Louisd75
Adventurer
Well, the latest addition to my truck is a new, more powerful alternator. Now the lights don't dim when I turn the seat heaters on high :wings:
I first tried a high output alternator, which was basically a re-wound version of the stock one. It worked perfectly except for at idle. When the RPMs dropped below a certain point the alternator output dropped to zero and the battery wouldn't charge. You could watch the voltage fall while sitting at a traffic light and the headlights would dim. Most importantly, the seat heaters would begin to cool off if they were on the high setting. After discussing this at my local alternator shop, I learned that this is common with re-wound alternators. They'll put out a lot of amps so long as the RPM stays above a certain point. One option is to go with a smaller pulley, but then it's possible to run into longevity issues with the belt slipping at higher loads or premature wear on the bearings and belt because of higher tension used to keep the belt from slipping. Going with a smaller pulley may have required custom machining a new pulley if one weren't available.
I hunted around a bit more and found this thread on TTORA: http://www.ttora.com/forum/showpost.php?p=1789951&postcount=1
A bit of looking around at the various other websites out there and it seemed that there were enough success stories that I figured it'd be worth a shot. Back to the alternator shop I went for the GM CS-144, 1995 Cadillac DeVille alternator mentioned in the above thread. I opted for the one without the heated windshield so that I wouldn't have to deal with the extra plugs that it comes with. When I compared the test sheets between the HO alternator and the Cadillac alternator I could see that the max output was about the same but the Cadillac alternator reached it at a lower RPM.
Here's the performance plot for the HO (rpm is alternator speed, not engine speed)
Here's the performance plot for the Cadillac alternator (rpm is alternator speed, not engine speed)
You can see that the Caddy alternator curve is shifted to the left meaning that its output starts and peaks at lower RPMs than the high output. Note that these curves are for my specific alternators, your experience may vary. Note also that the RPM is alternator RPM, not engine RPM, which will be lower.
With more power comes a need for larger diameter wiring. I didn't want to find out the hard way that my stock wiring couldn't handle the load, so I opted to go with 4 gauge wire going straight from the alternator to battery with a fuse for just-in-case, wired like so:
(The alternator is the circle on the left that I forgot to label... sorry!)
The other issue that you'll find as you hold the two alternators in hand is that the Caddy alternator has four pins for the plug while the Toyota has three. I picked up a new pigtail connector to fit the Caddy and installed it on the 'yota wires after snipping its connector off. The P, L, F, and S connections are labelled on the Caddy alternator, the 'yota wires should be labeled on the original alternator:
You won't need the middle, IGN wire (red in the above), I just nipped it, folded it over on itself and taped it up to keep it insulated. For my situation, the yellow wire in the above drawing corresponded to the L lead, the white corresponded to the S lead. I wired the new connector so that the leads matched up with the L and S leads on the new alternator.
Once I got the wiring figured out, it was time to test fit. I had to pull the batteries to get the new alternator into position. I also needed to add 1/4" of spacer washers as mentioned in the writeup linked above. These spacers go on the bolt that passes through the upper ear of the alternator between the aft edge of the alternator and the threaded portion of the bracket. Here's a poor picture of what I'm talking about:
If you buy the Caddy alternator and hold it up to your original one, you'll probably (hopefully) notice that the locations of the plug and terminal are different. I talked with the alternator shop about this and they recommended that I give it a trial fit. If the connections wound up in a very awkward location, bring it back and they'd remove the back cover and clock things differently. Of course it didn't work, with the connections facing right at the engine in a difficult to reach spot. They wound up clocking the rear cover 180° from the stock position to put the plugs on the outboard-most part of the alternator. This allowed me to reach the plug from above (as seen in the above pic... the yellow and blue wires) and tighten the wire between the alternator and fuse by moving the flap in the wheel well as if I were changing my oil filter, like so:
(oil filter is visible at the bottom of pic for reference)
Another issue I ran into involved the belts. The new alternator is slightly larger and has a slightly larger pulley than stock. This prevented me from using the stock alternator belt, which was just a little too short. A bit more research showed that every writeup that I'd read involved a truck with a supercharger on it. Apparently that belt is plenty long. So, after unsuccessfully lobbying the minister of finance (aka, wife) for a supercharger, I snooped around a bit more on the interweb and found that the power steering belt might be the right length.
I tried removing the stock alternator belt only to find that I first had to remove the A/C belt, which required dropping the skid plate to access the tension pulley. And before I could remove the A/C belt, I'd first have to remove the power steering belt, which, of course, meant removing the fan. I would also like to add that none of this is much fun working at night, outside, in the rain. After finally getting all the belts off I slipped the power steering one into place on the alternator to ensure that it would work. It does. In the morning I borrowed the wife's car and picked up a new A/C belt and 2 power steering belts. The new alternator pulley is wider than stock, having five ribs vs three ribs. I lined up the belt so that it ran in a straight line and it wound up being on the ribs furthest away from the alternator:
This shouldn't matter and I've had no issues so far.
Finally, after getting the new alternator in, new belts run, fan back on, skid plate back on, and belts tightened up, I was ready to finish the new battery connection. I used a Blue Sea AMI/MIDI Safety Fuse Block with a 150A fuse. I drilled and tapped two holes in the top of my Columbia Overland dual battery holder and installed the fuse on top like so:
So far everything is running/working great. Voltage while running is between 13.4 and 14.7 depending on what accessories I've got running. On startup I'll occasionally see just a little higher at 15.0v for a couple of seconds, just long enough to set the alarm off on the National Luna battery monitor. I've spoken with the alternator shop about this and was told that for a few minutes on startup it is not an issue. If it's happening while driving around, it's an issue. So far it's only happened in the morning after a night below freezing. Once the engine has been running for a few seconds it drops down.
All in all it was a bit of work but being able to run the seat heaters on high and still charge the battery at idle is totally worth it :REOutCampFire03:
I first tried a high output alternator, which was basically a re-wound version of the stock one. It worked perfectly except for at idle. When the RPMs dropped below a certain point the alternator output dropped to zero and the battery wouldn't charge. You could watch the voltage fall while sitting at a traffic light and the headlights would dim. Most importantly, the seat heaters would begin to cool off if they were on the high setting. After discussing this at my local alternator shop, I learned that this is common with re-wound alternators. They'll put out a lot of amps so long as the RPM stays above a certain point. One option is to go with a smaller pulley, but then it's possible to run into longevity issues with the belt slipping at higher loads or premature wear on the bearings and belt because of higher tension used to keep the belt from slipping. Going with a smaller pulley may have required custom machining a new pulley if one weren't available.
I hunted around a bit more and found this thread on TTORA: http://www.ttora.com/forum/showpost.php?p=1789951&postcount=1
A bit of looking around at the various other websites out there and it seemed that there were enough success stories that I figured it'd be worth a shot. Back to the alternator shop I went for the GM CS-144, 1995 Cadillac DeVille alternator mentioned in the above thread. I opted for the one without the heated windshield so that I wouldn't have to deal with the extra plugs that it comes with. When I compared the test sheets between the HO alternator and the Cadillac alternator I could see that the max output was about the same but the Cadillac alternator reached it at a lower RPM.
Here's the performance plot for the HO (rpm is alternator speed, not engine speed)
Here's the performance plot for the Cadillac alternator (rpm is alternator speed, not engine speed)
You can see that the Caddy alternator curve is shifted to the left meaning that its output starts and peaks at lower RPMs than the high output. Note that these curves are for my specific alternators, your experience may vary. Note also that the RPM is alternator RPM, not engine RPM, which will be lower.
With more power comes a need for larger diameter wiring. I didn't want to find out the hard way that my stock wiring couldn't handle the load, so I opted to go with 4 gauge wire going straight from the alternator to battery with a fuse for just-in-case, wired like so:
(The alternator is the circle on the left that I forgot to label... sorry!)
The other issue that you'll find as you hold the two alternators in hand is that the Caddy alternator has four pins for the plug while the Toyota has three. I picked up a new pigtail connector to fit the Caddy and installed it on the 'yota wires after snipping its connector off. The P, L, F, and S connections are labelled on the Caddy alternator, the 'yota wires should be labeled on the original alternator:
You won't need the middle, IGN wire (red in the above), I just nipped it, folded it over on itself and taped it up to keep it insulated. For my situation, the yellow wire in the above drawing corresponded to the L lead, the white corresponded to the S lead. I wired the new connector so that the leads matched up with the L and S leads on the new alternator.
Once I got the wiring figured out, it was time to test fit. I had to pull the batteries to get the new alternator into position. I also needed to add 1/4" of spacer washers as mentioned in the writeup linked above. These spacers go on the bolt that passes through the upper ear of the alternator between the aft edge of the alternator and the threaded portion of the bracket. Here's a poor picture of what I'm talking about:
If you buy the Caddy alternator and hold it up to your original one, you'll probably (hopefully) notice that the locations of the plug and terminal are different. I talked with the alternator shop about this and they recommended that I give it a trial fit. If the connections wound up in a very awkward location, bring it back and they'd remove the back cover and clock things differently. Of course it didn't work, with the connections facing right at the engine in a difficult to reach spot. They wound up clocking the rear cover 180° from the stock position to put the plugs on the outboard-most part of the alternator. This allowed me to reach the plug from above (as seen in the above pic... the yellow and blue wires) and tighten the wire between the alternator and fuse by moving the flap in the wheel well as if I were changing my oil filter, like so:
(oil filter is visible at the bottom of pic for reference)
Another issue I ran into involved the belts. The new alternator is slightly larger and has a slightly larger pulley than stock. This prevented me from using the stock alternator belt, which was just a little too short. A bit more research showed that every writeup that I'd read involved a truck with a supercharger on it. Apparently that belt is plenty long. So, after unsuccessfully lobbying the minister of finance (aka, wife) for a supercharger, I snooped around a bit more on the interweb and found that the power steering belt might be the right length.
I tried removing the stock alternator belt only to find that I first had to remove the A/C belt, which required dropping the skid plate to access the tension pulley. And before I could remove the A/C belt, I'd first have to remove the power steering belt, which, of course, meant removing the fan. I would also like to add that none of this is much fun working at night, outside, in the rain. After finally getting all the belts off I slipped the power steering one into place on the alternator to ensure that it would work. It does. In the morning I borrowed the wife's car and picked up a new A/C belt and 2 power steering belts. The new alternator pulley is wider than stock, having five ribs vs three ribs. I lined up the belt so that it ran in a straight line and it wound up being on the ribs furthest away from the alternator:
This shouldn't matter and I've had no issues so far.
Finally, after getting the new alternator in, new belts run, fan back on, skid plate back on, and belts tightened up, I was ready to finish the new battery connection. I used a Blue Sea AMI/MIDI Safety Fuse Block with a 150A fuse. I drilled and tapped two holes in the top of my Columbia Overland dual battery holder and installed the fuse on top like so:
So far everything is running/working great. Voltage while running is between 13.4 and 14.7 depending on what accessories I've got running. On startup I'll occasionally see just a little higher at 15.0v for a couple of seconds, just long enough to set the alarm off on the National Luna battery monitor. I've spoken with the alternator shop about this and was told that for a few minutes on startup it is not an issue. If it's happening while driving around, it's an issue. So far it's only happened in the morning after a night below freezing. Once the engine has been running for a few seconds it drops down.
All in all it was a bit of work but being able to run the seat heaters on high and still charge the battery at idle is totally worth it :REOutCampFire03:
