Couple of questions about DC-Dc charging
I've been thinking about adding a DC-DC charger now that I've added 400 amp hours of AGM batteries. There are lots of useful posts but I haven't run into a couple of things I'm curious about. One ...
Forum Discussion
Steve, IMO that output wattage limit is "nominal" not for real, that goes with the "12v nominal". IE, 20 x 12 = 240 and says 250 limit, and 40 x 12 = 480 and says 500 limit.
To meet the actual specs of doing 40 amps at 14.7v output, that would be 588 watts right there. I have seen 20 amps at 14.7v holding on my 20 amper for 294 watts (where "nominal" is 250w)
I have to redo my test using a simple load instead of the inverter and fridge that confused things. I don't have a good way to measure input amps, but can improve the jury- rigged ammeter connections. I plan to also try it with my fat wire long jumper cable set, to simulate a fatter wire installation from engine batt to Renogy to get a better notion how much that would help.
Whatever, I still think you could get the 40 and don't have to settle for the 20. I have a 105 amp alternator in the truck with the 20 so your 220 amper should do ok with a 40 in yours IMO.
To meet the actual specs of doing 40 amps at 14.7v output, that would be 588 watts right there. I have seen 20 amps at 14.7v holding on my 20 amper for 294 watts (where "nominal" is 250w)
I have to redo my test using a simple load instead of the inverter and fridge that confused things. I don't have a good way to measure input amps, but can improve the jury- rigged ammeter connections. I plan to also try it with my fat wire long jumper cable set, to simulate a fatter wire installation from engine batt to Renogy to get a better notion how much that would help.
Whatever, I still think you could get the 40 and don't have to settle for the 20. I have a 105 amp alternator in the truck with the 20 so your 220 amper should do ok with a 40 in yours IMO.
