RV.Net Open Roads Forum: Question about Redarc 40A DC to DC charger wiring.

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Question about Redarc 40A DC to DC charger wiring.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 2  
Next
Sponsored By:
Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/20/21 12:53am Link  |  Quote  |  Print  |  Notify Moderator

In the instructions it says:

The BLUE wire is used to switch the vehicle input turn ON trigger mode between:
• Standard trigger (for fixed voltage or temperature compensating alternators)
• Low Voltage trigger (for variable voltage alternators)

Standard trigger the blue wire is disconnected
Low voltage trigger the blue wire is connected to the ignition

My question is which kind of alternator do I have? My motorhome is a 2000 Airstream Land Yacht Class A with the 7.4 Vortec and a 124A alternator. Any ideas, or how I can find out?

noteven

Turtle Island

Senior Member

Joined: 02/13/2011

View Profile



Posted: 11/20/21 07:25am Link  |  Quote  |  Print  |  Notify Moderator

See if there is a tag or plate attached to the alternator frame somewhere. I would guess it is a Delco sumthin sumthin on your GM engine.

A good GM commercial vehicle dealership parts dept might be able to discover the original equipment alternator model from the engine number or chassis number build info.

Is there an original build line sheet deep in the file folder from Airstream?

Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/20/21 08:41am Link  |  Quote  |  Print  |  Notify Moderator

noteven wrote:

See if there is a tag or plate attached to the alternator frame somewhere. I would guess it is a Delco sumthin sumthin on your GM engine.

A good GM commercial vehicle dealership parts dept might be able to discover the original equipment alternator model from the engine number or chassis number build info.

Is there an original build line sheet deep in the file folder from Airstream?

I'll look through the paperwork. I need to know more about the two types of alrenators.

Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/20/21 08:47am Link  |  Quote  |  Print  |  Notify Moderator

Well I suppose I should have just Google it first. I most certainly have a fixed voltage alternator.

t alternators vs fixed voltage alternators

 

Fixed voltage alternators are becoming less common on new vehicles as reduced fuel consumption targets and more stringent environmental and emissions standards are adopted by manufacturers. A fixed voltage alternator has a high enough voltage to charge a secondary battery in the vehicle to a usable level for leisure or auxiliary use.

The smart alternator system, also known as variable voltage alternators, allow the vehicle to control the output voltage and current from the alternator based on vehicle operating conditions. The idea behind this is to reduce electrical load and in turn mechanical load on the engine by the alternator. Unfortunately, this renders it unsuitable for charging a secondary battery system to a usable level.

 

How do I tell if I have a smart alternator?

 

Smart alternators are par for the course in most modern vehicles, but when measuring or monitoring output voltage from a vehicle with a variable voltage alternator you will find the voltage can range between 12.3V-15V. It’s not easy to tell if it’s a variable voltage alternator by only measuring voltage as sometimes the result may be deceiving or look similar to a standard alternator at time of testing. 

A good way to determine whether your vehicle has a variable voltage alternator is to look at the vehicle start battery. What you are looking for is a module mounted on or close to the battery terminal (usually the battery negative). This is the battery sensor, if it’s got one of these, you have a variable voltage alternator.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 11/20/21 05:36pm Link  |  Quote  |  Print  |  Notify Moderator

I ASSumed my 1991 C has an alternator that starts at about 14.6 and soon tapers to 13.8 like my 2003 truck has. Nope!

I was going to install a DC-DC charger to maintain the voltage at 14.6, but happened to put a voltmeter in the dash cig lighter socket for a two hour drive recently, and voltage stayed at 14.6ish the whole trip. Surprised me.

Since the alternator amps stay around 23 amps, (low amp 2G alternator) it would be a complete waste to install my 20 amp DC-DC now in the TC.

I suspect it would be the same for the OP with a higher amp alternator and his 40 amp DC-DC. Wasted effort!

Only excuse for the DC-DC would be for LFP house batts and that idea they might overload the alternator. Seems that idea is in dispute and I have no clue about that.


1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/20/21 06:23pm Link  |  Quote  |  Print  |  Notify Moderator

Worked as it should. The starting battery voltage is too low to turn the charger on but as soon as the alternator is engaged the voltage is sufficient. Everything works like it should and yes i installed a LiFePo battery. That was the reason for the DC to DC charger.

* This post was edited 11/20/21 07:43pm by Teleman *

otrfun

On The Road

Senior Member

Joined: 09/08/2012

View Profile



Good Sam RV Club Member


Posted: 11/21/21 07:14am Link  |  Quote  |  Print  |  Notify Moderator

Teleman wrote:

Worked as it should. The starting battery voltage is too low to turn the charger on but as soon as the alternator is engaged the voltage is sufficient. Everything works like it should and yes i installed a LiFePo battery. That was the reason for the DC to DC charger.
Glad to hear your install went well.

We used a battery isolator to activate our dc to dc charger. We installed our BI (and dc to dc charger) inside our truck camper (vs. the truck) so the truck's battery is only subjected to parasitic current when the TC is connected to the truck.

It'll be interesting to see how your 124a alternator handles the 40-45a dc to dc charger input load for the long haul---especially if you have any plans to charge while idling.

Enjoy!

Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/21/21 08:23am Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

Teleman wrote:

Worked as it should. The starting battery voltage is too low to turn the charger on but as soon as the alternator is engaged the voltage is sufficient. Everything works like it should and yes i installed a LiFePo battery. That was the reason for the DC to DC charger.
Glad to hear your install went well.

We used a battery isolator to activate our dc to dc charger. We installed our BI (and dc to dc charger) inside our truck camper (vs. the truck) so the truck's battery is only subjected to parasitic current when the TC is connected to the truck.

It'll be interesting to see how your 124a alternator handles the 40-45a dc to dc charger input load for the long haul---especially if you have any plans to charge while idling.

Enjoy!

Pretty much the only time we're idling is at stoplights. When we're not driving we use the generator to charge the batteries.

noteven

Turtle Island

Senior Member

Joined: 02/13/2011

View Profile



Posted: 11/21/21 03:29pm Link  |  Quote  |  Print  |  Notify Moderator

The starting battery between the alternator and DC-DC cushions the load on the alternator during the odd low output idle time one would think. This DC DC probably has some control around overloading the alternator.

Especially REDARC equipment- Australia has been a decade or two ahead of north North America using on board charging equipment in campers and trucks operating in remote regions.

Teleman

Clayton, CA, USA

Senior Member

Joined: 08/11/2004

View Profile


Offline
Posted: 11/21/21 05:44pm Link  |  Quote  |  Print  |  Notify Moderator

noteven wrote:

The starting battery between the alternator and DC-DC cushions the load on the alternator during the odd low output idle time one would think. This DC DC probably has some control around overloading the alternator.

Especially REDARC equipment- Australia has been a decade or two ahead of north North America using on board charging equipment in campers and trucks operating in remote regions.

I put circuit breakers on both sides of the charger too. I'm pretty confident I won't have any trouble.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 2  
Next

Open Roads Forum  >  Tech Issues

 > Question about Redarc 40A DC to DC charger wiring.
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2021 CWI, Inc. © 2021 Good Sam Enterprises, LLC. All Rights Reserved.