LumenCache reviews welcome

lumencachelumencache Registered Users Posts: 3
Hello. I found this forum while answering a question about battery charging from simultaneous AC and Solar.  The responses and community were excellent so I figured this was a good audience to get involved with LumenCache.  There are 3 projects that I know of that use All-DC power (off grid).  They're using 24V and 48V batteries and the 48V system uses DC48/DC12 before entering our power distribution modules (PDMs).  New LED driver modules will accept 12-48V supply without intermediate voltage adapters.  Our dealer in Mexico is specifying 7500 small homes for earthquake relief and the same system designs would work well in other regions of course.
I'm not a solar guru so I'm happy to send an evaluation kit to the most eager and technical respondent if enough people on the discussion agree with that person.  http://www.LumenCache.com  Thanks!
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Comments

  • EstragonEstragon Registered Users Posts: 1,545 ✭✭✭✭
    A 48v nominal off-grid system using flooded lead acid batteries will typically operate with actual voltages ranging from roughly 47-60+v, so a 48v limit would be too low.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators Posts: 26,837 admin
    I would suggest that ~72 volts should be the upper working limit for a 48 volt battery bank (cold climate, equalization, etc.).

    And ~10.5 volts should be the minimum limit (perhaps 10.0 volts) for a 12 volt battery bank (warm climate, discharged, under load, wiring voltage drop).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lumencachelumencache Registered Users Posts: 3
    We were planning 65V upper limit so thanks for recommending 72v.  I'm leaning against 12V supply because it seems so limited.  At 10v the current gets pretty high on the PDM input.
  • EstragonEstragon Registered Users Posts: 1,545 ✭✭✭✭
    I regularly charge with low to mid 60s voltages for absorb with cool/cold batteries, so 72v would be much better than 65.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators Posts: 26,837 admin
    12 volts is so common because of many 12 VDC adapters (USB chargers, radios, laptop computer converters, etc.) and common for smaller solar power systems... But I do understand the limitations for a very wide range DC input voltage.

    There are a fair number of lower voltage wide range DC LED lamps (12/24 volt DC floods are common). And here are ~12-60 VDC solutions:

    https://www.amazon.com/Medium-Voltage-Fitting-Motorhome-Battery/dp/B009RHVYZC

    But they are not all highly rated, and sometimes of questionable quality/voltage capabilities. But you know this...

    I am a bit confused about your company/website... Seems to talk about the 380 VDC power grid (high voltage DC--avoid AC inverter costs and losses). However, your ordering page seems to deal with low voltage DC (12-50 VDC or so). Both are interesting classes of solutions--But I am unsure where "you" are heading.

    380 VDC certainly seems interesting--But it is not trivial from a safety point of view. 120/240 VAC 50/60 Hz can be much safer because AC has lower arc potential, and the ease of doing things like Ground Fault Protection, galvanic isolation via transformers, etc. Pure DC power systems are not near as easy (from an engineering point of view) to address these issues on a non-data center "professionally managed" installation.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lumencachelumencache Registered Users Posts: 3
    LumenCache deals with the low-power distribution side for installed devices, like lights, exhaust/ceiling fans, and USB outlets.  Anything under 100W.  We're working with US Department of Energy, EMerge, DC Nexus, ASE.org, and more groups who are working at the Microgrid level (districts, etc).  Lots of voltage standards around the world so adaptability is the key to interfacing with DC "mains".  There are great benefits to adding communication to the last 1000ft so that's what we do.
  • nickdearing88nickdearing88 Registered Users Posts: 92 ✭✭✭
    I took a look at the project.....very interesting. I like using the CAT 5 cable, and the ability to use other pairs for data. I'll be curious to see where it ends up.
    Current test system: 4-100w Renogy panels mono/poly, 1 string of 4 panels in series - 24v 100Ah AGM Battleborn LiFePO4 batteries - Morningstar MPPT40 CC - 1500W Samlex PSW inverter
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