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Big Battery 24LifePo4 Powerwall Gen 2 Experience?

Anderson connectors (genuine ones, not knockoffs) are great, tough and long lasting... that is why they are on folklifts and heavy military gear too ! You are not pulling them apart daily, rarely if ever in fact. just for Maintenance & disconnection purposes. I know there are knockoffs which are problematic, I had some, what a freakin nighmare... even used the solder plugs & MAPP Gas to the inserts up for it... Then I got Genuine Andersons and what a difference.
 
So here is a complete noob question:

The NEC ampacity chart shows 6 AWG wire can carry 55 amps at 140 degrees F, up to 2000 volts. I am used to thinking of wire size in reference to ampacity in residential electrical applications, so this DC is new to me. I think the wattage consideration makes more sense, since it considers both voltage and amperage. Is the NEC chart not relevant since it seems to cite just amperage and not voltage (except for upper limit voltage?) I am confused.

 
This Ampacity chart relates to Fine Copper Welding Wire (most commonly used on battery systems)
Royal Excelene Wire is some of the highest grade welding cable out there, it is a little more pricey but you really are getting every pennies worth.
An important difference is the Strand Count. More & Finer Strands provide for more surface for the charge to travel. It's NOT like AC.

Excelene-Wire-Info.JPG

Big Battery & such do sell Genuine Anderson Connectors.
If you wish to purchase some extras, they can be bought direct from Anderson or from their Amazon/EBay outlets.
 
Please pardon my ignorance, but I am struggling with the wire sizing. Can you show me the error in my thinking?

Wire size is determined my amperage, apparently independent of voltage, according the the NEC chart?

The battery in question produces 170 AH. Is this the same as 170 amps? If so, 170 amps x 24 volts = 4080 watts. Is there a chart using watts rather than amps to calculate wire size? Obviously, I don't understand the amperage factor regarding AH in battery lingo.

How many amps would this 24 volt battery bank produce at peak load, and is that relevant to wire sizing?

I have a lot to learn.
 
A Simple way to put it, a 100AH Battery Pack can discharge at 1C or 100 Amps, or if using 280AH cells, 280A maximum.
Battery Banks made of multiple packs can share Load & Charge if properly wired in parallel.
1000 Watts ÷ 24 Volts = 41.66A. 4000W @ 24V = 166A

When sizing the wires, you have to consider the Amperage the Inverter will pull. For Example, if you build with a 4000W Pure Sine Low Frequency Inverter, they can handle 3X The surge capacity of up to 12,000W. Obviously, people do not run Inverters into the Surge Capacity as a norm, that is for the exception. Therefore wisdom would say wire for 4000W / 166A rounded to 175A (think of Breaker / Fuse as well).

Myself, I run 24V with a Samlex EVO-4024 Inverter/Charger, I have hit 180A occassionally. Because of my Run Length (length of wires from battery packs / bank to SCC & Inverter which is 12 feet) I chose to go up in cable grade to ensure No Line Loss with 4/0 direct from battery pack through to nverter. 2/0 Would have been acceptable but "just" and leaving little room. In fact I replaced ALL of my 2/0 Wire with 4/0 when I upgraded from a 3000W Inverter to 4000W (there'a few hundred bucks, I could have saved had I bought 4/0 to start with). At that time I also upgraded my Main Breaker to 250A from 175A. NOTE: I have a Midnite Solar E-Panel for my Midnite Classic SCC and the DC Breakers + Lightning Suppressors.

Midnite E-Panels: http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=1&productCatName=E-Panel
Samlex EVO-4024: https://samlexamerica.com/products/ProductDetail.aspx?pid=575
Midnite Classic 200 SCC: http://www.midnitesolar.com/product...AND HYDRO&productCat_ID=25&sortOrder=2&act=pl
 
Evap cooling works fine, but the added humidity can be oppressive. Even in the high desert, which is much drier than the metro areas have become, it's only good for May, Jun and part of July. We have a couple of portable units that do reasonably well, but once mid July rolls around, humidity from monsoons makes evap cooling pretty ineffective.

The need to cool fresh, dry air and expel cool, moist air also means you're only going to get about a 20°F delta between outside and inside. When it's 110°F outside, 90°F with high humidity is worse than dry 110°F.
Those are pretty horrible units if that is what the numbers are. Nothing like I live with. Good Luck!
 
Those are pretty horrible units if that is what the numbers are. Nothing like I live with. Good Luck!

The Phoenix and Tucson areas aren't really the desert anymore. In addition to heat islanding, overnight irrigation can see local humidity near 100%. It takes longer to burn off, and you get way more humidity than you used to.

HBR is located in the high desert where we still see high 90s, but they are much more effective due to the lack of irrigation or farming. You still see the typical 30-35°F swings per day with rapid drops when the sun goes down. Of course, water is generally less available than solar, so it's a toss up for us.
 
I emailed watts24/7 to get their battery cable size recommendation for their 24 volt Growatt unit. I asked about the cable recommendation in their manual and the response was: "1x2AWG. Or 2 x 6AWG is the interpretation." So I assume that means #2AWG battery cable (or 2#6AWG cable.

I was referred to their education information and their calculation for battery cable size goes like this:

"Battery: Use the battery cable suggestion in the manual, keep cables as short as possible, when in doubt choose a thicker cable or double up. Battery Max amps =rated inverter output x 2/ battery voltage, Example 24V, 2.4 KW rated output x 2 /24V= 2400x2/24 =200A."

Will has referred to the chart below for cable sizing and it ultimately is dependent on amps, I assume once the above calculation has been done.


So, in my case, the Big Battery 12V 170 AH LiFePO4 power block would be 24V/170 AH with two in series. The Growatt 24VSPF 3000TL LVM -3KW 120 VAC is rated at 3000 watts. Using the calculation above:

3000 x 2 /24V = 240 amps.

The chart above stops at 200 amps, so the wire size would be greater than 2/0. I think there is something wrong with this calculation, since the manual suggests #2 cable.

The Big battery premade Andersen cables are only 6 AWG, so I would have to make up some big honkin Andersen cables on my own, and I don't know if an Andersen connector for 2/0 wire would fit the Andersen slot on their batteries.

I would prefer a 12V system so that it could be more easily transferred to a future RV application, but these watts24/7 all in one units only go up to 1000 watts in 12V, so I would have to either put at least 2 of their 12V units in series or put 2 batteries in series to get up to 2000 watts, which I think is the minimum inverter load I would need. I think I prefer the simplicity of one inverter, rather than multiple inverters because I think you just double the chance of electronic failures.


 
I just had a chat online with Big Battery regarding their new

12V 170Ah LiFePO4 Power Block​

I was thinking about putting 2 of these in series for a 24 volt bank. I has told that all of their Andersen cables are 6 gauge. I was told that the Andersen connectors can handle up to 1/0 gauge wire.

So, I have two questions:
1) Is 6 gauge wire big enough to handle 170 AH at 24 volts?
2) Is it worth while buying loose Andersen connectors, bigger cable, connector contacts, large crimper, and making my own 1'0 cables?
24 volt systems are cheaper to build and one of those cost are the wire size.
 
I just bought a 24v Gen2 battery and was wondering the same thing about the #6 wire connectors.
I didn't get it, figured I had to make my own with #2..
Not sure what to think when you get past the connector and look at those wires inside the box... Does the bigger wire help any??.
 
Will posted a review of the new Big Battery power block and he seems to like it. I still have a difficult time getting past the 30 day warranty, but I might pull the trigger on a couple of these and wire them into a 24 volt bank anyway.

 
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