[RE-wrenches] 120 Vac and 12Vdc mixed distribution system

Fri Apr 26 19:50:05 PDT 2024

I have a new client wanting to upgrade an old system with DR inverter, 4
golf cart batteries Trace C40 CC and two small PV panels. The system was
definitely installed by a professional with breakers and switched and I am
looking at the photo the customer emailed to me and other than upsizing the
PV array and new batteries, there seems to be no reason to change the
inverter which is very energy efficient. His loads are minimal with  a
vacuum the only load to be
added.  Another customer called about 18 years after I installed his DR
system,  Seems that the inverter failed. He had replaced the batteries once
or twice and no
other issues.  Got there to check out the failure, I had voltage at the
inverter DC connections. So I pushed the TINY little black start button and
it fired right up.
This system had been so reliable that he had forgotten that there was and
on/off reset button. For now though, I'm sticking with Outback in spite of
the FM100
seeming to have hair trigger GFCI circuit  As with many of my clients
off-grid second home with a view, access is sometimes difficult so I rely
heavily on OpticRE
to make sure their lights are on and to keep micro managing customers off
my back when they call ask why the solar input is only 1200 watts when they
have 7K of panels on a perfect sunny day. I look at optics and their
batteries are full... DUH  I even have two Magnum systems (not my install)
with FM60's with AUX Relay so I can use MATE3 & OpticsRE to check battery
voltage, charging, setting charging perameters and start and stop the
generator remotely.

John

On Fri, Apr 26, 2024 at 5:39 PM Jay via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I’ve had no issues with qo over the years for 12v except if they get dirt
> in them from mud dobber wasps.
>
> Jay
>
> On Apr 26, 2024, at 9:05 AM, Darryl Thayer via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> 
> I agree with John also.  one of the better-performing off-grid houses I
> worked on used a 48 to 12-V Samlex converter. The 12-volt thick-walled
> refrigerator was about 4 amps at 12 volts. The lights, radio, and small TV
> drew very few amps each/  I also used an Outback 3648 inverter, which the
> homeowner turned on only. when needed (wash machine, etc.), I used SQ-D QO
> panel board in case the owner wanted to go to 120 volt AC future breaker
> panel. All lighting was Edison base lamps, and all wiring was NMB Romex.  I
> wired like a normal house except for a 120-v panel and 12-v panel I relay
> and momentary switch by appliance for easy turning on of AC inverter.
>
> On Wed, Apr 24, 2024 at 8:49 AM Jay via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> I agree with John.
>>
>> Most 12v fridges have small compressors. But I don’t know what they have.
>> Personally a major reason to go 120/ac is to get a normal refrigerator.
>>
>> But you can measure the surge/load  and then size the charger
>> accordingly.
>>
>> One feature of going charger is the lights are a lot brighter at night
>> and last longer because they are not at 15v during the day.
>>
>> Jay
>>
>>
>> On Apr 24, 2024, at 5:01 AM, John Blittersdorf via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> 
>> Jason,
>>   I have a customer with the same situation except he already has a 12 V
>> VFX inverter,  He has a sunfrost fridge and other small loads with a very
>> fancy custom control board
>> originally set up to handle AC and DC systems.  We are adding a lot more
>> solar and I was considering a dual battery system but the owner didn't like
>> that idea.  We are going with and Iota 12v power supply (i use one at my
>> house for my sunfrost) to power up all his DC loads and will be adding a
>> large 48 V battery bank and over 4Kw of solar using a VFXR3648 directly in
>> place of the 12V inverter.  He complained that the existing inverter would
>> not handle all his current AC loads very well.  My own house is fully wired
>> for 12VDC as well as AC (lots of #10 copper not being used) and I have been
>> considering getting a small LFP 12V battery to put back on by DC System.
>> Then use the Iota as a secondary charging method with some of my large
>> stash of older modules hooked up for 12V direct with C40 charge controller
>> to recreate my original system just for kicks. I'm only using DC for my
>> Sunfrost and one "emergency light" in the livingroom right now.  For your
>> customer, a small LFP 12v battery (approximately $500 or less) to replace
>> his old battery bankm and more larger ones for the new AC side with 48V
>> inverter fed by his generator or through an Iota 48 V charger ifusing a
>> smaller non charging inverter. Unlike Dave, I like these challenges. Maybe
>> thats why I never seem to make money.!!
>>
>> John Blittersdorf
>> offgridvermont.com
>>
>>
>> On Wed, Apr 24, 2024 at 7:22 AM Jason Szumlanski via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>>> Fortunately, the owner is pretty handy and is willing to live with any
>>> negative consequences. That said, I want to offer him something as simple
>>> and bulletproof as possible. I am walking into this with eyes wide open,
>>> for sure.
>>>
>>> Jason Szumlanski
>>> Principal Solar Designer | Florida Solar Design Group
>>> NABCEP Certified Solar Professional (PVIP)
>>> Florida State Certified Solar Contractor CVC56956
>>> Florida Certified Electrical Contractor EC13013208
>>>
>>>
>>> On Tue, Apr 23, 2024 at 5:47 PM Dave Angelini Offgrid Solar via
>>> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>>
>>>> Not being helpful but I  walk away from these.  It will come back to you.
>>>>
>>>> *Dave Angelini Offgrid Solar
>>>> "we go where powerlines don't"
>>>>    <http://members.sti.net/offgridsolar/>https://offgridsolar1.com/ <https://offgridsolar1.com/>  <http://members.sti.net/offgridsolar/>
>>>> e-mail  offgridsolar at sti.net <offgridsolar at sti.net>
>>>> text 209 813 0060*
>>>>
>>>>
>>>> On 2024-04-23 2:40 pm, Jason Szumlanski via RE-wrenches wrote:
>>>>
>>>> I have an off-grid client who is working on replacing old equipment at
>>>> a cabin. He has a lot of 12 volt distribution in the house for lighting,
>>>> fans, and a 12 volt refrigerator. He also has 120 volt AC loads that run
>>>> through a separate distribution panel where the only source is a 2000 Watt
>>>> Honda generator. There is no inverter present. The batteries are charged
>>>> through a Trace C40.
>>>>
>>>> He currently has a few ancient solar panels and a struggling Bank of
>>>> AGM batteries. It's time for an upgrade. I can easily supply enough PV
>>>> power for what he needs. He currently has a 9 kilowatt hour battery
>>>> capacity that he was happy with when the batteries operated optimally.
>>>> Nonetheless, I would probably future-proof him with a 10 to 15 kilowatt
>>>> hour LiPo to double or triple his usable capacity.
>>>>
>>>> For convenience, obviously it would be nice to have an inverter to
>>>> eliminate or reduce the generator requirement. But he seems committed to
>>>> keeping his 12 volt distribution because it would be costly to replace
>>>> fixtures. I think he would consider replacing the 12 volt refrigerator if
>>>> he has an inverter.
>>>>
>>>> He definitely wants LiPo batteries.
>>>>
>>>> I don't like the idea of 12 volt direct from a battery plus connecting
>>>> an inverter to that same battery. It is going to be hard to measure and
>>>> monitor things.
>>>>
>>>> I am thinking about using a 48 volt battery with a single phase 120
>>>> volt inverter, getting him to change to a 120 volt refrigerator, and using
>>>> a DC converter to give him somewhere in the range of 100 amps at 12 volts
>>>> for his existing DC lighting and fan loads. Is this a bad idea? Should I
>>>> stick with a 12 volt battery system? He does have a tiny 12 volt pressure
>>>> pump which might be an issue for the converter. I'm not sure. I am a bit
>>>> worried about the efficiency loss and capacity of DC converters and not
>>>> sure how to size it.
>>>>
>>>> Jason Szumlanski
>>>> Florida Solar Design Group
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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