524923

Geoff

You are probalby not going to find an electric winch with a current draw down around what the typical high-output alternator will give you, and it's a certainty that you're not going to find an alternator that will have a high enough output to drive your winch directly - unless you get one off of a City bus, or it has "Leece-Neville" cast into its backside...

Therefore, you're going to have to pick your battery accordingly.

As has been mentioned, the "rated" output of an alternator is actually a "MAX" output, and can even then vary by 10% or more. You'll want a middlin'-high output to recharge your battery quickly, and I'd seriously consider adding a second (deep-cycle) battery if you plan to do a lot of winching, just to give you greater reserve.

The regulator for your alternator really is a voltage regulator - it maintains system voltage according to its "sense" lead, and current follows. If there is little draw, it sends a low voltage into the "field" coils, which generates a low current output. Higher draw? The voltage dips, and the voltage regulator sends more voltage into the field coils - creating, in turn, a higher output current (voltage is supposed to remain fairly constant.)

Running an "overdrive" pully on the alternator (if it's smaller, it spins faster, and it's an "overdrive." If it's larger, it spins slower, and that makes it an "underdrive") is going to be a tradeoff - yes, you'll make a little more power output at idle, but you'll also accelerate bearing and brush wear as well. Is it worth it? That's up to you - but nota bene that I am heavily into reliability - and all my replacement alternators that I get are spec'd for at least 150A full output, and have a 15% underdrive pully on them. I don't replace them very often... Once seems to be about the lot.

Something else to consider - if you've got a 1991-up XJ, and you plan to sit at idle a lot (or do a lot of winching,) there is an "extended idle" circuit available in your PCM, and addition of a toggle switch gives you the option to activate it. I don't have a lot of information on that, but it's been beated around pretty good here, and you should be able to find it with a brief search. The "Extended idle" was a police model option, and enabled something like 1200RPM elevated idle with the flick of a switch. Why? Imagine what all equipment a police vehicle has that draws electricity (lightbar, spotlights, radio repeater, handheld light charger, mobile data terminal, ...) Typically, alternators will hit "full rated output" at about 1200-1400 crankshaft RPM (because the alternator pully is so much smaller than the crank pully, it turns about three times as fast,) and that will extend your power availability without undue engine wear. Something else to think about...

As far as battery capacity, I don't think CCA is what you want to look for. That's "Cold Cranking Amps," and is a measure of instantaneous current delivery at 0*F. You'd be more interested in "Reserve Capacity" - sometimes listed as "RC", and expressed in "Ampere-hours" or "A-h." This is a measure of constant drain over time (you're not going to be drawing this "cold" - the battery will be well-heated by the engine by then...) and the "Amp-hour" rating is flexible - as long as the combinations add up. Take a 20Ah reserve battery...

80 Amperes for one-quarter hour
40 Amperes for one-half hour
20 Amperes for one hour
10 Amperes for two hours
5 Amperes for four hours
(see a pattern yet?)
4 Amperes for five hours
2 Amperes for ten hours
1 Ampere for twenty hours.

So, as long as you multiply "Amperes" by "hours" and get 20 (or whatever your rating comes out to be,) you know how much time you've got. That's key - as I'd said, "CCA" is instantaneous delivery, while "RC" is current over time. A critical difference! Granted, there is some relationship between the two (since they're both a function of plate chemistry and battery construction,) but the one does not necessarily imply the other. Take a deep-cycle battery - they're not designed for instantaneous high outputs, but they'll give you 10A all damn day!

I'm honestly not trying to say your SM doesn't know what he's talking about, but this is a little point that seems to elude most, and I thought I should clarify it...

As for the alternator, I'd highly suggest going with a small local shop, rather than a chain store. If they're anything like they are down here, you can figure that the chain buys their units by the truckload for about twenty points or so, and the reason they offer a "Lifetime" warranty is a crapshoot for them - they're betting that you won't get a bad one out of the box (it's happened. I wasted three and a half years at a chain store...) Going with a smaller shop, you'll have the advantage of dealing DIRECTLY with the people doing the rebuilding, and better QC - even if you have to pay a little more (I usually don't...) it's well worth it. I'm not sure about the guy on Ebay you'd be dealing with - but there's also greater peace of mind to be had in dealing with a smaller local shop...

You can run a pair of batteries - have a small primary "starting" battery, and a larger secondary "deep cycle" battery on an isolator or a solenoid. This will not only give you the best of both worlds, but you'll also be able to do pulls with the engine off for whatever reason (without impairing your ability to start,) or add an override switch and cut in your DC battery if you lose your starting battery.

Just a few thoughts...

5-90

5-90, I was hoping you'd pop by!

First, thanks for all the info. I've read your posts before and know you know your stuff.

With regard to amp hours... The local shop that sells the very expensive, high output alternators have told me that an 8000lb winch will draw 300-350 amps. That means that a 20Ah battery would drain in almost no time. Does this number of 300-350 amps sound reasonable to you?

My service manager's point essentially was that no battery will stand up to the draw from a winch for long, so get one that has a high CCA rating to account for the very high initial draw, and don't run your winch for long stretches.

And lastly, with a 150 Amp alternator, and a 15% underdrive pulley, is it right to assume that you are only making about as much amperage as you would with a good factory alternator? (Although the point about reliability is well taken.) It seems that what you are suggesting is simply a good alternator (not extremely high output) and a deep cycle battery. Is this accurate?

I'm going to go re-read what you posted.

Geoff

BTW, a co-worker is helping a buddy build a rock buggy. They were going to run a dual alternator set-up, but lucked out and got a junkyard alternator from an ambulance. It makes 250 amps.

5-90 said:

Running an "overdrive" pully on the alternator (if it's smaller, it spins faster, and it's an "overdrive." If it's larger, it spins slower, and that makes it an "underdrive") is going to be a tradeoff - yes, you'll make a little more power output at idle, but you'll also accelerate bearing and brush wear as well. Is it worth it? That's up to you - but nota bene that I am heavily into reliability - and all my replacement alternators that I get are spec'd for at least 150A full output, and have a 15% underdrive pully on them. I don't replace them very often... Once seems to be about the lot.

Click to expand...

just for comparison, i have a 120 amp delco alternator in the shop that has a smaller pulley than the nippondenso that we use on our rigs. and to my knowledge the delco (don't remember the model the newer one after the cs-1300 doesn't have a reliability issue. the diameter of that pulley is the same that kilby lists on there site. from what i can measure when i had a Tahoe the crank pulleys are very close in diameter, less that 1/2" large haven't done the math yet but I'm guess the alternator still turns faster on the Chevy. Also the nippondenso are very common on the newer import cars that see way engine rpm than the 4.0 ever will. just something I've noticed along the way.

5-90 said:

Something else to consider - if you've got a 1991-up XJ, and you plan to sit at idle a lot (or do a lot of winching,) there is an "extended idle" circuit available in your PCM, and addition of a toggle switch gives you the option to activate it. I don't have a lot of information on that, but it's been beated around pretty good here, and you should be able to find it with a brief search. The "Extended idle" was a police model option, and enabled something like 1200RPM elevated idle with the flick of a switch. Why? Imagine what all equipment a police vehicle has that draws electricity (lightbar, spotlights, radio repeater, handheld light charger, mobile data terminal, ...) Typically, alternators will hit "full rated output" at about 1200-1400 crankshaft RPM (because the alternator pully is so much smaller than the crank pully, it turns about three times as fast,) and that will extend your power availability without undue engine wear. Something else to think about...

5-90

Click to expand...

i don't think that info is entirely correct about the high idle switch. i have a 91 and have never bean able to get the idle any higher. From my time at the dealership there is a specific computer used for police package xj's i would guess that (at least in 91) the non-police computer doesn't have this option.
I found both pins that people had been talking about and neither with either ground or pos increased the idle. Believe me i would have loved it if it was possible but i don't think it was available in 91

Dingo

gcam said:

5-90, I was hoping you'd pop by!

First, thanks for all the info. I've read your posts before and know you know your stuff.

With regard to amp hours... The local shop that sells the very expensive, high output alternators have told me that an 8000lb winch will draw 300-350 amps. That means that a 20Ah battery would drain in almost no time. Does this number of 300-350 amps sound reasonable to you?

My service manager's point essentially was that no battery will stand up to the draw from a winch for long, so get one that has a high CCA rating to account for the very high initial draw, and don't run your winch for long stretches.

And lastly, with a 150 Amp alternator, and a 15% underdrive pulley, is it right to assume that you are only making about as much amperage as you would with a good factory alternator? (Although the point about reliability is well taken.) It seems that what you are suggesting is simply a good alternator (not extremely high output) and a deep cycle battery. Is this accurate?

I'm going to go re-read what you posted.

Geoff

BTW, a co-worker is helping a buddy build a rock buggy. They were going to run a dual alternator set-up, but lucked out and got a junkyard alternator from an ambulance. It makes 250 amps.

Click to expand...

Well...

That current draw figure sounds fairly reasonable - I'm thinking that 300-400A is not out of line, but I'd check with the manufacturer - not only to get the nominal current draw, but also to get a "tolerance" for that figure as well. If they don't give one, plan your system for 10-15% overage, just to be safe. Electrical fires suck - and putting wiring in that is too small is a great way to start one...

The 20Ah figure I gave was just for illustration - it was a means for me to make the maths easy to understand... 20Ah can be had from a battery about the size of two packs of smokes, so there's no reason at all that you can't get something much greater for automotive use!

Does anyone have any idea how long the "average" winch pull is? Take that time convert to hours, and multiply by current draw. That will give you a figure in Ah. Take that figure, add 25-30%, and use that to select your battery (I don't run on the edge - I like a little working room...)

Also, the "instant" draw from an electric motor runs about a half-second or less, then it drops significantly (usually.) If you can, get a "draw curve" for about a minute's operation. At least, that's what I'd do...

Yes, I'd also suggest that you run a solid alternator with a fairly high output - rather than extremely high output - and limit your winch pulls so you don't run at full output for too long (which can kill pretty much any alternator and/or regulator! For instance, if you've had to run on battery for a while, and you change your alternator due to failure, you'll want to charge your battery while you work on it (or you'll kill the new alternator as well...)

I can see using an ambulance or PD alternator, but mounting is probably an issue, and how much fabrication are you willing to do to come up with brackets...

5-90

FYI, the winch i have (warn M8000) pulls 285 amps at 4000LB load. most of the time, it will pull much lower current.

-Tim

Dingo509 said:

just for comparison, i have a 120 amp delco alternator in the shop that has a smaller pulley than the nippondenso that we use on our rigs. and to my knowledge the delco (don't remember the model the newer one after the cs-1300 doesn't have a reliability issue. the diameter of that pulley is the same that kilby lists on there site. from what i can measure when i had a Tahoe the crank pulleys are very close in diameter, less that 1/2" large haven't done the math yet but I'm guess the alternator still turns faster on the Chevy. Also the nippondenso are very common on the newer import cars that see way engine rpm than the 4.0 ever will. just something I've noticed along the way.



i don't think that info is entirely correct about the high idle switch. i have a 91 and have never bean able to get the idle any higher. From my time at the dealership there is a specific computer used for police package xj's i would guess that (at least in 91) the non-police computer doesn't have this option.
I found both pins that people had been talking about and neither with either ground or pos increased the idle. Believe me i would have loved it if it was possible but i don't think it was available in 91

Dingo

Click to expand...

I'd have to check to be sure, but I think most ChryCo SBEC's are essentially the same, they just blew different PROMs to make them work with different systems. I'll have to check - I think I have a 1991 FSM somewhere...

They didn't have the option for RENIX, tho - THAT I'm sure of!

5-90

5-90 said:

I'd have to check to be sure, but I think most ChryCo SBEC's are essentially the same, they just blew different PROMs to make them work with different systems. I'll have to check - I think I have a 1991 FSM somewhere...

They didn't have the option for RENIX, tho - THAT I'm sure of!

5-90

Click to expand...

that would be great if you could find it, i have been wanting to do that for a while now. let me know what pin you find and i'll try it.

Dingo

Your stock alternator will handle allmost all your needs for winching, as will your battery assuming its in good shape. Max amp draw for a M8000 at 8000lbs is 435 amps, even at max load you can halve the current draw with a snatch block, bringing you down near 200 amps at max load. Work your way down from there. Save some money, if you feel like spending, get a winch/recovery kit, and a stick to put under your throttle cable so you can raise your rpms