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The common brick lithium battery packs are the least safe because they are very vulnerable to abuse.? That is:? over-charging, over-discharging, shorting, puncturing, and failure to balance the cells.

Curious, we wound up at the same vendor.
From? ?

"About Us? ??Docan?Technology (Shenzhen) Co., Limited is a famous OEM battery factory with providing battery solution for customers, located in Shenzhen, Guangdong Province of China."

I've not used powerwholesale.? ....? ? ?I have had good results from Docan Power and their Houston, TX warehouse.

Andy,?
No real argument, I agree with most of what you say.

'Common usage' is a useful thing to be aware of, as this is how most other people describe
what they are doing, and even how manufacturers describe what they are selling.
In the world of lithium ion batteries, LiFePO4 chemistry is different enough that it is
necessary to call that out.? In particular, voltage per cell is different.? Everything else
often gets lumped together under the more generic term of lithium ion.

Some 15 years ago I bought a few raw pouch cells because they were cheap.
Big mistake.? If building a small battery pack, go with cylindrical cells like 18650's.
The pouch cells rupture easily and need far more physical protection.
You definitely want appropriate electrical protection circuitry.? If figuring all that out
does not sound fun, then buy a successful battery pack of some sort and use
the charging device that comes with it.? Could be borrowed from a shop tool,
an auto jump start device with a well protected low current port, or one of the
excellent Bioenno LiFePO4 batteries.

If building a big battery pack and you are interested in an educational project,
I can recommend the prisimatic LiFePO4 bricks from?? ?
Shipped from China, so may be tough to get if they go into lockdown again.
These have likely been passed over by electric vehicle manufacturers for
having specs somewhat out-of-family, but are relatively cheap.
Lots of even cheaper vendors on alibaba, but be careful as many are selling
used or damaged cells.? ?Good info on?https://diysolarforum.com

Being offgrid, there's a bank of 32 EVE LF280K cells in the basement powering
this conversation, configured as 2P16S, 29 kWh total, along with a JBD 200A BMS.

Jerry, KE7ER

On Thu, Nov 24, 2022 at 03:32 AM, AndyH wrote:

Yes, cobalt levels in some LiCoO variants are decreasing. The relative safety standings remain, however.?

? 'Common usage' isn't a useful metric. Folks interested in selecting a product within a family benefit from understanding when a disk ceramic doesn't replace an electrolytic, or why NP0 matters, right? Have you heard that nobody makes their own radios these days? hihi

? Metal cased cells are 'safer' only if one is working with individual cells and not a properly constructed battery. Anodes and cathodes need to be held together during charging and discharging. It's part of that 'safe if not abused or mishandled' thing.

? Look at how Tesla makes their reduced cobalt LiCoO batteries. Even though they start with metal cased cylindrical cells, they still have to encase them in fire retardant adhesives. In a crash they can still burn furiously and the fire can be difficult to extinguish.? (Sandy Munroe also shows how pouch cells are packaged into a proper battery.)




? Battery management chips are cheap these days, and one can purchase small battery management modules that provide cell balancing, charge and discharge current control, and cell-level high- and low-voltage protection while reporting battery health via low-power Bluetooth. Fun times to DIY batteries.

? 73, Andy

Andy,?
No real argument, I agree with most of what you say.

'Common usage' is a useful thing to be aware of, as this is how most other people describe
what they are doing, and even how manufacturers describe what they are selling.
In the world of lithium ion batteries, LiFePO4 chemistry is different enough that it is
necessary to call that out.? In particular, voltage per cell is different.? Everything else
often gets lumped together under the more generic term of lithium ion.

Some 15 years ago I bought a few raw pouch cells because they were cheap.
Big mistake.? If building a small battery pack, go with cylindrical cells like 18650's.
The pouch cells rupture easily and need far more physical protection.
You definitely want appropriate electrical protection circuitry.? If figuring all that out
does not sound fun, then buy a successful battery pack of some sort and use
the charging device that comes with it.? Could be borrowed from a shop tool,
an auto jump start device with a well protected low current port, or one of the
excellent Bioenno LiFePO4 batteries.

If building a big battery pack and you are interested in an educational project,
I can recommend the prisimatic LiFePO4 bricks from?? ?
Shipped from China, so may be tough to get if they go into lockdown again.
These have likely been passed over by electric vehicle manufacturers for
having specs somewhat out-of-family, but are relatively cheap.
Lots of even cheaper vendors on alibaba, but be careful as many are selling
used or damaged cells.? ?Good info on?https://diysolarforum.com

Being offgrid, there's a bank of 32 EVE LF280K cells in the basement powering
this conversation, configured as 2P16S, 29 kWh total, along with a JBD 200A BMS.

Jerry, KE7ER

On Thu, Nov 24, 2022 at 03:32 AM, AndyH wrote:

Yes, cobalt levels in some LiCoO variants are decreasing. The relative safety standings remain, however.?

? 'Common usage' isn't a useful metric. Folks interested in selecting a product within a family benefit from understanding when a disk ceramic doesn't replace an electrolytic, or why NP0 matters, right? Have you heard that nobody makes their own radios these days? hihi

? Metal cased cells are 'safer' only if one is working with individual cells and not a properly constructed battery. Anodes and cathodes need to be held together during charging and discharging. It's part of that 'safe if not abused or mishandled' thing.

? Look at how Tesla makes their reduced cobalt LiCoO batteries. Even though they start with metal cased cylindrical cells, they still have to encase them in fire retardant adhesives. In a crash they can still burn furiously and the fire can be difficult to extinguish.? (Sandy Munroe also shows how pouch cells are packaged into a proper battery.)




? Battery management chips are cheap these days, and one can purchase small battery management modules that provide cell balancing, charge and discharge current control, and cell-level high- and low-voltage protection while reporting battery health via low-power Bluetooth. Fun times to DIY batteries.

? 73, Andy

Yes, cobalt levels in some LiCoO variants are decreasing. The relative safety standings remain, however.?

? 'Common usage' isn't a useful metric. Folks interested in selecting a product within a family benefit from understanding when a disk ceramic doesn't replace an electrolytic, or why NP0 matters, right? Have you heard that nobody makes their own radios these days? hihi

? Metal cased cells are 'safer' only if one is working with individual cells and not a properly constructed battery. Anodes and cathodes need to be held together during charging and discharging. It's part of that 'safe if not abused or mishandled' thing.

? Look at how Tesla makes their reduced cobalt LiCoO batteries. Even though they start with metal cased cylindrical cells, they still have to encase them in fire retardant adhesives. In a crash they can still burn furiously and the fire can be difficult to extinguish.? (Sandy Munroe also shows how pouch cells are packaged into a proper battery.)




? Battery management chips are cheap these days, and one can purchase small battery management modules that provide cell balancing, charge and discharge current control, and cell-level high- and low-voltage protection while reporting battery health via low-power Bluetooth. Fun times to DIY batteries.

? 73, Andy

You are correct, though some of them don't have much cobalt these days.?
A web search for "lithium ion vs lifepo4" shows that common usage is to just say lithium-ion if it isn't LiFePO4.

Metal cylinder construction such as 18650's is generally safer than pouch cells.
If you want safe, buy a well regarded product that includes over-charge, over-discharge,
and over-current protection.? That should include most consumer products these days.
Get something that has been out for a year or two, and read the reviews to see if it has had trouble.

Jerry, KE7ER



On Wed, Nov 23, 2022 at 06:11 PM, AndyH wrote:

What many think are 'lithium ion' are lithium cobalt oxide cells.

What many think are 'lithium ion' are lithium cobalt oxide cells.

The safest lithium chemistry battery is a Lithium Iron Nanophosphate battery LiFePo4. (snip) Stay away form Lithium Ion and Lithium Polymer batteries.