Couple of questions about DC-Dc charging

NRALIFR wrote:

otrfun wrote:
You're correct. I miss-spoke slightly on the Renogy cable requirement for the 40a. My apologies.

By the way, did you see the "Notice" at the bottom of the Renogy pic you posted?

When charging converter is sending full charge, the amperage consumption will be 50% greater on the input side.

I believe this confirms what I've been saying about the Renogy dc to dc charger all along---that it *wastes* current. Contrary to your claim it doesn't. 50% greater than 40a is 60a. This concurs with the current measurements I observed with my friend's 40a Renogy dc to dc charger install.

I never suggested, implied, or tried to convince you in any way that you should use 2 gauge cable with your Redarc. My focus has ONLY been the Renogy's lack of conversion efficiency ("wasted" current)---nothing more, nothing less. You said the Renogy did not waste current, I said it did.

In any case, by your own admission you don't know what amperage your dc to dc charger is pulling, and don't care. I do care and regularly make current measurements to make sure all my various loads remain within tolerance. As such, my comments and observations are based on realworld measurements that I've personally made.

With all due respect, sometimes it's difficult to appreciate something unless you see it with your own eyes. For what it's worth, I've personally found a clamp-on ammeter to be a very useful and enlightening tool.

No problem, I posted that screenshot specifically because of how the data was formatted in that particular field. I think most people at first glance (me included) would look at that and only see the “4” in the top line, and not go any further. And yes, I did see the notice and intentionally didn’t crop it out. The inputs on my charger are fused at 60 amps as well. Renogy claims their charger efficiency is “Up to 90%”. If Redarc publishes the efficiency of their DC chargers, I haven’t found it.

Actually, I would be happy to measure the input amps on my charger for you. I should have had a clamp meter in my hands a few weeks ago for another project where I was interested in the DC amps that were above the range of my Fluke. I ended up getting misdirected by Amazon’s endless presentation of “similar” meters though, and got distracted by some accessories that came with the meter I ordered. When it arrived, I found out that I had ordered a clamp meter that could do everything very well……..except the one thing I was ordering a clamp meter for in the first place; measuring DC current. :S I should get another one soon.

:):)

I appreciate your offer to measure your Redarc's input current for me, NRALIFR; however, it's not necessary. I believe you'll find the measurements much more enlightening then I would. Helped a serious off-roading friend of mine in AZ install one last year. He uses it to power some important gear so we tested it every which way possible. Excellent unit for off-road use.

Hopefully this discussion didn't scare off any potential Renogy dc to dc charger owners. For the record, we're *completely* happy with our Renogy 40a dc to dc charger. A *lot* of performance for the money. We just got back from a 3,000 mi. trip through the SW US. Temps were already over 100+ in some areas. We regularly use our LifePo4 battery pack to power our a/c unit during our 30-45 min. breaks while we're on the road. After each break, the Renogy was tasked with charging the batteries back to 100%, which typically took 1-2 hours. All said and done, I'd say we had the Renogy producing its full-rated output of 40a for at least 20-25 hours during this trip. Worked flawlessly!