rca's off-grid battery and power control room

[rcavictim]

I've been trying to take advantage of the winter months, unable to do outdoor work on the wind turbine, so I figured I'd better get busy and install the electrical equipment that I will need to make everything come together once the turbine is making watts.  I have been busy installing metallic waterproof 1-1/2" conduit in the basement ceiling, two 19" equipment racks, my 10 kVA 48 volt inverter and the battery bank.  Today I finally finished wiring between the batteries, bussbars and inverter.

I have 72, 12 volt AGM valve regulated batteries wired in 18 strings of four.  A 30 amp DC breaker connects each string to copper bussbars.  The bank is split to operate as two separate banks of 9 strings and each bank can be switched in with a master 400 amp DC breaker.  Both banks can be run simultaneously as one larger bank.  52 of the batteries are 90 Ah.  The last 20 are 80 Ah.  I have the storage to supply my 10kW inverter to full output for four hours and still leave a 30% SOC for battery protection.  I have just acquired an additional 24,  120 Ah batteries and will be adding them as well once I build another set of battery racks. I honestly don't know where I'll find the room though.  I still have to leave room for the mechanics of the proposed ground source heat pump, solar hot water tanks and other stuff.

[rcavictim]

Here is another pic.

[rcavictim]

Another view, this one showing the bussbars, one on each side.

[rcavictim]

Here are the two big main battery bus breakers.  The two thin wires scooting off are a temporary run to a 48 volt float supply.  I can finally put some juice into the bank after the batteries have been sitting quite a while.  I was boosting them individually every couple of month's or so since I got them and that was tedious because there are so many to deal with.

Once I got everything hooked up today I ran an inverter test which was fine and then I ran a load which drew 27 amps off the bank @ 48 volts.  I tested each of the 18 strings one at a time for short runs and found that I have no apparent battery issues.  Good.  All strings sourced the 27 amps within a small voltage range of each other.

What I want to do now is draw off about 20% charge off the top of perhaps two strings at a time and then immediately recharge them to exercise the batteries and help wake them up and balance them.

I only have a 25 amp, 48 volt charging supply for each bank so I cannot drain the whole shebang.  The batteries would sulfate before I could recharge them.  The big 3-phase battery charger, a 400 amp Hobart welder won't be installed for a few months, then I'll be able to charge from my 3-phase diesel power from the shop building.  Eventually I hope to be able to charge from the wind turbine 3-phase AC also powering the system through the Hobart welder.

[rcavictim]

One more.  Some of this hardware is pretty hard to find in Canada.  The bussbar and those sexy red Glastic insulating bushings didn't come from the usual sources.

[LowGear]

When do you sleep? 

[wiebe]

Man.
What a ton of power is stored there.
Better be careful not to drop a spanner on there.
I get almost scared of the power it resembles on a short.

Nice work .

[deeiche]

rm /

[Shipo]

WOW ....bob let's move the server to RCA data center....

What's your plan to test the cell...semi annual or quarterly.

[rcavictim]

Thanx for the compliments.  RCA Data Center...I like the sound of that.   

I have pretty much spent every available moment putting all this system together for years now.  Gathering the parts has taken many years of searching.  I have discovered that you can generally find what you need at practically scrap price if you can wait long enough to trip over it. Many critical pieces only ever show up just once so you have to know when to pounce.  You snooze and you loose.  One once said "Chance favors the prepared mind".  In my case this appears to be true.  I got about $2500 worth of brand new liquidtite metal flex conduit on three big reels for $80 this winter from a scrap recyclng depot.  I was planning to use plastic well pipe prior to that score.  Wow, what a find.

When I was fresh out of high school I got a job with a big telco in Inside Plant Installation.  In the time I spent there I learned a lot about how to install stuff so that it looks nice and neat. I learned how to lace cables but the rule then was if it was laced we continued with lacing.  If it was a new install we'd use nylon tie-wraps. What I learned then has done me well throughout my life.  It helps that I am a stickler for detail and also care very much how the stuff I make looks.  In a way it is a curse because I absolutely cannot just throw something together.  My projects always take much more time, many of them more time than they deserve.

A couple of month's ago I chanced across an Ontario government auction where a trades college was selling all the welders in their welding shop.  I got really lucky and scored an identical pair of big 3-phase 400 amp DC Hobart machines which use SCR current control.  I practically stole them.  I have tested one in the shop on the 3-phase 460 volt output from my Changfa 1115 plant with the STC-24K and wow, what a powerful welder!  I can only power this up to about half of it's 35 kVA rating but holy crap, it can really weld heavy steel and do a sweet job on everyday stuff too.  It has found a good home.  The second machine has to be hauled down the basement to my power room to be used as a battery charger.  I need to concoct a circuit that will act as a regulator to deal with the wild voltage that will come from my wind turbine and aso act as a charge controller to properly charge my precious batteries.  On my budget I cannot afford to purchase a single battery at what these cost new.  The ones I have were well taken care of by a telco and have lots of life left in them.  I hope to get 5 years out of this pack.  All those grey 90 Ah Marathon units in the first rack are only 3 years into a 10 year rated life.

If anyone has any ideas for a 3-step charge controller that I can use to control the welder at the point the control potentiometer goes now to properly charge my battery bank I'd be keen to hear about it.  Thanx.  Bob would something you use with a Leese-Nevel (sp?) alternator to control the field possible be adaptable here?

[WGB]

Nice job!
Did you make your buss?

[rcavictim]

Nice job!
Did you make your buss?

Thanx.  It was salvaged from a factory install from inside rectangular metal buss boxes.  These pieces came with the 90 degree H bends at both ends. The bends worked out nicely for my main breaker install.  All I did was remove the old tapejob, clean and polish it cut to desired length, drill the holes I needed in it, tapped some of them to 1/4-20, add the heatshrink.  It is 2" x 1/4".  I wish I had more!!!  Fortunately I got enough for this job and have some useful scraps. This is great stuff for high energy lab projects.  I also got some aluminum lengths.

[veggie]

rcavictim,

That's a great job you did there ! A system to be envied.
Very well organized.

BTW are those 400 amp breakers rated for DC ?
Typically an AC breaker is not acceptable for DC power.

veggie

[rl71459]

Great Job RCA, very clean and professional

[rcavictim]

rcavictim,

That's a great job you did there ! A system to be envied.
Very well organized.

BTW are those 400 amp breakers rated for DC ?
Typically an AC breaker is not acceptable for DC power.

veggie

Yes Veggie, all the breakers on the battery bank are special ones made just for DC application.  The big 400 amp units are 175 VDC and made by Heinmann.  Top shelf hardware.  I need to install one more from that junction to the Hobart welder.  I found and bought five of them.  The small ones are 30 amp 80 VDC with a 38 amp trip rating.  I bought those all new on ebay.