LiFePO4 vs Lead Acid a cost analysis for energy storage.

[russ]

• The products currently being sold by A123 are not up to the same standards as what they sold before their bankruptcy and sale of the company.

I have no idea of this company/case but in general buying something where a Chinese or Indian company is in charge of quality control is asking for problems - Japan & Taiwan have long past got by the attitude problem for QC but others have a long way to go.

[Sunking]

And since you are a specialist what is your suggestion when off-grid battery storage is needed in cold climate for energy storage.
Legally you need to vent the box. So how do you keep the battery above freezing with temperatures below -30C for months?
And how much energy do you require to do so?

The only possible way a FLA battery can freeze is if it is left in a state of discharge. As the State of Charge (SOC) decreases, the electrolyte specific gravity approaches 1 or to a water state. Thus the freezing point temperature rises from -92 F at 100% SOC to -16 F at 40% SOC. The battery does not need to be heated other than the heat generated during daily recharge. If freezing becomes a real concern, just switch to AGM.

At any rate I would choose a lead acid chemistry over lithium in any cold weather application. All battery chemisties loose capacity when cold. FLA does not loose as much capacity as lithium when cold. Cold weather performance is one of the disadvantages of lithium based batteries. They will not freeze like FLA possible can, but performance is poor as has been discovered by EV owners during winter months stuck on the side of the road with dead batteries.

[Ian S]

And since you are a specialist what is your suggestion when off-grid battery storage is needed in cold climate for energy storage.
Legally you need to vent the box. So how do you keep the battery above freezing with temperatures below -30C for months?
And how much energy do you require to do so?

Obviously, this is a problem for lead acid batteries due to H2. Are you saying there is no issue with keeping LiFePO4 battery systems in an enclosed space?

[russ]

Obviously, this is a problem for lead acid batteries due to H2. Are you saying there is no issue with keeping LiFePO4 battery systems in an enclosed space?

Venting is no big deal - a very small opening at the highest point and it is impossible to keep the H2 anything. The important point is not to have any place a pocket can form with no way out and up.

[pleppik]

I have no idea of this company/case but in general buying something where a Chinese or Indian company is in charge of quality control is asking for problems - Japan & Taiwan have long past got by the attitude problem for QC but others have a long way to go.

No argument there. Chinese companies can build excellent quality products (iPhones are all assembled in China), but they don't always understand the need.

Three years ago I bought a 3D printer direct from a Chinese manufacturer. It was a nifty product, but required a lot of tinkering because of a long list of minor design and manufacturing defects. The manufacturer stood behind it and sent me a lot of replacement parts via DHL from China at no charge, but it wasn't up to American standards. Two years ago that company partnered with an American OEM reseller which gave them religion on quality. Six months ago I bought a second printer from the same manufacturer, and even though it was the same model it was like a completely different product. No defects, no tinkering, it just worked.

There's a lot of really smart people working for Chinese manufacturers. You just have to get them to focus on something other than lowest possible cost.

[russ]

No argument there. Chinese companies can build excellent quality products (iPhones are all assembled in China), but they don't always understand the need.

I blame the companies more really - always trying to cut corners without understanding the requirements.

On a project in India you test and inspect everything you buy and carefully. 304SS we would test every single plate for chemistry at a minimum. We were often offered off spec stainless from China and the suppliers would mix it in with on spec material. 304 is the cheapest grade of SS we used so everything else was checked more closely.

On many occasions we would end up with large quantities of carbon steel plate for construction use - the alloy was off from our own plant so the buyer would reject it. It was generally easier to use it in house for suitable applications since we were always building new sections of the plant.

[Mike90250]

0% SOC not the same with 0V not even close in any type of battery.
Depending on type of lithium battery and manufacturer 0% SOC is somewhere between 2.5V and 3V and the battery has no problem to recover from there there is no excessive battery degradation at 0% SOC

And this is the root issue. What are you calling SOC ? Amps in vs amps out? Some voltage ? This is a huge gray area, pull the Li cells too low (below 20% is the figure I hear) and you fry them. Charge them too high (over 90%) shortens them lots too. Pb can be pulled to 0% charge, and you still get a couple hundred cycles even at that.

[russ]

SOC as discussed here (to the best of my understanding)

100% SOC = topped off fully charged

20% SOC = 20% of energy still stored in the battery

0% SOC = the battery is totally toast

Is this not correct? Terms are always a problem when a new guy shows up with a different lexicon.

[electrodacus]

The only possible way a FLA battery can freeze is if it is left in a state of discharge. As the State of Charge (SOC) decreases, the electrolyte specific gravity approaches 1 or to a water state. Thus the freezing point temperature rises from -92 F at 100% SOC to -16 F at 40% SOC. The battery does not need to be heated other than the heat generated during daily recharge. If freezing becomes a real concern, just switch to AGM.

At any rate I would choose a lead acid chemistry over lithium in any cold weather application. All battery chemisties loose capacity when cold. FLA does not loose as much capacity as lithium when cold. Cold weather performance is one of the disadvantages of lithium based batteries. They will not freeze like FLA possible can, but performance is poor as has been discovered by EV owners during winter months stuck on the side of the road with dead batteries.

Most of the time in an offgrid application battery is not 100% SOC. Here where I live temperature cab be for days as low as -30C (-22F) during the day and as low as -40C(-40F) during the night.
If you have a box with batteries even with a single small opening at the top those batteries inside over night will get to the outside temperature unless insane amount of heat is provided somehow to the box.
And yes my LiFePO4 are inside the house no venting required on any type of lithium battery so they will sit at a comfortable temperature all the time. Most of you have plenty of lithium battery inside the house.
If you look in the Trojan L16RE datasheet you will see that only 32% or so of the capacity is available that is at -20F
Also at below freezing they recommend to maintain state of charge above 60% 0C (32F) and operating temperature range only from -20C (-4F) and up.
There is 3 moths here where is almost never above -20C(-4F) so I think is impossible to keep a box with an opening for venting much above outside temperature.
I'm really curios how this problem is solved if any of you live in cold climate not necessarily as cold as here but with temperatures below freezing.

[electrodacus]

SOC as discussed here (to the best of my understanding)

100% SOC = topped off fully charged

20% SOC = 20% of energy still stored in the battery

0% SOC = the battery is totally toast

Is this not correct? Terms are always a problem when a new guy shows up with a different lexicon.

0% SOC is not toast else you will not be able to do 100% DOD to test the battery life.
Most Lithium batteries are tested at 100% DOD and they cut the discharge test around 2.5V for LiCoO2
0% is when battery is at a safe low voltage but if you continue to go under that voltage you will damage the battery.

[electrodacus]

Here is how they test battery capacity for a small 2500mAh 18650 battery is same cell size as those used in most laptops but this is for high power applications like cordless power tools so is discharged down to 2V where they stop the charging and that is 100% DOD or 0%SOC but no there will be no damage to battery.

[electrodacus]

Just searching for LiFePO4 manufacturers I found this.
Valence with headquarters in Texas.
Has anyone heard about them before ?
They have a similar if not better battery than A123
It seems they can do 5000 cycles at 100% DOD and at the end of this still have 80% of original capacity and then 70% after 7000 cycles

Here is the spec Valence

[electrodacus]

Rich, Mike and Russ you have a very clever troll who is playing you like a fiddle Charlie Daniels style. You should have banned him several weeks ago when he asked you to do so. Kill it now before it grows up. Quit feeding the TROLL

In what way I'm a TROLL?
I opened a subject on the price of LiFePO4 vs Lead Acid.
I expressed my opinion (I'm even using LiFeMnPO4 for my offgrid house) so is an honest opinion.

You may say that I have an interest in making LiFePO4 more popular because I designed a Solar BMS.
That is not true since I designed that for my own use and decided to offer that to others.
There is absolutely no profit for me from that Solar BMS in fact if I consider my time spend in development is a huge loss.
But since no one has build one and needed for my own use I assumed that loss.

I do think LiFePO4 is a superior battery technology for stationary energy storage when compared to Lead Acid same as you probably think the reverse is true.

[Mike90250]

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[inetdog]

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