Wiring question

Howdy all,
Well I am still wiring on Jethro, life and work got in the way for a few years.
65 loadstar 1600, I have a 3 wire alt and external regulator on the motor now, would I be smart to upgrade to a single wire alt at this point or will I create other problems down the line? I have wiring diagrams that were provided by Irishmike (Thanks again) and am not seein any problems with what I am thinkin.

Thanks,
AJ

You can, if you want, but they tend to have higher "cut in" (turn on) speeds. If you do just tape up the two thin wires (not togther) so they don't ground out, Connect the main output wire (heavy) to the output of the alternator.

Thanks cornbinder89,
When I say wiring on Jethro, I mean I am putting in an entire wiring harness from painless wiring, does it make any difference now? My electrical skills are good enough that I generally let the smoke out, lol

If you want then just run the one heavy wire. Make sure it is heavy enough to carry the current. One wire alternators "sense" battery voltage at the ouptut terminal. If there is any voltage drop in the output wire (due to undersize or bad connections) the battery will be undercharged.
Personally I don't like the "one wire" or even any of the internal-fixed voltage regulators. I prefer external but have several internal regulated Delco 25SI's, At least these can be fitted with a regulator you can adjust. There are several different regulators made for the Delco SI series that take that white, sealed internal regulator several "set-points" are made but I prefer a regulator that I can adjust to any setting.
When you buy a "one wire" alternator you get a fixed set point regulator at whatever set-point the maker decided on. It may or may not be the ideal setting for your application.
The Three wire SI (terminals like --, not like II) have a sense and indicator/ exite wire. You can wire the sense to the battery to better sense the voltage at the battery, and indicator/exite wire when wired in series with a indicator lamp to ign feed will make for faster turn on of the alternator plus give you a "bat light" to tell if the alterantor belt is broken.

Cornbinder89 makes some really good points about the merits and limitations of the one wire alternators.

At the end of the day it all is going to be determined by how you are going to be using your truck.

IMHO, if you are not going to be running hard with a lot of electrical load a one wire should be sufficient for your needs if you size the alternator and battery large enough.

Back in the day when we were running gas powered Loadstar chassis school buses we discovered the alternators and batteries were sufficient if the weather was warm and if you used the buses every day. But get a really cold snap during Christmas and every one of the Loadstars needed a jump to get going after the first of the year.

We discovered the 90-amp alternators put out enough when you had the engine up to speed. But at a stop with all of the lights on and flashing in addition to the heaters/defrosters/blowers going the 90-amp was not large enough and it would take out of the battery to make up the difference.

With every day use it was sufficient but it didn't leave enough battery reserve for when it got cold and we had some time off.

I still have the original equipment Delco altrnator on my 71 Loadstar. It has the external regulator and seems to be adequate for any use I have put it to over the past 29 years. My S160 and R160 both have been upgraded to the single wire Delco alternator with internal regulator. These also work well so I guess the choice is yours.

Amp rateings can be mis-leading. I run a 75 amp 25 SI brushless to charge a 500 amp/hr battery pack on my truck that is deep-cycled every night running a heater and 'fridge. The 75 amp unit is belt driven at a speed that it will put out its max rated current at 1200 (engine) rpm, with 2100 being the max engine RPM. Many of the brush type air cooled alternators can not sustain their "rated" output for long periods, the 25 SI being the execption (along with some other brushless types) In general an alternator should not have to carry a sustained load of more the 1/3rd its max rated output. The 25 SI can maintain almost 100% duty cycle as it has large heatsinks and airflow for its output rateing.
If high amp loads are incountered at low engine RPM (like school buses, ambulance, fire or police) a higher then normal "duty cycle" requires either an alternator that can handle the higher cycle or an increased output altenator that can be loaded at the 1/3 level
In the above example, I may see a 50 amp charge rate for better then 3 hr,then tapering off but still requireing close to 8hr recharge time. I only see 75 amps for a very short time when the engine is 1st started.
With the school buses it might be possable to change the drive ratio of the pulley to increase the output at idle. Careful consideration must be paid to the max speed the alternator can see, and compare that with the goverened RPM of the engine X the drive ratio. The increase in speed will shorten the life of the unit, compared with turning slower, but if within the prematers the mfg allows should give acceptable life.

We realized we had a problem when we calculated that if the overhead flashers were going, the headlights and clearance lights were on, and all of the heaters/defrosters/blowers were on high the hotel load was in excess of 80 AMPS.

80 AMPS is way too much load for a 90 AMP alternator.

As those alternators bit the dust we replaced them with 150 AMP units. The cost difference was not that much but we never had to replace the larger ones.

But getting back to the original question, if the only hotel load is a standard Loadstar light package and heater, there should not be any problem updating to a one wire alternator if it is sized appropriately.

You have to remember most of the OEM alternators back in the day were much smaller than today's OEM alternators. I can remember when we started seeing alternators as optional equipment and thinking the 30 AMP alternators were something special. They were such a step up from the big Delco-Remy generators. With the generators you were lucky to ever see much more than 5 AMPS at idle. Because the alternators put out so much more at idle you didn't mind the fact the total output wasn't all that much.

I have two of the 50 amp Delco generators, If the 25SI's ever give me trouble, they will be replaced with a generator. Generator can supply their rated amps at 100% duty, meaning you can place a 50 amp load on a 50 amp generator indefanatly. Their draw back, as you mentioned is low output at idle. Since in my application (OTR semi) I do not idle, nor require large amounts of power at idle, 50 amps at speed is plenty, I just need something that can re charge the battery pack over a 10-11hr day.
In my quest to make an electrical system that meets my needs, I have discovered many things about the newer generation of lead/acid storeage batterys. Over the last 15-20 years the chemical makeup of the electolite and plates has been changed to minimize water useage. In doing so the chargeing voltage (because of changes in the internal resistance of the battery) has had to rise. Older chargeing systems are far too often set too low to fully recharge a modern battery, which in turn leads to sulphation and short life. Back in the early 70's 13.8 volts was the setting for long haul trucks, enough to fully recharge over along run where the truck may not be shut down for a week or more, but still have minimum water use. Today chargeing voltage may be as high as 14.8 or even 15 volts. Look thru a wholesale supplier of voltage regs and you will find close to 30 differnet Delco SI internal regs with different set points. Some are for other voltages (there are 6, 8, 12, 18, 24, 32,36 volt regs) and several regs in the 12 volt system with different set points, allowing the rebiulder or OEM to "adjust" to their needs.
Most heavy truck alternators are of the "one wire" type and you would be hard pressed to find a "techincion" in the heavy truck trade who knows how to diagnois or repair or that there are even choices in a chargeing system. If the load test shows its chargeing, its good, if not replace with a new, one wire alternator. If the truck only gets three years out of a set of batterys, it not their problem.
The old DN series of external regs could be adjusted, as were the electronic (transisorized) replacement that Delco came out with in the early 70's. The external reg allowed for two connections to the batterys, one heavy, to carry the charge current, and one light to sense the battery voltage independantly (to make sure that charge current actually got to the battery).
80 amp load is very high,even for a school bus. I concede, that the heater blower (both the number and draw) are a significant issue. I have worked on school buses as well as motor coaches. Coachs solve this by running a 24 volt system and most often an oil cooled alternator of 200 amps (remember 24 volts as well). Lighting, however shouldn't be higher then a semi esp one that tows mulitple trailers. I can rarely get my running load to exceed 25 amps on my semi with trailer. This is why a 75 amp unit is more then I need, 50-55 amps still leave 25 amps or more for chargeing. A Loadstar that is not a bus should funtion fine with any automotive alternator 45 amps or higher, even less but finding an alternator under 60 amps today is almost impossable.

Here's a page about one wire vs three wire alternators from Mark Hamilton at Mad Electrical:

http://www.madelectrical.com/electrical ... wire.shtml

Might take a browse around his site, especially the 'electrical tech' section- lots of good advice and info on car wiring.