A DIY Power Wall ???

[SunEagle]

RE: The "fire" in message #12 ( two posts above )

What is the "fire code" for the Power Wall?
Must it be installed on a non-flammable wall - like brick?
What if it is mounted outside on a vinyl sided house with a wood substrate = major fire hazard?
The Insurance companies will have a problem with this increase risk.
They hate anything that increases their risk of lost profits, and rightly so.

Are these PowerWalls ever installed inside the home - in the living quarters? in the basement?
It look like a significant amount of toxic smoke & fumes were released.

If each cell is individually fused, then how did the first cell catch fire, as seen in message #12 ?
If the individual fuse did not blow then one or more the cell(s) overheated while operating at "normal" amps.
So then the Temperature Sensor, if there is one, failed too?
At some high temperature, the circuit should have opened and stopped all charging amps or discharging amps, long before the ignition point?
Is it possible for a cell to continue in thermal run-away, even after the circuit is opened?

You can't (cheaply) monitor the temperature of each and every cell, so this seems to be very risky in hot weather.

Does it make more sense, from a safety point of view (increased cost), for each cell to fully protect itself from volts, amps & heat ?
Then the manufacturer can add another layer of safety to the battery pack as whole.

If this passed inspection then it must be UL Approved".
I wonder how UL tested these battery packs?

All good questions.

I would contact your local fire department or code compliance officials to determine where you can mount an energy storage system.

I would not assume that any installation pictured in post #12 was either UL approved or passed inspection. There are just too many DIY people out there that think they know what they are doing only to have something fail violently. I suggest you try not to be one of them.

[PNjunction]

The major problem is that most kids only know small cylindrical cells, and think that just scaling them up into the hundreds will be the diy solution, without understaning the major undertaking that is.

NONE of these diy powerwalls would be built if the builders had to PAY for all those cells!

Large prismatics, such as GBS, CALB, Winston, etc are much more applicable for our low-current solar storage application. Ironically, even these prismatics were the only thing going for "EV"s back in the day, and is the reason you can still get them from those vendors for DIY electric cars / trucks / utility vehicles.

Unfortunately, even early EV'ers were prone to sabotaging their project right from the start by purchasing used / gray market prismatics, and spent time in forums where only 1000 messages down the line did we learn that they shot themselves in the foot with a junk purchase right from the start.

Ok, so instead of a power-wall that is mounted in the space where your garden hose used to be, how about a "power bench" made of prismatics, which is yes, slightly larger, but much safer and easier to install and maintain?

[derekisastro]

The question is - why would you do that? There are plenty of batteries out there that are a lot cheaper than the above would cost.

I know I am a little late to the party on this one but can you link some options? Or do you mean non-lithium based options that are cheaper? And even of the lithium options, are there cheaper new options or are you talking cheaper other used options?

Thanks!

[jflorey2]

I know I am a little late to the party on this one but can you link some options? Or do you mean non-lithium based options that are cheaper? And even of the lithium options, are there cheaper new options or are you talking cheaper other used options?

Powerwall is about the cheapest out there, and it's still expensive.

If money is your concern, Costco T105's give you 1.3kwhr per battery for $100 each. And when you destroy them, 1) they will usually not catch on fire, 2) they will be easy to dispose of (lead recycling is a mature industry) and 3) they will be a very cheap way to learn.

[derekisastro]

Powerwall is about the cheapest out there, and it's still expensive.

If money is your concern, Costco T105's give you 1.3kwhr per battery for $100 each. And when you destroy them, 1) they will usually not catch on fire, 2) they will be easy to dispose of (lead recycling is a mature industry) and 3) they will be a very cheap way to learn.

That's a decent price! Are they flooded or AGM style? It seems that the 6V, 210Ah ones are flooded? Also, what's the cycle life on them? Maybe 3-500 cycles (best case scenario)?

The cycle life still potentially has implications for "cost"? I could see that with lithium, even used, the cycle life is some factor better than LA? Even a factor of just 2 or 3 times greater life cycle implies a 1/2 or 1/3 cost right? Though I guess this assumes that you can get 1000+ life cycles on lithium (possible if treated well?). Interesting things to calculate.

[derekisastro]

Especially if you consider LiFePO4's ... the lifecycle there is huge?

[SunEagle]

Especially if you consider LiFePO4's ... the lifecycle there is huge?

I believe the Trojan T105 have a cycle life of about 2000 to 50% DOD and I saw something about 1200 cycles for the Costco equivalent which isn't bad for low cost FLA type

[jflorey2]

That's a decent price! Are they flooded or AGM style? It seems that the 6V, 210Ah ones are flooded? Also, what's the cycle life on them? Maybe 3-500 cycles (best case scenario)?

Flooded. As SE mentions, you can get ~1000 cycles out of them if you baby them. On an installation down here I was getting ~600 cycles without too much babying. But keep in mind you will probably destroy them quickly as you learn.

The cycle life still potentially has implications for "cost"? I could see that with lithium, even used, the cycle life is some factor better than LA? Even a factor of just 2 or 3 times greater life cycle implies a 1/2 or 1/3 cost right? Though I guess this assumes that you can get 1000+ life cycles on lithium (possible if treated well?). . . . Especially if you consider LiFePO4's ... the lifecycle there is huge?

Again, getting 2000 potential cycles out of a battery doesn't mean much if you kill them after 100 cycles (due to overdischarge, bad BMS settings, charging while cold, uncorrected imbalance etc)

[Sunking]

Especially if you consider LiFePO4's ... the lifecycle there is huge?

Who told you that?

A good FLA battery can easily do over 1000 cycles, and cost 1/4 that of LFP.

[Paul Land]

It's a great project. To have success you need to test and mate batts by using 1-100 Imax RC chargers.It takes charge/discharge cycling to restore batts memory it can take weeks to cycle for optimum memory. Once batts have balanced SOC there good to go. Any batts out of spec at this time are bad. ev charger.jpg

[Paul Land]

Using iMax B6, each cycle takes at least 10 hours to complete. Multiply that by 20 sticks and you can quickly see that reconditioning the entire pack will take 25 days of round-the-clock reconditioning.

[derekisastro]

Who told you that?

A good FLA battery can easily do over 1000 cycles, and cost 1/4 that of LFP.

Isn't that common knowledge? All other things being equal ... cycle life, from lowest to highest is ... FLA < AGM < Li-Ion < LiFePo ...

I mean ... you might be right in saying that FLA can have 1000 at 1/4 the cost ... but then doesn't a GOOD LFP have 3000-5000 cycles? Essentially, 4 times the cost for 4 times the life?

I'm definitely still learning, so am keen to see some good solid data on all of the battery options ... it's sometimes hard to separate the chaff from the wheat when it comes to data on batteries it seems?

[SunEagle]

Isn't that common knowledge? All other things being equal ... cycle life, from lowest to highest is ... FLA < AGM < Li-Ion < LiFePo ...

I mean ... you might be right in saying that FLA can have 1000 at 1/4 the cost ... but then doesn't a GOOD LFP have 3000-5000 cycles? Essentially, 4 times the cost for 4 times the life?

I'm definitely still learning, so am keen to see some good solid data on all of the battery options ... it's sometimes hard to separate the chaff from the wheat when it comes to data on batteries it seems?

The problem is all batteries can be abused which will shorten their life.

Would rather pay more for batteries that may die sooner then expected or less for batteries that have a good track record and will last as long as you designed for?

[derekisastro]

The problem is all batteries can be abused which will shorten their life.

Would rather pay more for batteries that may die sooner then expected or less for batteries that have a good track record and will last as long as you designed for?

Ignoring the obvious logical fallacy, I do understand your point ... though the logical fallacy is hard to ignore.

Again, actual hard data is useful to see.

[SunEagle]

Ignoring the obvious logical fallacy, I do understand your point ... though the logical fallacy is hard to ignore.

Again, actual hard data is useful to see.

If you compare the stated data from a battery manufacturers you can find that a slightly more expensive battery will yield a higher cycle rate then the cheaper battery. While that is not really hard data it is a starting point. On the other side, just because a manufacturer makes a statement on it's product that data is not always 100% true.

If you are looking for hard data your best bet is to perform the tests yourself. At least you know the data collected is true and not embellished by someone trying to sell you something.