Renogy 20A dc to DC report

StirCrazy wrote:
all the dc to dc i have seen have a trigger wire so you can put it to a switch and onlly turn it on when you need it or hook it to the altanator trigger so it only starts when the altanator is putting out a voltage.

mine is going on a KOER upfitter switch so I have to physicly turn on the switch and the engine has to be running before it will energize as for me this will just be a emergency source of power and I want to controle when it is on and off.

with this you don't need a BI as it is built in, but if all you want to do is have it so you cant drain down your starting battery and not worry about charge profile then yes a BI is the way to go, but they serve two different purposes so one isnt a replacment for the other, well except in the case of the dc to dc as it has a built in BI so you get both if you go that way...

If I understand your explanation, your system is going to: Require the operator to physically turn on the KEOR upfitter switch, while the engine is running, before it (the dc to dc charger) will energize.. Based on this functional description, I don't see how your KOER upfitter switch offers any additional or different capability vs. a standard dc to dc charger installation, other than the ability to turn the dc to dc charger off an on at will. Any switch will do that. Now if you're also saying the KOER upfitter switch output is only active when the engine is running, then a BI wired through a simple off/on switch would function the same way. It would only allow the the dc to dc charger to be turned on when the switch is on and the engine is running.

You seem to infer the Renogy ignition trigger wire and/or Battery Isolator has some effect on the Renogy dc to dc charger's "charge profile". They do not! This is true regardless how they're used, or not used, as the case may be. They *only* turn the dc to dc charger off and on---nothing more, nothing less.

StirCrazy, you mention a BI (Battery Isolator) is "built-in" to a Renogy dc to dc charger. It is not! The ignition trigger wire by itself is *not* equivalent to a BI. The Renogy ignition trigger wire will activate the dc to dc charger when it senses *any* nominal amount of 12vdc (10-15v). It cannot tell the difference between the output of a battery or alternator. A Battery Isolator can. The BI is voltage selective to ensure it will *only* close the relay (activating the dc to dc charger) when the alternator is active, when voltage is >=13.3v. Battery voltage (12.7v) alone will *not* activate the BI relay. This protects the battery from being discharged by the dc to dc charger if the alternator is not operating for any reason. *None* of this capability is "built-in" to a Renogy dc to dc charger.

Lastly, yes, you can connect the Renogy ignition trigger wire directly to the alternator output. This will turn-off the dc to dc charger when the alternator is off-line. However, it's important to find a circuit that is not backfed by the battery when the engine is not running. On some vehicles, this is much easier said than done. Using a battery isolator can save time and grieve and accomplish exactly the same thing. Additionally, for those who have a dc to dc charger located inside a TT, 5R, or TC, mounting a BI inside the RV, next to the dc to dc charger, can save the hassle of running a 20-30 ft. ignition trigger wire all the way to the alternator in the TV engine compartment.