For BFL13 et al... FLA vs AGM vs Li vs heated Li

Itinerant1

It's a home brew hybrid Pb/Li system with several different charging parameters and charging sources. A hobby that turned into an obsession.

To date have not removed the Li cells from the RV but have once or twice manually balanced the cells with external loads.

We have several custom modified converters along with DC-DC chargers (just returned a Victron Orion-TR Smart 30amp IMO a POS due to it's lack of functionality, no way to adjust the output current) along with solar.

Always something to keep busy never dull moment

KJINTF wrote:
3 Tons
Now you know of someone that operates a home made 200amp 4 cell LiFe prismatic battery with no "installed" BMS. I built it from CALAB cells several years ago. It is my belief there are many others with similar installations most just not making comments here. Mine has been installed and fully operational for well over 5 years in the RV. I have a few Cell Log 8 battery monitors and audio visual alarms to help me keep and eye on the individual cells, nothing more. So far all has been wonderful no balance issues with charging or discharging. One of the best upgrades to date for our old RV.

OMG, and we’ve been strung along to believe (by the uninitiated -lol) that this task is well beyond the scope and adaptation of us mere mortals !!....As a drop-in user, I honestly had no idea Sir - looks like another LFP ‘mythology’ (talking point) just bit the dust!!

3 tons

pianotuna wrote:
3 tons,

I'd have to disagree about the well vetted. For example SiO2 was first developed in 1951.

I do agree and said the BMS is required. No one but a fool would use any Li "raw".

Well since (for some odd reason??) the persistent analogy keeps coming up between two battery technologies as uber dissimilar as are LFP vs SiO2, surely a competing (non-vendor sourced) white paper exist on old school SiO2’s, and if not why not??...

In my mind the comparison is a fools errand, and the difference is beyond stark, even though I have fond memories about the post WW II Eisenhower era, it’s kinda like comparing the vacuum tube, to say a MOSFET transistor...

3 tons

KJINTF wrote:
3 Tons
Now you know of someone that operates a home made 200amp 4 cell LiFe prismatic battery with no "installed" BMS. I built it from CALAB cells several years ago. It is my belief there are many others with similar installations most just not making comments here. Mine has been installed and fully operational for well over 5 years in the RV. I have a few Cell Log 8 battery monitors and audio visual alarms to help me keep and eye on the individual cells, nothing more. So far all has been wonderful no balance issues with charging or discharging. One of the best upgrades to date for our old RV.

Out of curiosity what are your charging parameters and what are you using for charging...scc, converter or pulling them occasionally and charge/ ballancing?

3 Tons
Now you know of someone that operates a home made 200amp 4 cell LiFe prismatic battery with no "installed" BMS. I built it from CALAB cells several years ago. It is my belief there are many others with similar installations most just not making comments here. Mine has been installed and fully operational for well over 5 years in the RV. I have a few Cell Log 8 battery monitors and audio visual alarms to help me keep and eye on the individual cells, nothing more. So far all has been wonderful no balance issues with charging or discharging. One of the best upgrades to date for our old RV.

3 tons,

I'd have to disagree about the well vetted. For example SiO2 was first developed in 1951.

I do agree and said the BMS is required. No one but a fool would use any Li "raw".

pianotuna wrote:
Hi Steve,

On the same search I found this:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiawbfU75HvAhVeTDABHYfqBSYQFjAMegQIFBAD&url=https%3A%2F%2Fwww.atlantis-press.com%2Farticle%2F25846169.pdf&usg=AOvVaw2oM6Shas53tE_nwfu5c5NT

"Through experimental analysis of batteries, we draw the conclusion that LiFePO4 battery has a long cycle life, good safety attributes, a high theoretical capacity, low environmental impact and other characteristics; however, it also has many shortcomings, such as need to prevent over-charge, over-discharge, and over-temperature. Otherwise, utilizable capacity of the battery will decrease rapidly, and cycle life will reduce quickly."

Translation: LiFePo4 are unforgiving of any abuse and may bite you in the behind.

However, in the spirit of ‘no cherry picking’ context, Question, why is it that ‘context’ seems the first casualty of far too many LiFePo4 discussions- lol ??), continuing on within this very same paragraph (3.4), it also points to how damage mitigation is provided via the BMS System, thus, the article should be taken in it’s objective entirety...

FWIW, I know of nobody who operates a LiFePo4 battery without a BMS (but that’s just me...), but per the standard pattern of discourse (more often hyperbole), then this will naturally segue into a subjective amateur analysis of whether or not the BMS is ‘properly designed’ - say it ain’t so!!

Therefore, I would conclude that LFP batteries may be in fact the most ‘well vetted’ battery in the entire battery world!!

3 tons

One needs a magnificent battery management system. It is not in my skill set to design such a beast.

Hi Steve,

On the same search I found this:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiawbfU75HvAhVeTDABHYfqBSYQFjAMegQIFBAD&url=https%3A%2F%2Fwww.atlantis-press.com%2Farticle%2F25846169.pdf&usg=AOvVaw2oM6Shas53tE_nwfu5c5NT

"Through experimental analysis of batteries, we draw the conclusion that LiFePO4 battery has a long cycle life, good safety attributes, a high theoretical capacity, low environmental impact and other characteristics; however, it also has many shortcomings, such as need to prevent over-charge, over-discharge, and over-temperature. Otherwise, utilizable capacity of the battery will decrease rapidly, and cycle life will reduce quickly."

Translation: LiFePo4 are unforgiving of any abuse and may bite you in the behind.

Steve,

The high temperature information came from a seller, not a maker. It seems quite counter intuitive to me for a seller to post such negative information.

I decided to look for a more scholarly article. I searched for 'temperature at which damages starts on LiFePo4' and this is what I found.

"The LIBs, however, are still facing barriers that limit their application space [18], [41]. One of the major limitations is the impact of temperature to the proper operation of the LIBs. Generally, the acceptable temperature region for LIBs is -20 °C ~ 60 °C [42]. Pesaran et al. [43] showed that the optimal temperature range for LIBs is 15 °C–35 °C. Once the temperature is out of these comfortable regions, LIBs will degrade fast with increased risk of facing safety problems that include fire and explosion."

For my American friends 15 C to 35 C = 59 F to 95 F, and -20 c to 60 c is -4 F to 140 F.

There is no way I want any type of large secondary battery in my living space.

https://www.sciencedirect.com/science/article/pii/S1002007118307536