Wurly,
I believe Jerrysimon gets his cells from an Ebay contact that can do custom packs. They are well priced for the work and genuine cells. The A123 cells are Lifepo4 cells which tend to allow more abuse without BMS and survive unlike other chemistries using Lithium.
I personally use Lipo and don't monitor the cells other than a watt meter as a fuel gauge. But balance each charg to allow them to remain ok. It also gives me a chace to see how the cells are performing each day. I believe Jerrysimon balance charges every 10 ish charges to make sure they don't go to far out of kilter.
He also had a couple cells fail and repaired them individually within the pack. (Good work by the way) and again if it was a lipo cell it could have gone horribly wrong. But with A123 it was far more robust to charging from dead without any adverse effects.
This seems to be the Merits of Lifepo4, Good dischage, life cycles, robust format, less voltage sag, better operating tempertures.
Its con's appear to be mostly weight, size and lower voltage (3.3v nominal).
I can't say whether they need more blancing or less balancing than lipo. All cells in a pack in series should be balanced properly as they will all perform slightly differently based on resistance. But the degree of this may well be less in Lifepo4... or maybe becasue of the less voltage sag people don't notice it so much...
I believe Jerrysimon gets his cells from an Ebay contact that can do custom packs. They are well priced for the work and genuine cells. The A123 cells are Lifepo4 cells which tend to allow more abuse without BMS and survive unlike other chemistries using Lithium.
I personally use Lipo and don't monitor the cells other than a watt meter as a fuel gauge. But balance each charg to allow them to remain ok. It also gives me a chace to see how the cells are performing each day. I believe Jerrysimon balance charges every 10 ish charges to make sure they don't go to far out of kilter.
He also had a couple cells fail and repaired them individually within the pack. (Good work by the way) and again if it was a lipo cell it could have gone horribly wrong. But with A123 it was far more robust to charging from dead without any adverse effects.
This seems to be the Merits of Lifepo4, Good dischage, life cycles, robust format, less voltage sag, better operating tempertures.
Its con's appear to be mostly weight, size and lower voltage (3.3v nominal).
I can't say whether they need more blancing or less balancing than lipo. All cells in a pack in series should be balanced properly as they will all perform slightly differently based on resistance. But the degree of this may well be less in Lifepo4... or maybe becasue of the less voltage sag people don't notice it so much...
