selectronic or victron inverter?

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Re: selectronic or victron inverter?

Postby australsolarier » Fri Dec 18, 2015 9:47 am

kurt,
after programming the selectronic inverter charger, charged the lifep4 with the selectronic. although no pv input into the midnite (connected to the lifepo4 only), the midnite was reversing again.
after further investigation, with the help of a 2000w kettle following result:
my midnite classic is doing the reversing when between absorb and float voltage. as the kettle pulled the voltage down to float, the reversing stopped and pv input started to work again. turned off kettle, the voltage went past the float V and reversing. and etc.

i suppose it is not bad for the lifepo4's as it pulls down the voltage faster when no use of electricity. however i am not sure whether it is such a good thing for the midnite. i suspect not.

all the best
urs
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Re: selectronic or victron inverter?

Postby offgridQLD » Fri Dec 18, 2015 10:11 am

what voltage are you charging the battery to in absorb. 56v? How long are you spending at absorb voltage (what are your setting in the classic) I have mine set for 45min absorb time or (end amps) set to 1A so what ever is triggered first.

What is your float voltage 53.8v?

That's what I run and the transition to float is always just the charger output stops after absorb and then there is a few min of zero output then the chargers start to cover the base load (typically 100 - 250w) I don't need to put any large loads on to get it to start covering the small base loads in float. It just gently transitions all by its self. I just watched live the transition to float about 10 min ago.

I don't see any reversing 30w consumption from ether of the controllers and the fans do not come on in this transition period.

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Re: selectronic or victron inverter?

Postby australsolarier » Fri Dec 18, 2015 11:19 am

possibly there is something wrong with that classic.

absorb is set to56v, float to 53.6v.

end amps is 8ampere. this is the recommendation from the gbs, 0.02c.

i have not set the absorb time yet, (2 hours) at the moment.

the 12v system can go into absorb at 65% soc, so setting a time there is useless.

the behavior with the 48v system is entierly different, it just stays in absorb a few minutes before float.

the problem with the 12v system is this: say it charges the battery at 70amps, the voltage loss between the midnite terminals and the battery terminals is somewhere about 0.4volts. this does not look much, but triggers absorb very early in the midnite. the midnite really needs battery sense wires in this configuration.

with the 48v there is not much voltage loss. for one thing the current is lower. but also the percentage of the voltage is much smaller too.

the voltage loss is not so much from the wires, but breakers and fuses. so absorb time is set to 2.5hours, which does not mean much, as the midnite thinks it is in absorb when the battery is still bulk charging. so on the 12v system with the 300a/h capacity end amps are set to 6a. it hangs around there for a few minutes before floating. a cloud can trigger it prematurely. not a major issue though, maybe 2% undercharge.
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Re: selectronic or victron inverter?

Postby offgridQLD » Fri Dec 18, 2015 11:49 am

Set the float voltage higher.

Set the end amps for less and set the absorb time for less.

I'm not seeing any of the issues other than voltage discrepancy on classic with voltage drop just make sure it's spot on under in float light output as that"a where its critical.

Reference your bat voltage with a good meter at float and adjust your v offset to match.keep cable runs short and as big as you can 25mm2 for the classic.

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Re: selectronic or victron inverter?

Postby australsolarier » Fri Dec 18, 2015 12:34 pm

well, as it hangs in absorb, the currency goes down and with it the voltage differential. it just takes longer as it throttles current back. (the 48volt system goes very close to a full charge before absorb kicks in) i have a dedicated voltmeter at the battery terminal and one at the midnite terminal, so i can see at a glance where the battery is. sort of hoovers around 13.45v at float. it depends how much electricity the inverter draws. so then basically absorb v at the battery terminal is up at 14.0v as well. in real terms it does what i want, although in a roundabout way.
the voltages have been checked with 3 voltmeters, all about 2/100reds of a volt corresponding and the midnite classic bat voltage adjusted to that level.
so on float SOC is 99%, remaining 297a. at the whizzbang jr sensor. but can go back up towards evening to 100% as current is reduced due to the sun reducing power to the midnite classic. (it sounds like an oxymoron but that is what happens)

the midnite classic really needs battery sense wires for the 12v configuration. running back and forth between the laptop in the house and the voltmeter at the lifepo4 in the shed really keeps me fit.

i just run out there to the shed:
midnite 13.500volt
lifepo4 13.445volt
whizzbang 0a (fluctuating rapidly)
inverter and dc drawing 650watts
if i could reduce the midnite 0.05volts, i would do it.

"equalized" yesterday to 14.6 volt. just before float, 40mV biggest difference of the cells. just after float 22mV
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Re: selectronic or victron inverter?

Postby offgridQLD » Fri Dec 18, 2015 2:18 pm

Yes 12v systems and the inherent high amps that go with them can be a issue.

I have my 400ah bank setup so even if it hits float at 9am and is in float for bulk of the daytime just covering loads it is always at about 99% SOC at the end of the day or somewhere around 398ah or so. So if anything it's very slightly discharged over the day rather than bursting at the seams overcharged.

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Re: selectronic or victron inverter?

Postby australsolarier » Fri Dec 18, 2015 3:13 pm

totally agree with you kurt.
after watching the lifepo4's charge and discharge for 8 months, i think that is the nature of the beast.

i try to use some of that "free" electricity and turn on the second computer or/and a 100watt incandescent light bulb and other things.
that small 12volt system provides 2/3 of my electricity power consumption at the moment. (it runs the freezer, fridge, solar controller and pumps, the computers and accessories, the pressure pump, the garden lights, remote witch devices.)
most panels for that system are installed flat, between the 30degrees installed panels of the grid feed system on the flat shed roof and get somewhat shaded in the winter. however they work excellent in overcast weather and dusk. another array hooked to this small system is 30 degrees but on the ground and gets much shade in the winter mornings and winter evenings.
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Re: selectronic or victron inverter?

Postby BrettTaylor » Mon Feb 01, 2016 1:20 pm

What voltage are you charging the battery to in absorb. 56v?
How long are you spending at absorb voltage (what are your setting in the classic) I have mine set for 45min absorb time or (end amps) set to 1A so what ever is triggered first.
What is your float voltage 53.8v?
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Re: selectronic or victron inverter?

Postby australsolarier » Mon Feb 01, 2016 2:33 pm

my setting for absorb is 56v. time 30m, end amp 8A. i am using gbs batteries and they recommend C0.02 end amps which is 8 amps for a 400ah battery.
i set the float to 53.6volts.
kurt or gordon might have slightly different settings.

however the midnite classic goes into absorb mode about 0.3v before the set absorb voltage. at the moment i have only 3 panels connected to the 48v system. so the midnite will switch into float a few decimals before 56v. thats not a problem at all.
when the system hits float, i can boil about 3 liters of water to bring down the voltage at the battery terminials to float voltage. the solar panels then provide power again.

as for the midnite classic reversing after going into float mode:
after i updated the latest firmware to 2079, the software limits that reversing to 90 seconds. i can live with that.
midnite has that new software updater for windows10 that is super easy to use. no more 34 step procedure. just follow the instructions and after 5 minutes updated.

as for the solar electrician supposing to connect the selectronic to the grid, have not heard anything from him. also not from the aircondition installer. was supposed to install the airconditioner in the shed a month ago and is coming the next week every next week, etc. i don't think i can remember a tradesman ever coming when he said he was going to come.

whilst boiling the kettle, using 2kw, the selectronic software tells me 0.2v difference between battery terminal and selectronic, 6watt loss in the wiring and breakers etc. that looks quite good to me. wires are 70mm2, fused bussman disconnect and the blue ev power safety disconnect and the whizbang jr shunt (the midnite classic device for sensing what is going in and out of the battery and calculating SOC) between the battery and inverter.
i am happy with that setup.
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Re: selectronic or victron inverter?

Postby australsolarier » Thu Sep 01, 2016 11:04 am

hi everbody,
an update for my 48V/400ah lifepo4 system.

the system was connected last tuesday to the house after much waiting and doing many phone calls to the licensed trades people. the system is now ready for the end of the 60 cents grid gross fit tariff at the end of the year. to properly use it though i have to wait until the authorities change the power meters into one bidirectional one.
hooking the selectronic inverter to the house was straight forward. two breakers in the meter box (source/load) a small din rail box underneath the selectronic with two breakers (source/load).

programming the selectronic was an other matter though. in default mode, it just drains the battery into the grid. the solar installer wasn't much help in programming the selectronic. as a matter of fact he was sceptical the selectronic can feed in power whilst dc coupled. they are used to install the selectronic ac coupled. this is much easier and straight forward than dc coupled. program and installation wise.
well, for example to program "solar hybrid control" in the selectronic, when you put the dates from 1.1.16 to 1.4. 17 , well, it refuses to do what you want it to do, the date has to be 1.1.16 to 31.12.16. after much experimenting i sussed that one out. from there on things were a bit easier.
the midnite classic and the selectronic have to work in tandem. so when the classic goes into float it sets the selectronic charging side into float too. to feed in the surplus of solar generation into the grid, float value in the selectronic has to be 0.1 V lower than in the midnite (for lifepo4 battery). you can set float lower in the selectronic but it will drain the battery into the grid until the selectronic's float value is reached. also the midnite classic shunt for SOC is used by the selectronic as well, so it knows what is going in or out of the battery. this shunt can be programmed to be SOC in the selectronic as well, and can be zeroed in via the software.
the selectronic does not fall back to bulk mode over night on its own, at the moment i am doing this externally with a timer. it needs to go back to bulk to work with the midnite classic when in bulk mode. or else the selectronic will feed whats over its float value into the grid and the battery probably never gets charged properly.
on an other matter, that selectronic sp pro 482 does not cause whistling in my induction cooktop nor the portable induction top. (my induction top after 8 years started to malfunction. made in germany, was 1700$. the repair people wanted 820$ to fix it, because two circuit board are blown!!!!!! took it apart myself, replaced two bloated caps in the power supplies. from jaycart 1.20$. works like a new one)

so i am happy with the hardware side of the selectronic. the software is a different matter. it is just not intuitive. at the moment it also does not have default settings for lifepo4, which causes the software to complain. that is supposed to be changed though with a software update according to davidg.

as for the cheap mpp products, they are now upset because their chinese countrymen do the same to them what they do so well, namely copying other products. have a look here:
http://www.aliexpress.com/store/629424? ... .30.LfzzMk
ok. i leave it at that for today, greetings urs
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