OK, I have a guy that can supply me, ALOT, up to 11ton ATM, of lithium pouch style batteries, already in 12v configuration, 2yr old, ex defibrillator batteries, we are as yet unsure of capacity as testing to begin shortly, however, he tells me that "u will never run an a/c on an inverter", is this accurate?, peter, ur probably already tested urs, I gotta be honest here, I'm kinda leaning towards this type of setup for my powerwall, I just need to get the configuration right so it will have the best performance
Li-po possibilities?
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neilmc
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Terry said:
Holy crap! With 11 ton of LIPOs you could run as many air-conditioners as you like!
It's really just a matter of looking at the capacity and constant discharge rating of the cells, and building a battery big enough for the load you'll have. (A few years ago people would have been saying there's no way you'd ever run an a/c on laptop cells.... it's not a problem if you have enough of them).
I certainly wouldn't rule them out for powerwall use if you have access to a large quantity. Pouch cells have a reputation for being more volatile, but they're not exactly ticking time bombs if handled well. Hell, I've flown pouch packs into trees and steel polesat over 120km/h many many timesand never had one go off. There are times where my bottom mounted batteries took the full impact of a high speed crash.
They don't have the same safety mechanisms as 18650 cells though, so I'd certainly put them in a battery shed or similar separate to your house.
As part of processing and testing them, I'd discard any cells that show signs of swelling/puffing.
Check out Paul Kennett's recent videos on bulding packs from pouch cells
neilmc
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Terry said:
It's probably just a matter of not having done the maths.
There might be 3-4 cells at 3ah in each 12 v battery (wild guess... like you said you'll do the capacity tests). Per cell, pouch LIPOs will often have a higher sustained discharge rating than other lithium cells. It'd be great if you can find data sheets for them. If not, go on the conservative side.
Say if you take 200 x 3amp cells and if they have a sustained discharge of 5amps each. Build those into a 3.7v pack and you have a 600AH capacity 3.7v battery that can sustain 1000A of current draw if needed. Connect 14 of those together and you have a 48V 600AH battery which will have no problems running a lot of different heavy loads, including aircon if the inverter is big enough.
A battery like that out of lipo will probably handle big loads better than a bank of big lead acid deep cycle batteries.
You'd need to plan out for the actual loads you have, but it's just a matter of paralleling enough cells to comfortably support the load.
If you can't get adata sheet for the cells, then you can be conservative on the current draw. Just parallel more cells so that each cell is under less load (and that also pushes your capacity & run time per charge up)
neilmc
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Terry said:
The nice thing about these is that there's a really good chance that they haven't been under any stress and have probably not lost much capacity.
I work in medical management. We have battery replacements scheduled for every 2 years for our defibrillators. They're not likely to be bad, but because they're in critical emergency equipment, that's the replacement schedule.
I'm keen to know how the testing goes. My guess is that you'll have plenty of cells in excellent condition.
Korishan
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Adding my 2cents worth here:
The only real reason why you couldn't run an A/C on an inverter (besides supplying enough power, which you have plenty of cells for that) is that if you don't use a Pure Sinewave inverter, you'll get a lot of hum from the a/c motors. And that's any of the motors; fans, fridge, microwave, etc. Anything that uses induction will need a Pure Sinwave to function properly. If you don't, besides having the annoying hum, you'll burn up the motor long before it's time.
And..
Holy Cow Poop! That's a lot of cells!!
Great find!
The only real reason why you couldn't run an A/C on an inverter (besides supplying enough power, which you have plenty of cells for that) is that if you don't use a Pure Sinewave inverter, you'll get a lot of hum from the a/c motors. And that's any of the motors; fans, fridge, microwave, etc. Anything that uses induction will need a Pure Sinwave to function properly. If you don't, besides having the annoying hum, you'll burn up the motor long before it's time.
And..
Holy Cow Poop! That's a lot of cells!!
Great find!1958 greyhound
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The motorhome people run ac's off inverters
.
Most have 20k watt, 24 volts 800ah capacity and 6k+ watts of solar.
The solar fits on the rv, trailer, and some deployable ground units.
And on the Pure Sinewave inverter, if you need 8k watts to run you need a inverter with almost double to be able to start the ac.
.
Most have 20k watt, 24 volts 800ah capacity and 6k+ watts of solar.
The solar fits on the rv, trailer, and some deployable ground units.
And on the Pure Sinewave inverter, if you need 8k watts to run you need a inverter with almost double to be able to start the ac.
Korishan said:
1958 greyhound said:
So, to run supply to my entire household, I would basically need pure sinwave converter capable of handling approx 50kw, to be on safe side, allowing for the remote chance that all motors would start at the same time, the main ac is a 9.8 kW split system, and 3 smaller window rattlers, would I be better of u think investing in 2-3 smaller ones and parralling them into the house?
Korishan
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Terry said:
Well, yes and no. As AZ_Tech said, 9.8kW for a central unit does seem like a lot. Unless you have something much larger than a 5 Tonn unit.
There are a few ways you can do this:
* Install smart circuitry that would keep the compressors from starting if another load has started within x-seconds (there's a few others working on this type of thing already)
* Have 2 smaller inverters, 1 on each hot leg and split your loads up (which, splitting the loads for balancingshould really be done anyways, regardless)
* For each window unit, you could install a dedicated inverter
-eitherrun DC wiring to the unit and install the inverter at the unit
-take the unit out of the main breaker box and put it in anotherone (1 breaker / load)
* Run 2 more inverters in parallel to give you better surge
Note: the inverters must be smart enough to sync with each other. This can be tricky, or impossible,if using standard inverters. If you choose this method, I would recommend commissioning old Smart-UPS's for this as they would sync up to mains (or each other) with very little setup. Altho, it's easier to set them up in series than parallel and get 240V output (120V - 0V - 120V) setup.
If you are new to all this, and electrically questionable/hesitant, I would recommend going the route of larger inverter, or larger Smart-UPS for the required loads. Paralleling or Serializing inverters/ups's is not a task someone unfamiliar with electrical properties, principles, or reservations. If not done right, worse thing would be you end up in the hospital.
Be safe
OK, so here are just a few photos of what I have so far, first one should be the power details from the side of my main a/c unit
,
next I have a few photos of said lipo packs, still need to find a way to charge and test properly.
only thing on any of the individual cells to indicate details, and only on 1 of them
Now the wires as u see them are as follows, large blue plug, power out, small wires in small white plug, charge wires, the guy who has them, got a little curious so he tested them out a little, first off tried to charge via the large blue plug, result, instant balloon, lol, so he modified another set if cords to charge through the small wires, second pack started at 9.3v and he charged it to 12.1v, still have no way to test the capacity of the packs yet. So he plugged it into an led overhead work light, and ran it for 14 hrs straight, and it didn't even look like being flat, however he didn't test the voltage after the 14 hrs to see how much it had drained it.
Oh, another question too, when doing ur initial multi meter tests on 18650's, what voltage is the minimum u guys usually have as a bottom end figure of cells that will be fine to charge and test further. Reason I ask, is I picked up a bag full of laptop batteries on Fri and busted em.open. and 1 of the cells was at like 0.9v. And a cpl @ 1.2-1.6v. I think I got a cpl of 17600's as well, as they're same length, just not as, fat, and no type numbers on em so I'm guessing.
,
next I have a few photos of said lipo packs, still need to find a way to charge and test properly.
only thing on any of the individual cells to indicate details, and only on 1 of them
Now the wires as u see them are as follows, large blue plug, power out, small wires in small white plug, charge wires, the guy who has them, got a little curious so he tested them out a little, first off tried to charge via the large blue plug, result, instant balloon, lol, so he modified another set if cords to charge through the small wires, second pack started at 9.3v and he charged it to 12.1v, still have no way to test the capacity of the packs yet. So he plugged it into an led overhead work light, and ran it for 14 hrs straight, and it didn't even look like being flat, however he didn't test the voltage after the 14 hrs to see how much it had drained it.
Oh, another question too, when doing ur initial multi meter tests on 18650's, what voltage is the minimum u guys usually have as a bottom end figure of cells that will be fine to charge and test further. Reason I ask, is I picked up a bag full of laptop batteries on Fri and busted em.open. and 1 of the cells was at like 0.9v. And a cpl @ 1.2-1.6v. I think I got a cpl of 17600's as well, as they're same length, just not as, fat, and no type numbers on em so I'm guessing.
BlueSwordM
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Usually, the lowest for a cell I'd say for me is 2.25V. Lower than that and I toss it in a 250mA charger, and if it gets warm, it means it's a bad cell. And I'll test the voltage if it's rising slowly or quickly, to estimate if it's a low capacity of a high capacity cell.
Below 1.8V, I just charge them at 125mA, and I check the temps and the voltage every 5 mins, checking if it's hot. At that point, I just assume it's below 1000mAh. Once though, I got some luck on 4 batteries which charged and discharged at 250mA each, and they had their original capacity if discharged/charged under this threshold. Over 275mA though, and voltage droop happened.
Below, 1.5V, I just toss it in the trash.
Below 1.8V, I just charge them at 125mA, and I check the temps and the voltage every 5 mins, checking if it's hot. At that point, I just assume it's below 1000mAh. Once though, I got some luck on 4 batteries which charged and discharged at 250mA each, and they had their original capacity if discharged/charged under this threshold. Over 275mA though, and voltage droop happened.
Below, 1.5V, I just toss it in the trash.
neilmc said:
That's what I'm hoping, as most of the 1.3-1.8 's came from dell batteries, and they were really old. Some of the packs looked like the were bout the 15 yr old mark..... 99% of cells harvested from that collection. Tested with at least some life, guess I just gotta wait another 2-3 weeks till my charger turns up to find out
PaulKennett
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Terry said:
The pouch cells are prosibly LiFePo4 cells which have a nominal voltage of 3.2 volts (fully charged at 3.6V). If it a pack of 4 cells then you *could* charge up to 14.4 V (but you'd probably want to cell to only 80% to prolong battery life).
In the last two pics of yours it looks like there's a puffy cell - that's a bad sign.
Re: 18650 initial voltage minimum: 0V is often fully recoverable. See this great video:
Cheers, Paul