I think a wiki is of no use as a plattform for a FAQ. The wiki-compatible subjects are already covered in the Wikipedia (for example the units if someone wants a deeper explanation of what they are exactly) and everything else needs an explanation that is hard to put into a single search term which you would need for a wiki. For example, imagine you are looking for the meaning of 14s80p. Unless there is an article on the wiki called 14s80p you will probably never find it. You have to make a FAQ page on the wiki and a HowTo to explain how people should use the wiki. I think this is much more effort than should be necessary, on our behalf as well as the person looking for information. Let's not forget, we are talking about basic stuff here.
FAQ
- Thread starter Oz18650
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Korishan
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I think the first post should list all the questions. Then the following posts would answer those questions/explanations and then link the post # back on the first post. That way we it can be easily navigated. At the and of each answer post have a link back to h main post so that it is circular. Also have liks to related questions at the bottom as well.
This would also allow for easy additions and edits. And more than one person can answer and those relevant answers be linked as well.
This would also allow for easy additions and edits. And more than one person can answer and those relevant answers be linked as well.
I just don't have the time to do this, but here is more stuff that has been deemed valuable for the FAQ:
"I want a 1kWh, what do I do?"
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This is just a matter of simple maths, a calculator isn't needed. And not helpful because you can reach the desired goal using many different approaches.
First of all, you can't have a 1kW battery pack. You can have a 1kWh battery pack, this is an important difference. 1kW is a power of 1000 watts, 1kWh is a power of 1000 watts over an hour, which is the energy stored in the battery.
A 1kWh battery can have all kind of different physical sizes/shapes and electrical configurations, there is no standard or THE single solution for this.
If you have, for example, 2000mAh 18650s then each of those stores 7.4Wh of energy and you need 136 of them (1000/7.4 ~ 136) for a 1kWh battery. 136 in parallel will give you a 1kWh battery with a nominal voltage of 3.7V.
If you want higher voltage, and you probably will, you have to put them in series as well. 7s is a typical minimum for a LiIon battery. 136 cells can't be evenly distributed over 7 packs in series, you then need 140 cells for a 7s20p setup. That will give you a battery with a nominal voltage of 25.9V (7x3.7V) and a capacity of 40Ah (20x2000mAh) which results in 1036Wh (25.9Vx40Ah).
And this is just one example, there are plenty other possibilities. It would be very hard to put this into an automatic calculator which then provides meaningful results because almost all of this depends on variables the calculator doesn't know or that have to be put in in the first place. It is easier to calculate this yourself.
For example you then have to figure out what your load is going to be and if 20p is enough to handle the current and if the runtime is what you want.
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About chemistries:
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I think magnesium isn't used Smile
Technically you are right, but this whole topic has a backpack full of naming issues, not only because people use it wrong or simplify it, but also because the manufacturers not always state the complete chemistry and because there are "in between / hybrid chemistries" which are a mix Smile Also some terms overlap with other ones.
It's also a nice topic for a little deep dive, so shall we? Might be worth copying it over to the FAQ!
I usually try to make an effort to give correct designations hence I use the term lithium cell a lot. This is always correct, but not always very precise. Depends on whether this kind of precision is important.
I use LiIon for all lithium chemistries with a fluid electrolyte and 3.6/3.7V nominal voltage, that covers basically all cylindrical cells. If I were more precise then I would differentiate between their chemistries. Most common ones are lithium cobalt / LiCo / ICR cells, usually found in laptops, powerbanks and so on. Then there is lithium manganese / LiMn / IMR which, unlike the ICR cells, are high drain cells for powertools and similar applications. They were superseded, sort of, by (and now fasten your seatbelts) lithium nickel manganese cobalt / LiNiMnCo / INR cells. This is a hybrid chemistry, not hard to figure out why. These are the main three chemistries, obviously some manufacturers also vary the amounts of the respective element in the mix. Samsungs ICR cells aren't chemically identical to the LG ones and also almost every manufacturer makes several different cells of each type.
There are more chemistries beside these three, a notable one is Teslas lithium aluminium chemistry which is like INR but swaps manganese for aluminium. It is called NCA.
Lithium iron phosphate / LiFe / LiFePo / IFR cells belong to the aforementioned ones technically, but are often handled separately because of their lower nominal voltage of 3.2V.
All of them come in cylindrical forms, LiFe also often in prismatic forms. The other LiIon chemistries come in prismatic forms as well, but not as often as LiFe (I think).
Lithium polymer cells always come in pouch form. They use similar chemistries with cobalt, manganese and so on, but their electrolyte isn't fluid. It isn't completely solid either but a semi solid gel. Basically it is a kind of plastic. They have the advantage of being lightweight and can easily be build in any shape you need.
LiIon: Refers to all of them, specifically ICR, IMR and INR, nominal voltage 3.6V-3-7V, usually cylindrical cells, sometimes prismatic
ICR: LiIon, made to provide highest capacity for applications where runtime is important but high current discharge isn't
IMR: LiIon, high drain cells for applications with high discharge currents
INR: LiIon, like IMR with some of the benefits of ICR while not losing IMR qualities completely
LiFe/LiFePo/LiFePo4/IFR: LiIon, but often mentioned separately because of lower nominal voltage of 3.2V, cylindrical and prismatic cells
LiPo: Like the other LiIons, but separated from them by their semi solid electrolyte, always in non-standard pouch cells
I hope this is comprehensible, I've put some effort into it to make it as clear as possible Smile
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I'll get back to sorting all this and thinking about Korishans ideas to add to the FAQ asap.
"I want a 1kWh, what do I do?"
-----
This is just a matter of simple maths, a calculator isn't needed. And not helpful because you can reach the desired goal using many different approaches.
First of all, you can't have a 1kW battery pack. You can have a 1kWh battery pack, this is an important difference. 1kW is a power of 1000 watts, 1kWh is a power of 1000 watts over an hour, which is the energy stored in the battery.
A 1kWh battery can have all kind of different physical sizes/shapes and electrical configurations, there is no standard or THE single solution for this.
If you have, for example, 2000mAh 18650s then each of those stores 7.4Wh of energy and you need 136 of them (1000/7.4 ~ 136) for a 1kWh battery. 136 in parallel will give you a 1kWh battery with a nominal voltage of 3.7V.
If you want higher voltage, and you probably will, you have to put them in series as well. 7s is a typical minimum for a LiIon battery. 136 cells can't be evenly distributed over 7 packs in series, you then need 140 cells for a 7s20p setup. That will give you a battery with a nominal voltage of 25.9V (7x3.7V) and a capacity of 40Ah (20x2000mAh) which results in 1036Wh (25.9Vx40Ah).
And this is just one example, there are plenty other possibilities. It would be very hard to put this into an automatic calculator which then provides meaningful results because almost all of this depends on variables the calculator doesn't know or that have to be put in in the first place. It is easier to calculate this yourself.
For example you then have to figure out what your load is going to be and if 20p is enough to handle the current and if the runtime is what you want.
-----
About chemistries:
-----
I think magnesium isn't used Smile
Technically you are right, but this whole topic has a backpack full of naming issues, not only because people use it wrong or simplify it, but also because the manufacturers not always state the complete chemistry and because there are "in between / hybrid chemistries" which are a mix Smile Also some terms overlap with other ones.
It's also a nice topic for a little deep dive, so shall we? Might be worth copying it over to the FAQ!
I usually try to make an effort to give correct designations hence I use the term lithium cell a lot. This is always correct, but not always very precise. Depends on whether this kind of precision is important.
I use LiIon for all lithium chemistries with a fluid electrolyte and 3.6/3.7V nominal voltage, that covers basically all cylindrical cells. If I were more precise then I would differentiate between their chemistries. Most common ones are lithium cobalt / LiCo / ICR cells, usually found in laptops, powerbanks and so on. Then there is lithium manganese / LiMn / IMR which, unlike the ICR cells, are high drain cells for powertools and similar applications. They were superseded, sort of, by (and now fasten your seatbelts) lithium nickel manganese cobalt / LiNiMnCo / INR cells. This is a hybrid chemistry, not hard to figure out why. These are the main three chemistries, obviously some manufacturers also vary the amounts of the respective element in the mix. Samsungs ICR cells aren't chemically identical to the LG ones and also almost every manufacturer makes several different cells of each type.
There are more chemistries beside these three, a notable one is Teslas lithium aluminium chemistry which is like INR but swaps manganese for aluminium. It is called NCA.
Lithium iron phosphate / LiFe / LiFePo / IFR cells belong to the aforementioned ones technically, but are often handled separately because of their lower nominal voltage of 3.2V.
All of them come in cylindrical forms, LiFe also often in prismatic forms. The other LiIon chemistries come in prismatic forms as well, but not as often as LiFe (I think).
Lithium polymer cells always come in pouch form. They use similar chemistries with cobalt, manganese and so on, but their electrolyte isn't fluid. It isn't completely solid either but a semi solid gel. Basically it is a kind of plastic. They have the advantage of being lightweight and can easily be build in any shape you need.
LiIon: Refers to all of them, specifically ICR, IMR and INR, nominal voltage 3.6V-3-7V, usually cylindrical cells, sometimes prismatic
ICR: LiIon, made to provide highest capacity for applications where runtime is important but high current discharge isn't
IMR: LiIon, high drain cells for applications with high discharge currents
INR: LiIon, like IMR with some of the benefits of ICR while not losing IMR qualities completely
LiFe/LiFePo/LiFePo4/IFR: LiIon, but often mentioned separately because of lower nominal voltage of 3.2V, cylindrical and prismatic cells
LiPo: Like the other LiIons, but separated from them by their semi solid electrolyte, always in non-standard pouch cells
I hope this is comprehensible, I've put some effort into it to make it as clear as possible Smile
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I'll get back to sorting all this and thinking about Korishans ideas to add to the FAQ asap.
I've updated my previous post: http://secondlifestorage.com/t-FAQ?pid=16494#pid16494
Changes:
- Added the explanation of unit prefixes to 3.
- Added 7, MPPT and PWM
- Added 8, solar panel specs
- Added 9, sizing of wires
- Added 10, building a battery of a specific energy
- Added 11, Chemistries
As usual, feel free to comment on the content. Also, I feel it is time to put this into some official thread and have a separate discussion thread for it. Where do we put this?
Changes:
- Added the explanation of unit prefixes to 3.
- Added 7, MPPT and PWM
- Added 8, solar panel specs
- Added 9, sizing of wires
- Added 10, building a battery of a specific energy
- Added 11, Chemistries
As usual, feel free to comment on the content. Also, I feel it is time to put this into some official thread and have a separate discussion thread for it. Where do we put this?
Korishan
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#3: those would be suffixes, not prefixes. 
#7&8: I would recommend switching these two around. That way you can introduce solar panel specs first, then reference it later. This comes in handy if you split the forum into each question being a separate posting and you're just linking to them.
I went through and did some minor editing. Fixed some spelling errors and a few grammatical issues (hope you don't mind). Other than that, looking pretty good
We might be about ready to put this into the live section. What ever "live" means. Umm, in a more appropriate location. Maybe post it in both DIY Powerwall Builds and Batteries, Cells, and More as a sticky. Hrmm, can you have 1 post listed in several spots and only need to edit it once? *ponders*
#7&8: I would recommend switching these two around. That way you can introduce solar panel specs first, then reference it later. This comes in handy if you split the forum into each question being a separate posting and you're just linking to them.
I went through and did some minor editing. Fixed some spelling errors and a few grammatical issues (hope you don't mind). Other than that, looking pretty good
We might be about ready to put this into the live section. What ever "live" means. Umm, in a more appropriate location. Maybe post it in both DIY Powerwall Builds and Batteries, Cells, and More as a sticky. Hrmm, can you have 1 post listed in several spots and only need to edit it once? *ponders*
A prefix is added in front of something, hence "pre"fix and a suffix is added at the end
The order of the topics is still a bit random, sort of, I haven't put too much thought into it yet. As this gets extended it might be necessary to change the order in the future anyway.
Yeah, I don't mind minor edits, no problem. I'm not a native English speaker so there will be mistakes, especially since I did that at 02:30am
I will start by putting this in DIY Powerwall Builds and then we can have a look at how to link it so the other sections!
The order of the topics is still a bit random, sort of, I haven't put too much thought into it yet. As this gets extended it might be necessary to change the order in the future anyway.
Yeah, I don't mind minor edits, no problem. I'm not a native English speaker so there will be mistakes, especially since I did that at 02:30am
I will start by putting this in DIY Powerwall Builds and then we can have a look at how to link it so the other sections!
Korishan
Administrator
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hahah, now that my brain is swimming in benedril, I see where the prefix is at. In reference to the 'm', 'k', etc before W, A, etc. Got it
yeah, 2:30am is a bit early, or late, depending. Doin a great job, though. Better than I could create, for sure. I'd still be stuck on question #1
In reference to the 'm', 'k', etc before W, A, etc. Got it yeah, 2:30am is a bit early, or late, depending. Doin a great job, though. Better than I could create, for sure. I'd still be stuck on question #1
Guys, I just don't have the time to prepare all this at the moment. If someone wants to take over, we need a FAQ thread in DIY Powerwall Builds, a post in the new thread for every FAQ entry (11 as of now) and a FAQ discussion thread here in Feedback & Suggestions. At least that is how I would do it.
Korishan, as you became a moderator lately I nominate you! Honestly, probably not the worst idea. You can lock the FAQ thread after creation so no one can post in this thread and you can pin it.
Korishan, as you became a moderator lately I nominate you!
Honestly, probably not the worst idea. You can lock the FAQ thread after creation so no one can post in this thread and you can pin it.