Looking at Chinese units on Amazon. They state never charge battery while hooked up. How would that work? 

Glenn, good question but I have no idea what "they" are talking about. I'm rusty as an engineer being so long retired, but believe the laws of physics still apply. Any black box device which converts DC of X volts to DC of Y Volts IS NOT 100% EFFICIENT there are heat losses, same as for Inverters or Chargers etc. I don't understand "never charge battery while hooked up"  

If I recall you are going to use a 24 or 48 volt system but need a DC to DC Converter to power up 12 VDC appliances. If so that's all well n good but as you know its NOT 100% efficient.

Perhaps ?? They mean when no load is applied to the devices output it doesn't draw any current from its input source ??? If so I like that !!

John T  Sorry I just don't understand what they are talking about

Chinglish. Poor translation skills. 

Glenn look at the Orion ones by Victron. More expensive but not horrible.

Glen if you take it literally they dont want you putting power into battery bank while using the product. If this is what they mean it sure would not work well with a solar set up. I am unsure of your battery setup but if you are using 6 volt in series the first two will give you 12 volts.

Oh, 48v lithium battery packs. I did not want to go Victron since I need at least 50 amps. Was going to get 60 amp unit. I would have to buy two and that price I can buy a lot of 12v batteries. That why wanting to try these Chinese units. 100.00 dollars so if it doesn't hold up not out of a lot. 

oh, found one that works while battery being charged with solar, wind,etc. Ordering that one.

  On 11/22/2019 at 9:19 AM, GlennWest said:

oh, found one that works while battery being charged with solar, wind,etc. Ordering that one.

Plus, Amazon has an excellent return policy, even for outside sellers.

They all have a range of acceptable voltage. That maybe exceeded if it is charging voltage rather than battery voltage.

I wouldn't be wasting 100 bux on anything not fit for the job. Victron makes robust converters. 

Glenn - please not to be burning down of your home to save $

I also think you are making a mistake here Glenn. Don't put unknown components in the middle of a very nice system.

\

But the Orion unit is also a charger. Don't need that. All I need is a simple bulk converter. Could use my existing converter but it is inefficient compare to a dc/dc unit https://www.amazon.com/HUAZHU-Converter-Step-Down-Module-Waterproof/dp/B07Z2NN95X/ref=mp_s_a_1_6?keywords=48v+to+12v+converter+60+amp&qid=1574454438&sr=8-6

Edited November 23 by GlennWest

FROM the specs on the above linked converter:

"1. Can not used long time Under the MAX. LISTED LOAD POWER."  LOL.  Sounds like 'me love you long time'.

Don't waste your time on that cheap Chinese unit. Notice (as you mentioned) max input voltage is 50.  Your batteries at rest will be around 52v, even more  when they're being charged.

If need be you can parallel a couple Victrons.  Yeah, they're expensive, but there's a reason for that.

Edited November 23 by hemsteadc

states 30-60 volts