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Open Roads Forum  >  Tech Issues

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

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otrfun

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Posted: 11/22/21 09:11am Link  |  Quote  |  Print  |  Notify Moderator

Teleman wrote:

I put circuit breakers on both sides of the charger too. I'm pretty confident I won't have any trouble.
Circuit breakers and fuses are very imprecise devices. A batch of 60a breakers/fuses of the same type, from the same manufacturer, may open at 70a, 85a, or even higher. It's wishful thinking to assume a 60a breaker/fuse is going to open at 61a. Breakers/fuses are primarily designed to protect in the event of a short or massive overload condition. They don't have the precision necessary to effectively protect an alternator or battery from all over-current conditions.

BTW, the Redarc instruction manual (pg 10) states it does not recommend the use of self-resetting circuit breakers. They recommend the use of low-resistance MIDI fuses.

Teleman

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Posted: 11/22/21 09:21am Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

Teleman wrote:

I put circuit breakers on both sides of the charger too. I'm pretty confident I won't have any trouble.
Circuit breakers and fuses are very imprecise devices. A batch of 60a breakers/fuses of the same type, from the same manufacturer, may open at 70a, 85a, or even higher. It's wishful thinking to assume a 60a breaker/fuse is going to open at 61a. Breakers/fuses are primarily designed to protect in the event of a short or massive overload condition. They don't have the precision necessary to effectively protect an alternator or battery from all over-current conditions.

BTW, the Redarc instruction manual (pg 10) states it does not recommend the use of self-resetting circuit breakers. They recommend the use of low-resistance MIDI fuses.

They are not self resetting.

otrfun

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Posted: 11/22/21 09:27am Link  |  Quote  |  Print  |  Notify Moderator

noteven wrote:

. . . 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.
Outside of input/output connections and a trigger input to turn the unit off and on, there are no other connections or sensors on a Renogy dc to dc charger that would relay any info about an alternator's condition, load or output rating. I've briefly read through the 25a/40a Redarc manual and I believe this is also true for the Redarc.

There are a number of ways to program the *output* of a dc to dc charger to protect and properly charge the battery; however, very few options (if any) to regulate the *input* load to protect the alternator (the only exception is the half-power mode on the Renogy).

This is why choosing a dc to dc charger with the proper current rating is important (in respect to alternator load).

otrfun

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Posted: 11/22/21 09:31am Link  |  Quote  |  Print  |  Notify Moderator

Teleman wrote:

otrfun wrote:

Teleman wrote:

I put circuit breakers on both sides of the charger too. I'm pretty confident I won't have any trouble.
Circuit breakers and fuses are very imprecise devices. A batch of 60a breakers/fuses of the same type, from the same manufacturer, may open at 70a, 85a, or even higher. It's wishful thinking to assume a 60a breaker/fuse is going to open at 61a. Breakers/fuses are primarily designed to protect in the event of a short or massive overload condition. They don't have the precision necessary to effectively protect an alternator or battery from all over-current conditions.

BTW, the Redarc instruction manual (pg 10) states it does not recommend the use of self-resetting circuit breakers. They recommend the use of low-resistance MIDI fuses.
They are not self resetting.
The "self-resetting" comment was more for general consumption. However, I do believe Redarc's recommendation to use MIDI fuses might be something you may want to consider (vs. using circuit breakers).

* This post was edited 11/22/21 09:45am by otrfun *

noteven

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Posted: 11/22/21 10:31am Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

noteven wrote:

. . . 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.
Outside of input/output connections and a trigger input to turn the unit off and on, there are no other connections or sensors on a Renogy dc to dc charger that would relay any info about an alternator's condition, load or output rating. I've briefly read through the 25a/40a Redarc manual and I believe this is also true for the Redarc.

There are a number of ways to program the *output* of a dc to dc charger to protect and properly charge the battery; however, very few options (if any) to regulate the *input* load to protect the alternator (the only exception is the half-power mode on the Renogy).

This is why choosing a dc to dc charger with the proper current rating is important (in respect to alternator load).


I think otr is correct ^. I have a Renogy on the project shelf. It is a 40amp model. The literature states input amps are 60amps at 40amps output.

High output alternators are not super expensive if your oem one kicks the bucket..

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