Powerwall chargers?

F

Filip

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Hi all, this is my first post to this forum, I have been reading for a while but now I thought I'd register and become a member for real!

I have been thinking of chargers for my (in the making) powerwall, do you guys have any suggestions on how I can solve my problem wich is this: I already have a solar system with a three phase grid tie inverter, the easy solution is just to buy a new hybrid inverter, but my solar system is located in a "shed" on my property, in the wintertime the batteries will not work due to cold weather if i place them with the inverter, so I have to move them inside my house. What Ive been thinking so far is to use my already installed smart meter and a Raspberry to control the charger, or chargers, since I want one charger on all three phases. When Im exporting, lets say, 500w on one phase the charger on that phase will start to charge until Im importing power again. Do you think I can use just ordinary DC power supplys or will they realease some smoke when charging at the same time?

Or do you guys have a more simple and better solution? :D
 
You need something that you can remotely controll. An Eltek PSU could work for instance.
You can also just make sure your shed is isolated. If you do that the equipment inside will keep the heat up high enough. That might just be an easier sollution and you dont have to have the cells in your house and this would make it safer!
 
Lithium batteries are less sensitive to lower temperatures compaired to lead-acid, so maybe no problem there ( maybe some isolation like Daromer says )
I use a Eletek PSU to charge my batterie ( three of them...) type Flatpack2 HE 2000W, they can be controlled by the Batrium BMS if you are thinkingto use one of them.
But you needa inverter anyways to convert thebatterie power to 220V, so why notsomething like a PIP ?

Oh,BTW, Welcome... ;)
 
Thank you for your inputs so far! I have been thinking of isolation but its a lot of work to do that in my old shed! But maybe its the best thing to do anyway...

But Im not leaving my initial thought just yet :cool:

I was thinking of some cheaper power supply units :D
Like this one:
[img=200x200]http://i.ebayimg.com/00/s/NTAwWDUwMA==/z/AnQAAOSwQM9UZJqx/$_3.JPG?set_id=2[/img]
"Controlled" by a Raspberry with a relay board:
[img=200x200]https://i.ebayimg.com/images/g/DS0AAOSw6YtZXNea/s-l300.jpg[/img]


When my smart energy meter tells the Raspberry that it exports for example 500w on one phase, the charger on that phase starts to charge until the smart meter tells the Raspberry that power is imported again. The idea is from your youtube video daromer, but you showed us how to use excess power to heat water, I want to use it for charging instead.
The question is if I can parallel three power supply units to my battery bank, one from each phase? What happens when all three are allowed to charge? Smoke? :D
My existing inverter alters between phases when there is not enough sun (which is quite often here), that is also why I need a charger on each phase.

I do need another inverter for the battery bank, a PIP will not work for me because it is a on OR off grid inverter I think? I need something like a SUN with limiter but of course preferably a thee phase one...

Thank you wim :)
 
Of course you can do it like that. Its not optimal but it works
 
Thank you daromer! I know I will loose efficiency by doing what I want but I have to do something to use more of my solar power by myself because my grid company soon starts too moan that I sell too much kwh. I was worried that I was going to smoke the psu:s if they had different phase supply in between them.
 
The output of the chargers is DC, so when they are on a different phase makes no difference.
You only have to controll the chargers somehowto start and stop charging on time...
Overcharging is a bigno no...and you have to keep thes-packs a bit in balance... are you gonna do this with the Pi ?

When your batteries are in your house, i would not trust any diy bms to watch overthem, hence Batrium :D
Safety first, but thats just me... ;)
 
wim said:
The output of the chargers is DC, so when they are on a different phase makes no difference.
You only have to controll the chargers somehowto start and stop charging on time...
Overcharging is a bigno no...and you have to keep thes-packs a bit in balance... are you gonna do this with the Pi ?

When your batteries are in your house, i would not trust any diy bms to watch overthem, hence Batrium :D
Safety first, but thats just me... ;)
Click to expand...

Thats what I thought too, but I was not 100% sure :D

My initial thought is to use something like 17s (71,4V) but use 70V psu (~4,12V).

Batrium soon to be ordered! I will not launch any system without a first class BMS system, Im with you on that one :cool:
I have not done the reading on the Batrium system yet, maybe I can use another relay board in series and the batrium switches off the chargers when the batteries are full or unbalanced. I will have to do a readup on what the Batrium system can do!
If you have any suggestions Im really keen on hearing them :)
 
Glad to hear you are taking the safe route...
Batrium is just one of the bms'es out there, and populair on the forum.

It can control several chargers, the eltek flatpack2 is just one of them... And by control i mean full control like voltage, current, trottle down at end of charge...
here a link fromEbay, it is a expencive one, but with a bitof patience you will find them around 100Euro (i did ;) )
https://www.benl.ebay.be/itm/Eltek-...189310?hash=item4b2b4fadbe:g:~MsAAOSwiYlZ8lMF

But there are more chargers possible, youfind them in thesupport on therewebsite.

Batrium canalso control a remote controlleddisconnect or breaker (shunt trip)todisconnect the batteriein case of a critical event...

Yousee, lots of reading to do,andwatch all of te YouTube vids of Danielen Peter... :)
 
I have several of those kinds of PSUs for this specific reason.

Initially I was converting AC power from EnPhase and dumping it into batteries when pushing back to the grid as I cannot get a net metering agreement.

Now I have a mix of panels split between EnPhase S280s and MidNite Classic chargers and that works great, you might consider pulling a string of 4 panels and wiring them in series to a MidNite or just getting a few additional panels to mess around with, it works quite well.

Here is a graph of my MidNite charging up some batteries on a cloudy day.

http://solar.iceisfun.com/PowerWallCharge.aspx

Depending on when you look at this you might see big drops in Batt V, thats me switching it over to charge a different pack getting all the packs up to the same voltage so they can be connected to a fused bus bar (fused pos and neg)

I have several of those kinds of PSUs for this specific reason.

Initially I was converting AC power from EnPhase and dumping it into batteries when pushing back to the grid as I cannot get a net metering agreement.

Now I have a mix of panels split between EnPhase S280s and MidNite Classic chargers and that works great, you might consider pulling a string of 4 panels and wiring them in series to a MidNite or just getting a few additional panels to mess around with, it works quite well.

Here is a graph of my MidNite charging up some batteries on a cloudy day.

http://solar.iceisfun.com/PowerWallCharge.aspx

Depending on when you look at this you might see big drops in Batt V, thats me switching it over to charge a different pack getting all the packs up to the same voltage so they can be connected to a fused bus bar (fused pos and neg)


image_pibzvn.jpg
 
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