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Author Topic: LiFePO 4 batteries  (Read 2619 times)

W9IQ

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Re: LiFePO 4 batteries
« Reply #30 on: September 22, 2020, 01:24:21 PM »

Dave last thing you want to do is charge any Lithium battery to 100% SOC. If you do that you cut cycle life some 50 to 75%.

I think that is too broad of a generalization. We manufacture a commercial product powered by a LiPo cell that is regularly charged to 100% SoC using a fit for purpose charge management circuit with temperature monitoring, etc. This charging level is recommended by the manufacturer and we see no lab or field life degradation as a result.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KD8SKM

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Re: LiFePO 4 batteries
« Reply #31 on: October 01, 2020, 04:18:54 PM »

I will second Glenn's comment and add some more info -

There is a big difference between Lithium Polymer and Lithium Iron Phosphate in terms of safety and stability....  The Lithium Iron Phosphate are far more safe and stable, tolerate overcharge without fire or explosion, have a much flatter voltage discharge curve, and will deliver many more cycles over a lithium Polymer variant.  Only advantage of Polymer is slightly higher energy density but not by a lot.... and maybe a bit cheaper.

All of those fires / explosions from Lithium Batteries are from the Polymer variants and NOT the Iron Phosphate ones.... this is also where the CLASS 9 shipping of lithium batteries came from... and they don't exclude out the LFP types which they should.

The problem with the Polymer is at full state of charge if they get above about 50-60 degrees C they will self destruct usually resulting in a fire....Overcharge will also usually cause this thermal event on the LiPo types... think hoverboards from a few years ago.

Iron Phosphate does not do that and can be left at 100% state of charge within their operating range of -20 to 60C without any safety concern. 

I have old LiFePO4 batteries that have been charged to full daily for nearly 8 years now from Solar Power... no issues yet. 

Cheers,

Rob
KD8SKM
DIY Solar for U
https://www.diysolarforu.com
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N3EG

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Re: LiFePO 4 batteries
« Reply #32 on: November 10, 2020, 09:03:05 PM »

I have a 200 AH CALB LiFePO4 battery that my boss gave me when he swapped out the batteries in his RV.  Small, light, perfect for solar.  It charges from 3 100 watt panels during the summer, and from a manually controlled MFJ-4230DMP power supply during the winter.  For failsafe, I have a 15 amp switching supply under the table set for 12.4 volts to prevent over discharge.  They have an interesting charge/discharge curve - charging voltage takes off over 13.4 volts, is nearly flat discharging from 13.2 volts down to 12.8, and then drops like a rock.  Full discharge is somewhere around 11 volts, but that's way too low and I never risk it.  I run everything on it - routers, webcams, TV, radios, chargers - except for the solid state KW amp, the tube radio, and the 24VDC UPS.
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