Charging inverter capacitors?

wellbuilt
wellbuilt Solar Expert Posts: 763 ✭✭✭✭
Is it necessary to charge the capacitors on my out back 36/48v 
inverter  before I turn the power on? 
 I was reading about this on a rv form 
 when I turn the breaker on it dose seam a little harsh when it starts 
Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .

Comments

  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    edited September 2021 #2
    It is not great on any circuit breaker contacts.  I usually momentarily jumper the breaker with a foot long piece of #14 wire before I turn the breaker on.

    Lithium with a BMS is a different story.  Some BMS's will have an overcurrent shutdown.  They self reset after some time, or require a manual reset.
  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    Hmmm I’ll have to figure some thing out for it 
     my breaker is All enclosed so there is no way to jumper it . 
    Thanks for the reply 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    I would not worry about it. They are designed for this. Obviously you are not turning the inverter on with a load running right?

    If you are really remote, you should always have a spare or know how to get a spare fast. The fast part can be an issue these C19 days. A plan is a good thing as running from a genset can get really old ;)
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    edited September 2021 #5
    If you want to pre-charge the DC input... you could always do a push button (hold button for a few seconds, then turn on breaker) with a power resistor in series (to limit current):
    • 12 volt bus / 1 Ohm resistor = 12 amps max surge/capacitor charging current
    • P=V*I = 12 volts * 12 amps = 144 Watt rated power resistor (probably way overkill--A couple Watt power resistor probably would work fine--And if it pops, get a size larger).
    Quick and dirty--But easy to do.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    Thanks Dave
     I turn on the main breaker then the cc fm80 then solar 
     then fndc 
     then inverter on in the mate and then the breaker going to my panel . 
      I would not worry about it but it makes a bad noise when I turn on the breaker . 
     
        Bill , I may try to make one 
       I’m sure it would be ok if I wasn’t powering the unit every week 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    edited September 2021 #7
    Double checked my math... Multiple mistakes and now corrected in my previous post.
    -Bill :s
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Would suggest switching the Inverter's breaker to ON,  rapidly  --  do not cringe or be afraid,  switch that sucker ON,  quickly.

    If one must use that breaker often,  then the pushbutton precharge is a great way to go.

    Historically,  have switched those breakers in use here,  several times per decade   ...   FWIW,  YMMV,  and so on.   Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    Vic 
     I just turn the system on on Friday nite
     and off Monday after noon , so 45 times a season +- 
     once a year would not worry me 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • Saggys
    Saggys Solar Expert Posts: 189 ✭✭✭
    Could you leave the battery breaker on and turn the inverter off, but in standby? That is what I do every weekend, also turning the AC breaker off to the cabin. Been doing this for years without any problems.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    The issue with leaving the inverter in Standby...

    Most AC inverters draw between 6 and 40 Watts when "ON", and something like 1/2 that (+ or -) (larger inverters, larger standby current)... As long as your system is operating correctly (good sun daily, or at least every few days, nothing on the AC side takes the into "INVERT" mode, then all is OK.

    Where you get into issues... Some folks have bad shading or even drifted snow on panels (in winter)--And the standby draw can take the batteries down and even to dead (in a couple weeks or so). These "small loads" (and vampire loads, alarm systems, camera systems, cell/internet phone home devices, etc.) can take even a relatively large bank down to dead in a few weeks).

    Have even a member or two report their fancy large MPPT solar charge controller take a battery bank dead when a bad snow season covered the array, or a MPPT charge controller faulted and decided to not charge anymore until reset/repaired.

    The two solutions are: Charge bank to 100%, and turn EVERYTHING OFF when leaving. In warm climates, an FLA bank will need to be fully recharged in ~30 Days (25C/77F). In cold climates (say bank stays under 0C or -32F, the bank will go upwards of 2.5 to 3 months between recharging. AGM batteries will go 6 months between charges at 25C. Li Ion will go >1 year with no loads.

    Another solution--Hang a 100-200+ watt panel on the side of the building (or vertical up high if drifting snow is issue), and use a small PWM charge controller. The panel on the side of the building will not cover from snow fall (there is always drifting issues)--And the PWM controllers draw much less power when no sun is present. That will keep the bank pretty happy over winter (cold lead acid batteries have much lower self discharge, basically 1/2 self discharge rate for every 10C drop below 25C).

    You can also "run the math" and see how susceptible to inverter/charge controller discharge you are... Say you go away for 1 month and have an MPPT controller and Inverter (in standby)... Don't want the FLA bank to discharge below 75% State of charge and there is a risk of snow drifts (or you just want to ensure the battery bank does not get "killed" if there is a charging fault). Some made up numbers:
    • 400 AH @ 24 volt bank
    • 400 AH * 0.25 discharge = 100 AH of no-sun capacity
    • 100 AH * 24 volts = 2,400 WH of capacity
    • 2,400 WH * 1/30 day no-sun storage = 100 WH per day available capacity
    • 100 WH per day / 24 hours per day = 4.2 Watt average load
    In the above example--If you lose charging for 30 Days, a 4.2 Watt load running for 30 Days will take your bank from 100% to 75% State of Charge...

    For example an Outback FXR series inverter (mid size) takes 
    https://www.solar-electric.com/lib/wind-sun/FXR_A_specsheet.pdf
    Idle Power Full: ~34W Search: ~9W Off: ~3W 
    Just the inverter "OFF" (inverter "soft switch control") could take a mid-size battery bank pretty close to 75% SoC in a month (with no charging). Vs truly ZERO Watts if you switch off the Inverter's DC circuit breaker. (There is the surge current to recharge the inverter's input filter capacitors--Which does have a non-zero chance of causing eventual capacitor failure from current spike--Cycling DC power to the inverter daily--Probably something I would avoid. Once per season, probably not much of a risk of early life failure).

    For an Outback FM60/80 MPPT charge controller:
    https://www.solar-electric.com/lib/wind-sun/Outback_FM60_FM80_Specifications.pdf (1 Watt in standby)

    For a Midnite Classic:
    https://www.solar-electric.com/lib/wind-sun/Classic-specifications.pdf (2.5 Watt in standby)

    Not picking on the mfg's... Just showing that you need to look at the specifications and what can "go wrong" when you are not there...

    And you have multiple factors... The above shows 4.2 Watt average load can take a (fictional) bank to 75% in 30 Days... An FLA battery bank needs to be recharged every 30 days (at 25C/77F room temperature)... If the bank in "hot" (hot climates), an FLA would need charging every 15 Days (if stored at 35C/95F).

    And other things happen too... EASY--Switch off Main DC breaker to all loads (leave solar charging breaker "ON"). Vs manually turning of AC inverter, USB charger, water pump, lighting, and other DC branch circuit(s). With humans--ONE can be done pretty reliably... Doing multiple breakers/soft key on inverter remote--Something is more likely to be forgotten.

    Sort of the issue with aircraft... Things to "lock controls" (prevent wind damage), cover for Pitot tubes (to keep bugs and water out), engine vent covers, etc. have red ribbon hang tags to make it obvious when putting plane to bed, or getting ready for flight. Just another method to help ensure "mistakes are not made".

    Hanging a red ribbon on the main load disconnect breaker--Just another reminder as the family heads out to the car for the trip home. (i.e., put the ribbon/tag next to front door, on car keys, or other obvious location to have that double check that battery bank loads are off for the season).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
     A quality inverter like Outback should not have much draw at all in standby. XW's are less than 2 watts and I know Outback is similar. He should try the off mode or Inverter disabled from. Even in search mode like in stacked inverters, when the slave when not being called on, the load is about 8 watts. The power bridge is off in stand-by and that is what uses 90+ percent of the tare loss. Just the network card is on in XW. I have not done much with Outback lately but it should be similar. I have forgot their terminology but he could ask on their forum. Not hard to measure either with a good ammeter.

    If he is leaving it all winter, that is not what I understood he said.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Just trying for the "larger answer"... Leaving inverter on (or "off") for weekly use--Not a big issue. However, over winter, larger loads (security systems, inverter left "ON" by mistake, solar charger fails, etc.)--There can be issue.

    For example, a 34 Watt "forgot to turn inverter off" situation, and failure of solar charger, did get snow on panels, etc.... The example 400 AH @ 24 volt battery bank will drain to 75% SoC in:
    • 100 AH * 24 volts * 1/34 Watts = 70.6 Hours = 2.9 Days
    Miss a couple weekend trips (sick kids, holiday traffic, work around the house, etc...) and in less than 12 day, battery bank would be dead (example of failure to charge example). And not only have the (possible) repairs to solar charger, need a new battery bank too.

    Not trying to be argumentative here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    I’m going to try just turning the inverter to off in the mate and see what happens . 
     I’ll be back in 10 days I think. 
      This could work for most of the year , I get heavy snow DEC to may .
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .