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 ...
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StirCrazy wrote:You're welcome!
thanks for posting that picture, that is exactly what I needed to see. they are specking a non critical volatage drop of 3 - 10% so of course the more the voltage drops the more the input current is going to raise to acomadate the lower supplied voltage. if we size the cable runs with a <1% voltage drop then you should only have an increase slightly above the efficiencey of the dc to dc charger. I am not worried to much about my altanatore on its output but rather on heat and the amount of use. I idealy want to size the load at 30% but weather that would be possible depends on the actual usage at 60 amps I am sitting at 38% , at 50 amps I am at 31%and at 45 amps I am at 28% so that is great and means I can go with the 40 amp charger no problem.
Steve
I was shocked when I saw the 3-10% non-critical voltage drop comment. A 10% voltage drop is huge.
Good idea to strive for a <1% voltage drop!! That's what you gotta do if you want to get the best conversion efficiency. We didn't quite get there with our install, but we got close.
I give Renogy kudos for their dc to dc charger's ability to handle low input voltages. However, I think they should make it much more clear the downsides to operating a dc to dc charger this way.
Good luck with your install!
