Bob's Powerwall Project

Robert Baumer

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May 6, 2017
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Greetings Everyone,

I have already started collecting cells, of course everything is running extremely slow.... I have 2 OPUS and 1 IMAX. I originally thought of putting this in my basement but have since reconsidered that idea and will be putting the battery packs out in the garage which is separated from the house by firewall. My question is that the batteries will be about 75 feet from the my electrical panel, does anyone see problems. Also, in about a month Tesla Energy will be coming to install one of their turnkey solar systems which is rated at 9.1kW. Does anyone have a recommendations on how I let them know I do not want to buy one of their Powerwalls?

-Bob
 

daromer

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75feet is fine if you run AC and cables that are designed for the current.

You can just tell Tesla to not install the powerwall? (Im not sure I see the issue?)
 

Robert Baumer

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I am now researching the AC Coupler theory, my nephew is an electrician so he might be able to help. I am excited about the DIY Firewall and I am already invested in it, it would suck to find that there is nothing short of me buying a Tesla Powerwall. I am wondering if anyone else in this group has experience with the AC Coupler for grid tie system.
 

Robert Baumer

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So I just got off the phone with the folks from Tesla Energy, they want to upsell me on the Powerwall2. They failed, any attempt to add third party batteries to the mix would void the warranty. I am going to do some research into this AC Coupling using a MagnaSine inverter or some other system. Perhaps more people would be interested in this thread. I have a couple hundred laptop batteries to scavenge but I only want over 2000 mA.

The guy from TE told me that I will still have to pay a customer charge of 10.00 a month... My system will produce about 3,000 kW a year more than I need.
 

Robert Baumer

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Woohoo.... Up to 3 OPUS chargers... at this rate I might get 1680 cells sometime in 2019 :( So far I have almost one pack done, waiting for my new soldering iron as I had to send back that cheap Chinese crap. I took the advice of Mike on this forum and bought a Weller. Since my solar will be installed by Tesla Energy I will have to adapt using a AC Coupling method. I have been looking at the MS4448PAE from Magnum Energy.

I have a question for anyone reading... Should my packs be Amp Balanced? Meaning my first pack will have 300 amps, if my next pack is say 250 amps won't things die when the 250 amps exhaust?

So do you calculate your total amps based on the lowest pacK?
 

LithiumSolar

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RobertBaumer said:
I have a question for anyone reading... Should my packs be Amp Balanced? Meaning my first pack will have 300 amps, if my next pack is say 250 amps won't things die when the 250 amps exhaust?

So do you calculate your total amps based on the lowest pacK?

They should be close to being balanced, 250 vs 300 isn't good. To balance them easily, I don't build packs until I have enough cells for the entire string. I throw all the cells in a big box and mix them up, that way they're all randomly distributed between the packs you're building. Let's say you're building packs as you go and you come across a few high capacity cells. The pack that gets the high capacity cells is now going to be off balance from the rest. If you use the mix and randomize method, they're "more likely" to be distributed evenly.

Hopefully that makes sense. I'm still half asleep here.
 

owitte

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if you put the packs in parallel, that wouldn't be any problem. But all packs connected in series should have nearly same capacity, as Mike said.

Btw, if you want to speed up the testing process, buy some cheap TP4056 charging PCBs, battery holders and a power supply (I use an older ATX from a computer) to pre-charge your cells after disassembling the battery packs. This way, the OPUS can proceed faster with the tests. I have 3 OPUS and can test 30-35 cells per day. Now, the bottleneck is me, because I'm not fast enough to feed the chargers with new cells... ;)
 

Robert Baumer

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owitte said:
if you put the packs in parallel, that wouldn't be any problem. But all packs connected in series should have nearly same capacity, as Mike said.

Btw, if you want to speed up the testing process, buy some cheap TP4056 charging PCBs, battery holders and a power supply (I use an older ATX from a computer) to pre-charge your cells after disassembling the battery packs. This way, the OPUS can proceed faster with the tests. I have 3 OPUS and can test 30-35 cells per day. Now, the bottleneck is me, because I'm not fast enough to feed the chargers with new cells... ;)

Let me ask you think, should I abandon my current process of "Discharge Refresh"? I was thinking that was the best way to get accurate numbers for a cell, I mean if the cell is going to go belly up, wouldn't doing a discharge refresh were the OPUS is doing 3 iterations of charge/discharge/test?
 

Robert Baumer

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mike said:
I think you are wasting time and electricity doing a refresh test (3 iterations). If the cell is bad, it's going to show poor performance on the first test, in terms of heat and/or low capacity.

Thanks Mike, changing my testing procedure.
 

daromer

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I only test 1 time as well. I doubt they go better after recycling and if they do... thats perhaps 1 cell in 100... Spending that much extra time on doing it is not worth it :)
 

LithiumSolar

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RobertBaumer said:
This is great news, tomorrow I should get 2 more OPUS chargers... I should be able to get a lot more done.

They're really fast. With a few of them on your hands, you'll get through cell testing quickly :) Love my Opus, glad I switched from the Foxnovos. My test amount per day has almost doubled with the same amount of chargers.
 

Scepterr

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mike said:
RobertBaumer said:
This is great news, tomorrow I should get 2 more OPUS chargers... I should be able to get a lot more done.

They're really fast. With a few of them on your hands, you'll get through cell testing quickly :) Love my Opus, glad I switched from the Foxnovos. My test amount per day has almost doubled with the same amount of chargers.

Mike, Ifound the opposite to be true, on a 1A dischargethe opus avgs about 500mA, a side by side discharge of a4400mah(pair of cells)batterytook 8hrs on the opus, 5.5hrson the foxnovo, Ichosepairs with identical resistance to do the tests
 

LithiumSolar

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Scepterr said:
mike said:
RobertBaumer said:
This is great news, tomorrow I should get 2 more OPUS chargers... I should be able to get a lot more done.

They're really fast. With a few of them on your hands, you'll get through cell testing quickly :) Love my Opus, glad I switched from the Foxnovos. My test amount per day has almost doubled with the same amount of chargers.

Mike, Ifound the opposite to be true, on a 1A dischargethe opus avgs about 500mA, a side by side discharge of a4400mah(pair of cells)batterytook 8hrs on the opus, 5.5hrson the foxnovo, Ichosepairs with identical resistance to do the tests

I'm pretty certain the 1A setting on the Foxnovo doesn't even pull 1A. It wastes so much time charging between 4.2 and 4.22v that don't even matter. Are you sure your Opus is not a Chinese copy and that it's set to 1A? That sounds VERY unusual.
 

Scepterr

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mike said:
Scepterr said:
mike said:
RobertBaumer said:
This is great news, tomorrow I should get 2 more OPUS chargers... I should be able to get a lot more done.

They're really fast. With a few of them on your hands, you'll get through cell testing quickly :) Love my Opus, glad I switched from the Foxnovos. My test amount per day has almost doubled with the same amount of chargers.

Mike, Ifound the opposite to be true, on a 1A dischargethe opus avgs about 500mA, a side by side discharge of a4400mah(pair of cells)batterytook 8hrs on the opus, 5.5hrson the foxnovo, Ichosepairs with identical resistance to do the tests

I'm pretty certain the 1A setting on the Foxnovo doesn't even pull 1A. It wastes so much time charging between 4.2 and 4.22v that don't even matter. Are you sure your Opus is not a Chinese copy and that it's set to 1A? That sounds VERY unusual.

Got it from Amazon, pretty sure its legit, Yeah the foxnovo doesnt really do 1A either but its much closer being 5.5hrs for 4.4Ah vs 8hrs and yes the 4.20 to 4.22 timeis frustrating, I tend to switch them to tp4056 to finish charging once its at 4.1ish on the foxnovo. Also I seriously missed having a beep on completion, and the intermittent discharge causes the results to be inflated, I was getting 100-200mAh more on the opus vs foxnovo on the same cells
 

owitte

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mike said:
I think you are wasting time and electricity doing a refresh test (3 iterations). If the cell is bad, it's going to show poor performance on the first test, in terms of heat and/or low capacity.

yes, that's right. Me too, I'm just doing one charge/discharge/charge cycle. But only the discharge part is done by my OPUSses, both charge parts are done by TP4056s. I made two banks of them, one for pre-charge and the other one for charging after the test, so I don't get confused which cells are already processes and which are not...
 

Robert Baumer

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owitte said:
mike said:
I think you are wasting time and electricity doing a refresh test (3 iterations). If the cell is bad, it's going to show poor performance on the first test, in terms of heat and/or low capacity.

yes, that's right. Me too, I'm just doing one charge/discharge/charge cycle. But only the discharge part is done by my OPUSses, both charge parts are done by TP4056s. I made two banks of them, one for pre-charge and the other one for charging after the test, so I don't get confused which cells are already processes and which are not...

I just ordered the parts to build 40 of those TP4056 and since my computer PS can handle up to 120amp, I should be good to go.....

Here is the video I watched:

I bought 4 packs of 10 of these:http://www.ebay.com/itm/27258452672...49&var=571700784834&ssPageName=STRK:MEBIDX:IT

and I bought 5 sets of these: http://www.ebay.com/itm/172546327816?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

I'd like to find that wire stripper he uses in the video.

-Bob
 

Korishan

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Robert, your 1st ebay listing is no longer valid.

What I would recommend with soldering up the TP's like in the video, if you do more than the 5 shown there, is to run a loop. So, instead of terminating at the farthest TP, run a continuous wire back to the main wire.
Or, run a heavier wire as your main bus and then tier off it to the TP's.

The reasons for this is that after each TP, the voltage/amperage will drop. There is a thread that talked about this awhile back. After putting a continuous wire to make a loop, all his TP's started functioning correctly.
 

Robert Baumer

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Korishan, I must have bought them all.....

Can someone please recommend a glue gun, I am going to need one for my packs and for this charging monstrosity.

-Bob
 
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