Advice, 36V or 48V?

I have a 24V setup too.  The battery consists of 3 x 24V 120AH lifepo4 in parallel.  Each one is rated at 175A continuous but I have no need for that level of power since it's just me here.  My peak draw is probably around 2.5kW (including inverter losses), approx 96A, when I boil the kettle.  The rest of the time the average draw is around 400W, which includes a room AC.  The climate is pretty easy most of the year with only a few days below 15C and a few days over 35C.

Hot water, the little I use, is done at about 450W for a couple of hours from a secondary array every 2 days.  In fact, the thermostat on the tank just clicked on, but the sun is on the wrong side of the sky now, the afternoon, so it won't get any loving until tomorrow.

Yep, I only use about 500 watts mainly, and every oh 10 mins maybe my heater in the grow tent kicks on for about 3 mins and goes up to 1400 watts.

If the whole house ac kicks on, it only use about 2k.  during the summer, I program the AC to kick on early in the morning to cool the house as much as I can stand it, and then during the day it don't work as hard.

My next project is installing atic fans in the atic to pull the heat out during the day.   I noticed my house has vents on the over hang, and they make duct fans that fit into those with thermostats, so I was going to probley get two of them one for one side and the other for the other side of each end of the house.

10 hours ago, Tim said:

Sid with both 6000gs together 1master 2nd come in as needed.will 200ah lpo4 be sufficient for whatever had 12000w draw?

Like <a contenteditable="false" data-ipshover="" data-ipshover-target="/profile/31-cali-carlos/?do=hovercard" data-mentionid="31" href="/profile/31-cali-carlos/" rel="">@Cali Carlos and <a contenteditable="false" data-ipshover="" data-ipshover-target="/profile/3-the-blind-wolf/?do=hovercard" data-mentionid="3" href="/profile/3-the-blind-wolf/" rel="">@The Blind Wolf pointed out, this depends heavily on the ratings for your LiFePo4 (LFP) batteries AND the system voltage.  If they're commercially overpriced "ready-made units", they may trip if overloaded.  If you made the bank yourself...figure not more than 1C discharge rating UNLESS you have an official cell datasheet that indicates more.

It's just the tiny Li-Po cells that can do 10-30C discharge ratings.  The bigger Li-Ion / LiFePo4 prismatic cells can't.

Talking discharge, I sized the bank for capacity primarily, but voltage well under 1C.

6000W / 48V = 125A at 48VDC. 16S3P = I guess I could expect to cut the current per cell to around 1/3rd (3 in parallel): 125A / 3 = 41A per cell at peak draw. Unless there's a major drift in voltage I can very reasonably expect 1/4C or lower draws. Could run the 12kW unit on this bank, too.

11 hours ago, Sid Genetry Solar said:

It's just the tiny Li-Po cells that can do 10-30C discharge ratings.  The bigger Li-Ion / LiFePo4 prismatic cells can't.

This is what makes the Tesla packs both awesome and scary. 74 of those tiny monsters in parallel, the pack can discharge 250A with no cooling and well over 1000A IIRC water cooled. I wonder sometimes what pedal-to-the-floor acceleration draws on those banks, it must be nutty.

Actually, you be surprise, it don't draw that much as you would think, cause the Tesla pack is running at such a high voltage level, 400Vdc.  Its not pulling that much amperage.  The battery pack only really needs the cooling or heating for two things.  

If you going to drag race it on the model s and x, it will heat up the batts, because heated up batteries have a higher discharge rate then a cold battery.

The cooling is only done during charging and or extremes Temps outside.  Most of the cooling system is for is to cool the DC to AC, Dc to DC inverters, and the transaxel and rotor during high speeds, such as over 75 MPH down the highway.

Other then that, the batts are just normal Temp.

Ran some quick numbers on a Tesla Model X.

The P90 has 2 drive motors, totaling 568kw.  Battery voltage is 375v.  So 568,000W / 375v = 1,514A. 

That's a lot of juice.

Yes, but, remeber, your talking about dc to AC conversion. the motors in tesla are AC not DC. 😛

Correction 3 phase AC to be exact.

I know for fact the VDC fuse ise a 40A fuse to the inverter that converts the DC to 3 phase AC.  The Heat pump DC to DC inverter uses a 30A fuse.  But, both motors uses a 40A fuse.  From what I've seen.

Sorry for the posting and posting, this fourm won't let me edit postings.  Anyhow.  The Dc to Dc inverter is able to output 170a at 12v.  and there is no way in frozen north pole you going to push 1k amps through a 11 awg wire. . .  You would litterly make a lighting wire lol.  I forgot what size the wire is but, I know its not that big.

Fun fact, there is 74 feet of High Voltage wire in a model S prir to 2018.

Cause think about it, they basically use 18650 batts and the biggest cell I've seen is 3.800 and each modual is what 24v. . or a bit higher if I remeber, so and they are 11kw.  from top of my head, but that means there is 880cells at 3.8 each module being 24+Vdc 7s 125p = 475A output. . .  Not bad.  But, really your asking for trouble if your not properly cooling a output like that for home use.  Thats why the voltage is so high, so that way they don't pull such high amprage.

I might not have all the facts correct, cause its late at night, but this just on top of my head, which is running on less then 1Vdc right now  *smirks*

Yep. Just because a certain standard says you are doesn't mean that you really are. I just gave up my CDL because I felt I would be unsafe due to restricted vision. But I passed the eye exam at the DMV&HS. I can see the LCD screens without glasses on the MSB controllers and figure the same on the GS inverters with the bad eye, but it requires swiveling the head to read the screen on the 21" monitor. So I use the right eye most of the time which has  a wide view but has to be corrected to see clearly. And connecting thru the app on the phone saves going down the stars and walking about 100' to get to the controller. Plus it is larger.

Now they are starting to get into the realm of locomotives I have operated. 746kW on two of them and 1.2mW on another. That's a lot of batteries.

So the CONTINUOUS rating is much lower--but the system has to be able to handle over 1,000A for that 5 second 0-60 speed.  I've ridden in a Tesla Model X...and boy was that an experience (YouTube videos don't do it justice). 

There is simply no way that a Tesla has only 40A a fuse on the motors.  Literally: 40A * 400v = 16kw / 745 = 21HP of "go juice."  My Accord has right around 130hp, and it can't accelerate CLOSE to that fast.  Going down the same hill that that Tesla Model X flew up.

Here's a link to the specs of the Front drive motor on a Tesla Model S or Model X: https://stealthev.com/product/tesla-front-drive-unit/

Max current? 650A.  This is ONE of the 2 motors in a Tesla Model X.

Continuous load?  47hp...much less than the peak 300hp rating...but that is roughly 87A @ 400v continuous...for the ONE motor.

My point?  Can't be a 40A fuse on the motor drivers.

Okay, my mistake.  I just wnet back to research the high voltage and actaully  it has a 2000 amp pyrotechnic fuse  wire that goes from the rabbit distributor to a fused box in the front, that has two 40A and two 30A fuse, however, I fail to hear that that fused wire the 2000 amp pyrotechnic fuse  goes straight through to the DC to AC inverter where the motor is. and the fuse is basicly rated to cut off at 1500A.

So my mistake, like I said, I was running at 1Vdc and now I went back to fix my fried brain cell that must have over voltage :P.

I just got the 40a and 30a mix up thinking the 40a was the fus for the motor and it isn't.

So, Sid, your Right.  *Gives you $10 Bucks. . .*

Not sure if I can do it, or is it worth doing it.

I've been considering on switching to 36v for both my Gs inverts.  Would would the amprage be for 12k at 36v?

If I go that rought, the only issue is I only got 15 100watt panels up at the moment, I got another 30 panels sitting in my house to go up.

Also if I switch my batts to 36v, thats only going to give me 2 strings of 100+AH and 1 string  200+ah of batts to work with. also that will take out my wind power system as it only goes up to 24v.

which will give me around 14kw in storage if I go that rout.

If I stick with the 24v.  That gives me 5 strings of 100+ah and 1 200+ah strings at 24v.nearly 17kw, if I use the 2 18650 in the system.

48v would be really pushing it.

I might can get 1 string of 100+ah and 1 200+ah.  But, from what I'm seeing the higher the voltage the more darn panels I need to keep up.

What do you all think I should do? ?  I personaly don't like the idea of going over 24v, as I know what 12v feels like getting sap and 24v is pushing it.