Page 1 of 1

Wiring the Dual Alt. Controller

PostPosted: Sun Apr 24, 2011 11:27 pm
by GRichards
In looking at the wiring diagrams before installing the DAC and SAR V3, one question regarding the fusing:

B+ on the SAR is indicated with a 15A fast fuse.... is that fuse still required to protect B+ when current is being supplied by DAC (which in-turn is protected by its own 15A fast fuse) and the joining wire will be appx 18" long and in a fairly safe wall mounted position??

and one regarding possible airflow/heat issues:

The SAR comes in a nice finished aluminium box, while the DAC is open. Is there any specific contraindication to installing the DAC in say PVC juction box to achieve a more aesthetically "finished" install?


Re: Wiring the Dual Alt. Controller

PostPosted: Mon Apr 25, 2011 12:53 pm
by Coulomb
Fuses are there to prevent wires from burning up if shorted, so one fuse at the positive distribution pick-off will be fine.

There are no heat issue with the DAC, so it can be mounted in a closed box. If you find one that doesn't cost more than the DAC, let us know.

There are no low voltage electronic devices on the DAC, so normal atmospheric conditions are fine. If there is a good chance it will get wet, then further protection is necessary.

Re: Wiring the Dual Alt. Controller

PostPosted: Tue Apr 26, 2011 4:44 pm
by GRichards
Thanks for the confirmation.

Coulomb wrote:**snip**... so it can be mounted in a closed box. If you find one that doesn't cost more than the DAC, let us know. ***snip***

My install includes a "two device" grey PVC box with 1" hole.... of the Home Depot variety, but slightly modified:

The conduit port, 4 mounting posts for AC devices, and AC grounding provisions are all extraneous... 4 minutes with a flushcut saw and they were gone and lo there is now a perfectly tailored space for the DAC to mount inside. I also decided to put strain relief just to keep things safe. That needed a quick reduction on the ONE side of its hex nut to fit against the back wall.

Since its mounting is in a dry location anyway and the wires will come in the open bottom but and allow drainage forever, I will just screw the rack strip native to the DAC through back of the box to the wall and call it a day. if moisture is a concern, then perhaps someone else can devise a more elegant internal mount method which does not penetrate the housing, but in the 15 minutes total thought and effort I am throwing at it, thats not in the cards.

parts list:

CE9802FR, Carlon 31.5 box
61E8, Carlon Blank outlet cover
I cant quite make out the sku on the strain relief sorry...

As for pricing... I think I was out the door for less than 20$ cdn... or about $21 us$ ;)

Re: Wiring the Dual Alt. Controller

PostPosted: Wed Apr 27, 2011 12:02 pm
by Coulomb
Looks great. Thanks for info and photos.

Re: Wiring the Dual Alt. Controller

PostPosted: Sat May 14, 2011 7:53 pm
by GRichards
I have finally started to actually run wires for the DAC and Smart reg...
so many projects, so little time before summer sets in!!!

some confusion has arisen:

SAR v3 literature is quite clear that jumpering the alternator field neg is verboten. OK, I am good with that, and am willing to throw some nice black Ancor tinned 12ga at it since I have a roll on hand, but how?? The DAC in my mind [sh/w]ould interrupt ALL connections specific to the individual alternators, which would include the field ground return. Since DAC diagram makes no mention of the GND to alternators would you elaborate a bit?? I get that jumpering is not permitted due to the voltage drop associated with heavy current through the cables, hence the need for a dedicated "bat volts" and "B+" both, and the dedicated "alternator gnd" but from where I sit, that benefit gets lost when I see that there is no ALTERNATOR gnd connection to the DAC, only neg distribution, to which it would then supply as "alt gnd" to the SAR...
:? :?
I have gone a little overboard on my cables; I am allergic to voltage drops so for 100a alternators, my 4' port and 14' stb alternator cable runs are 2/0 for both pos and neg, plus an extra 2/0 gnd common to both (the original starter/engine ground was left in play and just supplemented with new) all coming back to a common 600a rated bus bar and 4' of 4/0 to the house and 14' of 2/0 to the start bats.... so Not to be flippant, but [serious, earnest tone]why would we get finger smacked for riding the common gnd return path when there is only one alternator (per SAR papers) but with two its ok?? (per DAC wiring diagram) [/serious earnest tone]

Re: Wiring the Dual Alt. Controller

PostPosted: Fri May 20, 2011 11:03 am
by Coulomb
Sometimes it's better to state a general case without getting into every possible exception.

In the case of the SARV3, jumping the Ground terminal and the Alt. Gnd terminal with a single wire to negative will disrupt regulation with oscillations as the voltage drop at ground changes between no field current and current.

At one time the two Alt. Gnd wires were returned to their respective alternators, but many people are not as concerned as you are about voltage drops in the negative leads. Some of the Alt. Gnd wires overheated as a result. Returning them to the same place at negative distribution eliminates that

Re: Wiring the Dual Alt. Controller

PostPosted: Sun May 22, 2011 9:14 am
by GRichards
Thanks chief

I know many systems have been successfully wired as per the drawing in circulation since revision in aug2005 (if memory serves me), BUT, I still didn't get it. I am happy in my knowledge that I won't get everything- especially the engineering in the boxes- but this one just didn't sit well since it seemed like either an omission or or outright error considering the detail and emphasis conveyed by your SAR paper about running everything without shortcuts.

I am proceeding WITHOUT dedicated alternator ground sensing wires as per DAC instructions

Thank you for clarifying,