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

Itinerant1 wrote:
You can get 280 cells fairly cheap add a bms and no soldering needed. You have better help at diysolarforum.com and lot of reading on this subject and everything else speculated in this thread. Need warming pads for cool weather there is section there for that and a good thread going on now.

Thanks for the link, lots of great info. :C

What amazes me is that THIS is a ‘Technological Forum’ yet (as we’ve seen...) it’s truly taken a concerted Yoeman’s effort to unravel the mystic-like scientism surrounding LFP tech...But as with most applications of new technologies, an initial resistance often develops (SOP). In objective terms (mainly, below freezing charging limitations) LFP’s are not for everybody, and can require a slightly modified charging regime (in some cases even a charger upgrade), and a lithium compatible SOC meter...

Speaking for myself (anecdotally, as a former GC lead-acid user), I view this as a practical and worthy trade-off, but agree that one should not dismiss an enquiry into the benefits of SiO2...

3 tons

Yes, plenty of good info at diysolarforum.com

You can get 280 cells fairly cheap add a bms and no soldering needed. You have better help at diysolarforum.com and lot of reading on this subject and everything else speculated in this thread. Need warming pads for cool weather there is section there for that and a good thread going on now.

I have read all the posts in this thread with great interest. Up until the last few posts I was going to ask if anyone has built there own 12 v 100 amp hr LiFePO4 battery. I wasn’t even aware that it was possible until watching a YouTube a few days ago. Apparently it is possible to assemble a lithium battery pack at different levels of complexity, from spot welding the individual cells together to buying already assembled cell packs.
It would seem to me that assembling already assembled cell packs adding a bms soldering the connections placing it all into a container would not be all that difficult, saving hundreds of dollars. Has anyone done this??

Steve, if you properly top balance them before putting them in service they should stay close to voltage per cell. Many folks get obsessed with having every cell matching exactly to each other when in fractional use they will stay pretty darn close to each other. Now when charging or discharging and getting into the knees you might see a runner, solution is stay out of the knees.

Never saw a need for a BMS - Just another thing to go wrong
Balancing of the cells has not been an issue
Quality cells have been staying within 10 to 15mv from high to low with very limited intervention

KJINTF wrote:
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

so if I may ask, why did you decide not to put a BMS on your LFP cells. they can be had rather cheel and have active balancing. the one I was refering to is a very high end one that has temparature compensated charging nd all the other bells and whistles including bluetooth.

Steve

pianotuna wrote:
Hi Steve,

On the same search I found this:

https://www.google.com/url?sa=t&rct=j&q=........169.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.




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

who needs to build a BMS. you pay 140 cdn and you have a very good one. if you can wire a battery bank togeather you can build a LFP battery. all your doing is conecting four 3.2V cells togeather with bussbars and you hook the 6 or 7 wires from the BMS to thoes cells.

Steve

KJINTF wrote:
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

Well, maybe not so much for those faint of heart, and LFP’s appear to be of no appeal to the buggy and whip Luddites!!
3 tons