100 a/h Lithium Battery for $21?

rlw999 wrote:

LiFePo4 batteries are *safer* than other chemistries, but still require an operational BMS to make them safe. And in some cases, the BMS in the battery itself can fail and cause a fire.

LFP are not subject to thermal runaway like nicad and other chemistries. this is why a lot of people are switching to them, tesla for one. the BMS protects the battery from damage from misuse. I guerss in a rare case if a BMS shorts it could cause heat, but so could a regular lead asid battery, or a inverter, or a charger..., probably more of a chance with some of the wiring jobs I have seen in RVs.

BMS are electronic devices when they fail they usaly just stop working, there are no mechanical contacts that can weld in place and such. its like saying your cell phone electronics an catch on fire (not the battery but the phone its self) so if you have any actual documented cases of where a BMS starts a fire on a LifePo4 battery I would be very interested in reading them.

Steve

StirCrazy wrote:


LFP are not subject to thermal runaway like nicad and other chemistries.

It is only more difficult. It can, and does happen.

https://onlinelibrary.wiley.com/doi/abs/10.1002/er.5298

While it is unusual here is what may happen.

https://youtu.be/07BS6QY3wI8

All battery banks should be vented to the outside.

pianotuna wrote:

StirCrazy wrote:


LFP are not subject to thermal runaway like nicad and other chemistries.

It is only more difficult. It can, and does happen.

https://onlinelibrary.wiley.com/doi/abs/10.1002/er.5298While it is unusual here is what may happen.

https://youtu.be/07BS6QY3wI8

All battery banks should be vented to the outside.

IMO, it's important to put both of these links into context.

I believe the wiley.com link references a minor amount of thermal runaway (caused by overcharging) where damage is completely limited to the inside of the battery. The user may see the top "vent" rupture, but nothing more. I would surmise if a typical non-phosphate, lithium battery was subjected to the same overcharging, it would very likely explode and/or erupt in flames. Huge difference IMO.

I've seen this YT video before. To me this is akin to someone purposely puncturing a gas tank on a vehicle and having it explode or catch fire. It can happen, but . . .

Will Prowse at diysolarforum.com was the OP for a thread titled: "Can LiFePO4 Batteries Combust in Thermal Runaway Event?" One of his comments after someone posted a link to the above YT video: "The electrolyte is flammable. If a cell is physically damaged, you can catch it on fire. But for an exothermic reaction to occur to cause combustion, from the literature I've read, is impossible with lifepo4 . . . to have combustion caused internally, is impossible."

Lastly, I'm not aware of any external venting requirements for lifepo4. Do you have any supporting links that explain why this would be necessary? Thx.

otrfun,

Murphy's Law.

I believe it is best practice for any and all battery banks to be vented. It may be best to plan for worst case. It's not an expensive thing to do.

For that matter, AGM batteries rather rarely vent.

pianotuna wrote:
otrfun,

Murphy's Law.

I believe it is best practice for any and all battery banks to be vented. It may be best to plan for worst case. It's not an expensive thing to do.

For that matter, AGM batteries rather rarely vent.

Ok, venting all batteries is your personal preference. No problem with that.

I only posed the question because because I’ve seen a number of installs by very reputable firms where they mounted LifePo4’s in the heated, interior space of RV’s, to include sleeping areas, without any venting whatsoever. Everything I’ve read or heard about lifepo4’s say it’s safe to do so.

A properly built system with LFP being charged/ discharged within the parameters of the chemistry should be safe even inside a trailer from venting.

Now with that said if your cheap skate that's using bargin price parts of the system to try and save a quarter then maybe Mr Murphy will come and visit.

As far as the one video don't harpoon your batteries in the bedroom and it shouldn't be a problem. ;)

otrfun wrote:

pianotuna wrote:

StirCrazy wrote:


LFP are not subject to thermal runaway like nicad and other chemistries.

It is only more difficult. It can, and does happen.

https://onlinelibrary.wiley.com/doi/abs/10.1002/er.5298While it is unusual here is what may happen.

https://youtu.be/07BS6QY3wI8

All battery banks should be vented to the outside.

IMO, it's important to put both of these links into context.

I believe the wiley.com link references a minor amount of thermal runaway (caused by overcharging) where damage is completely limited to the inside of the battery. The user may see the top "vent" rupture, but nothing more. I would surmise if a typical non-phosphate, lithium battery was subjected to the same overcharging, it would very likely explode and/or erupt in flames. Huge difference IMO.

I've seen this YT video before. To me this is akin to someone purposely puncturing a gas tank on a vehicle and having it explode or catch fire. It can happen, but . . .

Will Prowse at diysolarforum.com was the OP for a thread titled: "Can LiFePO4 Batteries Combust in Thermal Runaway Event?" One of his comments after someone posted a link to the above YT video: "The electrolyte is flammable. If a cell is physically damaged, you can catch it on fire. But for an exothermic reaction to occur to cause combustion, from the literature I've read, is impossible with lifepo4 . . . to have combustion caused internally, is impossible."

Lastly, I'm not aware of any external venting requirements for lifepo4. Do you have any supporting links that explain why this would be necessary? Thx.

also if you look at that second video the bottom foot or so of the pic is wet, so he has dipped it in somthing that increases the reaction with the battery. I have seen several puncture tests where nothing happens so I am wondering if this is why he got the smoke.

Steve

Thoughts on this battery?

BurbMan wrote:
Thoughts on this battery?

The weak point in most of the these budget lifepo4 batteries is the BMS. Both from a capability and reliability perspective. BMS's probably fail much more often than the cells themselves.

The lifepo4 battery in your link (12v 100ah) is only capable of producing 50a of continuous current. They got the price down cutting-corners with the BMS and the wiring. Even two of these cells paralleled will only provide you with 100a of continuous current. That's not enough to power a microwave or other high current device with a 2000w inverter. Two 100ah lifepo4 batteries, capable of 100a of continuous current, paralleled, would be the minimum I'd use to power a 2000w inverter.

Of course, if your power needs will remain minimal, now and in the future, then this 100ah 50a battery might be worth considering. Me, I'd pass.

BurbMan,

Write them and ask the parameters of the battery management system.

Here is a link to a pdf from them.

himaxelectronics.com/wp-content/uploads/2021/04/HiMASSi-Battery-Manual.pdf