[RE-wrenches] Brown-Out Prone Opportunity Charging

Jeff Clearwater jeffc at villagepowerdesign.com
Mon Mar 16 13:50:20 EDT 2020 

Yes LFP - the grid is only on a few hours in the morning and a few hours 
in the evening and even that is not reliable.  Diesel is to be avoided 
as much as possible as diesel prices are volatile now that Venezuela is 
closing the tap and local maintenance is iffy.    So I'm looking at 
buffering with as many batteries as financing will allow.  So PS and 
battery need to be sized above power consumption.  It's a small hospital 
so consumption varies quite a bit daily - the more they have the more 
they use and can serve. Solar roof space is limited to about 16 KW - so 
grid opportunity charging could make all the difference for them. We are 
in the 24 KW (5 sec) peak, 8 KW typical, 60-100 KWHrs/day range.  Doing 
more data logging to pin that down more.  Thanks for your input!

Jeff Clearwater
Village Power Design

Starlight Solar Power Systems wrote on 3/16/20 10:05 AM:

> Did you mean to say LFP? It depends on who made the battery. LFP 
> batteries can be charged using CC/CV. Some, like the Elite PS/GBS 
> battery packages can accept a simple CV power supply of 3.65 Vpc.
>
> The inverter is always on and isolated from the grid so it’s not 
> affected by poor power quality unless you allow ripple or spikes to 
> the battery system. That should be protected at the AC input of your 
> charger/PS and PS filtering.
>
> What is the daily power consumption? If the battery and PS are sized 
> to meet your loads, then it won’t matter when the grid is available. 
> Grid Outages longer than you design for can be backed up with a 
> generator.
>
> Larry Crutcher
> Starlight Solar Power Systems
>
>
>
> On Mar 13, 2020, at 6:09 PM, Jeff Clearwater 
> <jeffc at villagepowerdesign.com <mailto:jeffc at villagepowerdesign.com>> 
> wrote:
>
> Thanks All,
>
> Mick and Tump - I'll look into the Victron - good suggestion - Thanks!
>
> Chris - I'm not sure a transformer will buffer the spikes and 
> frequency but just pass them on - others?
>
> Larry and Jerry - If I were to go with the separate battery charger/PS 
> approach - what specific  48 V  LFeP battery Charger/PS might you 
> recommend and how to protect it with what sort of surge and LV 
> equipment?  If either the inverter or PS/Charger is protected within 
> too narrow a range then it might defeat the purpose - wanting to 
> maximize pulling in as much opportunity charging as we can get.
>
> Seems to me like there might be a market for a highly tolerant battery 
> charger between 160-260 VAC and frequency tolerant as well - something 
> bulletproof we could put on these systems - perhaps that is the 
> Victron - but I'd rather have it in a separate beefy battery charger 
> then risk the inverters - especially if we are going to buffer the 
> customer from the grid with the battery/inverter system.
>
> For instance we have a hospital that can only use the available grid 
> for the office but they can't risk it for their hospital equipment.  
> But If I could pull the grid into batteries safely and always power 
> their loads with the high reliability battery/inverter system - now we 
> are talking.
>
> So specific 48V battery chargers that can take it? Any equipment out 
> there anyone is aware of?
>
> Thanks!
>
> Jeff
>
> Tump wrote on 3/13/20 2:47 PM:
>> Check out the Victron line of Chargers as well as the inverter 
>> charger units. AC in 187-265 45-65 Hz. for the inverters 230V/50Hz, 
>> inverter.
>> Please feel free to e mail me 4 additional info. Great BT support / 
>> internet access. well thought out product.
>>> On Mar 13, 2020, at 5:11 PM, Jerry Shafer <jerrysgarage01 at gmail.com 
>>> <mailto:jerrysgarage01 at gmail.com>> wrote:
>>>
>>> Jeff
>>> I have been there too in most cases we have programmed in the VAC 
>>> max/mins with tighter setting so as the grid starts to go we just 
>>> disconnect. I did just do a charger instead of the inverter because 
>>> the grid was generally low on frequency but the charger just charged 
>>> and l see it on optics when that happens
>>> Jerry
>>>
>>> On Fri, Mar 13, 2020, 12:03 PM Jeff Clearwater 
>>> <jeffc at villagepowerdesign.com <mailto:jeffc at villagepowerdesign.com>> 
>>> wrote:
>>>
>>>     Good Day Esteemed Wrenchers,
>>>
>>>     So we are doing more work in developing countries where the grid
>>>     is super unreliable but on for some hours almost daily.
>>>
>>>     So let's say we have a grid that's on 9 AM - 11 AM and 4 PM - 7
>>>     PM each day but often browns-out during those hours and comes on
>>>     and off during those hours. 230 VAC voltage can drop to 160-180
>>>     periodically or go above 260 in spikes.
>>>
>>>     The present practice in many of these situations is for battery
>>>     based system designers/installers is to set up an off-grid
>>>     system in parallel to the mains but not relying on them - so the
>>>     grid AC IN is not connected.  They just install a transfer
>>>     switch and manually switch or they wire a critical loads panel
>>>     to the solar.
>>>
>>>     This avoids constant switching and nuisance shut-downs from the
>>>     battery inverter and protects it from burning out trying to
>>>     handle the grid.
>>>
>>>     MY QUESTION:
>>>
>>>     I'm wondering what we can do to use the grid when it is up for
>>>     opportunity charging of the batteries while at the same time not
>>>     subjecting our nice new battery inverters to constant brown-out
>>>     tripping and possibly long term damage.
>>>
>>>     So question #1 - Is anyone using existing battery inverters but
>>>     succesfully navigating such a grid variablity settings such that
>>>     you are able to take advantage of the grid even if browning out
>>>     often?
>>>
>>>     or question #2 - Can we add some sort of high Voltage and
>>>     Frequency tolerant battery charger to the system - keep the
>>>     battery inverter/charger off grid - but charge the batteries
>>>     from something able to handle the wonky grid without constantly
>>>     nuisance charging or burning itself up?
>>>
>>>     Your thoughts and wisdom I await!!!
>>>
>>>     Best,
>>>
>>>     Jeff
>>>
>>>
>>>     -- 
>>>     ~~~~~~~~~~~
>>>     Jeff Clearwater
>>>     Village Power Design
>>>     linkedin <https://www.linkedin.com/in/jeff-clearwater-0622a312/>
>>>     www.villagepowerdesign.com <http://www.villagepowerdesign.com/>
>>>     cell - 413-559-9763
>>>     ~~~~~~~~~~~~~~~~~~~~~~~
>


-- 
~~~~~~~~~~~
Jeff Clearwater
Village Power Design
linkedin <https://www.linkedin.com/in/jeff-clearwater-0622a312/>
www.villagepowerdesign.com <http://www.villagepowerdesign.com>
cell - 413-559-9763
~~~~~~~~~~~~~~~~~~~~~~~
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20200316/86928a37/attachment.htm>

More information about the RE-Wrenches mailing list