LFP and C-rates

[john61ct]

In normal House bank usage there should be little to no internally generated heat rise during charging or discharging.

But a small portable powerpak is perfectly capable of powering say a well loaded winch / windlass or heat-producing appliance.

Even though yes a 20C rate will reduce longevity some, with quality cells and proper care the pack will still last decades, that's the beauty of LFP.

[john61ct]

This topic split off from here

http://www.cruisersforum.com/forums/....php?p=3040989

in response to

Originally Posted by tanglewood

The negative effects of high C charging, and high temps, typically a direct result of high C charging and discharging, has figured prominently in the literature for a very long time. So nothing really earth shattering. But these are all multi-C rates.

To me the important thing is that a house battery system typically operates at the other end of the spectrum from all the literature. And all the batteries we typically use (LFP) call for "normal" charge in the .25 to .5C range, and discharge in the .5 to maybe 1C range. But those are still huge numbers. For a 500Ah battery, .5C is 250A charge rate, and will fully recharge in 2 hrs. And a .5C discharge rate will drain the battery in 2 hrs. Who's boat works like that? Not mine. Even a 20hr discharge would be quick, which is .05C if my math is right. That's tiny. And all this is reflected in temp rise of packs. I see only a couple degrees rise when charging at .3C. It's immaterial.