I have a 2016 Ford F150, with a smart alternator and my 2019 FWC Hawk has a Blue Sea 7611 Auto Charging Relay with Aux Battery priority. During every trip I've taken, plus leaving my National Luna 50L Refrig/Freezer on all the time, I have never had a problem with getting my 2 x 6 volt 260 amp hour AGM batteries to 100% charge........ until this last trip.
In past trips I would drive to a location, such as Big Bend NP in the winter, or some high elevation mountain spot in Colorado and then only drive short distances to a trail head or fishing spot. The truck would sit most of the day in full sun and the 2 x 100 watt Renogy solar panels would fully charge the house batteries. When parked at home, the truck is in full sun and the batteries stay at 100%
This last trip I did about 400 miles on the IDBDR, so I drove most of each day, often in the forest and didn't setup camp until around 4pm. My batteries never got to 100%, so now I'm convinced I need a DC to DC charger. I never saw the need for one before this trip.
I'm thinking about getting Renogy's 20amp unit, it's reasonable and I'm assume if I drive for 5 hours it will yield 100 amps into my batteries which is more than I use in a day. So I have some questions for the electronic wizards in the group.
1- Is my math correct, will 5 hours of driving with a 20 amp DC to DC charger give me 100 amps?
One of the advantages of the 20 amp unit over a 30 amp or 40 amp unit, is that according to their website, with the 20 amp unit, Renogy specs out 8 AWG copper wire for runs 11- 20 ft from the starter battery and 10 - 8 AWG for runs 11- 20 ft to the house battery. (My current wiring done by the Montana FWC is 10 AWG. ) Their website also says to place the charger close to the starter battery, but reading this forum it appears most people mount the charger in their camper.
2- Does the DC to DC charger replace the Blue Sea 7611?
3- If the DC to DC charger doesn't replace the Blue Sea 7611, then does the charger get wired before the Blue Sea unit?
Thanks in advance.