Need help with electrical design

[Gordie Allen]

I'm looking at a Delco Remy 40SI brushless 300 amp.  It's $1500 at http://www.finditparts.com/products/635857/delco-remy-8600299

It also comes in 240 and 275 amp models

It's a "single wire" alternator, but has an "R" terminal for feeding a tach, an "I" terminal that feeds a monitoring LED and a "S" terminal that monitors battery system voltage at the battery.  It also has a dedicated Ground terminal to ensure a solid ground in addition to the mounting bracket.  You can use all or none of these extra terminals - it won't affect the alternator's performance.

You can review all the specs at http://www.delcoremy.com/Documents/Alternator-Instruction-Sheets/40SI-installation-instructions_10523421.aspx

[Lee Bradley]

More information about how 70 amps equals 220 amps. I understand that in wind driven systems there is advantages to PMA but this is engine driven. 

[Len Silva]

Personally, I would never use a one wire alternator in a bus conversion as you have no control over the charging voltage.  I would always suggest an external regulator unit so that if needed you can use a smart multi stage regulator.

[Gordie Allen]

As I read the spec sheet it appears that the "S" terminal monitors battery voltage and adjusts alternator output accordingly.

[Uglydog56]

Lee, I went back and reread the posts on the 70vs220 thing, and their reasoning was that the brush type alt's are not rated for 100% duty cycle, that with the small frame and small contact area of the brushes, their life would be very short if ran this hard.  Another thing they pointed out is that with the existing regulators, the voltage would pull down and not maintain the batteries, but that can be addressed with the 3 stage requlators. The PMA's and big DC generators are rated for 100% duty cycle and more rugged.  This is all hearsay, mind you, but it seemed logical to me.

[Len Silva]

As I read the spec sheet it appears that the "S" terminal monitors battery voltage and adjusts alternator output accordingly.

That's correct, but it only adjusts the output to what the manufacturer set it for (14.2 MOL).  That's fine for truck service, but when you are charging a large battery bank, you want more control.  A smart regulator will provide bulk and float charging as needed and can be user controlled.

[Gordie Allen]

Len,
Is that a feature that some inverter/converters refer to when they talk about four stage charging?  If not the Delco, what would you recommend?  I want 300 amps and to be able to wire in a tach.  There's a lot to learn.
Gordie

[Len Silva]

Here is one example of the regulator I am talking about:  http://www.xantrex.com/power-products/power-accessories/alternator-regulator.aspx

There are others made by Balmar, Hehr and others.  These will require an externally regulated alternator.

If you are going to be running a large house bank, these will extend the life of your batteries considerably.

That said, I respectfully disagree and urge you to reconsider the entire concept.  I think you would be miles ahead spending the same money for a good diesel generator and running it all the time instead of alternator/battery bank/inverter to get air conditioning.  You will still need to run a generator (or the main engine) when stopped and it is a much more complicated system with more failure points.

Secondly, all those amps take horsepower and you are quite limited with the 6-71.  That's the reason they used an aux engine for the bus air conditioning, there just wasn't enough power until the 8V-71 came along.

[luvrbus]

My 2 cents worth you don't want a tach that runs of the alternator r terminal 2 places on the 6-71 to use a pulse generator which is a way better set up IMO

good luck

[Zeroclearance]

Gordie,  Leece Neville has some very good 200amp and greater alternators that allow for external regulation.   Go to the Balmar website.   Years back Balmar and Leece Neville worked together.   There are surplus systems out there.