T&T: Alternators -- Adding a second one

[Al Thomason]

John,

I added a 2nd alternator to the front of my Cummins 6B (also a Monk, but a 
45' Monk/McQueen ;-) to charge the house battery while retaining the 
existing alternator dedicated to the starter battery.

I added a large case Leece Neville, 200A, but you could use the same method 
with a smaller alternator.  (BTW, these LN alternators are tuff guys, and 
can be had on Ebay for around $200 or so.  Make sure you get the larger case 
one for best life and low RPM charging ala a 4800 or 4900 series.  Factory 
addaptor to convert for an external regulator is about $20 or so)

I will send you a separate Email with pictures, but basically I secure an 
additional pulley and spacer from Cummins to the front of the crank shaft to 
drive an additional dual belt alternator.  Then I built a bracket / frame by 
coming off both sides of the front engine mounts.  On this frame I attached 
the new alternator.  In this mode it runs backwards, but most alternators 
are OK with this (need to verify the cooling fan will allow for backwards 
rotation).

My philosophy was to keep the starter battery/alternator 100% separate from 
the house ckt which had its own battery and alternator.  (though I can cross 
connect as a backup).  Doing so not only gave me total redundancy, but also 
kept things simple. (No diode isolators, echo-chargers, etc)...  Might add 
that for my Electronics / Nav sub-panel, I ran it through a typical A/B 
switch.  But instead of connecting the common side to an alternator, I used 
that as my Sub Pannel feed.  That way I can run the important Nav stuff from 
the house battery (normal operation), or switch over to the Starter battery 
as a backup.

-al-

<SNIP>

>
> Another route would be to retain the stock alternator and route it to
> the engine start battery only, and not combine it with the house
> bank, and add a 165 with two belts and new bracket for the house
> bank. A switch could then be used to use the house bank for start in
> the event the start battery got flattened.