Question about Redarc 40A DC to DC charger wiring.

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..

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).

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 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.

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.

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.

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.

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.

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!

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.