LiFePO4 in 5-10 years

[mvonw]

I've got 6 server rack 120ah (Trophy) batteries that have been running great for over year now. I've been wondering if these are more likely to just diminish in capacity or fail outright as the years go by. I guess nobody really can say, but is it likely that I could just add new batteries to the the array of the same voltage (48v) even if the new batteries are not 120ah.??

Of course, I'm hoping by then, these batteries will either be a lot cheaper, or will be replaced with fusion reactors.

 

[JoeHam]

Of course, I'm hoping by then, these batteries will either be a lot cheaper, or will be replaced with fusion reactors.

Yes please for a personal fusion reactor ?.

I have one LiFePO4 battery which is approaching 10 years old and shows minimal degradation despite being somewhat abused when I was more ignorant about how to take care of them so don’t worry too much.

My guess is that in 10 years we will have superior battery technology (solid state?) and we will have moved to 800V architecture.

As to your non theoretical question, you absolutely can parallel batteries of the same chemistry and different capacities. Make sure they are charged to the same voltage before connecting.

See here :

 

[JJJJ]

fusion reactors.

Flux capacitor?

 

[RCinFLA]

There is a saying that DIY'ers batteries do not die of old age, they are murdered first.

If properly used, normal wear out mode is degradation of electrolyte and loss of available free lithium due to repeated small incremental SEI protective layer regrowth during battery charging.

Graphite negative electrode expands 11% from depleted to full state of charge. This expansion/contraction cracks the SEI protective layer around graphite granules which is regrown/repaired on subsequent recharging. The regrowth process consumes some of electrolyte and some of free lithium, gradually reducing capacity of cell. Also, the continual rebuilding of SEI thickens it over time which increases the internal impedance of cell causing more terminal voltage slump under high load current.

SEI protective layer helps to restrict electrons from escaping graphite electrode. If electrons get out of graphite into electrolyte they bond with incoming lithium ions creating lithium metal which is not reversible and results is less lithium for battery capacity. Electrolyte can also be degraded when electrons escape graphite.

Electrolyte breakdown happens big time when a cell is overcharged. Electrolyte decomposes into several gases (mostly CO2 and CO) that bloats up cell and leaves behind hydrocarbon tars that clogs up the electrode pores increasing the resistance to lithium-ion flow between positive and negative electrodes. The electrodes pore clogging is the main damage.

 

[upnorthandpersonal]

I've been wondering if these are more likely to just diminish in capacity or fail outright as the years go by. I guess nobody really can say, but is it likely that I could just add new batteries to the the array of the same voltage (48v) even if the new batteries are not 120ah.??

So, I'm around 4 years in with my DIY LiFePO4 pack, going into my 5th year. They still run the house like they always have, I've not done a capacity test but it doesn't feel like they're performing less, and I can just add a battery pack if needed.
Will there be new tech coming up in the next five years that could be attractive? Possibly: I'm looking at you Sodium Ion. However, even if that becomes an option in the next five years, I still expect my LiFePO4 pack to be running just fine by then.

 

[mvonw]

So, I'm around 4 years in with my DIY LiFePO4 pack, going into my 5th year. They still run the house like they always have, I've not done a capacity test but it doesn't feel like they're performing less, and I can just add a battery pack if needed.
Will there be new tech coming up in the next five years that could be attractive? Possibly: I'm looking at you Sodium Ion. However, even if that becomes an option in the next five years, I still expect my LiFePO4 pack to be running just fine by then.

That’s comforting to hear! Sodium ion looks really good for us in cold climes. keeping my batteries warm in -20F is not too bad, but I’d rather have to not worry about heaters failing too.