270amp Alternator Install

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baggar11

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I posted a sneak peek on Monday of a DC Power Inc 270 amp alternator I ended up purchasing for the Cruiser. I got around to installing it, along with the wiring kit I had user @Fourrunner make yesterday. Wanted to give everyone the low down on the install.

First of all, my reasoning for grabbing this alternator was obviously the anemic 80 amp stock alternator. And, since I've had my winch for about 4 years now, I've run into scenarios where I'm doing 6-8k pulls, and the battery and alternator are just not able to keep up. Literally only getting 30 seconds to a minute of pulling before the system conks out.

It could be that my Costco battery has been depleted too many times over the years to give me a strong reserve of power, but I know that the 80 amp alternator is only giving me about a 1/3rd of the power needed for an 8k pull, according to my winch's spec sheet. To do a dual battery system seemed like several hundred bucks to begin with, and would only give me twice as much pulling time along with twice as much charging time needed. So I thought a more powerful alternator would be more cost and performance effective out of the gate. I still may end up doing a dual battery setup down the road.

Cost of this alternator was $630 + $20 for shipping. Pretty hefty price tag, I know.

Onward to the install....

I've only seen 1 other post on here indicating that the install only needed a slight modification to the bracket. Well, this install took for far longer than thought, and I ran into quite a few things that I thought I'd pass along.

First, to get this bad boy into place, the return coolant hose, distributor and top alternator bracket needed to be removed.

tight-fit.webp


The top bracket needed to be ground slightly for a nice easy fit.

bracket.webp


Once you I got the alternator into place, I was able to get the top bracket reinstalled. And then I noticed that the bottom screw holes weren't tapped correctly to accept the stock oem bolt of 8 x 1.25. They seemed to be tapped for 7 x 1.25. I ended up tapping one of the holes for the proper 8 x 1.25.

Then there were fitment issues with the lower swing bracket. The alternator was simply too big for both mounting points(nut and bolt). I ended up just using the left mounting nut side along with the tension and lock bolts. I felt that the bracket itself was such a tight fit it wouldn't move anywhere.

swing-bracket.webp


The only other issue after that was that the alternator was so big, that it didn't swing close enough to the block to allow me enough tension on the alternator belts to slip on. So I had to remove the lower bracket and to bracket to cock the alternator diagonal to allow for the belts to slip on. Then reinstall top and bottom brackets again. Fun times. I can imagine any kind of trail repair to be lots of fun.

installed.webp


I did finally get it installed. Whole process took me about 8 hours, way longer than I anticipated. Aren't most repairs on the Cruiser though.

size1.webp


Anyways, I thought I'd give folks a somewhat thorough alternative option to getting more electrical power. Next time I'm up in the mountains, I plan on taking some video of winching performance. I'll post another thread when I get around to that.
 
If you are only getting 30sec - 1min from your battery, then it is stuffed or your wiring is stuffed.

You need to get a DC current clamp on the alternator output and actually measure what can be delivered to the load and at what engine RPM. Most alternators do very little at idle.

cheers,
george.
 
george_tlc said:
If you are only getting 30sec - 1min from your battery, then it is stuffed or your wiring is stuffed.

You need to get a DC current clamp on the alternator output and actually measure what can be delivered to the load and at what engine RPM. Most alternators do very little at idle.

cheers,
george.
Click to expand...

I know my Costco battery is pretty small. I think 630 CCA's. Especially for running a winch. Also, it probably didn't help that this was the state of the original alternator cable. From the looks of it, only about a 1/3rd of the cable was still in place. I'm sure a couple more winch pulls down the road and it would have fried itself apart. I ended up cutting it off, cleaning out the loom as best as possible and crimping on a new end.

oem-cable.webp
 
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I'm with @george_tlc, 270 amps at 4000 RPM isn't nearly as interesting as how many it makes at 600 RPM.
 
Here's the spec sheet.

http://www.m2kinc.com/pdf/40-brochure.pdf

According to it, it'll make 198 amps at 650 rpm idle and max output above 1000 rpm's. From what I gather, it's an all new Denso constructed alternator that is tested to produce those numbers at 200F. I'm no electrical guru, but seems decent to me.
 
Any alternator will do very little during high current draws like winching. A fully loaded winch can draw over 400 amps. All of your current is coming from the battery, not the alternator. During high current draw, the alternator will do its best to keep up, but they are not meant for long duty cycle. It will go into thermal protection or simply burn up. If you have very short winch time then your battery is done.

FWIW, I've run a Warn M12K on my 91FJ80 with the stock alternator for close to 18 years with many many fully loaded long pulls, but I don't play games with batteries. Odyessy PC1500 lives in my trucks.
 
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jonheld said:
Any alternator will do very little during high current draws like winching. A fully loaded winch can draw over 400 amps. All of your current is coming from the battery, not the alternator. During high current draw, the alternator will do its best to keep up, but they are not meant for long duty cycle. It will go into thermal protection or simply burn up. If you have very short winch time then your battery is done.

FWIW, I've run a Warn M12K on my 91FJ80 with the stock alternator for close to 18 years with many many fully loaded long pulls, but I don't play games with batteries. Odyessy PC1500 lives in my trucks.
Click to expand...

+1.

Warn M12K, hand throttle, and a Odyssey battery in my 80.
I have a Sequoia alt & a Photoman bracket, never have installed it.
 
That'll be a nice alternator for sure, and nice to have, but it's not going to increase your winch-to-rest time. The limiting factor of long pulls is heat. Even if you had a bank of 10 giant batteries connected to a 1000 amp charger, you'll still be constrained by winch cool down time, not amps.
On a long hard pull, the run to rest time on a 72°F day is about 1:8. That's right. Run for one minute, let it cool for 8. And that's with a little 12V fan blowing on the winch.
Try 1:6 on a heavy pull and you're asking for trouble.

Also as mentioned, winches run on batteries, not alternators.

I have a stock wimpy 55 amp alternator in my FJ60. It's output is perfectly matched to the cool down time required for my Warn 10K winch. A bigger alt wouldn't help me.

The best thing you can do for a winch is to connect it to two big brand new batteries.

That alternator looks amazing. The most important thing to do now (to be able to use some of those awesome amps) is to buy two big brand new batteries for it to charge.
 
I still want to see someone use an 8D battery in a land cruiser...
 
@jonheld On my winch, a full 12,000 lb pull will require 360 amps, according to the spec sheet. At 8,000 lbs, it requires 250 amps. I'll have to disagree with you on where the power is coming from during high amp draw or for that matter normal use. You can jump start a car that has a dead battery and it'll keep running until you stop it. Alternators are very capable of keeping up with a vehicle's electrical demand. If you're moving so much current that you're alternator can't provide it, then yeah, the rest is going to come from the battery.

Also, think of guys with small alternators that put in large stereo systems. Several thousand watt stereos put way more demand on the electrical system than occasional winching. The only reason those stereo nuts find they need larger alternators is the electrical demand of their stereo exceeds that of their alternator and now their battery won't keep a charge. You don't see them putting in dual battery setups when their small alternator is undersized to begin with. They'd be going through batteries like candy.
 
They don't say what voltage it puts out at 270 amps, so chances are it is way lower than 12V, which is not particularly useful for a 12V winch.

The reality is that the power (volts X amps) an alternator puts out is directly related to the weight of the copper wire in it. There is a limit to their efficiency and the way to optimize their efficiency has been known for at least 50 years. The upshot of this reality is that an alternator that is going to make 3 times the power of the stock alternator is going to weigh 3 times more.
 
@Output Shaft You're definitely right about having the winch rest after a good pull due to heat. At least now, I'll have a fighting chance to get to that point. Generally, most of my winch pulling happens up in the mountains in the dead of winter where temps are typically around 20-30F.

My problem before was probably twofold, the undersized Costco battery rated at 630 CCA's(unsure of amp hours, possible around 35-45) and the above posted picture of my stock alternator wire with barely a 1/3rd of the wiring still intact. With this 270 amp alternator, if I ever exceed that, the battery is in a much better spot to provide the rest of the power needed.

I'll definitely post up videos and feedback next time I find myself up in the mountains needing to winch. And yes, I'll probably end up doing dual batteries in the future.
 
^ get decent batteries that are sized ALONG with wiring to deal with the winch loads. The batteries will be doing all the work when winching so don't skimp in that area (and wiring, including ground wire upgrades). I went to 1/0 for my ground wires to engine block and between batteries and a suitably rated marine switch for paralleling/isolating etc when winching.

No issues when needing to winch for a few minutes:

sn6.jpg


Hand throttle to raise rpm into the 1500 range to recover some charge and stock alternator does just fine.

cheers,
george.
 
Having never used a winch myself, if you reduce the load via snatch block how are pull times affected? Is it easier on the winch/battery/charging system to pull a longer line at a lower load?
 
Pin_Head said:
They don't say what voltage it puts out at 270 amps, so chances are it is way lower than 12V, which is not particularly useful for a 12V winch.

The reality is that the power (volts X amps) an alternator puts out is directly related to the weight of the copper wire in it. There is a limit to their efficiency and the way to optimize their efficiency has been known for at least 50 years. The upshot of this reality is that an alternator that is going to make 3 times the power of the stock alternator is going to weigh 3 times more.
Click to expand...

If these videos are any indication, it's probably pretty close to 14v at max amperage. I did my research beforehand. These DC Power alternators seem to be pretty high build quality with all new Denso parts. Believe me, it's heavy. I was carrying it around Ace Hardware for 30 minutes trying to source the lower bracket bolt before deciding to tap it to the bigger stock size 8 x 1.25.



Voltage drop. 1 dc power 270 amp alt.
what voltage drop? dc power 270xp

Of course, whenever you are pulling a lot of current there will be some voltage drop. Put some probes on your battery while engaging the starter to see first hand. It doesn't really matter too much though, as long your vehicle stays on it hasn't dropped too low.
 
@george_tlc Yeah, I have no doubt a nice set of dual 90 amp hour batteries would do circles around my Costco battery, which is probably rated around 35-45 amp hours. Ha!

The heavy duty cables provided by @Fourrunner are 1 gauge to the battery, so I'm looking good there. I'll probably pull for a hand throttle next.

Looks like a fun time up in the snow!

fzj80snow.webp
 
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