diy solar

diy solar

Feeling cute today, may build a 480V battery later. .

Did Edison not finance the first electric chair to show how dangerous AC was?
Apologies to OP for the tangent, but this discussion is very cool!
I have a passionate regard for Nikola Tesla. I'd call him a true genius "inventor", as he worked out entire functional systems of everything in his head, he knew when they'd work, all before he ever put pen to paper about it. Thomas Edison's "genius" came from very different discipline. He would "discover" concepts through tireless and much less-informed trial and error until he got it right. By modern standards and understanding Edison would be considered a hack compared to Tesla. The truth is Tesla was an eccentric recluse with no social interface and was terrible at self-marketing, portrayed no self-confidence even speaking in falsetto, where as Edison was a showman, a larger-than-life entertainer, a business man, and very skilled at connecting with people on their level. Edison died filthy rich (as did George Westinghouse), Tesla died penniless, his patents all sold off long before, and was forgotten in history for quite a while. I think it's cool these two came up in this discussion of AC vs. DC; when I was a kid nobody knew of or spoke of Nikola Tesla, they even told us Marconi "invented" radio. I'm glad now Tesla finally gets credit.
 
Apologies to OP for the tangent, but this discussion is very cool!
Tesla was a genius inventor and Edison was a business man. Agreed. Sadly Tesla lived out his elderly years dirt poor. Shame the way society works, even today.
 
Dear UPS fetish boy. You will love this story then:

I work in large data centers. Years ago one data center I was affiliated with had older APC UPS' rated at ~85% efficiency in an N+1 configuration. They were slated to be replaced with more efficient, I think 92% UPS'. Three months before the install day, one UPS had a bad controller and overcharged all 256 110Ah AGM batteries. Those bad batteries came out and new batteries went in to keep redundancy for the 3 months remaining.

Three months later the new UPS's went in. Where do you think a good majority of those 256 - 3 month old batteries went to. :)
I might be able to beat you on that. We had to overnight air freight something like 10 tons of batteries to Hawaii after a major power outage showed the client that a "10-year" SLA battery needs to be replaced much more frequently...

Same thing though; they were replaced 4 months later when a new UPS was installed. A number of the facilities people went with solar power shortly after...
 
Sorry OP!
Edison was a marketing strategist and either had people working for him that invented or he screwed people like Tesla out of them. Tesla was in a completely different league then the Bumbling Edison and it was the Power Elite who drove Tesla to poverty because no rich person would risk their loss of fortune helping him out. He was reduced to poverty because he scared the power elite to death with his free energy plans possibly screwing them out of financial control and billion. It was in fact the wealthy friends that paid for his accommodation until the day he died which was the most they were allowed to do without risk and loss or fortune. Edison was not a genius and actually created almost nothing, he was just greedy and had such improvements on other peoples designs.
George Westinghouse on the other hand was a true genius and entrepreneur thus taking Tesla's AC and ran with it shutting greedy Edison out of the way.
It is quite a frightful what people don't know about Teslsa and the bumbling idiot Einstein the fraud. Yes!, the bumbling fool in a purple clown suit himself as Tesla so put it.

"256 - 3 month old batteries" wow what a catch, so lucky!
 
Consider creating a new thread for the Edison/Tesla war. There's no relevance to this thread, and there are strong feelings on this subject which would completely overwhelm this thread and make it useless for its intended purpose.
 
If it were me I would definitely do what you're talking about here, especially considering that two of those modules in series are pretty much the perfect voltage, but of course there's plenty of precautions one would have to take.

Primarily I would start by removing all the bridges on the pack you're working on. Beginning with the middlemost bridge, in your picture looks to be the battery right above where the clamps are, so 2nd row 5th column starting from bottom left. Then work my way out. Of course all of this using decent gloves, boots and just being overly aware of everything. This is not the time to be working in an uncomfortable position or having anything that could cause involuntary movement, be it a rolling chair, working on a cluttered bench, having anything on the floor you might step on or kick by accident. Any tool you use, you put away before getting another. if you don't have HV tools you can just wrap electrical tape around the shaft of screwdrivers to the tip, if you need to use a wrench (which I don't think you will), do that too, only one tip should be exposed.

Once you remove the middle bridge the pack becomes relatively safer since you cut the voltages by half, but regardless, you do not want to be making modifications to them while you have 240v on tap. Just remove them all doesn't matter if its tedious or whatever. If shit hits the fan I would argue its easier to put out a battery fire from a bridge that slipped and shorted, than to somehow overpower the 240v going through your neurons and into your muscles.

Probably what I would do is put tape (2" painters tape works fine) over all the exposed contacts and slowly peel it off, remove the bridge, then put the tape back on, once you finish all batteries will be disconnected and will all be protected from any accidental tool drops.

And after pretty much "deactivating" the batteries, I would just look into the wiring and see what I would have to do in order to series connect them. You will only have to re-wire the "master" battery (the one that will ultimately go to your inverter, and they can only be connected in series pairs, so only one battery plugged into the master, and none into that one. Any paralleling would have to be done externally.

Not sure how the wiring is from the pictures, so you'll have to double triple and quadruple check, but if internally, the input of the master is directly paralleled with the daisy chained batteries, you'd basically just disconnect both + and - that come from that connector onto the breaker, disconnect either + or - that come from the master batteries themselves, and connect them in series, if you disconnect the battery negative for example, you'd connect it to the positive from the connector, and then use the negative from the connector as your new battery negative.

Just REALLY make sure to check everything with a multimeter before putting the bridges back up. If you're sure its good, you have enough wire to move the + terminal over and basically use only one 12v battery, for testing. Do that for both master and slave and then see if you get your 24v at the master output cable. If so, you're pretty much ready to cut and wire the master to the inverters, and then bridge them up, close them, turn breakers on then switch the battery d/c on your inverter.

I have no idea if those breakers are designed for such high voltages, but regardless, your inverter has I believe 25a battery fuses, which are going to blow WAY before those breakers trip, considering the packs are rated for 60A continuous.

People can hate all they want on SLA but they're free and you have a pretty much best-case scenario here, why not? I did the same with our golf cart. Company had 24x 12v 24ah sla's that they bought for a UPS but the UPS was replaced literally a week later. Got the batteries, made 6 4s packs for 48v, put them all in parallel. Now of course, did they last as long as regular golf cart batteries? Honestly not really. Did they get the golf cart around, and last around 4 years before losing most of their capacity? Yes. But it was a lot of cycles during those 4 years. Not that 6v batteries would've lasted much longer either... Eventually family friend gave up on an EV conversion he wanted to do, and gave us 28 nissan leaf cells, which we used to make a 52v battery pack and OFC its 3-fold better than the SLA batteries, but at the time it's what was available. My point is, ESPECIALLY with new EV's coming out each year, it'll be maybe 5 years until we see second hand reclaimed car battery packs drop drastically in price.

Right here you have over 10kwh of SLA. Even if you "derate" it by half its still enough to run several fridges/freezers for probably over 24h, way more than enough to last you the night till the sun comes up, if you were to lose the grid.
 
I still have a burning question.
Is there a use case for high voltage battery packs other than economics of wiring.

If you have one or more then I am all ears. I for one am already way past the danger line. So why not go all the way
Well my current thought is to be able to "DC link" between the batteries and an EV. I want to run 3x 240V 60A chargers worth, so ~14.4kw each. 43.2kwh of inverters is NO JOKE. That's 3x Sol-ark 15k's in parallel at a price of ~$24k for what amounts to 50 feet of AC.

The solar panels are 400-500V DC, the batteries could be 480v, and the car is DC. Why spend a five figure amount on a wear item just to go AC for 50-100ft from the batteries to the garage? Insanity.

As for the danger aspect, people run 450V lines from their solar array all the time. Not sure I buy the idea that it's suddenly impossible to manage when you get to the (much shorter, usually contained) battery lines.
 
I had an Exide 12KVA UPS with three 240VDC/9Ah battery packs. When a battery failed, the cells gracefully exploded on the side. Fortunately, the bad cells were depleted of wet electrolyte and couldn't spray the enclosure full of electrolyte and release energy and conduct energy of the rest into one big fireball event. That's what terrifies me about high voltage batteries. If one battery opens up, it might see the whole voltage across it and vaporize material everywhere.

The high voltage panels I really like. Mine were at 479 volts this morning until the controller started. Never had DC leakage yet. AC however, loves to transfer a bit of current to the chassis, which needs to always be grounded...or I'll feel it. I work with 480 volt three phase at work everyday enough to know what it can do... And with simple rules, it is safe. I just wish I had the chance to with the safe high voltage batteries though...
 
More than likely there could be a chemistry difference between the stationary pack and the EV. So to me the voltage curves would not be similar and you would need a high voltage programmable DC to DC converter to do that. I am not sure what the advantage would be over using a simple a Level 2 charging station..I charge my EVs during the day from solar and when I am done I sell to the grid. I do not see any efficiency benefit long term because an efficient system would want to use all the available solar production so that implies a GT inverter selling to the grid anyway. Some GT inverters are including a J1772 charging cable and software that can vary charging based on solar production.
My guess is that most people proposing a DC charging system do not yet drive an EV and do not understand how simple it is to use a Level 2 charging station.
 
Elite who drove Tesla to poverty because no rich person would risk their loss of fortune helping him out.
Actually George Westinghouse helped out Tesla..Later when Westinghouse hit a bump in the road, Tesla waived his royalty rights to three phase AC. This was mentioned earlier in the thread
 
I had an Exide 12KVA UPS with three 240VDC/9Ah battery packs. When a battery failed, the cells gracefully exploded on the side. Fortunately, the bad cells were depleted of wet electrolyte and couldn't spray the enclosure full of electrolyte and release energy and conduct energy of the rest into one big fireball event. That's what terrifies me about high voltage batteries. If one battery opens up, it might see the whole voltage across it and vaporize material everywhere.
I see, But I used wrong terminology I guess. I only have 3.2v Lifepo4 cells. Currently only 16 with an intended configuration of 48 volts.

I could add x amount of those cells to get to a "high" voltage battery array (I should have the word array from the get go).

Would that change anything from a "danger" perspective?
 
The high voltage panels I really like. Mine were at 479 volts this morning
I am very late to this thread. So please excuse me :( Are you referring to high voltage solar panels? My online searches after reading your comment for high voltage solar panels do not get any further than configuring panels in series. :(
 
I am very late to this thread. So please excuse me :( Are you referring to high voltage solar panels? My online searches after reading your comment for high voltage solar panels do not get any further than configuring panels in series. :(
Yes, I have the panels in series, 11 in a string. My solar controller is rated for 450 volts and usually sees around 350-420 volts during operation. There's a chance it could be more, but rare.
 
450V/420V = 1.07
Unless you're in a warm climate, I don't think 7% is enough margin for cold days.
I assume 16% until I've done the math.
 
Until reading this thread I never tried searching for 240V DC nominal MPPT Charge Controllers. They actually exist. Might not be able to get a manual in English, but they exist!
 
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